| 1. |
- Arheimer, B., et al.
(author)
-
Modelling nitrogen removal in potential wetlands at the catchment scale
- 2002
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In: Ecological Engineering. - 0925-8574 .- 1872-6992. ; 19:1, s. 63-80
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Journal article (peer-reviewed)abstract
- The reduction of nitrogen fluxes from land to sea is an important task in areas with estuarine or marine eutrophication. Wetland creation has been proposed as one method to reduce nitrogen from streams draining agricultural areas. In this study, a scenario of nitrogen removal in created wetlands was evaluated by mathematical modelling of nitrogen fluxes in a catchment (224 km2) in southern Sweden. The scenario was based on topographically realistic siting of 40 potential wetlands with a total area of 0.92 km2 (0.4% of the catchment area). Nitrogen removal in the wetlands was described with a simple and robust first-order model, which was modified and evaluated against data from eight monitored surface-flow wetlands. However, the modifications gave no substantial support for changing the basic model. For catchment-scale modelling this wetland model was incorporated into a dynamic process-based catchment model (HBV-N). The catchment was then divided to several coupled subbasins, so that the wetland influence on nitrogen load could be estimated separately for each potential wetland. The modelling showed that the 40 potential wetlands would reduce the nitrogen transport to the coast with approximately 6%. Specific removal rates ranged between 57 and 466 kg ha-1 yr-1 for the different wetlands, depending on residence time (size and hydraulic loading) and nitrogen concentration in inflow. Due to temperature dependence and seasonal variation in water discharge, significant decrease in nitrogen concentrations mainly occurred during summer periods with low loading. The study illustrates that catchment modelling is a useful method for analysing wetland creation plans, and that wetland creation must cover fairly large areas and be combined with other measures in order to achieve substantial reduction of nitrogen fluxes to coastal waters. Further monitoring of existing wetlands will improve the removal expression and decrease uncertainty. For instance, at present it could not be deducted whether wetlands with low average residence times (< 2 days) have net removal or net resuspension on an annual basis. © 2002 Elsevier Science B.V. All rights reserved.
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| 2. |
- Grimvall, Anders, et al.
(author)
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Time scales of nutrient losses from land to sea - A European perspective
- 2000
-
In: Ecological Engineering. - 0925-8574 .- 1872-6992. ; 14:4, s. 363-371
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Journal article (peer-reviewed)abstract
- Empirical data regarding the time scales of nutrient losses from soil to water and land to sea were reviewed. The appearance of strongly elevated concentrations of nitrogen and phosphorus in major European rivers was found to be primarily a post-war phenomenon. However, the relatively rapid water quality response to increased point source emissions and intensified agriculture does not imply that the reaction to decreased emissions will be equally rapid. Long-term fertilisation experiments have shown that important processes in the large-scale turnover of nitrogen operate on a time scale of decades up to at least a century, and in several major Eastern European rivers there is a remarkable lack of response to the dramatic decrease in the use of commercial fertilisers that started in the late 1980s. In Western Europe, studies of decreased phosphorus emissions have shown that riverine loads of this element can be rapidly reduced from high to moderate levels, whereas a further reduction, if achieved at all, may take decades. Together, the reviewed studies showed that the inertia of the systems that control the loss of nutrients from land to sea was underestimated when the present goal of a 50% reduction of the input of nutrients to the Baltic Sea and the North Sea was adopted. (C) 2000 Elsevier Science B.V.
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| 3. |
- Hellström, Daniel, et al.
(author)
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Storage of human urine : acidification as a method to inhibit decomposition of urea
- 1999
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In: Ecological Engineering. - 0925-8574 .- 1872-6992. ; 12:3-4, s. 253-269
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Journal article (peer-reviewed)abstract
- One strategy to increase the recycling ratio of nutrients from wastewater to agriculture is to handle urine separately and use it as a fertiliser in agriculture. Potential drawbacks to urine handling systems are the risk of ammonia evaporation and the relatively large volumes to be handled. The amount of urine solution could be reduced by using drying techniques if ammonia evaporation could be avoided. The objective of this project was to study how different acids could be used to prevent the decomposition of urea into ammonia during storage. The project was performed in two phases. The initial phase was conducted with one time dosage of urine in bottles of 0.5 l each to evaluate the effect of different storage conditions and to estimate suitable amounts of acids to be added. The second phase was conducted with multi-time dosages of urine, simulating the continuous addition of urine found in full-scale systems, in plastic cans of 10 l each. The results show that a one-time dosage of 60 meq sulphuric or acetic acid per litre undiluted urine at the beginning of the storage period could inhibit the decomposition of urea during more than 100 days of storage in cans with multi-time dosages of urine.
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| 4. |
- Abed, Suhail N., et al.
(author)
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Remediation of synthetic greywater in mesocosm—Scale floating treatment wetlands
- 2017
-
In: Ecological Engineering. - : Elsevier BV. - 0925-8574. ; 102, s. 303-319
-
Journal article (peer-reviewed)abstract
- Two different chemical recipes comprising various pollutants were selected to create high (HC) and low (LC) levels of contaminated synthetic greywaters (SGW). Remediation in macrocosm–scale floating treatment wetlands (FTW) vegetated with Phragmites australis (Cav.) Trin. ex Steud. (common reed) was investigated under natural weather conditions. The presence or absence of vegetation, short or long contact time of treatment, and low or high contamination loads are the main operational variables in the experimental set-up design of the FTW. The focus on removal processes (other than sedimentation) such as the role of macrophytes in phytoremediation was achieved by agitation of the treated outflow before sampling. To assess the impact of interactions between the experimental operational variables on removal performances of FTW, different approaches of statistical analysis were applied. The results revealed that total suspended solids (TSS) and turbidity values dropped significantly (p < 0.05) in the presence of vegetation compared with those values from unvegetated wetlands. The presence of vegetation can significantly (p < 0.05) improve the biodegradation possibility of greywater by increasing the five-day biochemical oxygen demand (BOD) and decreasing the chemical oxygen demand (COD) concentrations. In vegetated FTW, higher removal rates of COD can be achieved when treating HC-SGS compared to LC-SGW. However, no significant differences (p > 0.05) in the removal of BOD was noted. Significant increases (p < 0.05) in BOD concentrations have been recorded with increasing contact time of treatment, while high removals of COD have been recorded. The presence of vegetation in wetlands affected significantly (p < 0.05) the decrease of dissolved oxygen (DO) concentrations in outflow of both types of greywater. If limited sources of organic matter are available, vegetation has significantly (p < 0.05) enhanced the nutrient balance with increasing nitrate-nitrogen (NO3-N) and decreasing ortho-phosphate-phosphorus (PO4-P) concentrations in the outflow. Furthermore, significant increases (p < 0.05) in ammonia-nitrogen (NH4-N) and DO were observed with increasing contact time, while TSS, turbidity, and NO3-N concentrations significantly decreased (p < 0.05). In addition, yellow leaves and considerably lower growth rates were observed for the hydroponic plant rhizomes of P. australis, which might be an effect of light-induced fluorescein degradation due to the relatively open water surfaces of the wetlands.
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| 5. |
- Al-Rubaei, Ahmed, et al.
(author)
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Long-term hydraulic and treatment performance of a 19-year old constructed stormwater wetland : Finally maturated or in need of maintenance?
- 2016
-
In: Ecological Engineering. - : Elsevier BV. - 0925-8574 .- 1872-6992. ; 95, s. 73-82
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Journal article (peer-reviewed)abstract
- Constructed stormwater wetlands (CSWs) are a commonly used measure for stormwater retention and quality treatment. However, although questions have been raised about the long-term performance of CSWs, only a few studies have targeted this issue and none have evaluated the performance of CSWs more than approximately 5–10 years old. Further, most studies have not examined the development of the long-term performance of CSWs but delivered a snapshot at a certain point of time. The present study investigated the performance of a 19-year-old CSW in Växjö, Sweden, treating stormwater from a 320-ha urban catchment. Besides removal of sediment from the CSW’s forebay, no other maintenance had been conducted. However, regular inspections had been performed. The results of the present sampling campaign were compared to two existing datasets collected at the same CSW after three years of operation in 1997 and nine years of operation in 2003. The CSW was found to provide efficient peak flow reduction and, depending on the event characteristics, also volume reduction. It still treated stormwater effectively: removal of Cd, Cu, Pb, Zn, TSS and TP event mean concentrations were between 89 and 96%, whereas mean concentrations of TN were reduced by 59%. The load removal efficiencies were even higher. Comparative analysis of the three monitoring periods based on the load removal efficiency revealed that the CSW, despite the lack of maintenance, performed more efficiently and stably for most pollutants compared to when newly constructed. This underlines the importance of the establishment and maturation of constructed wetland systems. Overall, the results showed that CSWs are resilient systems, which if designed well and regularly inspected to prevent major issues, can work efficiently for at least two decades.
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| 6. |
- Almström, Björn, et al.
(author)
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Experiences of nature-based solutions for mitigating ship-induced erosion in confined coastal waters
- 2022
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In: Ecological Engineering. - : Elsevier BV. - 0925-8574. ; 180
-
Journal article (peer-reviewed)abstract
- Hydrodynamic forces from ships operating in sheltered, confined fairways can result in increased wave impact and sediment transport leading to loss of land and habitats. Nature-based solutions (NBS) offer the potential to mitigate ship-induced erosion and increase biodiversity and ecosystem services. The aim of this study is to evaluate the performance of NBS in a sheltered, confined fairway located in a cold, temperate region. The case study presents the results of a 2.5-year study of the morphologic response at two sites where NBS was implemented to mitigate bluff erosion and at one site where NBS was implemented to mitigate the retreat of a reed belt. Moreover, a qualitative assessment was made of the vegetation development at the sites. The results showed that fine sediments with planted vegetation could not withstand the hydrodynamic forces induced by the ships. However, by adding sills as stabilizing structures, the forces were sufficiently attenuated for the vegetation to establish. The vegetation, which reduced the ship-generated waves and currents, was especially important during high water-level events when the energy dissipation by the sill decreased. Moreover, a small-scale nourishment was successfully applied to mitigate bluff erosion without negatively affecting sediment supply to an adjacent sandy beach. This study demonstrates that NBS can be implemented to retain erodible sediment and favour vegetation growth in fairways experiencing primary and secondary waves produced by large, ocean-going ships.
