| 1. |
- Bojcevska, Hristina, 1977-, et al.
(författare)
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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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Ingår i: Ecological Engineering. - 0925-8574 .- 1872-6992. ; 29:1, s. 66-76
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Tidskriftsartikel (refereegranskat)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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| 2. |
- Drangert, Jan-Olof, 1944-, et al.
(författare)
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Generating Applicable Environmental Knowledge among Farmers : Experiences from Two Regions in Poland
- 2017
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Ingår i: Agroecology and Sustainable Food Systems. - : Taylor & Francis. - 2168-3565 .- 2168-3573. ; 41:6, s. 671-690
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Tidskriftsartikel (refereegranskat)abstract
- Raising environmental awareness among farmers is the key to successfully reaching environmental goals. The present study assessed the knowledge development process and the raising of environmental awareness among 30 farmers from Poland exposed to four approaches aimed to reduce phosphorus (P) and nitrogen (N) losses to water. The farmers were interviewed with open-ended questions on-farm both before and after the project intervention. As hoped, the farmers attempted to adjust their farm practices to the European Union regulations, which are in some cases supported by subsidies. As a complement, the project offered tools for system-thinking based on farm data and support from agricultural advisors: a) a survey of plant-available P, potassium (K), magnesium (Mg), and soil pH, resulting in soil maps; b) assessment of nitrogen leaching risks from individual fields; c) compilation of a farm-gate balance. Farmers were positive to soil surveys and maps, but had limited understanding of the nutrient balance concept and calculations. They generally relied on their own experiences regarding fertilization rather than on calculated farm nutrient balances and leaching risks. Farmers’ understanding and willingness to adopt new approaches to improve nutrient efficiency and reduce negative environmental impacts are discussed.
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| 3. |
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| 4. |
- Tonderski, Karin, 1958-, et al.
(författare)
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BONUS MIRACLE ‐ Mediating integrated actions for sustainable ecosystem services in a changing climate
- 2018
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Water and nutrient governance in the Baltic Sea Region face several challenges. The future is highly uncertain due to climate change and on-going land-use changes, and different sectors works towards partly contradicting objectives, which makes it difficult to bring about integrated governance. In BONUS MIRACLE, a social learning process has been enacted to identify new configurations for water governance based on the hypothesis that more effective approaches to 'nutrient governance' need to bring on-board new constellations of actors with stakes in local issues that are interconnected with nutrient enrichment. A series of learning events between stakeholder groups and researchers in four case areas have been orchestrated. To support the process of reconciling stakeholder interests, researchers were asked to provide ´on-demand´ results regarding effects, cost-efficiency and benefits of suggested measures on water flow, nutrient transport (using the HYPE model) and other ecosystem services benefits under different climate change and land-use scenarios. Results were visualized in the MIRACLE Visualization Tool. Lessons learnt and results of policy analyses were used to discuss governance approaches on the BSR level that could support more integrated actions. An important project insight is that case level stakeholders, in general, are not interested in learning how different measures perform in reducing nutrient enrichment at a larger Baltic Sea basin level. Rather, they are interested in the impact measures have in terms of addressing multiple demands in the local settings. Regarding stakeholder positions, insights have emerged pertaining the important role position holders play in hindering or enabling change processes. In the ´pathways to change´, application of mineral fertilizers was one of the more cost-efficient measures suggested, along with creation of increased water retention, floodplains and wetlands. The latter also provide other ecosystem service benefits, and an approach was developed to interactively assess those, despite considerable knowledge gaps regarding effects and values. On the BSR level, the Visualization Tool provided useful learning support by visualizing E-HYPE model results regarding water flow and nutrient transport, as on this level the stakeholder´s system of interest is on governance innovations that address the nutrient issue. E-HYPE scenario modeling showed that while the mean water flow is expected to decrease in some southern BSR catchments, a substantial increase is predicted for most others. Similarly, the load of nitrogen may increase up to 25 % in some parts of the northern BSR, whereas a slight decrease is predicted for the south/southwestern parts. Governance innovations are needed that can accommodate those differences. However, current policies are insufficiently coordinated and integrated between sectors, due to imbalanced power relations and opposing agendas. This remains a constraint for the effectiveness of existing policy strategies, regulations and directives in addressing multiple ecosystem benefits. The involvement of local stakeholders needs to be strengthened and new models for cooperative and collective measures with intermediaries tested, to stimulate the use of local knowledge in improving the effectiveness and efficiency of management measures and reducing transaction costs. The synthesized BONUS MIRACLE results will be translated into a "Roadmap for improving water resource management in the Baltic Sea Region", with suggestions for adaptation of policies, institutional settings and governance arrangements.
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| 5. |
- Weisner, Stefan, 1954-, et al.
