| 1. |
- Agstam-Norlin, O., et al.
(author)
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A 25-year retrospective analysis of factors influencing success of aluminum treatment for lake restoration
- 2021
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In: Water Research. - : Elsevier BV. - 0043-1354 .- 1879-2448. ; 200
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Journal article (peer-reviewed)abstract
- For more than 50 years, aluminum (Al)-salts have been used with varying degrees of success to inactivate excess mobile phosphorus (P) in lake sediments and restore lake water quality. Here, we analyzed the factors influencing effectiveness and longevity of Al-treatments performed in six Swedish lakes over the past 25 years. Trends in post-treatment measurements of total phosphorus (TP), Chlorophyll a (Chl_a), Secchi disk depth (SD) and internal P loading rates (Li) were analyzed and compared to pre-treatment conditions. All measured water quality parameters improved significantly during at least the first 4 years post-treatment and determination of direct effects of Al-treatment on sediment P release (Li) was possible for three lakes. Improvements in TP (-29 to -80%), Chl_a (-50 to -78%), SD (7 to 121%) and Li (-68 to -94%) were observed. Treatment longevity, determined via decreases in surface water TP after treatment, varied from 7 to >47 years. Lake type, Al dose, and relative watershed area were related to longevity. In addition, greater binding efficiency between Al and P was positively related to treatment longevity, which has not previously been shown. Our findings also demonstrate that adequate, long-term monitoring programs, including proper determination of external loads, are crucial to document the effect of Al-treatment on sediment P release and lake water quality.
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| 2. |
- Agstam, Oskar, et al.
(author)
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Optimization of aluminum treatment efficiency to control internal phosphorus loading in eutrophic lakes
- 2020
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In: Water Research. - : Elsevier BV. - 0043-1354 .- 1879-2448. ; 185
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Journal article (peer-reviewed)abstract
- Historical accumulation of phosphorus (P) in lake sediment often contributes to and sustains eutrophic conditions in lakes, even when external sources of P are reduced. The most cost-effective and commonly used method to restore the balance between P and P-binding metals in the sediment is aluminum (Al) treatment. The binding efficiency of Al, however, has varied greatly among treatments conducted over the past five decades, resulting in substantial differences in the amount of P bound per unit Al. We analyzed sediment from seven previously Al treated Swedish lakes to investigate factors controlling binding efficiency. In contrast to earlier work, lake morphology was negatively correlated to binding efficiency, meaning that binding efficiency was higher in lakes with steeply sloping bathymetry than in lakes with more gradually sloping bottoms. This was likely due to Al generally being added directly into the sediment, and not to the water column. Higher binding efficiencies were detected when Al was applied directly into the sediment, whereas the lowest binding efficiency was detected where Al was instead added to the water column. Al dose, mobile sediment P and lake morphology together explained 87% of the variation in binding efficiency among lakes where Al was added directly into the sediment. This led to the development of a model able to predict the optimal Al dose to maximize binding efficiency based on mobile sediment P mass and lake morphology. The predictive model can be used to evaluate cost-effectiveness and potential outcomes when planning Al-treatment using direct sediment application to restore water quality in eutrophic lakes.
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| 3. |
- Agstam, Oskar, et al.