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| 7. |
- Almuktar, Suhad A.A.A.N., et al.
(author)
-
Recycling of domestic wastewater treated by vertical-flow wetlands for irrigation of two consecutive Capsicum annuum generations
- 2017
-
In: Ecological Engineering. - : Elsevier BV. - 0925-8574. ; 107, s. 82-98
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Journal article (peer-reviewed)abstract
- Due to water scarcity, there is great interest in reusing various nutrient-rich wastewaters. The aim of this article is consequently to evaluate if domestic wastewater treated by various wetland systems can be successfully recycled to irrigate generations of commercial crops such as Chilli (Capsicum annuum) grown in compost within a laboratory environment to obtain a cultivar adapted to domestic wastewater. The corresponding objectives were to assess the irrigation water for long-term growth when applying recycled wastewater, the impact of various wastewaters subject to the wetland characteristics, the impact of treated wastewater volume for irrigation, and the economic return of different experimental set-ups in terms of marketable yields. The vertical-flow wetlands treated domestic wastewater well, meeting the irrigation water quality standards for most water quality parameters, except for phosphorus (4.2 ± 0.48 mg/l), ammonia-nitrogen (4.2 ± 2.64 mg/l), potassium (7.0 ± 3.03 mg/l) and total coliforms (69647 ± 64852.6 CFU/100 ml), which showed high values significantly (p < 0.05) exceeding common thresholds set for irrigation applications of 2 mg/l, 5 mg/l, 2 mg/l, and 1000 CFU/100 ml. Chilli generations were grown successfully when applying wastewater treated by wetlands and organic soil. High Chilli generation yields concerning economic return were linked with wetlands containing small aggregates with long contact and resting times and fed with a high inflow loading rate (undiluted wastewater), releasing more nutrients into their effluent producing the best fruit quality with respect to weight, length and width resulting in a greater marketable profit of about 46% compared with the others. First generation Chilli plants were grown with considerably shorter heights and produced abundant fruit numbers, which were harvested earlier than their mothers due to the reduction (approximately 55%) of irrigation water volume used for them compared to their mothers. However, excessive nutrients applied on mother plants via irrigation water resulted in better fruit quality regarding dimensions and weights compared with their corresponding first generation plants, leading to a greater marketable profit by about 25%.
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| 8. |
- Angelstam, Per, et al.
(author)
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Tall herb sites as a guide for planning, maintenance and engineering of riparian continuous forest cover
- 2017
-
In: Ecological Engineering. - : Elsevier BV. - 0925-8574 .- 1872-6992. ; 103 Part B, s. 470-477
-
Journal article (peer-reviewed)abstract
- Continuous cover riparian forests host significant plant and animal species richness, a range of habitats, and natural processes of importance for both terrestrial and aquatic ecosystems. Riparian forest is thus a green infrastructure for biodiversity conservation. However, a long history of landscape alteration now calls for maintenance and restoration by ecological engineering. This study evaluates management guidelines advocating constant vs. variable width of riparian forest protected zones in managed landscapes. In naturally dynamic forests, stands with gap-phase dynamic along streams often provide a network of habitats with a high degree of continuity in tree canopy cover and dead wood for biodiversity conservation and delivery of ecosystem services including water purification. Based on the observation that tall herb sites indicate a potential for temporally continuous forest cover, we tested three null hypotheses. Tall herb sites ( 1) are equally common in the riparian zone and in the surrounding forest landscape; ( 2) have the same width on both sides of a stream; and ( 3) their widths are independent of the width of the adjacent stream. We described the ground vegetation in transects along and perpendicular to streams, and in the surrounding landscape, in six 3rd stream order catchment located in Sweden, Lithuania and the Komi Republic of Russia. The results showed that tall herb sites were 21-27 times more common along streams compared to in the rest of the landscape, the width of tall herb sites varied considerably along streams, and it was independent of the width of the adjacent stream. This study suggests that rather than fixed-width guidelines for riparian set-asides, to support cost-efficient maintenance of riparian forest, local site conditions should be used as guide for planning, maintenance and engineering of riparian ecotones. Because tall herb forest sites were historically cleared for agricultural purposes, the potential natural amount of riparian forest is severely underestimated. (C) 2016 Elsevier B.V. All rights reserved.
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| 9. |
- Axelsson, Petter, et al.
(author)
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Lessons learned from 25 years of operational large-scale restoration: The Sow-A-Seed project, Sabah, Borneo
- 2024
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In: Ecological Engineering. - 0925-8574 .- 1872-6992. ; 206
-
Journal article (peer-reviewed)abstract
- While restoration projects globally scale-up to meet the growing demand to restore degraded ecosystems, data on the long-term benefits of restoration are still rare. Here, we describe the lessons learned from the Sow-A-Seed project in Sabah, Borneo: a long-term and large-scale restoration project launched in 1998 with the aim to rehabilitate 18,500 ha of tropical rainforest degraded by logging and forest fires. The project was built from the ground-up, including establishment of essential infrastructure and knowledge creation via trial-and-error. Three restoration techniques were used depending on the level of degradation; 1) Assisted Natural Regeneration (weeding, climber cutting and selective girdling) to promote natural regeneration of late-successional species in the least disturbed forests, and; 2) Enrichment Planting in gap-clusters in moderately disturbed forests, and; 3) Enrichment Planting in rows (i.e, line-planting) throughout heavily degraded forests with no- or few late successional tree species in the overstory. The project includes successful propagation of 92 native tree species including dipterocarps and fruit trees, and planting of over 5 million trees during the last 25 years. Long-term monitoring shows that the mortality rate of planted seedlings is -15% per year up to 3 years, but decreases to -2% between years 3-10 and 10-20. One of the largest trees, a Shorea leprosula planted in 1998, is now 74 cm in DBH and some planted trees have reached reproductive age and are contributing to natural regeneration. A range of wildlife including orangutans, elephants, hornbills and all five wildcat species in Sabah have been documented in the area. In 2015, the area was classified as a Class 1 protected forest, the highest level of conservation status in Malaysia, and removed from commercial forestry. We highlight that there is much knowledge to be gained by research dove-tailing with operational activities, and we encourage that the lessons learned from operational restoration are shared among practitioners and restoration ecologists. We present 8 key lessons learned from the Sow-a-Seed project.
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| 10. |
- Bergsten, Urban
(author)
-
Restoration of reindeer lichen pasture after forest fire in northern Sweden: seven years of results.
- 2017
-
In: Ecological Engineering. - : Elsevier BV. - 0925-8574 .- 1872-6992. ; 108, s. 143-151
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Journal article (peer-reviewed)abstract
- Fire suppression since the 19th century has modified the functioning of boreal forest ecosystems in northern Sweden. In the long run, it induces changes in understory vegetation that result, especially on mesic sites, in feather mosses and Ericaceous dwarf shrubs outcompeting ground lichens, thus decreasing winter pastures for reindeer husbandry. In 2008, a field experiment was established in which, two years after a large forest fire, reindeer lichen (Cladonia spp.) was transplanted across various plots. The general objective was to accelerate the recovery of lichen-rich reindeer pastures, and test the ability of lichen thalli to establish on burnt surfaces following different post-fire treatments (tree harvest and standing trees retained), in different transplantation seasons (summer and winter) and at different doses (0.45 L m(-2) and 2.25 L m(-2)). The abundance and level of occupancy of viable and established lichen fragments was determined in 0.25 m(2) quadrats in 2010, 2013 and 2015. There was a continuous increase in lichen establishment over time, and seven years after transplantation, established lichen occupied, on average, 55% and 83% of the 0.25 m(2) quadrats treated with the lower and higher doses, respectively. Nine years after fire, no lichen had colonized the control, i.e. the burnt surface outside the experimental area. At the site with standing trees retained, lichen had already formed a well-established mat with a significantly higher lichen occupancy and abundance than in the open, clear-cut sites, where lichen agglomerated in proto-mats. Lichen transplanted in late-summer exhibited higher abundance and occupancy than that transplanted in late-winter. On average, the difference in lichen occupancy and abundance between different doses after seven years was of lower magnitude than between the doses of lichen transplanted initially. The experiment reveals useful results for the restoration of reindeer pastures and for specifying fire management regimes adapted to both forestry and reindeer husbandry. (C) 2017 Published by Elsevier B.V.
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| 11. |
- Blecken, Godecke-Tobias, et al.
(author)
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Impact of a submerged zone and a carbon source on heavy metal removal in stormwater biofilters
- 2009
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In: Ecological Engineering. - : Elsevier BV. - 0925-8574 .- 1872-6992. ; 35:5, s. 769-778
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Journal article (peer-reviewed)abstract
- Biofilters are an effective treatment option for the substantial heavy metal loads in urban stormwater. However, to increase their nitrogen treatment efficacy, the introduction of a submerged (anoxic) zone (SZ) and a cellulose based carbon source (C) has been recommended because it has been shown to enhance denitrification and thereby increase overall nitrogen removal. To examine the impact of this design modification on heavy metal treatment, a laboratory study using biofilter mesocosms with different levels of SZ and with or without added C was conducted. The results show that SZ and C have a significant impact on metal treatment. In particular, the removal of Cu was improved significantly. The presence of SZ and C allows outflow Cu concentrations to meet Swedish and Australian water quality guidelines, which are not met with a standard biofilter without SZ or C. Although Zn and Pb removal was enhanced slightly by the presence of a SZ, this improvement is of less practical importance, since Zn and Pb removal is already very high (>95%) in standard biofilters. The best metal treatment was achieved with 450 and 600 mm SZ. Based on these results, the incorporation of SZ with C in stormwater biofilters is recommended.
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| 12. |
- Bodin, Hristina, 1977-, et al.
