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Approximately 8.6% of Swedish agricultural soils are classified as organic soils (Berglund et al. 2010). In the early 19th century, the Swedish government drained peatlands to make land suitable for agricultural production (Berglund 2008). When drained, organic soils are a significant source of CO2 because of the breakdown of organic materials (Ballantyne et al. 2014). In order to reach climate national and international climate goals, the agricultural sector has the important task of reducing its climate impact and thus greenhouse gas (GHG) emissions. For this purpose, the European Union and some Nordic countries see potential in changing land use on organic soils to ley production or perennial green fallow as an alternative to rewetting peatlands. However, there is lacking scientific consensus about the effectiveness of reducing GHG emissions using these interventions. In many studies, different sites or years are compared, which limits the comparability between land uses because of the many variables that influence the outcome (Kasimir-Klemedtsson et al. 1997; Maljanen et al. 2001; Lohila et al. 2004; Beetz et al. 2013), and thus the conclusions that can be taken for future policies. This systematic review aims to answer the question of which land use(s) can be suggested as a valid alternative for decreased GHG emissions on organic soils in temperate and boreal climates. The review will be conducted by establishing a detailed review protocol, following the Collaboration for Environmental Evidence (CEE) guidelines (Pullin et al. 2022), including a methodology for literature search, eligibility screening, data extraction, and critical appraisal. After implementation of the protocol, and if enough valid data can be found, data synthesis, interpretation and a scientific publication about the outcomes will follow. Sources: Beetz, S., Liebersbach, H., Glatzel, S., Jurasinski, G., Buczko, U., & Höper, H. (2013). Effects of land use intensity on the full greenhouse gas balance in an Atlantic peat bog. Biogeosciences, 10(2), 1067–1082. https://doi.org/10.5194/bg-10-1067-2013Berglund, K. (2008). Torvmarken, en resurs i jordbruket igår, idag och även i morgon. In Svensk mosskultur - Odling, torvanvändning och landskapets förändring. (Vol. 41, pp. 483–498). Runefelt, Leif.Berglund, Ö., & Berglund, K. (2010). Distribution and cultivation intensity of agricultural peat and gyttja soils in Sweden and estimation of greenhouse gas emissions from cultivated peat soils. Geoderma, 154(3), 173–180. https://doi.org/https://doi.org/10.1016/j.geoderma.2008.11.035Andrew S Pullin, Geoff K Frampton, Barbara Livoreil, & Gillian Petrokofsky. (2022). Guidelines and Standards for Evidence Synthesis in Environmental Management. Guidelines and Standards for Evidence synthesis in Environmental Management. Version 5.1. https://environmentalevidence.org/information-for-authors/ [5-01-23]Kasimir-Klemedtsson, Å., Klemedtsson, L., Berglund, K., Martikainen, P., Silvola, J., & Oenema, O. (1997). Greenhouse gas emissions from farmed organic soils: a review. Soil Use and Management, 13(s4), 245–250. https://doi.org/https://doi.org/10.1111/j.1475-2743.1997.tb00595.xLohila, A., Aurela, M., Tuovinen, J.-P., & Laurila, T. (2004). Annual CO2 exchange of a peat field growing spring barley or perennial forage grass. Journal of Geophysical Research: Atmospheres, 109(D18). https://doi.org/https://doi.org/10.1029/2004JD004715Maljanen, M., Martikainen, P. J., Walden, J., & Silvola, J. (2001). CO2 exchange in an organic field growing barley or grass in eastern Finland. Global Change Biology, 7(6), 679–692. https://doi.org/https://doi.org/10.1111/j.1365-2486.2001.00437.x

