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With growing urbanization cities become hotspots for nutrients. Food items are imported, and food residues, including excreta and not-eaten food, are often exported to landfill sites and water bodies. However, urban sanitation systems can be designed to achieve a high degree of nutrient recovery and food security while counteracting current nutrient resources depletion, environmental degradation, and wasteful energy use. This article illustrates how an extended solid waste hierarchy also including human excreta and wastewater can guide actions to save and recover phosphorus (P) by the three sectors: food industry, households, and waste utilities. P use in diets and agricultural production is not part of the analysis, despite the potential to save P. Novel systems thinking and material flow analysis show that waste prevention can replace over 40% of mined P presently used for making fertilizers. Reuse and recycling of P in excreta and food waste can replace another 15–30%, depending on P efficiency from mine to plate. Keeping excreta separated from other wastewater facilitates such measure. Incineration and land filling are deemed the least appropriate measures since mainly P is recovered in the ashes. The European Union (EU) waste management policy is analyzed for real barriers and opportunities for this approach. The EU Parliament policy guidelines were watered down in the EU Commission's Directives, and today most biowastes are still being landfilled or incinerated instead of recovered. An anticipated overcapacity of incineration plants in Europe threatens to attract all combustible materials and therefore, irrevocably, reduce nutrient recovery. On the other hand, reduced generation and enhanced recovery can delay exhaustion of P resources by several centuries and simultaneously reduce environmental degradation.

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.

Recycling essential plant nutrients like nitrogen (N), phosphorus (P), and potassium (K) from organic waste such as human and animal excreta will be an essential part of sustainable food systems and a circular economy. However, transportation is often cited as a major barrier to increased recycling as organic waste is heavy and bulky, and distances between areas of abundant waste may be far from areas with a need for fertilizers. We investigated the effect of increased input data spatial resolution to an optimization model on the weight, distance, and spatial patterns of transport. The model was run in Sweden and in Pakistan to examine cost-effectiveness of transporting excess excreta to areas of crop need after local recycling. Increasing the resolution of input data from political boundaries (municipalities and districts) to 0.083 decimal grids increased the amount of N requiring transport by 12% in Pakistan and increased P requiring transport by 14% in Sweden. The average distance decreased by 67% (to 44 km) in Pakistan but increased by 1 km in Sweden. Further increasing the resolution to 5 km grids in Sweden decreased the average transportation distance by 9 km (down to 123 km). In both countries, increasing resolution also decreased the number of long-distance heavy transports, and as such costs did not increase as much as total distance and weight transported. Ultimately, transportation in Pakistan seemed financially beneficial: the cost of transport only represented 13% of the NPK fertilizer value transported, and total recycling could even cover 78% of additional fertilizer purchases required. In Sweden, the cost of transporting excreta did not seem cost effective without valuing other potential benefits of increased recycling: costs were three times higher than the fertilizer value transported in excreta at the 5 km resolution. In summary, increasing input data resolution created a more realistic picture of recycling needs. This also highlighted more favorable cost to fertilizer value ratios which could ...

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.