(author)
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Effects of biopellets composed of microalgae and fungi on pharmaceuticals present at environmentally relevant levels in water
- 2016
-
In: Ecological Engineering. - : Elsevier. - 0925-8574 .- 1872-6992. ; 91, s. 169-172
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Journal article (peer-reviewed)abstract
- Removal of seven pharmaceuticals (acetaminophen, carbamazepine, diclofenac, metoprolol, naproxen, ranitidine and sulfamethoxazole) from water was investigated using three different microbial treatments with: (1) the microalga Chlorella vulgaris, (2) the fungus Aspergillus niger and (3) biopellets composed of both microorganisms. The three-day experiment was performed under laboratory conditions and pharmaceuticals were spiked at the environmentally relevant concentration of 10 mu g L-1. The biopellets and fungal treatments resulted in significantly lower ranitidine concentration compared with the initial value. Also, treatment with biopellets resulted in significantly lower final ranitidine concentrations compared to those found after control and microalgal treatments. Low removal rates were obtained for other substances, possibly because the amount of microbial biomass used was 16-500-fold lower than that normally used in activated sludge processes in wastewater treatments plants. Thus, the pharmaceutical removal potential, elimination potential and performance of biopellets should be further investigated at higher biomass concentrations. (C) 2016 Published by Elsevier B.V.
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| 13. |
- Bodin, Hristina, et al.
(author)
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Effects of biopellets composed of microalgae and fungi on pharmaceuticals present at environmentally relevant levels in water
- 2016
-
In: Ecological EngineeringThe Journal of Ecotechnology. - : Elsevier BV. - 0925-8574 .- 1872-6992. ; 91, s. 169-172
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Journal article (peer-reviewed)abstract
- Removal of seven pharmaceuticals (acetaminophen, carbamazepine, diclofenac, metoprolol, naproxen, ranitidine and sulfamethoxazole) from water was investigated using three different microbial treatments with: (1) the microalga Chlorella vulgaris, (2) the fungus Aspergillus niger and (3) biopellets composed of both microorganisms. The three-day experiment was performed under laboratory conditions and pharmaceuticals were spiked at the environmentally relevant concentration of 10 mu g L-1. The biopellets and fungal treatments resulted in significantly lower ranitidine concentration compared with the initial value. Also, treatment with biopellets resulted in significantly lower final ranitidine concentrations compared to those found after control and microalgal treatments. Low removal rates were obtained for other substances, possibly because the amount of microbial biomass used was 16-500-fold lower than that normally used in activated sludge processes in wastewater treatments plants. Thus, the pharmaceutical removal potential, elimination potential and performance of biopellets should be further investigated at higher biomass concentrations. (C) 2016 Published by Elsevier B.V.
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| 14. |
- Bodin, Hristina, et al.
(author)
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Tracer behaviour and analysis of hydraulics in experimental free watersurface wetlands
- 2012
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In: Ecological Engineering. - Amsterdam : Elsevier BV. - 0925-8574 .- 1872-6992. ; 49, s. 201-211
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Journal article (peer-reviewed)abstract
- Effects of inlet design and vegetation type on tracer dynamics and hydraulic performance were investigated using lithium chloride in 18 experimental free water surface wetlands. The wetlands received similar water flow but had different vegetation types: 6 emergent vegetation wetlands (EVWs), 6 submerged vegetation wetlands (SVWs) and 6 free development wetlands (FDWs). Two types of inlet designs were applied: half of each wetland vegetation type had a barrier near the inlet to help distribute incoming tracer solution, while the rest had no barrier. Residence time distribution (RTD) functions were calculated from tracer data using two techniques: method of moments and a novel Gauss modelling approach. RTD functions were used to quantify hydraulic parameters: active wetland volume (e-value), water dispersion (N-value) and hydraulic efficiency (λ-value).For wetlands without barrier, significantly lower tracer mass recoveries were found from EVWs compared to FDWs and SVWs, signifying a risk of tracer methodological problems in small densely vegetated wetlands. These problems were minimized in wetlands with an inflow construction promoting distribution of incoming tracer solution.Compared to the method of moments, Gauss modelling seemed to produce more reliable λ-values but less reliable N-values. Data for precise hydraulic quantification were lost by Gauss modelling, as indicated by overall lower variance in these data sets and lower mass recoveries. However, Gauss modelling may minimize uncertainties associated with lithium immobilization/mobilization. Parameters were significantly affected by the RTD data analysis method, showing that the choice of method could affect evaluation of wetland hydraulics.The experimental wetlands in this study exhibited relatively high e-values and low N-values. This was probably caused by the small size of the wetlands and low water flow velocities, emphasizing that hydraulic parameter values obtained in small experimental wetlands may not be applicable to hydraulics in larger wetlands.The method of moments revealed lower e-values from EVWs compared to SVWs and FDWs. It was indicated that lower e-values were mainly caused by vegetation volumes. This highlighted a need for regular maintenance to secure efficient treatment volume in wetlands with dense vegetation.
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| 15. |
- Bojcevska, Hristina, 1977-, et al.
(author)
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Impact of loads, season, and plant species on the performance of a tropical constructed wetland polishing effluent from sugar factory stabilization ponds
- 2007
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In: Ecological Engineering. - 0925-8574 .- 1872-6992. ; 29:1, s. 66-76
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Journal article (peer-reviewed)abstract
- The effects of wastewater loading rates and two macrophyte species on treatment of sugar factory stabilization pond effluent were investigated in a pilot-scale free water surface constructed wetland (FWS CW) system in western Kenya. For 12 months, four CWs were operated at a hydraulic loading rate of 75 mm day−1 and four at 225 mm day−1. Half the CWs were planted with Cyperus papyrus and half with Echinochloa pyramidalis. Water samples were taken at the inlets and outlets and analyzed for TP, TDP, NH4-N, and TSS. Mass removal rates of the selected water quality parameters were compared during three periods designated the short rain (period 1), dry (period 2), and long rain (period 3) seasons. There was a significant linear relationship between the mass removal rate of TP, NH4-N, and TSS and the mass load, and season had a significant effect on the mass removal rate of TSS, NH4-N, and TDP. Mass loading rates for TDP were about 78% of those for TP, whereas TDP comprised 78–99% of TP mass outflow rates, indicating a release of dissolved P within the CWs. The only significant difference between the two macrophyte species was associated with mass removal of NH4-N, with more efficient removal in CWs planted with C. papyrus than those with E. pyramidalis. TP mass removal rates were 50–80% higher when a mean water loss for CWs 6–8 during periods 1 and 2 was assumed to represent evapotranspiration for all CWs in period 3 instead of pan evaporation data. This illustrated the importance of accurate estimations of evapotranspiration for pollutant mass removal rates in CWs in tropical climates.
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| 16. |
- Bojcevska, Hristina, 1977-, et al.
(author)
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Impact of loads, season, and plant species on the performance of a tropical constructed wetland polishing effluent from sugar factory stabilization ponds
- 2007
-
In: Ecological Engineering. - : Elsevier BV. - 0925-8574 .- 1872-6992. ; 29:1, s. 66-76
-
Journal article (peer-reviewed)abstract
- The effects of wastewater loading rates and two macrophyte species on treatment of sugar factory stabilization pond effluent were investigated in a pilot-scale free water surface constructed wetland (FWS CW) system in western Kenya. For 12 months, four CWs were operated at a hydraulic loading rate of 75 mm day−1 and four at 225 mm day−1. Half the CWs were planted with Cyperus papyrus and half with Echinochloa pyramidalis. Water samples were taken at the inlets and outlets and analyzed for TP, TDP, NH4-N, and TSS. Mass removal rates of the selected water quality parameters were compared during three periods designated the short rain (period 1), dry (period 2), and long rain (period 3) seasons. There was a significant linear relationship between the mass removal rate of TP, NH4-N, and TSS and the mass load, and season had a significant effect on the mass removal rate of TSS, NH4-N, and TDP. Mass loading rates for TDP were about 78% of those for TP, whereas TDP comprised 78–99% of TP mass outflow rates, indicating a release of dissolved P within the CWs. The only significant difference between the two macrophyte species was associated with mass removal of NH4-N, with more efficient removal in CWs planted with C. papyrus than those with E. pyramidalis. TP mass removal rates were 50–80% higher when a mean water loss for CWs 6–8 during periods 1 and 2 was assumed to represent evapotranspiration for all CWs in period 3 instead of pan evaporation data. This illustrated the importance of accurate estimations of evapotranspiration for pollutant mass removal rates in CWs in tropical climates.
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| 17. |
- Bowes, Rachel E., et al.
(author)
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Cobble substrate in a surface bypass reduces bypass acceptance by common roach Rutilus rutilus
- 2021
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In: Ecological Engineering. - : Elsevier. - 0925-8574 .- 1872-6992. ; 172
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Journal article (peer-reviewed)abstract
- Historically, ecological engineered solutions for fish passage across anthropogenic barriers in rivers has mainly focused on facilitating upstream passage for long-migrating diadromous fish, such as salmonids. More recently, passage solutions have shifted their focus to a more holistic ecological perspective, allowing passage for species with different swimming capacity, both upstream and downstream. This experiment investigated whether the addition of cobble in the passageway of a surface bypass could facilitate downstream movement of a cyprinid fish, the common roach Rutilus rutilus. Surface bypasses were constructed in large experimental flumes and roach were released into the flumes and monitored for bypass passage using PIT-telemetry through 11-h night-trials. Behavior was scored using four continuously-recording video cameras at the bypass construction. There was a negative effect of substrate-treatment on the passage rate through the bypass. The majority of the fish in the No substrate treatment had successfully passed within 4 h, while a lesser proportion of the fish in the Substrate treatment had done so (additional fish in the latter treatment passed later in the trials). Fish exposed to cobble substrate in the bypass passageway showed more avoidance-like behaviors at the ramp section of the bypass and tended to return back upstream more often than the fish in the no-substrate control trials. When reaching the passageway, the substrate-exposed fish expressed no behaviors that could be indicative of reduced passage success, as compared to controls. We conclude that passage was not hindered by the presence of cobble substrate, but passage was delayed due to avoidance behavior at the bypass ramp when cobble substrate was present. Based on these results, the addition of cobble substrate in a surface bypass cannot be recommended as a measure to facilitate the downstream passage performance of the common roach through surface bypasses.
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| 18. |
- Buffam, Ishi, et al.