Background Soil-based on-site wastewater treatment systems (OWSs) are suspected to contribute to eutrophication of surface waters, due to the discharge of phosphorus (P). However, along the flow path between the facilities and surface waters, different processes contribute to delay the transport of phosphorus through the ground. This may reduce the unwanted impact on receiving water bodies. However, the strength and significance of this so-called soil retention remains unclear. In Sweden, there are nearly one million OWSs. To protect surface waters, a high P removal rate (up to 90%) is often required by the local municipalities. However, since these requirements may have costly consequences to property owners, it is debated as to whether they are too strict. In this debate, it is often claimed that the retention of P occurring in natural environments may be underestimated by authorities. Accordingly, there is a need for a scrutiny of the available evidence related to soil retention of phosphorus from OWSs. This is the objective of the planned systematic map. Focus will be on boreal and temperate climate zones. Methods Searches will be made for peer-reviewed articles and grey literature using bibliographic databases, search engines, specialist websites and stakeholder contacts. The references will be screened for relevance according to a predefined set of eligibility criteria. At stage one, after testing and clarifying the eligibility criteria, the references will be single-screened based on title and abstract. At stage two, potentially relevant references will be screened in full-text independently by two reviewers. We will compile a detailed database of the relevant studies. Moreover, a narrative report will be produced, describing the research landscape in general terms. This will be carried out with a conceptual model, describing the processes involved in P retention in natural environments, as a foundation. It will be discussed where the respective studies/study types fit into the conceptual model, and also evaluated how each study/study type can be related to the overarching question of eutrophication. Moreover, we will describe identified knowledge gaps that warrant further primary research effort, as well as identified knowledge clusters that could be suitable for systematic reviews.

Systematic reviews are becoming a widely accepted gold standard in evidence synthesis for evidence-based and –informed policy and practice. Many organisations exist to coordinate the registration, conduct and publication of systematic reviews across a range of disciplines, including medicine, international development, and environmental management and biodiversity conservation. As the term ‘systematic review’ becomes more widely recognised, however, there is a risk that stakeholders may have only partial understanding of the rigorous methods required to produce a reliable systematic review. Here, we highlight one such example from the field of education and international development, where a World Bank report claimed to ‘systematically review’ six ‘systematic reviews’ that found divergent results. We critically appraise the six included reviews and the World Bank report itself using an a priori quality assessment tool. Our analysis shows that none of the six included reviews are classifiable as systematic reviews according to widely accepted criteria. We also find that the World Bank report failed to use true systematic review methods to synthesise the included reviews findings. Our study demonstrates the risks associated with partial understanding of the added value associated with systematic reviews and highlights a need for improved awareness of what systematic reviews are. Keywords: Evidence-based policy, Evidence, Evidence synthesis, Grey literature, Risk of bias, Science policy

Background:\ud The bacterium Bacillus thuringiensis serovar israelensis (Bti) is used in many countries as a biological larvicide to control dipteran insects of the suborder Nematocera, especially mosquitoes and black flies. Bti is generally accepted to be target-specific and efficient, with low potential for development of resistance among the target species. However, even though Bti may have minimal direct effects on non-target organisms, it might potentially be associated with knock-on effects on food webs and other ecosystem properties, including biodiversity and ecosystem functioning. Evidence from previous research is mixed, with some finding no evidence for indirect effects on biodiversity and ecosystem-level properties, but others indicating that such effects are possible. The fact that many studies have been conducted by organisations coordinating the control programs, and that many of those studies have been published outside peer reviewed scientific journals, highlights the challenges for decision makers and others to assess the results of the existing studies. In this protocol we outline how we aim to systematically and transparently synthesise all available evidence in a forthcoming systematic review.\ud \ud Methods:\ud We will use six bibliographic databases/platforms and the online search engines Google and Google Scholar in searches for literature. Searches will also be made on specialist websites. We will screen the search results for eligibility in stage one based on title and abstract, and in stage two based on the full text of the material. At stage one, after testing and clarifying the eligibility criteria, two reviewers will split and single screen the search results. At stage two the articles will be screened independently by two reviewers. We have developed a preliminary critical appraisal tool that will be used as basis for assessing study validity. Each study will be critically appraised independently by two reviewers. Disagreements will be reconciled through discussions seeking to reach consensus. It is unclear whether a quantitative synthesis based on meta-analysis will be feasible. A narrative synthesis will include descriptive statistics outlining the evidence base in terms of bibliographic information and study metadata. A narrative synthesis table in the form of an Excel spreadsheet will be provided.