(author)
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Ökad kunskap om kassodlingens miljöeffekter med fokus på fosfor
- 2023
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Reports (other academic/artistic)abstract
- Öppen kassodling av regnbåge och röding i nordliga sjöar och vattenkraftsmagasin är den vanligaste formen av vattenbruk i Sverige idag. Det finns både fördelar och nackdelar med öppen kassodling. Fiskens välfärd är bättre eftersom de lever i en mer naturlig miljö, men avfallsprodukterna från denna typ av vattenbruk kan inte behandlas innan de når miljön.Allt jordbruk påverkar miljön, och vattenbruket är inte annorlunda. En av de främsta formerna av påverkan i samband med livsmedelsproduktion är läckage av näringsämnen. Nästan alla djur i jordbruk behöver utfodras och de flesta odlade växter behöver gödslas. Mycket arbete läggs på att utveckla foder och utfodringsstrategier som maximerar utfodrade djurs förmåga att ta upp och behålla näringsämnen. Men vissa näringsämnen går oundvikligen förlorade i urin, avföring och oätet foder. I dag använder alla former av jordbruk i Sverige näringsämnen på ett effektivare sätt än vad som gjordes tidigare, detta gäller även för vattenbruket. Därför är äldre studier av vattenbrukets miljöpåverkan inte längre fullständigt relevanta eftersom industrin använder näringsämnen mer effektivt än tidigare.Fosfor och kväve är de två huvudsakliga näringsämnena som släpps ut i miljön genom matproduktion. När dessa näringsämnen kommer ut i sötvatten eller i havet kan de bidra till ett problem som kallas "övergödning". Näringsämnen är gödningsmedel som främjar ökad tillväxt i vatten av exempelvis alger och andra växter. När dessa växter dör och sjunker till botten kan de orsaka ytterligare problem, inklusive förbrukning av syre i vattnet, försämring av sedimentkvaliteten och förlust av biologisk mångfald.I svenska fjällsjöar och vattenkraftsmagasin är fosfor typiskt sett det vanligaste begränsande näringsämnet. Eventuella ytterligare fosfortillsatser kan därmed bidra till ökad tillväxt i vattnet och en för stor tillförsel av näringsämnen kommer att orsaka övergödning. Att kvantifiera påverkan på vatten- och sedimentkvalitet vid öppen kassodling i sötvattensförhållanden som är typiska för norra Sverige är en pusselbit på vägen mot en ökad hållbarhet för vattenbruket.I den här rapporten, där studien är finansierad av Jordbruksverket, fokuserar vi på fosfor och dess omvandling i miljön vid fiskodling i öppna kassar. Vi svarar på tre frågor: hur mycket fosfor släpps ut vid fiskodling? Vad händer med fosforn efter att det släppts ut? Hur lång tid tar det för miljön att återhämta sig efter att en fiskodling upphört? Vi fann att drygt hälften (54 %) av fosforn som finns i ett kommersiellt foder släpps ut i miljön. Cirka 1/5 (21 %) av fosforn i fodret kommer sannolikt att bidra till en omedelbar växttillväxt, medan cirka 1/3 (33 %) kommer att deponeras i sedimentet under odlingskassarna.Internationella studier har visat att näringsämnen som frigörs vid vattenbruk i öppna kassar under vissa omständigheter kan ha positiva effekter, särskilt i näringsfattiga system. Dessa fynd kan vara relevanta för svenska vattenkraftmagasin.Att veta vad som händer med fosforn i sedimentet är nyckeln till att förstå den långsiktiga miljöpåverkan från fiskodlingar. Våra resultat antyder att cirka 2/3 (70 %) av fosforn i sediment under fiskodlingar inte kommer att läcka ut. Av de 30 % som kan läcka kommer potentiellt cirka 10 % (dvs. 3 % av totalen) släppas ut varje år. Våra resultat antyder att dagens vattenbruk i öppna kassar är mindre förorenande än det var tidigare. De lyfter också fram behovet av ytterligare arbete med foderutveckling i framtiden samt behovet av en ökad förståelse kring var de näringsämnen som frigörs vid fiskodling tar vägen.Kunskap om miljöpåverkan från fiskodling i öppna kassar i kalla, näringsfattiga system behöver göras tillgänglig och kommuniceras till svenska intressenter. Specifikt behöver vi dokumentera den nuvarande vetenskapliga förståelsen för vart det fosfor (P) som släpps ut vid fiskodling i öppna kassar tar vägen i vatten och sediment. Vi behöver också dokumentera och utvärdera andra nationella eller internationella studier som kan bidra till att förstå den nuvarande svenska situationen. Vi behöver veta mer om den långsiktiga depositionen av det fosfor som frigörs vid fiskodling, inklusive den tid det tar för återhämtning efter att fiskodlingen upphört.
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| 4. |
- Baho, Didier Ludovic, et al.