(author)
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Environmental drivers of seasonal variation in green roof runoff water quality
- 2016
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In: Ecological Engineering. - : Elsevier. - 0925-8574 .- 1872-6992. ; 91, s. 506-514
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Journal article (peer-reviewed)abstract
- Green (vegetated) roofs provide many beneficial environmental services but can also pose a disservice by leaching nutrients and metals, via storm water runoff, to downstream aquatic ecosystems. Current estimates of water quality impacts rely on limited samples (snapshots in time) and may not accurately reflect the true influence of green roof ecosystems, which likely vary temporally as do natural ecosystems. Using a 46 m(2) green roof in Cincinnati, OH, we analyzed runoff from >80 events over two years for pH, conductivity, and concentrations of dissolved nutrients, base cations, and metals. We related the variation in water chemistry to environmental variables including air temperature, storm event magnitude, and estimated antecedent moisture. We observed strong seasonal patterns in bioactive elements, with carbon, nitrogen, phosphorus, and base cation concentrations highest in the summer, and positively correlated with temperature. This suggests temperature-mediated processes such as microbial mineralization of organic matter, desorption or weathering, rather than plant uptake or hydrologic variation among storms, are the major controlling mechanisms for runoff water quality in this newly constructed green roof. The large temporal variation in green roof effluent water quality supports the need for long-term studies to characterize the complexity of these engineered ecosystems and their responsiveness to environmental variation. (C) 2016 Elsevier B.V. All rights reserved.
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| 19. |
- Bundschuh, Mirco
(author)
-
Mitigation of fungicide pollution in detention ponds and vegetated ditches within a vine-growing area in Germany
- 2016
-
In: Ecological Engineering. - : Elsevier BV. - 0925-8574 .- 1872-6992. ; 89, s. 121-130
-
Journal article (peer-reviewed)abstract
- Large amounts of fungicides are commonly applied to agricultural fields, particularly vineyards. Following their application, fungicides may accidentally be introduced into agricultural surface waters posing a potential risk for the integrity of aquatic ecosystems. In this context, the present study characterized the aquatic fungicide exposure at base flow and during rainfall-related runoff events in viticulture in Southern Palatinate (SW-Germany) between 2006 and 2009. The mitigation performance of three vegetated ditches (VD) and five vegetated detention ponds (DP) was assessed. The measurements uncovered the presence of 4 to 11 different fungicide compounds in each of the 81 samples. During runoff events, the ecotoxicological potential-expressed as the sum of toxic units calculated based on the acute toxicity towards algae, Daphnia and fish-of some of the mixtures detected at the inlet of the VD or DP exceeded the Uniform Principle threshold set by the European Union. Both the VD and the DP systems reduced the median fungicide concentrations and thus their associated ecotoxicological potential by 56% and 38%, respectively. This fungicide mitigation efficiency was mainly explained by the plant density and size-related properties of the vegetated systems. Although VP and DP are promising tools to mitigate fungicide exposure, a better mechanistic understanding of the factors triggering the remediation potential finally feeding back into policy decision making is required. (C) 2015 Elsevier B.V. All rights reserved.
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| 20. |
- Calles, Olle, 1974-, et al.
(author)
-
Efficient and timely downstream passage solutions for European silver eels at hydropower dams
- 2021
-
In: Ecological Engineering. - : Elsevier. - 0925-8574 .- 1872-6992. ; 170
-
Journal article (peer-reviewed)abstract
- The European eel population is critically endangered due to a multitude of human-induced factors such as habitat fragmentation, parasites, fishing, and climate change. In freshwater, downstream migrating silver eels encountering hydroelectric plants often suffer substantial delays and increased mortality from trash-rack impingement and turbine-induced mortality. Downstream passage problems can be ameliorated by implementing different types of downstream passage solutions that show variable but promising results for salmonids, but their performance for silver eels remains largely unknown. To address these knowledge gaps, radio telemetry was used to monitor the downstream migration of silver eels during 2 years past a hydroelectric plant recently equipped with two new fish passage solutions, consisting of an angled bar rack with a full-depth bypass, and a nature-like fishway. No tagged eels passed through the turbines, but bypassed the dam evenly between the two passage solutions, resulting in a 95% impediment passage efficiency and a median passage time of 1 h. Movement patterns and route selection were associated with variation in discharge and most individuals approached both passage solutions before passing, resulting in route-specific efficiencies of 69% for the angled rack and bypass, and 46% for the nature-like fishway. We conclude that the combination of a new bypass, paired with an angled rack, and a large nature-like fishway provided downstream migrating silver eels with a highly effective combination of passage solutions, with high impediment passage success and relatively low passage times.
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| 21. |
- Calles, Olle, 1974-, et al.
(author)
-
Evaluating technical improvements for downstream migrating diadromous fish at a hydroelectric plant
- 2012
-
In: Ecological Engineering - The Journal of Ecosystem Restoration. - : Elsevier. - 0925-8574. ; 48, s. 30-37
-
Journal article (peer-reviewed)abstract
- Technical improvements to ameliorate downstream passage for diadromous fish have rarely been eval-uated in regulated rivers in northern Europe. The current study evaluated rehabilitative measures for downstream migrating Atlantic salmon, brown trout and European eel at a hydroelectric plant in south-ern Sweden. Smolts (N= 66), kelts (N= 20) and silver eels (N= 55) were caught, radio-tagged and tracked whilst passing the facilities in spring (salmonids) and fall (eels) of 2007. A surface gate in combination with a 90 mm-spaced turbine intake rack had a fish guidance efficiency ranging from no effect for eels and trout smolts to 50% for trout kelts. A siphon discharging water from the bottom of the same 90 mm rack did not bypass any tagged fish, and only a few untagged eels. The poor function of the measures was attributed to the failure of the rack to stop smolts and eels from entering the turbines. The kelts, on the other hand, could not pass through the rack, and instead took a long time to locate the surface bypass entrance. The conditions for downstream migrating fish have improved at the hydroelectric plant, but the total losses remain quite high for the studied groups (10–67%), and there is a need for a new rehabilitative measure that effectively allows all fish to bypass the turbines.
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| 22. |
- Choudhury, Maidul, et al.
(author)
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Importance of plant species for nitrogen removal using constructed floating wetlands in a cold climate
- 2019
-
In: Ecological Engineering. - : Elsevier BV. - 0925-8574 .- 1872-6992. ; 138, s. 126-132
-
Journal article (peer-reviewed)abstract
- Constructed floating wetlands (CFWs) have been tested in different climatic regions and aquatic habitat types for nitrogen (N) removal from surface water, but there is limited knowledge about their applicability for N removal in cold climate regions. Most CFWs studies are conducted at the micro- or mesocosm scale, while the application of CFWs at in situ is rare. Moreover, most CFWs studies have focused on plant N accumulation without considering macrophyte root-associated denitrification as a possible N removal pathway. Here, we study the N removal potential of CFWs through N accumulation by macrophytes and potential denitrification activity (PDA) associated with plants. At a mining area in the sub-arctic region of Sweden receiving N-rich mine effluents, we tested the concept of CFWs and evaluated the performance of six native, emerging macrophyte species planted in CFWs. The CFWs were deployed in two types of systems: in situ in the recipient lake, subjected to ambient N concentrations, and CFWs placed in water-side "eco-tanks", subjected to higher N concentrations. We showed that macrophyte establishment in CFWs is feasible under cold climatic conditions, both in situ and eco-tanks. The standing biomass of macrophytes, bulk N accumulation in plant biomass and PDA in mesocosms were 0.54-2.25 kg m(-2), 7.56-24.75 mg N m(-2) d(-1) and 31.82-2250.77 mg N2O-N m(-2) d(-1), respectively. In the recipient, the variation was larger and the values were higher (standing biomass, 0.37-6.74 kg m(-2); bulk N accumulation, 8.09-106.93 mg N m(-2) d(-1); PDA, 11.89-8446.15 mg N m(-2) d(-1)). Macrophyte root-associated denitrification was the main N removal pathway in the CFWs. Given the demonstrated applicability of CFWs and the high denitrification rates that can be obtained, future studies should focus on designing CFWs to enhance denitrification as this process leads to permanent removal of N from the water phase.
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| 23. |
- Czemiel Berndtsson, Justyna
(author)
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Green roof performance towards management of runoff water quantity and quality: A review
- 2010
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In: Ecological Engineering: the Journal of Ecotechnology. - : Elsevier BV. - 1872-6992. ; 36:4, s. 351-360
-
Research review (peer-reviewed)abstract
- This review paper addresses the role of green roofs in urban drainage considering both management of water quantity and quality. Results from investigation of full scale installations as well as from laboratory models are reviewed. The following factors affecting runoff dynamics from green roofs are discussed: type of green roof and its geometrical properties (slope): soil moisture characteristics: season, weather and rainfall characteristics; age of green roof; vegetation. Design parameters as suggested by different authors are also reviewed. Factors which affect influence of a green roof on runoff water quality are discussed in general terms followed by the review of data regarding concentrations of phosphorus, nitrogen, and heavy metals in green roof runoff, its' pH. and first flush effect. Linking among fertilization, runoff pollution and vegetation development is given a particular focus. The review indicates clearly that there is a need for more research into a green roof performance in an urban environment. The differences measured by few existing studies between the early years performance of green roofs and the later years indicate a need for long term monitoring of green roofs. (C) 2010 Elsevier B.V. All rights reserved.
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| 24. |
- Czemiel Berndtsson, Justyna, et al.
(author)
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Runoff water quality from intensive and extensive vegetated roofs
- 2009
-
In: Ecological Engineering: the Journal of Ecotechnology. - : Elsevier BV. - 1872-6992. ; 35:3, s. 369-380
-
Journal article (peer-reviewed)abstract
- Vegetated roofs are becoming a trend in urban design, among others as a tool for city greening, mitigating urban heat island effect, and lowering urban storm runoff. Additionally, pollutant removal within vegetated roofs is often expected; however, it is commonly riot a design feature. This study investigated influence on runoff water quality from two fullscale vegetated roofs (an intensive from Japan and an extensive from Sweden). Results show that both extensive and intensive vegetated roofs are a sink of nitrate nitrogen and ammonium. nitrogen with similar performance. The intensive vegetated roof is also a sink of total nitrogen in contrast to the extensive roof. Phosphorus release is observed from the extensive vegetated roof but not from the intensive vegetated roof;, release of dissolved organic carbon and potassium is observed from both roofs. The vegetated roofs, if not retaining the metal pollutants, were generally not a significant source. The increase of average pH during rainwater passage through the intensive vegetated roof indicated rapid neutralization of the acid depositions. (C) 2008 Elsevier B.V. All rights reserved.