Wetlands are essential parts of Arctic landscapes, playing important roles for the sustainable development of the region, and linking to climate change and adaptation, ecosystem services, and the livelihood of local people. The effects of human and natural change drivers on key landscape characteristics of Arctic wetlands may be critical for ecosystem resilience, with some functional aspects still poorly understood. This paper reviews the scientific literature on change drivers for Arctic wetland landscapes, seeking to identify the main studied interactions among different drivers and landscape characteristics and their changes, as well as emerging research gaps in this context. In a total of 2232 studies of various aspects of Arctic wetland landscapes found in the literature, natural drivers and climate change have been the most studied change drivers so far, particularly regarding their impacts on carbon cycling, plant communities and biodiversity. In contrast, management plans, land use changes, and nutrient-pollutant loading, have not been investigated as much as human drivers of Arctic wetland change. This lack of study highlights essential gaps in wetland related research, and between such research and management of Arctic wetlands.

Water quality in freshwater lakes and coastal areas has deteriorated in many densely populated areas with increasingly intensive agriculture. For example, eutrophication of aquatic environments has become a major environmental problem in large parts of the world. Biogeochemical transformations occurring in wetlands generally result in reduced nutrient content of water, but quite commonly these ecosystems have been drained or filled to create new forest and arable land. In recent decades efforts have been made to compensate for the losses of natural wetlands by creating new wetlands or restore drained wetlands. However, the large variation in measured nutrient removal rates in such wetlands has made it difficult to assess the effectiveness of such interventions. In this chapter we discuss the role of created wetlands in regulating water quality at the catchment scale. First, we pay attention to a recent systematic review of nitrogen and phosphorus removal in single wetlands in boreal, temperate and sub-tropical regions. Second, in a more focused case study, we evaluate the efficacy of large numbers of constructed wetlands in southern Sweden to remove nutrients from runoff in the context of the eutrophication of the Baltic Sea. The removal efficiency of total nitrogen and total phosphorus in single wetlands is in general relatively high (median values are 37% and 46%, respectively). However, to make a significant difference on a catchment scale, more and larger wetland areas need to be created, and they need to be wisely placed where nutrient loading rates are high.

Background Soils are important global carbon pools that are under threat from intensive land use through a variety of agricultural practices. Sustainable management of agricultural soils may have the potential to mitigate climate change through increased carbon sequestration and increase their fertility. Among management practices to increase carbon sequestration, crop rotation designs have often been tested on yield effects in long-term agricultural experiments. However, in these studies, soil organic carbon (SOC) was monitored but not always the key objective. Thus, here we provide a method for a systematic review to test the effects of common crop rotations on SOC sequestration to provide evidence on the most sustainable management regimes that can promote SOC storage. Methods This systematic review incorporates studies concerning selected crop rotations (rotations-vs-monocultures, legumes-vs-no legumes, and perennials-vs-annuals) collated in a recently completed systematic map on the effect of agricultural management on SOC, restricted to boreo-temperate systems (i.e., the warm temperate climate zone). Some 208 studies relevant for this systematic review were identified in the systematic map. An update of the original search (September 2013) will be undertaken to identify newly published academic and grey literature. Studies will be critically appraised for their internal and external validity, followed by full data extraction (meta-data describing study settings and quantitative study results). Where possible, studies will be included in meta-analyses examining the effects of the different rotational practices. Implications of the findings will be discussed in terms of policy, practice and research, and the nature of the evidence base.