(author)
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Assessing temporal scales and patterns in time series: Comparing methods based on redundancy analysis
- 2015
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In: Ecological Complexity. - : Elsevier BV. - 1476-945X. ; 22, s. 162-168
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Journal article (peer-reviewed)abstract
- Time-series modelling techniques are powerful tools for studying temporal scaling structures and dynamics present in ecological and other complex systems and are gaining popularity for assessing resilience quantitatively. Among other methods, canonical ordinations based on redundancy analysis are increasingly used for determining temporal scaling patterns that are inherent in ecological data. However, modelling outcomes and thus inference about ecological dynamics and resilience may vary depending on the approaches used. In this study, we compare the statistical performance, logical consistency and information content of two approaches: (i) asymmetric eigenvector maps (AEM) that account for linear trends and (ii) symmetric distance-based Moran's eigenvector maps (MEM), which requires detrending of raw data to remove linear trends prior to analysis. Our comparison is done using long-term water quality data (25 years) from three Swedish lakes. This data set therefore provides the opportunity for assessing how the modelling approach used affects performance and inference in time series modelling. We found that AEM models had consistently more explanatory power than MEM, and in two out of three lakes AEM extracted one more temporal scale than MEM. The scale-specific patterns detected by AEM and MEM were uncorrelated. Also individual water quality variables explaining these patterns differed between methods, suggesting that inferences about systems dynamics are dependent on modelling approach. These findings suggest that AEM might be more suitable for assessing dynamics in time series analysis compared to MEM when temporal trends are relevant. The AEM approach is logically consistent with temporal autocorrelation where earlier conditions can influence later conditions but not vice versa. The symmetric MEM approach, which ignores the asymmetric nature of time, might be suitable for addressing specific questions about the importance of correlations in fluctuation patterns where there are no confounding elements of linear trends or a need to assess causality. (C) 2015 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).
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| 5. |
- Baho, Didier Ludovic, et al.
(author)
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Microplastics in terrestrial ecosystems: Moving beyond the state of the art to minimize the risk of ecological surprise
- 2021
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In: Global Change Biology. - : Wiley. - 1354-1013 .- 1365-2486. ; 27, s. 3969-3986
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Journal article (peer-reviewed)abstract
- Microplastic (plastic particles measuring <5mm) pollution is ubiquitous. Unlike in other well-studied ecosystems, for example, marine and freshwater environments, microplastics in terrestrial systems are relatively understudied. Their potential impacts on terrestrial environments, in particular the risk of causing ecological surprise, must be better understood and quantified. Ecological surprise occurs when ecosystem behavior deviates radically from expectations and generally has negative consequences for ecosystem services. The properties and behavior of microplastics within terrestrial environments may increase their likelihood of causing ecological surprises as they (a) are highly persistent global pollutants that will last for centuries, (b) can interact with the abiotic environment in a complex manner, (c) can impact terrestrial organisms directly or indirectly and (d) interact with other contaminants and can facilitate their transport. Here, we compiled findings of previous research on microplastics in terrestrial environments. We systematically focused on studies addressing different facets of microplastics related to their distribution, dispersion, impact on soil characteristics and functions, levels of biological organization of tested terrestrial biota (single species vs. assemblages), scale of experimental study and corresponding ecotoxicological effects. Our systematic assessment of previous microplastic research revealed that most studies have been conducted on single species under laboratory conditions with short-term exposures; few studies were conducted under more realistic long-term field conditions and/or with multi-species assemblages. Studies targeting multi-species assemblages primarily considered soil bacterial communities and showed that microplastics can alter essential nutrient cycling functions. More ecologically meaningful studies of terrestrial microplastics encompassing multi-species assemblages, critical ecological processes (e.g., biogeochemical cycles and pollination) and interactions with other anthropogenic stressors must be conducted. Addressing these knowledge gaps will provide a better understanding of microplastics as emerging global stressors and should lower the risk of ecological surprise in terrestrial ecosystems.
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| 6. |
- Collentine, Dennis, et al.