(författare)
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Näringsavskiljning i anlagda våtmarker i jordbruket : Analys av mätresultat och effekter av landsbygdsprogrammet
- 2015
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- I denna rapport sammanställs och analyseras tidigare mätningar av avskiljning av fosfor och kväve i anlagda våtmarker. Resultaten indikerar hur hög fosfor och kväveavskiljning som kan uppnås i anlagda våtmarker i jordbrukslandskap i Sverige. Resultaten har även använts för att ta fram nya modeller för beräkning av avskiljning av fosfor och kväve i våtmarker där mätningar inte gjorts. Slutligen har dessa modeller använts för att beräkna hur hög avskiljning som kommer att uppnås i våtmarker som beviljats stöd inom landsbygdsprogrammet åren 2007– 2013 och hur mycket transporten av kväve och fosfor till havet kommer att minskas genom att dessa våtmarker har anlagts.De nya mätresultaten visar att fosforavskiljning underskattats i tidigare mätningar och i modeller som använts i tidigare utvärderingar. I enskilda väl utformade och placerade våtmarker kan 100 kilo fosfor och 1 000 kilo kväve per hektar våtmarksyta och år avskiljas. De nya resultaten indikerar även att man i framtida program för anläggning av våtmarker i jordbrukslandskapet bör kunna uppnå en genomsnittlig fosfor och kväveavskiljning på 50 respektive 500 kilo per hektar våtmarksyta och år, förutsatt att näringsavskiljning kan prioriteras vid placering och utformning av våtmarker. Kostnaden för avskiljning uppskattas till cirka 100 kronor per kilo fosfor och cirka 10 kronor per kilo kväve för sådana våtmarker om 50 procent av kostna derna fördelas till andra ekosystemtjänster och biologisk mångfald.Modellberäkningar på ett urval av våtmarker inom landsbygdsprogrammet som skalats upp till de 5 261 hektar som beviljats stöd under 2007–2013 visar att transporten av fosfor och kväve till lokala vattendrag kommer att minskas med cirka 25 ton fosfor per år och cirka 200 ton kväve per år. Det innebär att minsk ningen av transporten till havet som åstadkoms genom dessa våtmarker blir cirka 18 ton fosfor per år och cirka 170 ton kväve per år, vilket motsvarar 1,9 respektive 0,5 procent av transporten till havet från jordbruksmark.Anläggningen av våtmarker inom landsbygdsprogrammet har således haft betydelse för att minska fosfor och kvävetransporter såväl till lokala vattendrag som till havet. En jämförelse av genomsnittlig avskiljning per hektar våtmarksyta mellan landsbygdsprogrammet och den avskiljning som uppnås i individuella våtmarker visar emellertid att effektiviteten skulle kunna höjas betydligt i framtiden genom en bättre placering och utformning av våtmarker i landskapet.
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| 6. |
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| 7. |
- Akram, Usman, 1984-
(författare)
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Closing nutrient cycles
- 2020
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Adequate and balanced crop nutrition – with nitrogen (N), phosphorus (P), and potassium (K) – is vital for sustainable crop production. Inadequate and imbalanced crop nutrition contributes to the crop yield gaps – a difference in actual and potential crop yield. Yield gap is one of the many causes of insufficient food production, thus aggravating hunger and malnourishment across the globe. On the other hand, an oversupply of nutrients is highly unsustainable, in terms of both resource conservation and global environmental health. A decreasing excreta recycling in crop production is one of the many reasons for nutrient imbalances in agriculture. Previous studies show that increasing agricultural specialization leads to spatial separation of crop and animal production. Increasing distance between excreta production and crop needs is one of the leading factors that cause reduced excreta recycling. Studies focusing on excreta recycling show that a substantial barrier to a more efficient excreta nutrient reuse is the expensive transportation of bulky volumes of excreta over long distances. In order to overcome that barrier, more detailed spatial estimates of distances between excreta production and crop nutrient needs, and the associated costs for complete excreta transport in an entire country are needed. Hence, the overall aim of this thesis was to quantify the amount of nutrients in the excreta resources compared to the crop nutrient needs at multiple scales (global, national, subnational, and local), and to analyze the need for excreta transports, total distances and costs, to meet the crop nutrient needs in a country.On the global scale, annual (2000-2016) excreta supply (livestock and human) could provide at least 48% of N, 57% of P, and 81% of K crop needs. Although excreta supply was not enough to cover the annual crop nutrient needs at the global scale, at least 29 countries for N, 41 for P, and 71 for K had an excreta nutrient surplus. When including the annual use of synthetic fertilizers, at least 42 additional countries had a N surplus, with the equivalent figures for P being 17 countries, whereas 8 additional countries attained a K surplus. At the same time, when accounting for the use of synthetic fertilizers, each year, at least 57 countries had an N deficit, 70 a P deficit, and 51 countries a K deficit, in total equivalent to 14% of global N and 16% of each P and K crop needs. The total surplus in other countries during the period was always higher than the deficit in the countries with net nutrient deficits, except for P for some years. Unfortunately, both the deficits of the deficit countries and surpluses of the surplus countries were increasing substantially during the 17 years. Such global divergence in nutrient deficits and surpluses have clear implications for global food security and environmental health.A district-scale investigation of Pakistan showed that the country had