There is a broad correlation between the eNd values for rivers (including both the water and the particulate material it carries) and the age of the source terrain. This paper presents Nd isotope distribution data for soil, soil water, groundwater, and stream water samples gathered in a small catchment in northern Sweden. The results show that the release of Nd and Sm from boreal forests into streams and, eventually, into the oceans is more complicated than previously realized. The weathering of till causes changes in both the Nd isotopic composition and Sm/Nd ratios. Both the Sm/Nd ratio and eNd were higher in strongly weathered soils horizons than in less weathered till, since minerals with high Sm/Nd ratios were, on average, more resistant to weathering than those with low Sm/Nd ratios. In contrast to the situation for the main minerals and the major elements, the weathering of rare earth elements (REE) was not restricted to the E-horizon: the measured REE concentrations continued to increase with depth in the C-horizon. In addition, REE released by weathering in the upper parts of the soil profile were partly secondarily retained at deeper levels. Therefore, the dissolved Nd released by weathering in the upper soil horizons was trapped and did not enter the groundwater directly. Rather, the Nd in the groundwater largely originated from weathering within the groundwater zone. However, this was not the only source of Nd in the stream water. The Nd isotope composition and Sm/Nd ratio were determined by the mixing between of Nd and Sm in the groundwater and REE-carrying organic material washed out of the soil profile. The groundwater close to the stream reaches the upper soil horizons during high discharge events such as snowmelts, and organic matter carrying Nd and Sm is washed out of the soils and thus released into the stream. Therefore, the Nd exported from catchment is derived from both the weathering within the groundwater zone, and the organic matter washed out from the soil. If longer timescales with more advanced weathering stages in the groundwater zone are considered, it cannot be ruled out that there will be a shift towards more radiogenic values in the exported Nd. Recorded shifts in the Nd isotopic composition in the ocean may thus not only reflect changed source regions, but also the weathering history of the same source region.

Neonicotinoid insecticides (NNIs) have been routinely used in arable crop protection since their development in the early 1990s. These insecticides have been subject to the same registration procedures as other groups of pesticides, thus meet the same environmental hazard standards as all crop protection products. However, during the last 10 years the debate regarding their possible detrimental impact on non-target organisms, particularly pollinators, has become increasingly contentious and widely debated. Against this background, legislators and politicians in some countries, have been faced with a need to make decisions on the future registration of some or all of this class of insecticides, based on published evidence that in some areas is incomplete or limited in extent. This has created much concern in agricultural communities that consider that the withdrawal of these insecticides is likely to have significant negative economic, socio-economic and environmental consequences. The proposed systematic map aims to address the following primary question: What is the available evidence for the effects of neonicotinoids used in arable crop production on non-target organisms and concentrations of residues in relevant matrices? The primary question will be divided into two sub-questions to gather research literature for (1) the effect of NNIs on non-target organisms (2) the occurrence of concentrations of NNIs in matrices of relevance to non-target organisms (i.e. exposure routes). The systematic map will focus on NNIs used in arable crop production: imidacloprid, clothianidin, thiamethoxam, acetamiprid, thiacloprid and dinotefuran. Separate inclusion criteria have been developed for each sub-question. Traditional academic and grey literature will be searched for in English language and a searchable databases containing extracted meta-data from relevant included studies will be developed.

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 × 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.

Three Si isotope materials have been used for an inter-laboratory comparison exercise to ensure reproducibility between international laboratories investigating natural Si isotope variations using a variety of chemical preparation methods and mass spectrometric techniques. These proposed standard reference materials are (i) IRMM-018 (a SiO2 standard), (ii) Big-Batch (a fractionated SiO2 material prepared at the University of California Santa Barbara), and (iii) Diatomite (a natural diatomite sample originally deposited as marine biogenic opal). All analyses are compared with the international Si standard NBS28 (RM8546) and are in reasonable agreement (

Lateral moraines constructed along west to east sloping outlet glaciers from mountain centred, pre-last glacial maximum (LGM) ice fields of limited extent remain largely preserved in the northern Swedish landscape despite overriding by continental ice sheets, most recently during the last glacial. From field evidence, including geomorphological relationships and a detailed weathering profile including a buried soil, we have identified seven such lateral moraines that were overridden by the expansion and growth of the Fennoscandian ice sheet. Cosmogenic 10Be and 26Al exposure ages of 19 boulders from the crests of these moraines, combined with the field evidence, are correlated to episodes of moraine stabilisation, Pleistocene surface weathering, and glacial overriding. The last deglaciation event dominates the exposure ages, with 10Be and 26Al data derived from 15 moraine boulders indicating regional deglaciation 9600 ± 200 yr ago. This is the most robust numerical age for the final deglaciation of the Fennoscandian ice sheet. The older apparent exposure ages of the remaining boulders (14,600–26,400 yr) can be explained by cosmogenic nuclide inheritance from previous exposure of the moraine crests during the last glacial cycle. Their potential exposure history, based on local glacial chronologies, indicates that the current moraine morphologies formed at the latest during marine oxygen isotope stage 5. Although numerous deglaciation ages were obtained, this study demonstrates that numerical ages need to be treated with caution and assessed in light of the geomorphological evidence indicating moraines are not necessarily formed by the event that dominates the cosmogenic nuclide data.

