| 1. |
- Al-Rubaei, Ahmed Mohammed, et al.
(author)
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Effectiveness of a 19-Year Old Combined Pond-Wetland System in Removing Particulate and Dissolved Pollutants
- 2017
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In: Wetlands (Wilmington, N.C.). - : Springer. - 0277-5212 .- 1943-6246. ; 37:3, s. 485-496
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Journal article (peer-reviewed)abstract
- This study monitored the stormwater runoff quantity and quality treatment performance of a 6.8 ha 19-year old combined pond-wetland system, located in south Sweden, over one year. The mean volume reductions for 53 storm events for the pond and wetland were 40% and 28%, respectively, while the mean flow reductions were 60% and 76%, respectively. Pollutant concentrations in the influent to the wetland were highly variable. The pond-wetland system could efficiently remove an average of 91%, 80%, 94%, 91%, 83% and 92% of TSS, TP, particulate Cd, Cu, Pb, and Zn, respectively, whereas the removal of particulate and dissolved Ni was highly variable with an average of 67% ± 62% and −5% ± 41%, respectively. The removal of TN, NH4-N and NO3 + NO2-N was highly variable with an average of 45% ± 27%, 12% ± 96% and 45% ± 43%, respectively. These removal percentages are high in comparison to other studies and underline that relatively old systems can also provide efficient treatment. Although the pond accounted for a substantial reduction of pollutant concentration, the wetland significantly enhanced both the treatment performance and the peak flow reduction. This underlines that a combined pond/wetland system is a more beneficial solution than a pond only. The pollutant removal efficiency was significantly influenced by some factors including Antecedent Dry Days, seasonal variations, air temperature, retention times, rainfall depth and duration, and peak rainfall intensity.
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| 2. |
- Grasset, Charlotte, et al.
(author)
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Can Soil Organic Carbon Fractions Be Used as Functional Indicators of Wetlands?
- 2017
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In: Wetlands (Wilmington, N.C.). - : Springer Science and Business Media LLC. - 0277-5212 .- 1943-6246. ; 37:6, s. 1195-1205
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Journal article (peer-reviewed)abstract
- This work aimed to determine whether the organic carbon in wetland soils correlated with physico-chemical characteristics of wetlands (e.g. nutrient content, pH) and differentiated wetlands according to their plant community composition definied by the CORINE Biotope nomenclature. 96 wetlands were sampled in southeastern France, belonging to 14 CORINE habitats grouped into 3 CORINE hydrological categories: wet meadows, peatlands and aquatic wetlands. The total organic carbon content, the carbon content of humic fractions (humic acid (CHA), fulvic acid (CFA) and Chumin), and water extractable organic carbon were measured in samples collected in the upper 20 cm soil layer. These soil organic carbon fractions correlated with pH and soil nutrient content but differed slightly among the 14 CORINE habitats. In contrast, soil organic carbon fractions greatly differed among the 3 CORINE hydrological categories. The CFA/CHA ratio was significantly lower for wet meadows and peatlands and the proportion of CHumin was significantly higher for peatlands and aquatic wetlands. These soil organic carbon fractions inform on the hydrological status of wetlands and may consequently be used as functional indicator in addition to a plant-based classification as the CORINE Biotope nomenclature.
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| 3. |
- Jaramillo, Fernando, et al.
(author)
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Effects of Hydroclimatic Change and Rehabilitation Activities on Salinity and Mangroves in the Cienaga Grande de Santa Marta, Colombia
- 2018
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In: Wetlands (Wilmington, N.C.). - : Springer Science and Business Media LLC. - 0277-5212 .- 1943-6246. ; 38:4, s. 755-767
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Journal article (peer-reviewed)abstract
- The Cienaga Grande de Santa Marta (CGSM), Colombia is possibly the wetland that has experienced the largest mangrove mortality on record due to modification of hydrologic connectivity and consequent hypersaline conditions. We used hydroclimatic, salinity and mangrove basal area data collected in five stations from 1993 to 2015 to study the relation between ongoing mangrove recovery, changes in salinity in the wetland and hydroclimatic changes in precipitation, potential evapotranspiration and freshwater inputs. We found that until 2015, the mangrove ecosystems in CGSM are in general terms in a path of recovery due to the combined effect of favorable hydroclimatic conditions and management operations to increase freshwater inputs into the wetland. We observed in three stations that the annual growth of mangrove basal area increased as pore water salinity decreased. Regarding surface water salinity, El Nino/Southern Oscillation explained most of the inter-annual variability in the wet season by regulating freshwater and in the dry season by regulating potential evaporation from the wetland. However, persistent channel reopening appeared to be the cause for the largest salinity decreases, whereas lack of persistent dredging slowed recovery in other areas. The monitoring of the mangrove-salinity-hydroclimate system must continue in order to increase its understanding and to avoid more recurring episodes of mangrove mortality.
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| 4. |
- Sjöström, Jenny K., et al.
(author)
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Procedure for Organic Matter Removal from Peat Samples for XRD Mineral Analysis
- 2019
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In: Wetlands (Wilmington, N.C.). - : Springer. - 0277-5212 .- 1943-6246. ; 39:3, s. 473-481
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Journal article (peer-reviewed)abstract
- Ombrotrophic peatlands are recognized archives of past atmospheric mineral dust deposition. Net dust deposition rates, grain size, mineral hosts and source areas are typically inferred from down-core elemental data. Although elemental analysis can be time efficient and data rich, there are some inherent limitations. X-ray diffraction (XRD) analysis allowsdirect identification of mineral phases in environmental samples but few studies have applied this method to peat samples and a well-developed protocol for extracting the inorganic fraction of highly organic samples (>95%) is lacking. We tested and compared different levels of pre-treatment: no pre-treatment, thermal combustion (300, 350, 400, 450, 500 and 550 degrees C) and chemical oxidation (H2O2 and Na2S2O8) using a homogenised highly organic (>98%) composite peat sample. Subsequently, minerals were identified by XRD. The results show that combustion is preferred to chemical oxidation because it most efficiently removes organic matter (OM), an important pre-requisite for identifying mineral phases by XRD analysis. Thermally induced phase transitions can be anticipated when temperature is the only factor to take into consideration. Based on the data required in this studythe recommended combustion temperature is 500 degrees C which efficiently removes OM while preserving a majority of common dust minerals.
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| 5. |
- Struyf, E., et al.
(author)
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The Role of Vegetation in the Okavango Delta Silica Sink
- 2015
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In: Wetlands (Wilmington, N.C.). - : Springer Science and Business Media LLC. - 0277-5212 .- 1943-6246. ; 35:1, s. 171-181
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Journal article (peer-reviewed)abstract
- We assessed the role of vegetation and hydrology in the Si cycle in the Okavango Delta. Our results show a large storage of biogenic Si (BSi) in vegetation and the sediments. The biological storage is among the highest observed so far for any ecosystem worldwide. Floodplain vegetation accumulates similar amounts of BSi in both the temporary floodplains and the permanent floodplains, with most values observed between 20 and 100 g Si m(-2). This vegetation Si, after litterfall, contributes to a large biogenic Si storage in the sediments. In temporary floodplains, sediments contain less BSi (375-1950 g Si m(-2) in the top 5 cm) than in the permanent floodplains (1950-3600 g Si m(-2) in the top 5 cm). BSi concentrations in the floodplain sediments decline exponentially indicating rapid dissolution. In the occasional and seasonal floodplains, unidirectional solute transfer from floodplains to the islands will remove Si from the riverine systems. Our work clearly emphasizes the crucial role of floodplains and wetlands in Si transport through tropical rivers, and the potential interference of hydrology with this role.
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