a national deficit of 0.62 million tons of P and 0.59 million tons of K, but an oversupply of N. The spatial separation was not significant at this resolution; only 6% of the excreta N supply needed to be transported between districts. Recycling all excreta, within and between districts, could cut the use of synthetic N to 43% of its current use and eliminate the need for synthetic K, but there would be an additional need of 0.28 million tons of synthetic P to meet the crop nutrient needs in the entire country. The need for synthetic fertilizers to supplement the recycled excreta nutrients would cost USD 2.77 billion. However, it might not be prohibitively expensive to correct for P deficiencies because of the savings on the costs of synthetic N, and K. Excreta recycling could promote balanced crop nutrition at the national scale in Pakistan, which in turn could eliminate the nutrient-related crop yield gaps in the country.The municipal-scale investigation using Swedish data showed that the country had a national oversupply of 110,000 tons of N, 6,000 tons of P, and 76,000 tons of K. Excreta could provide up to 75% of N and 81% of P, and more than 100% of the K crop needs in the country. The spatial separation was pronounced at the municipal scale in the country. Just 40% of the municipalities produced over 50% of the excreta N and P. Nutrient balance calculations showed that excreta recycling within municipalities could provide 63% of the P crop needs. Another 18% of the P crop needs must be transported from surplus municipalities to deficit municipalities. Nationally, an optimized reallocation of surplus excreta P towards the P deficit municipalities would cost USD 192 million for a total of 24,079 km truck transports. The cost was 3.7 times more than the total NPK fertilizer value transported, and that met the crop nutrient needs. It was concluded that Sweden could potentially reduce its dependence on synthetic fertilizers, but to cover the costs of an improved excreta reuse would require valuing the additional benefits of recycling.An investigation was also done to understand the effect of the input data resolution on the results (transport needs and distances) from a model to optimize excreta redistribution. The results showed that the need for excreta transports, distances, and spatial patterns of the excreta transports changed. Increasing resolution of the spatial data, from political boundaries in Sweden and Pakistan to 0.083 decimal grids (approximately 10 km by 10 km at the equator), showed that transport needs for excreta-N increased by 12% in Pakistan, and the transport needs for excreta-P increased by 14% in Sweden. The effect of the increased resolution on transport analysis showed inconsistency in terms of the excreta total nutrient transportation distance; the average distance decreased by 67% (to 44 km) in Pakistan but increased by 1 km in Sweden. A further increase in the data resolution to 5 km by 5 km grids for Sweden showed that the average transportation distance decreased by 9 km. In both countries, increasing input data resolution resulted in a more favorable cost to fertilizer value ratios. In Pakistan, the cost of transport was only 13% of the NPK fertilizer value transported at a higher resolution. In Sweden, the costs decreased from 3.7 (at the political resolution) to slightly higher than three times of the fertilizer value transported in excreta at the higher data resolution.This Ph.D. thesis shows that we could potentially reduce the total use of synthetic fertilizers in the world and still reduce the yield gaps if we can create a more efficient recycling of nutrients both within and between countries, and a more demand adapted use of synthetic fertilizers.
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| 8. |
- Andersson, J., et al.
(författare)
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Free water surface wetlands for wastewater treatment in Sweden : Nitrogen and phosphorus removal
- 2005
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Ingår i: Water Science and Technology. - 0273-1223 .- 1996-9732. ; 51:9, s. 39-46
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Tidskriftsartikel (refereegranskat)abstract
- In South Sweden, free water surface wetlands have been built to treat wastewater from municipal wastewater treatment plants. Commonly, nitrogen removal has been the prime aim, though a significant removal of tot-P and BOD7 has been observed. In this study, performance data for 3-8 years from four large (20-28 ha) FWS wetlands have been evaluated. Two of them receive effluent from WWTP with only mechanical and chemical treatment. At the other two, the wastewater has also been treated biologically resulting in lower concentrations of BOD7 and NH4+-N. The wetlands performed satisfactorily and removed 0.7-1.5 ton N ha-1 yr-1 as an average for the time period investigated, with loads between 1.7 and 6.3 ton N ha-1 yr-1. Treatment capacity depended on the pre-treatment of the water, as reflected in the k20-values for N removal (first order area based mode). In the wetlands with no biological pre-treatment, the k20-values were 0.61 and 1.1 m month-1, whereas for the other two they were 1.7 and 2.5 m month-1. P removal varied between 10 and 41 kg ha-1 yr-1, and was related to differences in loads, P speciation and to the internal cycling of P in the wetlands. © IWA Publishing 2005.
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| 9. |
- Bojcevska, Hristina, 1977-, et al.
(författare)
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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
-
Ingår i: Ecological Engineering. - : Elsevier BV. - 0925-8574 .- 1872-6992. ; 29:1, s. 66-76
-
Tidskriftsartikel (refereegranskat)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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| 10. |
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