Once or twice weekly, water sampling was undertaken for a two and a half year period in the Kalix River, northern Sweden. Soil water, groundwater, water in tributaries and mire water were also samp ...

The till east of the Liikavaara Ostra ore deposit in northern Sweden is in some parts rich in Cu and other sulphide-associated metals. Groundwater flowing in this till has higher concentrations of Cu than groundwater in a reference area where the till has low concentrations of Cu and other metals. To understand the processes that release metals from the mineralized till at Liikavaara into the groundwater, the authors performed a detailed study of the

Background There is a growing concern in Sweden and elsewhere that continued emissions of per- and polyfluoroalkyl substances (PFASs) may cause environmental as well as human health effects. PFASs are a broad class of man-made substances that have been produced and used in both commercial products and industrial processes for more than 60 years. Although the production and use of some PFASs has been phased-out in some parts of the world, it is not known what effect these actions to date have had on PFAS concentrations in the environment. Owing to the wide diversity of PFASs, it is difficult to generalize their properties, environmental fate and production histories. However, the strength and stability of the C-F bond renders the perfluoroalkyl moieties resistant to heat and environmental degradation. Several PFASs are now occurring even in very remote areas in large parts of the world, but the environmental transport and fate of substances within this group is not well understood. A systematic review may be able to determine whether the concentrations of these substances in different environments are changing in any particular direction with time, and whether the phase-outs have had any effects on the concentration trends. Methods Searches for primary research studies reporting on temporal variations of PFAS concentrations in the environment will be performed in the scientific literature as well as in other reports. Relevant samples include both abiotic and biological samples including humans. No particular time, document type, language or geographical constraints will be applied. Two authors will screen all retrieved articles. Double screening of about 10% of the articles will be performed by all authors at both title/abstract and full-text levels. Kappa tests will be used to test if the screening is consistent. Relevant articles will be critically appraised by four authors (double checking of 25% of the articles). Quality assessment will focus on selection bias, dating of samples, sample integrity and analytical procedures. Data synthesis will be based on statistical analysis of temporal concentration trends.

In order to determine the metal-bearing phases with special emphasis on Cu, a sequential extraction has been carried out on seven soil samples from a sulphide-bearing spodosol profile in Liikavaara Ostra, close to the Aitik Copper Mine in northern Sweden. A reference spodosol profile with very low abundances of sulphides located far from anthropogenic emissions was also studied. Five fractions were selected for the extraction: (I) CH3COONa-extractable (exchangeable/adsorbed/carbonate); (II) Na4P2O7-extractable (labile organics); (III) 0.25 M NH2OH·HCl-extractable (amorphous Fe oxyhydroxides/Mn oxides); (IV) 1 M NH2OH·HCl-extractable (crystalline Fe oxides); and (V) KClO3/HCl-extractable (organics and sulphides). The distribution of trace elements (Co, Cr, Cu, Ni, Pb and Zn) in the profile in Liikavaara Ostra is different from that in the reference profile. Possible explanations for these differences are (i) the presence of sulphides in the soil, (ii) atmospheric deposition of dust derived from mining activities at the Aitik Copper Mine, and (iii) mineralogical heterogeneities inherited from the deposition of the till. There is no straightforward correlation between the amount of the extracted phases and the metal extractability in the soils. This fact indicates that other factors are important for the retention of trace metals as well. The data presented in this study suggest that Co, Cr and Ni, to a fairly large extent, are associated with the organic matter in the B-horizon in both profiles, while in the C-horizon in Liikavaara Ostra, sulphides are probably the more important carriers of these elements. For Co and Ni, Fe oxyhydroxides seem to be important. Most of the Cr occurred in the residual remaining after the leaching procedure. Copper and Zn seem to be associated with the organic matter to some extent in the B-horizon. The concentration of Cu in the C-horizon in Liikavaara Ostra is high (2310 ppm), but only a very small fraction is likely to be hosted by sulphides. It is concluded that the major part of Cu in the C-horizon and a prominent fraction in the B-horizon in Liikavaara Ostra are associated with some secondary phase that is extractable during extractions III and IV. Possible candidates for this phase are goethite and inclusions of native Cu in weathered biotite.