(author)
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Realising the potential of natural water retention measures in catchment flood management: trade-offs and matching interests
- 2018
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In: Journal of Flood Risk Management. - : Wiley. - 1753-318X. ; 11, s. 76-84
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Journal article (peer-reviewed)abstract
- Natural water retention measures (NWRM) are a multifunctional form of green infrastructure that can play an important role in catchment-scale flood risk management. While green infrastructure based on natural processes is increasingly recognised as being complementary to traditional flood control strategies based on grey infrastructure in urban areas, there are a number of outstanding challenges with their widespread uptake. At a catchment scale, it is widely accepted that NWRM in upstream areas based on the concept of 'keeping the rain where it falls' can help reduce the risk of downstream flooding by enhancing or restoring natural hydrological processes including interception, evapotranspiration, infiltration, and ponding. However, both the magnitude of flood risk reduction and the institutional structures needed for widespread uptake of NWRM are inadequately understood. Implementing NWRM can involve trade-offs, especially in agricultural areas. Measures based on drainage management and short rotation forestry may help 'keep the rain where it falls' but can result in foregone farm income. To identify situations where the implementation of NWRM may be warranted, an improved understanding of the likely reductions in downstream urban flood risk, the required institutional structures for risk management and transfer, and mutually acceptable farm compensation schemes are all needed.
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| 7. |
- Dahlgren Strååt, Kim
(author)
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Simulating Transport and Understanding Future Fluxes of Organic Carbon in Rivers Draining into the Baltic Sea
- 2017
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Licentiate thesis (other academic/artistic)abstract
- Riverine organic (TOC, Total Organic Carbon) and inorganic (DIC, Dissolved Inorganic Carbon) carbon are the main sources of carbon in the Baltic Sea. While the importance of this contribution has been evaluated, there are currently several gaps in our knowledge of the mechanisms governing organic carbon dynamics in this region, especially for the particulate form, and the impact of future climate change on organic carbon transport. This licentiate thesis addresses this research deficit by (1) developing a model for assessing the flux of particulate organic carbon (POC), and by (2) simulating the potential climate effects on the transport and fate of TOC, both particulate and dissolved organic carbon, in the Baltic Sea environment.Study I developed a novel dynamic model for simulating the generation and transport of POC in all the major rivers discharging into the Baltic Sea. The POC load was assessed using algorithms for the processes governing the input i.e. erosion, litterfall and in-stream primary production. Using daily information on precipitation and temperature, the water discharge from each river was calculated. The total annual POC load from the Baltic Sea drainage basin was predicted within a factor of about 2 and was estimated to be 0.34 Tg POC, or 7-10 % of the annual TOC. The prediction of the timing of the monthly peak loads, however, was hampered by the current lack of field measurements of POC loads to the Baltic Sea.Study II assessed the potential future climate effects on riverine TOC (particulate and dissolved organic carbon, DOC) in the Baltic Sea drainage basin. A small decrease in POC load (-7 %) was predicted and no changes in DOC load on an annual and total basin scale, but the simulations showed significant variations between seasons and across sub-basins by the end of this century. Seasonal total loads were predicted to increase in winter and decrease in summer. Due to counterbalancing increases and decreases in predicted TOC loads in various parts of the Baltic Sea catchment, the impact of climate change on the total carbon budget in this region was limited. However, our simulation results indicated significant differences over time in POC and DOC export across the six Baltic Sea sub-basins, and an altered seasonal pattern in the timing and magnitude of the delivery.This thesis comprises a first attempt to better describe the mechanisms and dynamics of OC generation and transport in the Baltic Sea catchment and assess the potential climate effects on the transport with a spatiotemporal resolution. The work provides a starting point for further development of the understanding of large scale organic carbon export and how it may be affected in the future. This thesis also discuss the role of riverine organic carbon in biogeochemical processes, food web structures and contaminant transport in inland, coastal and marine waters.
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| 8. |
- de Sá, Luis, et al.
(author)
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Studies of the effects of microplastics on aquatic organisms: What do we know and where should we focus our efforts in the future?