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| 25. |
- Deng, Zhiqiang, et al.
(author)
-
Variable residence time-based model for BOD removal in free-water surface wetlands
- 2016
-
In: Ecological Engineering. - : Elsevier BV. - 0925-8574. ; 97, s. 334-343
-
Journal article (peer-reviewed)abstract
- Constructed wetlands have been increasingly used for treatment of secondary wastewater containing various contaminants. This paper presents a Variable Residence Time (VART)-based model, called VART-BOD model, for simulation of BOD removal processes in constructed wetlands with free water surface (FWS). Mathematically, the VART-BOD model describes a free water surface wetland with three vertical layers, including vegetated water column layer, advection-dominated upper root layer, and diffusion-dominated lower root layer. Biogeochemically, the VART-BOD model simulates various BOD removal processses and mechanisms, including monod kinetics of bacterial growth, mass exchange between water column and root layers, advection, dispersion, and diffusion. A unique feature of the VART-BOD model is the incorporation of a dynamic diffusion-dominated root-zone. The VART-BOD model was tested with data collected from two distinct FWS wetlands: Gustine Wetland, USA and Manzala Wetland, Egypt. Testing results showed that the coefficient of determination (r2) and root mean square error (RMSE) values vary in the ranges of 0.73–0.99 and 0.41–8.70 mg/L, respectively, for Gustine Wetland cells while r2 = 0.98 and RMSE = 0.72 mg/L for Manzala Wetland. The VART-BOD model is a reliable and efficient tool for designing constructed wetlands and for understanding effects of various processes and mechanisms on the treatment efficiency of wastewater in constructed wetlands.
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| 26. |
- Dimitrova Mårtensson, Linda-Maria
(author)
-
Methods of establishing species-rich meadow biotopes in urban areas
- 2017
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In: Ecological Engineering. - : Elsevier BV. - 0925-8574 .- 1872-6992. ; 103, s. 134-140
-
Journal article (peer-reviewed)abstract
- The biodiversity of meadow vegetation can be preserved in several ways, ranging from the conservation of historical traditionally managed meadows to the establishment of new meadow biotopes managed with modern machinery. Municipal plans often state that the value of natural habitats and the quality or functionality of green infrastructure should be improved. This requires scientific knowledge on the creation of new habitats with distinctive ecosystem services in the urban and peri-urban landscape. This paper presents a re-analysis of the results of research on methods of establishing species-rich grassland vegetation in the urban setting carried out in Sweden during the 1980s. It was found that hay or straw, used as mulch to protect meadow plant seeds, improved the success of establishment (higher number of individuals per m(2)) compared to establishment on bare soil. The use of rye (Secale cereale L.) as a nursery plant also improved the establishment compared to bare soil, whereas using ryegrass (Lolium perenne L.) as a nursery plant had no effect on the establishment of meadow species. The stripping method used to break up an existing sward did not affect the success of sown meadow plant species establishment, whereas broader strips improved the longer-term establishment (four years after sowing). The gapping method used to open up a closed grass sward was, however, important; sward removal resulted in successful establishment of meadow plant species, while burning did not. Gap size was found to be important for the establishment success rate of sown meadow plant species in the longer term (three years after sowing). Generally, the number of individuals per m(2) was higher in the first year than the second year after sowing and Leucanthemum vulgare and Rumex acetosa showed the highest number of individuals per m2 among the species included in the experiments. Planting plug plants directly in a closed grass lawn sward was found to be very successful, and the rate of survival was high. Further research is required on methods of establishing meadow plant species or meadow biotopes in an urban context, including the investigation of conflicting views on land use and residents' needs in urban and peri-urban areas. The ways in which constructed meadow biotopes contribute to the fulfilment of environmental goals and provide ecological functions and ecosystem service should also be assessed. (C) 2017 Elsevier B.V. All rights reserved.
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| 27. |
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| 28. |
- Djerf, Henric, et al.
(author)
-
Evaluation of treatment performance for one constructed wetland in a Swedish forest : A case study with emphasis on brownification mitigation
- 2023
-
In: Ecological Engineering. - : Elsevier. - 0925-8574. ; 194
-
Journal article (peer-reviewed)abstract
- Brownification refers to the increase in water colour reported in many freshwater systems. Constructed wetlands (CW) are commonly used for pollutant mitigation, including the causes of brownification. This study aimed to investigate the effects of a CW established in a forest area with high colour and low pH on its capability to reduce nutrient and colour. The inflow and outflow colour (mg Pt/L), total organic carbon (TOC), and iron (Fe) were assessed daily over a period of recorded dynamic flows during spring and autumn 2019 (15 and 19 days, respectively). Total nitrogen (Ntot) and phosphorus (Ptot) were also assessed to verify the removal efficiency of this mature constructed wetland. The prevailing hydraulic retention time (HRT) was assessed using conservative tracing. The results showed that the colour, TOC, and Fe were not reduced during the evaluation period. In contrast, while colour did not change (4–8% increase) over the assessed periods, TOC and iron significantly increased by 7.7% and 29.5%, respectively, during spring (4.2% and 10.6% during autumn). As Ntot and Ptot increased by 14.8% and 120%, respectively, during spring (7.4% and 8.8% during autumn), we concluded that constructed wetlands designed for nutrient control offer little potential for the mitigation of brownification, as expressed by colour, under low pH conditions.
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| 29. |
- Ellison, David
(author)
-
Induced precipitation recycling (IPR): A proposed concept for increasing precipitation through natural vegetation feedback mechanisms
- 2016
-
In: Ecological Engineering. - : Elsevier BV. - 0925-8574 .- 1872-6992. ; 91, s. 553-565
-
Journal article (peer-reviewed)abstract
- In this proof of concept paper, we address the potential role of forests and vegetation cover as an adaptation tool. In contrast to work addressing the carbon benefits of afforestation, we highlight the potential usefulness of forests as major contributors to the water cycle. Integrating water and carbon cycle benefits into a common objective enhances discussions about the role and value of forests. Herein, we describe a method for increasing regional precipitation in semi-arid environments, thereby potentially helping to increase scarce water resources. The approach capitalizes on observed interactions between forest cover and the hydrologic cycle, with the express aim of returning much needed water resources to an increasingly vulnerable region. The natural processes behind "precipitation recycling" (PR), and vegetation based cross continental transport of atmospheric moisture form the core of this solution. Induced precipitation recycling (IPR) initiates these processes by irrigating afforested land using locally available surplus water. This paper discusses the underlying processes and a proposed demonstration project that functions as both a "proof of concept" and a research testing ground, providing potential validation for promoting future expansion to the wider region. The proposed IPR project utilizes treated wastewater and surplus storm run-off, thus averting additional burdens on the existing water supply, while performing additionally valuable environmental and ecosystem services. IPR provides an alternative approach to supplement existing and typically far costlier plans to address regional water shortages and handle wastewater treatment. The proposed integrated solution would not only contribute positively to regional water supply, but would also provide additional eco-system services and end-products that add value and utility, thereby improving the project's potential economic viability. This project should be of particular interest to land use and water management planners in the Los Angeles Basin area for whom it is conceived, as well as to those along much of the coastal region in California where climate change-driven drought cycles have been increasing in length and intensity
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| 30. |
- Emilsson, Tobias, et al.
(author)
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Effect of using conventional and controlled release fertiliser on nutrient runoff from various vegetated roof systems
- 2007
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In: Ecological Engineering: the Journal of Ecotechnology. - : Elsevier BV. - 1872-6992. ; 29:3, s. 260-271
-
Journal article (peer-reviewed)abstract
- Extensive vegetated roofs are becoming popular as a way to improve the environmental quality of cities. As more vegetated roofs are installed, there is a need for knowledge pertaining to maintenance and impact vegetated roofs have on stormwater quality Our study investigated nutrient runoff, substrate nutrient storage and plant uptake following fertilisation of vegetation mats, shoot-established vegetation systems and unvegetated substrate using three levels of fertiliser applied as either controlled release fertiliser (CRF), or as a combination of CRF and conventional fertiliser. Conventional fertilisers caused high nutrient concentrations in the runoff water. Concentrations decreased during the duration of the experiment but at the end of the experiment they were still higher than after fertilisation with CRF. Conventional fertiliser also increased the total nutrient runoff. Vegetation system type influenced nutrient runoff and fertilisation of old vegetation mats reduced the risk for nutrient leaching compared to fertilisation of newly established surfaces. This can be attributed to temporary storage in substrate and increased uptake by vegetation. The temporary storage of nutrients following fertilisation indicated that there might be a risk for prolonged leaching. Thus, addition of conventional fertilisers or nutrient-rich material during production can reduce stormwater quality. (C) 2006 Elsevier B.V. All rights reserved.
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| 31. |
- Eriksson, Eva, 1973-, et al.
(author)
-
Greywater pollution variability and loadings
- 2009
-
In: Ecological Engineering. - : Elsevier BV. - 0925-8574 .- 1872-6992. ; 35:5, s. 661-669
-
Journal article (peer-reviewed)abstract
- Small on-site greywater treatment and reuse plants are susceptible to high short-term variation in flow and pollutant concentrations. As demonstrated in this study of a bathroom greywater plant in Copenhagen, Denmark, the flow ranges from no-flow periods to high-flow periods reaching 34 l min−1. Concentrations of both macro- and micro-pollutants (organic matter and parabens) were found to range by several orders of magnitude in the influent, based on sampling every 20 min. Paraben degradation was proven to occur in the rotating biological contactor (RBC), while the remnant organic matter in the effluent was proved not to be readily degradable. Ammonium content, presumably from urine contamination, was found to undergo nitrification in the RBC. Mass flow (daily loads) for individual substances was calculated for several pollutants. Macropollutants were found to be generated in low numbers of grams per person per day, whereas the paraben loadings were below 1 mg per person per day. These data are highly relevant for comparing decentralised treatment options with existing end-of-pipe treatments, for feeding into risk assessments and for design purposes.
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| 32. |
- Farahat, Emad, et al.