Rare earth element (REE) data from weekly sampling of the filtered (

Barium/Sr and Ca/Sr ratios have been used to model the relative importance of different sources of stream water. Major and trace element concentrations together with 87Sr/86Sr ratios were measured in precipitation, soil water, groundwater and stream water in a small (9.4 km2) catchment in northern Sweden. The study catchment is drained by a first order stream and mainly covered with podzolized Quaternary till of granitic composition. It is underlain by a 1.8 Ga granite. A model with mixing equations used in an iterative mode was developed in order to separate the stream water into 3 subsurface components: soil water, shallow groundwater, and deep groundwater. Contributions from precipitation are thus not included in the model. This source may be significant for the stream water generation, but it does not interfere with the calculations of the relative contributions from the subsurface components. The results show that the deep groundwater constitutes between 5 and 20% of the subsurface water discharge into the stream water. The highest values of the deep groundwater fraction occur during base flow. Soil water dominates during snowmelt seasons, whereas during base flow it is the least important fraction. Soil water accounts for 10–100% of the subsurface water discharge into the stream water. Shallow groundwater accounts for up to 80% of the subsurface water discharge with the lowest values at peak discharge during snowmelt seasons and the highest values during base flow. The validity of the model was tested by comparing the measured 87Sr/86Sr ratios in the stream water with the 87Sr/86Sr ratios predicted by the model. There was a systematic difference between the measured and modelled 87Sr/86Sr ratios which suggests that the fraction of soil water is overestimated by the model, especially during spring flood. As a consequence of this overestimation of soil water the amount of shallow groundwater is probably underestimated during this period. However, it is concluded that the differences between measured and predicted values are relatively small, and that element ratios are potentially effective tracers for different subsurface water flowpaths in catchments.

Weathering of till in northern Sweden results in the formation of well-developed spodosols. The till is dominated by 1.9–1.8 Ga granitic material. The REE are among the elements most strongly depleted during weathering, and the loss of REE from the E-horizon decreases as the atomic number increases. To study if weathering leads to a change of the Nd isotope composition, we have analysed the Nd isotopic composition of the various horizons including living plants and humus of two profiles of weathered till (typic haplocryods) in northern Sweden. As much as between 65.6 and 75.3% of the Sm and Nd in the

Chemical weathering rates and erosionrates of granitic till in northern Sweden have beenestimated. The present-day chemical weathering rate iscompared with the long-term average weathering ratesince the last deglaciation approximately 8,700 yearsago. Also, the present-day release rates of major andtrace elements due to chemical weathering are comparedwith the mobility of these elements in a spodosolprofile as shown by soil water samples from the vadozezone. The estimation of the past weathering rate isbased on elemental depletion trends in a soil profile(typic haplocryod), whereas the present weatheringrate is based on elemental input/output budgets in asmall catchment (9.4 km2). The long-term averagechemical erosion rate, expressed as the sum of majorelement oxides (SiO2, Al2O3, CaO,Fe2O3, K2O, MgO, MnO, Na2O,P2O5, TiO2), was estimated to be4.9 gm-2 yr-1. The long-term base cation(Ca2+, Mg2+, Na+, K+) depletionwas 0.325 keq ha-1 yr-1. The currentchemical erosion rate was estimated to be2.4‐3.0 g -2 yr-1, which is at least an order ofmagnitude higher than the rate of physical erosion,and the base cation flux due to chemical weathering is0.356–0.553~keq ha-1 yr-1. However,0.074 keq ha-1 yr-1 of this flux may be related tocation exchange processes induced by atmospheric inputof acid rain. There is no evidence for any recentlyincreased weathering rate of silicates in this area.The inputs of Cd, Cu, Ni and Zn exceed the outputs,and hence, these elements are currently accumulatingin the soil. There is a distinct seasonal variation in thechemical composition of the soil water. Results fromthe soil water samples show that Na, followed by Siand S (Cl was not measured), are the most mobileelements in the spodosol profile between the E-horizonand the C-horizon, and that Al and Fe were the leastmobile elements. However, there is no simplerelationship between the mobility of an element in thespodosol profile and the current release rate due toweathering of that element. This fact may haveimplications for the validity of the comparisonbetween the past and present weathering rates asperformed in this study.