Combatting eutrophication is currently a major challenge for policy makers in the Baltic Sea region, and it is likely to remain so in the decades to come. Although total nutrient loads to the Baltic Sea have recently declined, the gap between current loadings and those required to ensure the desired status is still substantial (Reusch et al. 2018). This Special Issue is dedicated to research that helps inform how the eutrophication challenge might best be addressed by improving our understanding of technological constraints, societal drivers of change, land uses, environmental policies, and innovative governance with stakeholder involvement. These issues are important for the current generation and those to come and are issues we must address in order to succeed in reducing nutrient loads to the desired levels to gradually achieve the desired good environmental status of the Baltic Sea. Currently, we witness a new era of water policies across the entire Baltic Sea region. Our changing climate is impacting on precipitation and runoff, and is also the reason why new EU climate policies seek to tie carbon sinks more visibly to carbon sources. Both these aspects have repercussions for water policies. Thus, solving eutrophication challenges requires sharpening of existing policies and instruments, as well as creating new insights and governance approaches with broad stakeholder involvement in a changing environment. In order to design coherent water and climate policies, and target and implement those policies more efficiently, policy makers need to combine new insights regarding the inhabitants in the region, the catchments, and the Baltic Sea itself. Such insights can be expected from soil scientists, agronomists, hydrogeologists, marine ecologists, economists, and social and policy scientists. What is needed is on the one hand effectively targeted governance at appropriate spatial and temporal scales, adapted to differing interests and motivations of citizens living around the Baltic Sea, and on the other hand fine tuning and co-designing of policies at local, national, Baltic Sea regional and EU level. This Special Issue brings together recent research from four BONUS-funded projects—BONUS BALTICAPP, BONUS GO4BALTIC, BONUS MIRACLE and BONUS SOILS2SEA—that comprised part of the 'Viable Ecosystem' and 'Sustainable Ecosystem Services' BONUS research programmes. The projects addressed these common concerns through somewhat different, but inter-related, themes. Key messages emphasized and discussed in the research papers of this Special Issue are summarized under four interlinked themes: Scenarios for the future, Policies and ecosystem services in water governance, Novel approaches for managing nutrients, and Advanced modelling from field level to the entire Baltic Sea region. ; Funding agencies: BONUS (Art 185) - EUEuropean Union (EU); BONUS (Art 185) - Denmark (Innovation Fund Denmark); BONUS (Art 185) - Estonia (Estonian Research Council ETAG); BONUS (Art 185) - Germany (Forschungszentrum Julich GmbH); BONUS (Art 185) - Latvia (Latvian Ministry

Background: Eutrophication of aquatic environments is a major environmental problem in large parts of the world. In Europe, EU legislation (the Water Framework Directive and the Marine Strategy Framework Directive), international conventions (OSPAR, HELCOM) and national environmental objectives emphasize the need to reduce the input of nutrients to freshwater and marine environments. A widely used method to achieve this is to allow water to pass through a created or restored wetland. However, the large variation in measured nutrient removal rates in such wetlands calls for a systematic review. Methods: Searches for primary studies were performed in electronic databases and on the internet. One author performed the screening of all retrieved articles at the title and abstract level. To check that the screening was consistent and complied with the agreed inclusion/exclusion criteria, subsets of 100 articles were screened by the other authors. When screening at full-text level the articles were evenly distributed among the authors. Kappa tests were used to evaluate screening consistency. Relevant articles remaining after screening were critically appraised and assigned to three quality categories, from two of which data were extracted. Quantitative synthesis consists of meta-analyses and response surface analyses. Regressions were performed using generalized additive models that can handle nonlinear relationships and interaction effects. Results: Searches generated 5853 unique records. After screening on relevance and critical appraisal, 93 articles including 203 wetlands were used for data extraction. Most of the wetlands were situated in Europe and North America. The removal rate of both total nitrogen (TN) and total phosphorus (TP) is highly dependent on the loading rate. Significant relationships were also found for annual average air temperature (T) and wetland area (A). Median removal rates of TN and TP were 93 and 1.2 g m(-2) year(-1.), respectively. Removal efficiency for TN was significantly correlated with hydrologic loading rate (HLR) and T, and the median was 37 %, with a 95 % confidence interval of 29-44 %. Removal efficiency for TP was significantly correlated with inlet TP concentration, HLR, T, and A. Median TP removal efficiency was 46 % with a 95 % confidence interval of 37-55 %. Although there are small differences in average values between the two quality categories, the variation is considerably smaller among high quality studies compared to studies with lower quality. This suggests that part of the large variation between studies may be explained by less rigorous study designs. Conclusions: On average, created and restored wetlands significantly reduce the transport of TN and TP in treated wastewater and urban and agricultural runoff, and may thus be effective in efforts to counteract eutrophication. However, restored wetlands on former farmland were significantly less efficient than other wetlands at TP removal. In addition, wetlands with precipitation-driven HLRs and/or hydrologic pulsing show significantly lower TP removal efficiencies compared to wetlands with controlled HLRs. Loading rate (inlet concentrations x hydraulic loading rates) needs to be carefully estimated as part of the wetland design. More research is needed on the effects of hydrologic pulsing on wetlands. There is also a lack of evidence for long-term (>20 years) performance of wetlands. ; Funding Agencies|Mistra Council for Evidence-based Environmental Management (Mistra EviEM); Swedish Foundation for Strategic Environmental Research (Mistra)Swedish Foundation for Strategic Research