(author)
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Effects of treated wastewater irrigation on size-structure, biochemical products and mineral content of native medicinal shrubs
- 2013
-
In: Ecological Engineering: The Journal of Ecosystem Restoration. - : Elsevier BV. - 0925-8574. ; 60, s. 235-241
-
Journal article (peer-reviewed)abstract
- tThe aim of this study is to evaluate the impact of treated wastewater irrigation on five native medic-inal shrubs (Artemisia monosperma, Zilla spinosa, Farsetia aegyptiaca, Deverra tortuosa and Calligonumpolygonoides) in abandoned areas of a desert plantation in Egypt. Mineral content, size-structure andbiochemical products of shrub shoot samples were determined for the plantation and an adjacent,non-irrigated control site outside the forest. We found that the application of wastewater significantlyincreased trace metal concentrations (Cd, Cu, Mn, Ni and Pb) in the plantation-soil compared to the control,showing phytotoxic concentrations of Ni. Each shrub species showed different selectivity to accumulatespecific elements in their shoots, with high concentrations of N, P, K, Mn, Zn, Ni, Cu, Cd and Pb in forest siteplants. Cd and Ni concentrations in shoot samples from both the planation and control sites were about13 and 500 times above permissible levels, respectively. Our results suggest that native medicinal shrubsirrigated by wastewater may not be safe for medicinal use or grazing purposes and represent potentialrisks. More efforts should be directed to monitor the potential hazards of using wastewater irrigation onall components of the ecosystem.
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| 33. |
- Faulwetter, Jennifer L, et al.
(author)
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Microbial processes influencing performance of treatment wetlands : A review
- 2009
-
In: ECOLOGICAL ENGINEERING. - : Elsevier BV. - 0925-8574. ; 35:6, s. 987-1004
-
Journal article (peer-reviewed)abstract
- This review summarizes the microbial mechanisms responsible for removal of carbon, nitrogen. and sulfur compounds in treatment wetlands (TWs) and identifies, categorizes and compares various techniques, from plate count to more modern genomic methods used to elucidate these mechanisms. Removal of a particular pollutant is typically associated with a specific microbial functional group, therefore employment of design and operational methodologies that enhance the activity of that group will better optimize performance. Redox condition is a manipulable parameter that can be used to optimize growth of a targeted functional group, therefore factors influencing the TW redox condition and its influence on organic carbon removal mechanisms are emphasized. Environmental factors influencing growth and activity of N and S cycling microbes (including temperature, pH, salinity, plant species selection and availability of organic carbon and/or inhibiting substances) are discussed with particular attention to factors that might be manipulated. This information is used to offer design and operational methodologies that might enhance growth of a desirable microbial functional group and project what additional microbially-focused research is required to better optimize TW performance.
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| 34. |
- Gage, H. J. M., et al.
(author)
-
Assessing moss transplant methods to enhance Sphagnum moss recovery in post-wildfire hydrophobic peat
- 2024
-
In: Ecological Engineering. - : Elsevier. - 0925-8574 .- 1872-6992. ; 205
-
Journal article (peer-reviewed)abstract
- Wildfire is the dominant disturbance in northern peatlands and can release large quantities of carbon to the atmosphere through combustion. Post-fire peat hydrophobicity can inhibit moss regeneration, thereby decreasing the potential for post-fire carbon sequestration. To investigate how to enhance post-fire recovery we assessed two moss restoration methods (plugs and fragments) in an Alberta poor fen two and three years following wildfire. We first characterized post-fire peat hydrophobicity and moss regeneration in four surface cover types: Severely Burned Feather moss hollows (SB-F), Severely Burned Sphagnum fuscum hummocks (SB-S), Lightly Burned S. fuscum hummocks (LB-S), and Lightly Burned Feather moss lawns (LB-F). Across burn severities, hydrophobicity was high in feather moss and relatively low in Sphagnum moss. Similarly, hydrophobicity increased with depth over the top several centimeters in feather moss, but not in Sphagnum moss surface cover. Peat hydrophobicity appears to limit post-fire regeneration. LB-S was the least hydrophobic of the four treatments and was the only cover type in which Sphagnum moss recovered to >10% surface area, though SB-F had marginal recovery of pioneer moss species. Consequently, we conducted experiments testing the success of moss plugs and fragments of varying moss species at LB-F and SB-F surface covers, which had high hydrophobicity and low post-fire moss recovery. Experimental results indicate that the species type used in transplants is less critical in their survival than the microenvironment into which they are transplanted (i.e., burn severity). Transplant success was slightly higher in plugs than fragments, and larger plug sizes (10–15 cm) were more successful than small plugs (<10 cm). Growth was greater in SB-F than LB-F surface cover, owing to differences in post-fire hydrophobicity, and thus moisture availability. We conclude that in appropriate areas post-fire, peatland management efforts could employ large mixed-moss or Sphagnum moss transplant units while accounting for pre-fire vegetation composition and burn severity to fast-track post-fire moss and ecosystem recovery.
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| 35. |
- Garcia-Gasulla, Dario, et al.
(author)
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A logic-based environmental decision support system for the management of horizontal subsurface constructed wetlands
- 2012
-
In: Ecological Engineering. - : Elsevier BV. - 0925-8574 .- 1872-6992. ; 47, s. 44-55
-
Journal article (peer-reviewed)abstract
- The use of Horizontal Subsurface Constructed Wetlands (HSCWs) for treating wastewaters in small communities has increased in the last years due to HSCW's ecological singularities. Unfortunately, the same singularities that differentiate HSCWs complicate any attempt to develop models and produce generic decision-support systems for them. Classical mathematical and statistical approaches used in other Wastewater Treatment Plants do not properly fit the particularities of HSCW and provide little insight in the domain of HSCW. We introduce a novel approach based on logic-based declarative specifications, i.e. non-monotonic causal logic, to capture explicit and implicit knowledge about HSCWs. By expressing all the relevant aspects of a HSCW in a declarative way, we produce a logic-based model which captures features that other approaches fail to formalize. At the end, we produce a complete decision-support system based on that model and test it against a set of realistic scenarios validated by experts. We discuss in which aspects this approach performs better than the most commonly proposed solutions in the bibliography and why it does so. (C) 2012 Elsevier B.V. All rights reserved.
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| 36. |
- Greenberg, Larry, 1955-, et al.
(author)
-
Effect of trash diverters ad overhead cover on downstream migrating brown trout smolts
- 2012
-
In: Ecological Engineering. - : Elsevier. - 0925-8574 .- 1872-6992. ; 48:November, s. 25-29
-
Journal article (peer-reviewed)abstract
- Power plant dams constitute barriers for downstream migration by smolts. The purpose of this study was to measure guidance efficiency of existing trash diverters and the use of overhead cover in combination with trash diverters to guide brown trout (Salmo trutta L.) smolts away from turbine intakes into trash spillway gates at two power plants in the Emån River, southern Sweden. A total of 44 trout smolts were caught, radio-tagged, released at the two power plants and tracked daily for six weeks. The trash diverter at the lower power plant had a significant guiding effect, as the proportion of smolt that entered the spillway gate was significantly greater than the relative proportion of water that flowed through the gate (52% vs 17%). In contrast, there was no evidence of a guidance effect at upper Finsjö, where the proportion of smolts that entered the spillway gate did not differ significantly from the relative proportion of water that flowed through the gate (0% vs 10%). The lack of a guidance effect at upper Finsjö could not be explained. The effect of overhead cover was tested at the upper power plant as illumination from outdoor, overhead lamps at the power station was believed to attract smolts to the turbine intake. This was accomplishing by setting up and removing a tarpaulin placed between the trash deflector and the turbine intake approximately every 2–5 days for about one month, so that 52.6% of the time the tarpaulin was in place and 47.4% of the time it was not. The presence of the tarpaulin reduced turbine passage, as 31% of the smolts swam through the trash spillway gate instead of the turbines when the tarpaulin was in place, whereas all smolts entered the turbines when no tarpaulin was used. For fish that passed through the turbines, mortality was higher at the upper power plant, equipped with two twin-Francis turbines, than at the lower one, equipped with a single Kaplan turbine.
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| 37. |
- Gren, Ing-Marie, et al.
(author)
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Values of mussel farming for combating eutrophication: An application to the Baltic Sea
- 2009
-
In: Ecological Engineering. - : Elsevier BV. - 0925-8574 .- 1872-6992. ; 35, s. 935-945
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Journal article (peer-reviewed)abstract
- The purpose of this study is to estimate the value Of mussel farming for reducing nutrient contents ill the Baltic Sea, which is made in a cost effectiveness framework. The value of mussel farming is then calculated as savings in costs from replacement of more costly nutrient abatement options. In addition to mussel farming, the cost minimisation model includes 20 abatement measures which affect agriculture, industry. transports and households in each of the 24 drainage basins of the Baltic Sea. The results indicate that calculated marginal cleaning costs of nutrients by mussel farming can be considerably lower than other abatement measures, but also relatively high depending on mussel growth. sales options, and formulation of nutrient load targets for the Baltic Sea. The estimated values range between approximately 0.1 and 1.1 billions of Euros per year depending on Baltic Sea nutrient target and net cleaning cost Of mussel farming, which correspond to cost savings between 2 and 11 percent. The results also show that the value from contributions to savings of control costs for achieving the Baltic Sea action Plan Suggested by Helcom ranges between 5 and 60 percent of the market price of live mussel for human consumption. (C) 2009 Elsevier B.V. All rights reserved.
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| 38. |
- Grönlund, Erik, et al.
(author)
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Sustainability of wastewater treatment with microalgae in cold climate, evaluated with emergy and socio-ecological principles
- 2004
-
In: Ecological Engineering. - : Elsevier BV. - 0925-8574 .- 1872-6992. ; 22:3, s. 155-174
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Journal article (peer-reviewed)abstract
- The sustainability of a microalgae wastewater treatment plant model (ALGA), assumed serving a small Swedish town with 10,000 inhabitants at latitude 60°N, was tested by comparing it to a conventional three-step treatment plant (WWTP), and a mechanical and chemical treatment plant (TP) complemented with a constructed wetland (TP + CW). Using two assessment methods—the socio-ecological principles method and emergy analysis—the ALGA model considered to have a better position for sustainable development, than the other two. In emergy terms the ALGA model had about half the resource use of the other two alternatives, and used most local free environmental resources, four times the TP + CW, and 100 times the WWTP. The violations against the second and third socio-ecological principles were considered equal for the three alternatives, the fourth was estimated to be in favor of the ALGA model, and the first principle was calculated to be in favor of the ALGA model with about eight times lower indicator value sum. Recirculation of nutrients back to society or production of economically viable products from the treatment by-products would strongly influence the sustainability. The ALGA model has a potential advantage due to interesting biochemical contents in the microalgae biomass, depending on what species will become dominating.