Past and present chemical weathering rates in granitic till have been estimated. The Kalix River watershed in northern Sweden was used as a study area in which 17 evenly distributed soil profiles were investigated. The two estimations are based on elemental depletion trends in soil profiles and input/output budgets for the elements in the watershed, respectively. In the calculations of the past weathering rate it was assumed that zircon is resistant, and thus Zr was considered to be immobile during weathering. The long-term average chemical erosion rate since the area was deglaciated 8700 a ago, expressed as the sum of major element oxides (SiO2, Al2O3, CaO, Fe2O3, K2O, MgO, MnO, Na2O), was estimated to be 5.8 g·m−2·a−1. In terms of base cation (Ca2+, Mg2+, Na+, K+) depletion this corresponds to 0.36 keq·ha−2·a−1. All elements analysed have been depleted from the E-horizon, and the most affected elements are P with an average mass loss of 86% (as P2O5), La 81%, Co 78%, Cu 77% and Ni 76%. The present-day weathering rate was calculated as the difference between outputs and inputs in the Kalix River watershed. The input was considered as the contribution from precipitation, while the output was calculated as the sum of (1) the river-transported dissolved fraction, (2) the river-transported suspended non-detrital fraction (chemically precipitated Fe- and Mn-oxy-hydroxides and matter sorbed on these particles), and (3) the biotic nutrient net uptake. River-transported outputs were measured for an annual cycle starting in September 1991 and ending in August 1992. The present-day chemical erosion rate of the till was estimated to be 6.3 g·m−2·a−1 (sum of major element oxides), or a base cation flux of 1.42 keq·ha−2·a−1. Part of this present-day rate is related to carbonate weathering in the Caledonian mountain range which makes it difficult to compare the present weathering rate with the historical weathering rate. After correction for carbonate weathering the resulting present-day weathering rate of granitic till in terms of base cation flux was estimated to be 0.65–0.75 keq·ha−2·a−1. This result indicates that the present cation flux has increased by a factor of 1.8–2.1 compared to the long-term average. However, given the uncertainties introduced by the carbonates in the Caledonian mountain range it is not possible to prove any significant difference between the mean post-glacial and the present-day weathering rate with the methods used in this study.