Background: Eutrophication of aquatic environments is a major environmental problem in large parts of the world.In Europe, EU legislation (the Water Framework Directive and the Marine Strategy Framework Directive),international conventions (OSPAR, HELCOM) and national environmental objectives emphasize the need to reducethe input of plant nutrients to freshwater and marine environments. A widely used method to achieve this is to letwater pass through a constructed or restored wetland (CW). However, the large variation in measured nutrientremoval rates in such wetlands calls for a systematic review. The objective of this review is to quantify nitrogen andphosphorus removal rates in constructed or restored wetlands and relate them to wetland characteristics, loading characteristics, and climate factors. Wetlands are created to treat water from a number of different sources. Sources that will be considered in this review include agricultural runoff and urban storm water run-off, as well as aquaculture wastewater and outlets from domestic wastewater treatment plants, with particular attention to thesituation in Sweden. Although the performance of wetlands in temperate and boreal regions is most relevant tothe Swedish stakeholders a wider range of climatic conditions will be considered in order to make a thorough evaluation of climatic factors. Methods: Searches for primary studies will be performed in electronic databases as well as on the internet. Oneauthor will perform the screening of all retrieved articles at the title and abstract level. To check that the screeningis consistent and complies with the agreed inclusion/exclusion criteria, subsets of 100 articles will be screened by the other authors. When screening at full-text level the articles will be evenly distributed among the authors. Kappatests will be used to evaluate screening consistency. Data synthesis will be based on meta-regression. The nutrient removal rates will be taken as response variables and the effect modifiers will be used as explanatory variables. More specifically, the meta-regression will be performed using generalized additive models that can handle nonlinear relationships and major interaction effects. Furthermore, subgroup analyses will be undertaken to elucidate statistical relationships that are specific to particular types of wetlands.

Coastal global oceans are expected to undergo drastic changes driven by climate change and increasing anthropogenic pressures in coming decades. Predicting specific future conditions and assessing the best management strategies to maintain ecosystem integrity and sustainable resource use are difficult, because of multiple interacting pressures, uncertain projections, and a lack of test cases for management. We argue that the Baltic Sea can serve as a time machine to study consequences and mitigation of future coastal perturbations, due to its unique combination of an early history of multistressor disturbance and ecosystem deterioration and early implementation of cross-border environmental management to address these problems. The Baltic Sea also stands out in providing a strong scientific foundation and accessibility to long-term data series that provide a unique opportunity to assess the efficacy of management actions to address the breakdown of ecosystem functions. Trend reversals such as the return of top predators, recovering fish stocks, and reduced input of nutrient and harmful substances could be achieved only by implementing an international, cooperative governance structure transcending its complex multistate policy setting, with integrated management of watershed and sea. The Baltic Sea also demonstrates how rapidly progressing global pressures, particularly warming of Baltic waters and the surrounding catchment area, can offset the efficacy of current management approaches. This situation calls for management that is (i) conservative to provide a buffer against regionally unmanageable global perturbations, (ii) adaptive to react to new management challenges, and, ultimately, (iii) multisectorial and integrative to address conflicts associated with economic trade-offs. ; Funding Agencies|BONUS; EU; Innovation Fund Denmark (Denmark); Estonian Research Council (Estonia); Academy of Finland (Finland); German Federal Ministry of Education and Research (BMBF, Germany); National Centre for Research and Development (Poland); Swedish Research Council (FORMAS, Sweden); Swedish Environmental Protection Agency (Sweden); German Cluster of Excellence "The Future Ocean"