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| 39. |
- Gustafsson, Stina, et al.
(author)
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Macroinvertebrate colonization of a nature-like fishway : The effects of adding habitat heterogeneity
- 2013
-
In: Ecological Engineering: The Journal of Ecosystem Restoration. - : Elsevier BV. - 0925-8574. ; 61, s. 345-353
-
Journal article (peer-reviewed)abstract
- Nature-like fishways are designed to imitate the characteristics of natural streams, thereby providing both fish passage and habitat for a variety of aquatic organisms. To date, however, the potential for habitat rehabilitation of nature-like fishways has not been fully realized. To develop the concept of how to design a nature-like fishway, a 500-m long nature-like fishway, termed the biocanal, was constructed at the Eldforsen hydroelectric facility, Sweden. It included four habitat types: riffle, pool, floodplain and braided (i.e. with islands), each replicated three times. The riffle sections were considered controls for typical Swedish nature-like fishways. Thus the biocanal had a more varied in-stream environment than those of conventional fishways. To test the prediction that the biocanal had a positive effect on biodiversity, we compared the physical habitat and benthic fauna composition of the more diverse habitat types in the biocanal to the riffle habitats. We also made comparisons between the biocanal and six natural reference streams in the area. After two years, 63% of the benthic fauna families found in the reference streams had colonized the biocanal. Families present in the reference streams, but not in the biocanal, were predominantly slow colonizers or taxa linked to riparian vegetation, which was scarce and in an early successional stage along the biocanal. In the biocanal, pool and floodplain habitats contained the highest number of families, the highest family diversity (Shannon-Weaver) and the highest densities of Ephemeroptera, Plecoptera and Trichoptera. Since these habitats contained more families and had higher diversities than the riffle habitats which are typical of conventional nature-like fishways, we suggest that the construction of biocanals indeed possesses the potential for high biodiversity. (C) 2013 Elsevier B.V. All rights reserved.
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| 40. |
- Haller, Henrik, 1977-, et al.
(author)
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Bioaccumulation and translocation of field-weathered toxaphene and other persistent organic pollutants in three cultivars of amaranth (A. cruentus ‘R127 México’, A. cruentus ‘Don León’ y A. caudatus ‘CAC 48 Perú’) – A field study from former cotton fields in Chinandega, Nicaragua
- 2018
-
In: Ecological Engineering. - : Elsevier BV. - 0925-8574 .- 1872-6992. ; 121, s. 65-71
-
Journal article (peer-reviewed)abstract
- Soils polluted by persistent organic pollutants threatens habitats for plants and animals as well as basic human needs such as food security and provision of potable water. Toxaphene is a persistent organic pollutant that was heavily used as a pesticide in Central America, Brazil, Soviet Union etc. until it was banned in 1993. The objective of this study was to determine the bioaccumulation and translocation characteristics of three different cultivars of amaranth in soils contaminated with field-weathered toxaphene and other POPs in former cotton fields in Chinandega, Nicaragua to identify safety issues for human consumption and/or potential for phytoremediation. The concentration of toxaphene and other POPs in the edible parts of the amaranth (leaves and seeds) exceeded the maximum residue level for human consumption established by the European Union for most of the tested compounds. Concentrations of toxaphene congeners and other POPs were found in all vegetative organs. Many substances were accumulated to concentrations more than 10 times higher than in the soil. Of the three cultivars, A. caudatus 'CAC48 Perú' and A. cruentus 'Don Leon' presented the highest average BAF. None of the 3 cultivars can be considered a panacea hyperaccumulator for either toxaphene alone or in conjunction with other POPs but since many agricultural soils comprise a range of different contaminants, the broad-spectrum bioaccumulating capacity of amaranth can make it an interesting candidate for phytoremediation.
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| 41. |
- Hallin, Sara, et al.
(author)
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Potential denitrification rates are spatially linked to colonization patterns of nosZ genotypes in an alluvial wetland
- 2015
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In: Ecological Engineering. - : Elsevier BV. - 0925-8574 .- 1872-6992. ; 80, s. 191-197
-
Journal article (peer-reviewed)abstract
- Through denitrification, attached bacterial communities reduce water nitrogen loads during transport from land to river. In an in situ colonization experiment, spatial and temporal dynamics in composition of bacterial communities and denitrification activity were studied in bacterial biofilms in an alluvial aquifer. Mesh bags with glass beads were installed in different wells in an alluvial aquifer affected by surface water fluxes from an adjacent river and biofilms were sampled throughout the 15-month experiment. By combining structural (PCR-DGGE using nosZ genes) and functional (Denitrification Enzyme Activity measurements) descriptors, the denitrifiers community structure of biofilms and their functional responses were studied. Denitrifiers bacterial community composition developed on beads linked to denitrification capability were correlated with the modeled load of dissolved organic carbon coming from the river and dissolved oxygen concentration, which were set by the river channel water flow through the aquifer. (C) 2015 Elsevier B.V. All rights reserved.
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| 42. |
- Harbicht, Andrew, et al.
(author)
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Guiding migrating salmonid smolts : Experimentally assessing the performance of angled and inclined screens with varying gap widths
- 2022
-
In: Ecological Engineering. - : Elsevier. - 0925-8574 .- 1872-6992. ; 174, s. 1-8
-
Journal article (peer-reviewed)abstract
- The loss of longitudinal connectivity in regulated rivers, both up- and downstream, has been detrimental for biodiversity worldwide. While progress has been made regarding upstream fish passage solutions, many questions remain unanswered regarding downstream passage alternatives. To address these knowledge gaps, we used Atlantic salmon (S. salar) smolts to experimentally assess the guidance efficiency and passage rates produced by several common screen-and-bypass fish guidance systems. Vertical screens with horizontally oriented bars extending across a turbine intake channel at a shallow angle (angled guidance screens), combined with a single, full-depth bypass entrance at their downstream end, were on average 20% more effective and produced passage rates that were 10 times higher than screens which extended perpendicularly across a turbine intake channel with vertically oriented bars that rose gradually towards the surface (inclined guidance screens) and with a bypass at the surface, on either side of the screen. Among inclined screens, gap width was negatively associated with guidance efficiencies and the smallest gap width (15 mm) exhibited a 41% greater guidance efficiency than the largest (30 mm). Among angled screens, performance was more closely linked to construction material as metal racks produced passage rates over three times faster than flexible Kevlar netting. Overall, passage through the guidance screens, and therefore into a tentative turbine intake area, was positively associated with gap width and was twice as prevalent among the inclined relative to angled guidance screens. Ultimately, an angled guidance screen with a 30 mm gap width produced the highest guidance efficiency and passage rates (a 30% improvement over the next best screen), while an inclined screen with a 30 mm gap width produced the lowest guidance efficiencies and passage rates. These results have implications for the suitability and performance of downstream fish passage solutions at both large- and small-scale hydropower plants where passage solutions are currently lacking or inadequate.
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| 43. |
- Huerta Buitrago, Belinda, et al.
(author)
-
Ecotoxicological characterization of sediments from a constructed wetland system for treatment of landfill leachate
-
In: Ecological Engineering. - 0925-8574 .- 1872-6992.
-
Journal article (peer-reviewed)abstract
- In this study a bioassay test battery was used to assess the toxicity and the presence of dioxin-like compounds in 8 sediment samples obtained from a surface flow wetland system for treatment of municipal landfill leachate. The wetland system consists of sediment traps at the inlet followed by 10 ponds connected with overflows. In the 6 day solid phase microbiotest with the sediment-dwelling crustacean Heterocypris incongruens both acute and chronic effects were observed with a gradual decrease and loss of toxicity with treatment in the wetland system. Some samples showed low toxicity in pore water but no toxicity was observed in the whole sediment when assessed with Aliivibrio fischeri (Vibro fischeri). No genotoxicity was detected in the umu test with or without metabolic activation. The toxicity response in the H4IIE- luc test evaluating the presence of dioxin-like compounds was significantly higher in the samples closer to the inlet of the system; the first sample was found to be a 177 times more potent Ah-receptor (AhR) inducer in comparison to the other samples. In conclusion; no toxicity, low levels of dioxin-like compounds and low levels of heavy metals were detected in the sediments from the last part of the wetland. The results indicate that the surface flow wetland system has an effective design for concentrating toxic substances associated with particulate matter in a small area of the wetland. The battery of tests used provided a comprehensive assessment of the ecotoxicological status of this aquatic system.
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| 44. |
- Jauni, Miia, et al.
(author)
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Alkaline habitat for vegetated roofs? : Ecosystem dynamics in a vegetated roof with crushed concrete-based substrate
- 2020
-
In: Ecological Engineering. - : Elsevier. - 0925-8574 .- 1872-6992. ; 157
-
Journal article (peer-reviewed)abstract
- Using local and recycled materials is a sustainable way to establish a vegetated roof. In order to understand how the roof ecosystem functions and returns ecosystem services, it is important to study vegetation, soil organisms and runoff quality. We established a vegetated roof experiment based on a substrate containing lightweight crushed concrete, an alkaline side product from a concrete factory, mixed with compost. This five-year experiment in southern Finland tested how planting method (pre-grown vegetation mats vs. pot planting), compost content (20% vs. 40%, fresh volume), and substrate depth affect the cover and diversity of plants, the abundance of soil animals and the quality of runoff. Although the substrate had a high pH (7.3–11.8), many vascular plants were able to survive and establish viable populations. The planting method had a strong effect on plant diversity and the cover of individual species because the vegetation mats became dominated by the invasive, non-native Phedimus hybridus. Establishment with pot plants in turn provided bare ground that was colonised by spontaneous non-invasive species. This resulted in higher diversity, and a more even distribution of species. The amount of compost had only a weak impact on vegetation, whereas high pH generally reduced plant abundance and diversity. The concentrations of total phosphorus and total nitrogen in runoff were low as compared to values reported from many other vegetated roofs, were not affected by compost content and decreased over time. In summary, the high-pH substrate based on recycled materials is an environmentally responsible choice, suitable for a wide variety of plants, even rare and endangered species.