A sequential extraction has been carried out on seven soil samples from a spodosol profile in till with granitic composition. The soil profile was sampled in northern Sweden. Five fractions were selected for extraction: (A) CH_3COONa-extractable (exchangeable/adsorbed/carbonate); (B) Na_4P_2O_7-extractable (labile organics); (C) 0.25 M NH_2OH⋅HCl-extractable (amorphous Fe-oxyhydroxides/Mn-oxides); (D) 1 M NH_2OH⋅HCl-extractable (crystalline Fe-oxides); and (E) KClO_3/HCl-extractable (organics and sulphides). Extracted rare earth elements (REE) were determined with High Resolution ICP-MS. In addition to the soil, stream water suspended particulate matter was also analysed for REE. Total concentrations in the soil samples show that the REE have been fractionated during weathering. In the acidic (pH 4.28) E-horizon all REE are depleted relative to the unweathered till. The depletion decreases with increasing atomic number. Also in the B-horizon (pH 5.86) the REE are depleted, although to a lesser extent compared to the E-horizon. Secondary phases in the B-horizon fractionate the REE in different ways. Rare earth elements extracted in extractions A and C were enriched in the intermediate REE relative to heavy and light REE if normalized to local till. In extractions B and D, the heavy REE were enriched relative to the light REE, and in extraction E a large enrichment of light REE relative to heavy REE was found. Stream water suspended particulate matter is enriched in all REE relative to local till. The light REE are more enriched than the heavy REE. Normalized La/Lu ratios in the suspended matter ranged from 1.5 to 2.4, and were negatively correlated with stream water discharge as well as with content of detrital inorganic matter in the suspended load. The only extracted phase that potentially can explain the high normalized La/Lu ratio in the suspended matter is the phase extracted in extraction E, which has a ratio of 2.0–4.2. The normalized La/Lu ratio for the rest of the extractions ranged from 0.5 to 1.2. It is concluded that organic matter seems to be important for the particulate transport of REE in northern coniferous areas.

The groundwater chemistry in a small catchment in northern Sweden has been studied for a period of 15 months, including two snowmelt events. The groundwater was sampled from two wells in a slope ...

Continuous, volume-controlled sampling from the surface down to a depth of 130 cm was conducted at two stations on weathered till (typic haplocryods). All the samples were analysed for major and trace elements including the rare earth elements (REE). Eight thousand seven hundred years of weathering since the glacial ice left the area, has resulted in a strong depletion of REE in the E-horizon. This loss decreases as atomic number increases, so that 80–85% of the La and 54–60% of the Yb have been lost. Europium has been lost to a greater degree than have the neighbouring elements. Possible explanations for the release of REE are: weathering of common silicates such as hornblende and epidote (and plagioclase in the case of Eu); weathering of apatite; weathering of rare but REE-rich minerals such as allanite and monazite; and release of REE adsorbed on clay minerals. Further studies on various size fractions and minerals are needed to quantify the importance of the various possible mechanisms of REE release. The release of REE continues within and below the Bs1-horizon, but the results from one station show that light REE can be enriched in the Bs1-horizon. This secondary enrichment could be caused by adsorption on secondary oxy-hydroxides, on clay minerals or on organic material. However, the net result of the weathering is that all REE have been released to the groundwater.

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 plant nutrients to freshwater and marine environments. A widely used method to achieve this is to let water pass through a constructed or restored wetland (CW). However, the large variation in measured nutrient removal rates in such wetlands calls for a systematic review. The objective of this review is to quantify nitrogen and phosphorus 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 the situation in Sweden. Although the performance of wetlands in temperate and boreal regions is most relevant to the 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. One author will perform the screening of all retrieved articles at the title and abstract level. To check that the screening is 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. Kappa tests 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.

We demonstrate in this study that a single focusing multiple collector inductively coupled plasma massspectrometer (MC-ICP-MS) equipped with a hexapole gas-collision cell (GV-instrument Isoprobe) canprecisely determine the d29Si (2S.D., 0.2&) using a total Si consumption of less than 14 nmole (390 ngSi). Testing and evaluation of background, rinse time, and major matrix effects have been performed ina systematic way to establish a procedure to measure d29Si in small quantities. Chemical purificationprior to analysis is required to remove potential interferences. For data collected during a four-yearperiod, the average d29Si value of IRMM-018 relative to NBS-28 was found to be 0.95& (n ¼ 23,2S.D. 0.16&) with a 95% confidence interval (0.95 0.028&). The mean d29Si value of the Big-Batchstandard was found to be 5.50& (n ¼ 6, 2S.D. 0.26&). Although determination of the d30Simeasurements is not possible, with our current instrument we demonstrate that this system providesa fast and long-term reliable method for the analysis of d29Si in purified samples with low Siconcentration (18 mM Si). Silicon isotope-based reconstruction of silicon cycle and diatom production in the Baltic Sea; implications for climate change and eutrophication