- 2018
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In: Science of the Total Environment. - : Elsevier BV. - 0048-9697 .- 1879-1026. ; 645, s. 1029-1039
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Research review (peer-reviewed)abstract
- The effects of microplastics (MP) on aquatic organisms are currently the subject of intense research. Here, we provide a critical perspective on published studies of MP ingestion by aquatic biota. We summarize the available research on MP presence, behaviour and effects on aquatic organisms monitored in the field and on laboratory studies of the ecotoxicological consequences of MP ingestion. We consider MP polymer type, shape, size as well as group of organisms studied and type of effect reported. Specifically, we evaluate whether or not the available laboratory studies of MP are representative of the types of MPs found in the environment and whether or not they have reported on relevant groups or organisms. Analysis of the available data revealed that 1) despite their widespread detection in field-based studies, polypropylene, polyester and polyamide particles were under-represented in laboratory studies; 2) fibres and fragments (800-1600 mu m) are the most common form of MPs reported in animals collected from the field; 3) to date, most studies have been conducted on fish; knowledge is needed about the effects of MPs on other groups of organisms, especially invertebrates. Furthermore, there are significant mismatches between the types of MP most commonly found in the environment or reported in field studies and those used in laboratory experiments. Finally, there is an overarching need to understand the mechanism of action and ecotoxicological effects of environmentally relevant concentrations of MPs on aquatic organism health. (c) 2018 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).
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| 9. |
- de Wit, Heleen A., et al.
(author)
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Current Browning of Surface Waters Will Be Further Promoted by Wetter Climate
- 2016
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In: ENVIRONMENTAL SCIENCE & TECHNOLOGY LETTERS. - : American Chemical Society (ACS). - 2328-8930. ; 3:12, s. 430-435
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Journal article (peer-reviewed)abstract
- Browning of surface waters because of increasing terrestrial dissolved organic carbon (OC) concentrations is a concern for drinking water providers and can impact land carbon storage. We show that positive trends in OC in 474 streams, lakes, and rivers in boreal and subarctic ecosystems in Norway, Sweden, and Finland between 1990 and 2013 are surprisingly constant across climatic gradients and catchment sizes (median, +1.4% year(-1); interquartile range, +0.8-2.0% year(-1)), implying that water bodies across the entire landscape are browning. The largest trends (median, +1.7% year(-1)) were found in regions impacted by strong reductions in sulfur deposition, while subarctic regions showed the least browning (median, +0.8% year(-1)). In dry regions, precipitation was a strong and positive driver of OC concentrations, declining in strength moving toward high rainfall sites. We estimate that a 10% increase in precipitation will increase mobilization of OC from soils to freshwaters by at least 30%, demonstrating the importance of climate wetting for the carbon cycle. We conclude that upon future increases in precipitation, current browning trends will continue across the entire aquatic continuum, requiring expensive adaptations in drinking water plants, increasing land to sea export of carbon, and impacting aquatic productivity and greenhouse gas emissions.
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| 10. |
- Djodjic, Faruk, et al.
(author)
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Cost effectiveness of nutrient retention in constructed wetlands at a landscape level
- 2022
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In: Journal of Environmental Management. - : Elsevier BV. - 0301-4797 .- 1095-8630. ; 324
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Journal article (peer-reviewed)abstract
- Since 1990, over 13 000 ha of constructed wetlands (CWs) have been implemented to increase biodiversity and reduce nitrogen (N) and phosphorus (P) loads to Swedish waters. Despite the considerable number of CWs and ambitious investments planned for the coming three years, there is limited follow up of cost-efficiency of catchment- and landscape-scale nutrient retention by existing CWs. Such follow up evaluation could provide clear guidance regarding optimal size and location of future CWs. We present a three-step modelling approach to assess cost-efficiency of 233 CWs in two Swedish regions (East, 4321 km2, and West, 916 km2). Modelled nutrient retention in CWs was predominantly low, especially in the East, due to their suboptimal location in catchments, e.g., with inadequate upstream areas (low hydraulic loads) and/or low share of arable land (low nutrient loads). Suboptimal location of CWs generates both higher than necessary costs and low area-specific nutrient retention, leading to low cost-efficiency. Some high cost-efficiency CWs were identified, especially for N retention in the West. To increase their cost-efficiency, continued investments in CWs require clear guidance and instructions. To achieve optimal placement, both CW site and size in relation to incoming hydraulic and nutrient loads must be considered.
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