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| 45. |
- Johannesson, Karin M., 1982-, et al.
(author)
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Phosphorus and particle retention in constructed wetlands—A catchment comparison
- 2015
-
In: Ecological Engineering. - Amsterdam : Elsevier. - 0925-8574 .- 1872-6992. ; 80, s. 20-31
-
Journal article (peer-reviewed)abstract
- Abstract Seven constructed wetlands (0.05–0.69 ha), situated in agricultural catchments (22–267 ha) in the south of Sweden, were studied for two years with two aims: to (i) quantify their function as sinks for particles and phosphorus (P) lost from the catchments, and (ii) investigate to what degree catchment and wetland characteristics and modeled loads (using hydrochemical catchment models) could be used to explain differences in retention between the wetlands. The wetland areas ranged from 0.04 to 0.8% of the respective catchment area, and they were situated in areas dominated by fine-textured soils with relatively high P losses and the main proportion of P transported in particulate form. Net P and particle retention were estimated during two years from annual accumulation of particles on sedimentation plates (40 × 40 cm) on the bottom of the wetlands.There was an annual net retention of particles and P, but with a large variation (for particles 13–108 t ha−1 yr−1 and for P 11–175 kg ha−1 yr−1), both between wetlands and between years. The difference between the two years was larger than the difference in mean P retention between the seven wetlands. There was a positive relationship between P and particle retention and three catchment factors, i.e. P status (P-AL) of agricultural soils, average slope in the catchments and the livestock density, and a negative relationship with the agricultural soil clay content. In addition, there was a positive relationship with the wetland length:width ratio. Contrary to expectations, neither the modeled hydraulic load nor P load was significantly correlated with the measured particle and P retention. There was also a positive relationship between P concentration in the sediment and soil P status in the catchment. The results imply that considerable errors are introduced when down-scaling modeled regional nutrient losses to estimate the P loads to small wetlands in agriculturally dominated catchments. A more qualitative approach, using catchment characteristics for identification of hot-spot fields, may be equally good to identify suitable locations for constructed wetlands to reduce diffuse P loads. © 2014 Elsevier B.V.
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| 46. |
- Johannesson, Karin, 1982-, et al.
(author)
-
Temporal phosphorus dynamics affecting retention estimates in agricultural constructed wetlands
- 2017
-
In: Ecological Engineering. - Amsterdam : Elsevier. - 0925-8574 .- 1872-6992. ; 103, s. 436-445
-
Journal article (peer-reviewed)abstract
- Data from seven constructed wetlands (CWs) in the south of Sweden were analyzed to investigate the effects of water flow and season on inflow phosphorus (P) concentrations and temporal P retention variations in CWs receiving runoff from arable land. The form of P (dissolved or particulate) during different water flows (high and low) and seasons (warm and cold) was investigated using the results of total P (TP) and phosphate analyzed in grab samples that had been collected regularly or occasionally during two to nine years, along with continuous water flow measurements.The form of inflow and outflow P (particulate or dissolved P) differed between CWs, and also varied with season and flow. For instance, in three of the CWs, particulate P (PP) dominated the inflow during the cold period with high flow, while during the other periods the proportion of PP was approximately 50%. In one CW situated in a catchment with high clay content, PP dominated both inflow and outflow at all times. The average clay content in catchment top soils was positively correlated to the flow-weighted inflow TP concentrations.In three CWs receiving runoff through drainage pipes, the relationship between TP concentrations (TPin) and water flow was positive, both during high and low flow, and during warm and cold period. However, in four CWs that received surface water runoff, the relationship between TPin and water flow was positive during high flow periods (i.e. the 25% sampling occasions with the highest flow), and during low flow and warm period, the relationship was negative in these four wetlands, indicating either anoxic stagnant water upstream or influence from rural wastewater.The temporal dynamics of P concentrations mean that in some of the CWs, the main part of the annual P retention may occur during a few days with high water flows. The correlation between concentration and water flow suggests that the water sampling strategy may have a considerable impact on retention estimates, as exemplified by some calculation examples.
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| 47. |
- Josko, Izabela, et al.
(author)
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Effect of biochars, activated carbon and multiwalled carbon nanotubes on phytotoxicity of sediment contaminated by inorganic and organic pollutants
- 2013
-
In: Ecological Engineering. - : Elsevier. - 0925-8574 .- 1872-6992. ; 60, s. 50-59
-
Journal article (peer-reviewed)abstract
- To reduce the risk related with the presence of contaminants in sediments, methods based on the use of adsorbents (mainly activated carbon) are applied. Adsorbents neutralise the contaminants by reducing their mobility, bioavailability and toxicity. The objective of this study was to determine the toxicity of sediment contaminated with organic compounds and heavy metals with and without the addition of selected adsorbents. In the study three carbonaceous materials (CM) potentially useful in remediation were applied: activated carbon (AC), biochars (BC1, BC2), and multi- walled carbon nanotubes (CNTs). The effect of the dose, particle diameter and time of contact between sediment and CM on the effectiveness of the detoxification were estimated. Ecotoxicological assessment was made based on the Phytotoxkit FTM test, using Lepidium sativum as the test plant. The materials tested reduced the negative effect of sediment on L. sativum. The highest effectiveness was achieved after the application of AC (70% reduction of seed germination inhibition, 27.5% reduction of root growth inhibition). The reduction of phytotoxicity of the sediment as a result of addition of BC1, BC2 and CNT varied within the range from 30 to 40% (reduction of seed germination inhibition) and from 17.7 to 28.9% (reduction of root growth inhibition). The reduction of sediment toxicity decreased with decreasing diameter of the biochars applied. Probably because of increasing fouling extension of the time of contact between CM and sediment had an unfavourable effect on the reduction of root growth inhibition in the case of all materials tested.
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| 48. |
- Kallner Bastviken, Sofia, et al.
(author)
-
Effects of vegetation and hydraulic load on seasonal nitrate removal in treatment wetlands
- 2009
-
In: Ecological Engineering. - Amsterdam : Elsevier. - 0925-8574 .- 1872-6992. ; 35:5, s. 946-952
-
Journal article (peer-reviewed)abstract
- Optimising nitrate removal and identifying critical factors for nitrate removal in wetlands is an important environmental task in the effort to achieve better surface water quality. In this study, eighteen free water surface wetlands with similar shape and size (22 m2 each) received groundwater with a high nitrate-N concentration (about 11 mg l−1). The effects of two hydraulic loads, 0.13 m d−1 and 0.39 m d−1, and three vegetation types – emergent, submersed and freely developing vegetation – on the nitrate-N removal were investigated through mass inflow and outflow measurements.No significant difference in nitrate removal between the different hydraulic loads could be detected. Significantly higher area-specific nitrate removal and first-order area-based rate coefficients were found in the basins with emergent vegetation, with no difference between the basins with submersed and freely developing vegetation. The nitrate-N removal increased as the wetlands matured and the vegetation grew denser, emphasizing the role of dense emergent vegetation for nitrate removal at high nitrate concentrations.
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| 49. |
- Kallner Bastviken, Sofia, et al.
(author)
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Potential denitrification in wetland sediments with different plant species detritus
- 2005
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In: Ecological Engineering: the Journal of Ecotechnology. - : Elsevier BV. - 1872-6992. ; 25:2, s. 183-190
-
Journal article (peer-reviewed)abstract
- The effect of detritus originating from different plant species on denitrifying capacity was investigated in a Swedish wastewater treatment wetland. Intact sediment cores containing sediment with a detritus layer were collected from wetland basins dominated by Typha latifolia, Phragmites australis, or Elodea canadensis in November 2000 and potential denitrification was measured using the acetylene-inhibition method. The cores from stands of E. canadensis showed more than three times higher denitrification capacity than the cores of the other plants. Bacterial abundance per unit dry weight was both highest and lowest in the detritus of R australis, whereas the C/N ratio was lower in the cores of E. canadensis. This suggests that the submerged plant provided more organic material of high quality to support heterotrophic organisms. It is also possible that the surfaces of E. canadensis offered more or more suitable surfaces for bacterial growth and thereby increased the bacterial population. It is apparent that denitrifying bacteria were more favored by E. canadensis detritus than by detritus from the emergent plant species at the time of sampling. Since the turnover of plant detritus varies considerably among species, the seasonal variation in denitrification capacity is likely to be quite different for different plants.
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| 50. |
- Karlson, Mårten, 1983-, et al.
(author)
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The effect of fauna passages and landscape characteristics on barrier mitigation success
- 2017
-
In: Ecological Engineering. - : Elsevier BV. - 0925-8574 .- 1872-6992. ; 105, s. 211-220
-
Journal article (peer-reviewed)abstract
- Transport infrastructure can impose significant barriers to movements to many, if not most terrestrial animals. Barrier effects can lead to increased isolation of wildlife populations, which in turn might have demographic effects and even increase genetic differentiation between neighbouring populations. This study attempted to clarify the role of fauna passages and generic landscape patterns for connectivity in fragmented landscapes, and to improve the theoretical basis for future experimental approaches to evaluate the effectiveness of barrier mitigation strategies. Specifically, the issue of whether it would be more effective to construct a single large rather than several small crossing structures (SLOSS) was addressed by this study. Three hypotheses were formulated on the relationship between habitat connectivity, as a prerequisite for genetic exchange, and habitat aggregation and contrast between habitat types. Random landscapes with different combinations of aggregation, contrast and number and size of fauna passages were created in a GIS. Connectivity was then quantified as a function of movement resistance using circuit theory and related methods, and measurements from the random landscapes were statistically analysed. The results indicate that in any landscape, it would be more effective to construct several small fauna passages instead of a single large one to mitigate the effect of a barrier. The level of aggregation appeared to have no influence per se on connectivity, and increasing the level of contrast increased the variance in the results. It is recommended that barrier effect mitigation strategies focus on the location and design of several small fauna passages rather than a single large one. Future research should focus on the development of dispersal and movement models for a set focal species. The effectiveness of increasing fauna passage dimensions above those of crossing structures that are evidently used by the intended species should also need more research.
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