The question of the limiting nutrient(s) for production of phytoplankton and macrophytes was explored in two contrasting freshwater systems receiving N- and P-rich mine effluents from the Boliden and Kiruna mine sites, northern Sweden. For both sites, total N (TN), total P (TP) and TN:TP mass ratios in water, sediment and macrophytes were used to examine (1) spatial variations within the systems, (2) differences between the systems and (3) seasonal variations. The TN concentration from the discharge point at the Kiruna site was about seven times higher than at the Boliden discharge point, while the TP concentration was 10 times lower than in the discharge point at the Boliden site. The majority of the studied lakes showed elevated biomass of phytoplankton, with maximum values found in Lake Bruträsket (Boliden). Mining activities have affected the nutrient regime of the two recipients by contributing to elevated TN and TP concentrations and TN:TP mass ratios as well as elevated production of phytoplankton and macrophytes compared to the reference sites. Depending on the NH4 concentration in the effluent at the Boliden site, water column TN:TP mass ratios shifted from being >22, indicating P-deficiency, to between 9 and 22, indicating a transition from N- to P-deficiency (co-limitation). However, water column TN:TP mass ratios at the Kiruna site always indicated P-deficiency, while TN:TP mass ratios of macrophytes indicate that both sites may vary from N- to P-limitation. The study suggests that for the design of efficient monitoring programmes and remediation measures, it is important to consider the major N and P species in water, phytoplankton, sediment and macrophytes.

This paper presents a biogeochemical model developed for a clarification pond receiving ammonium nitrogen rich discharge water from the Boliden concentration plant located in northern Sweden. Present knowledge about nitrogen (N) transformations in lakes is compiled in a dynamic model that calculates concentrations of the six N species (state variables) ammonium-N (Nam), nitrate-N (Nox), dissolved organic N in water (Norg), N in phytoplankton (Npp), in macrophytes (Nmp) and in sediment (Nsed). It also simulates the rate of 16 N transformation processes occurring in the water column and sediment as well as water–sediment and water–atmosphere interactions. The model was programmed in the software Powersim using 2008 data, whilst validation was performed using data from 2006 to 2007. The sensitivity analysis showed that the state variables are most sensitive to changes in the coefficients related to the temperature dependence of the transformation processes. A six-year simulation of Nam showed stable behaviour over time. The calibrated model rendered coefficients of determination (R2) of 0.93, 0.79 and 0.86 for Nam, Nox and Norg, respectively. Performance measures quantitatively expressing the deviation between modelled and measured data resulted in values close to zero, indicating a stable model structure. The simulated denitrification rate was on average five times higher than the ammonia volatilisation rate and about three times higher than the permanent burial of Nsed and, hence, the most important process for the permanent removal of N. The model can be used to simulate possible measures to reduce the nitrogen load and, after some modification and recalibration, it can be applied at other mine sites affected by N rich effluents.

There has been a long-term decline in spring and fall numbers of Clethrionomys rufocanus in boreal Sweden in 1971-2005. Previous studies on permanent sampling plots in the centre of 2.5 x 2.5 km landscapes suggested that habitat fragmentation (sensu destruction) could have contributed to the decline. Therefore, we tested these findings in a field study and compared trapping results on the central sampling plots of landscapes with a low degree of fragmentation (LDF) and of "hot spot" type with trapping results in managed forest landscapes with a high degree of fragmentation (HDF). We predicted that C. rufocanus would be more common on the LDF plots. We used our permanent plots supplemented with a new sample of plots, mainly of the rare LDF type, inside or just outside the long-term study area. Very few voles were trapped on both plot types, and no difference was found. However, a subsequent pilot study with trapping in a national park with large areas of pristine, unfragmented forest yielded more voles than in the managed, more fragmented, areas. Consequently, the initial field study data and some other recent data were also re-analysed from a "local patch quality" perspective. This alternative approach revealed the positive importance of large focal patches of forest > 60 years old and their content of old-growth (pine) forest (> 100 years). Interestingly, at the landscape level, the frequency distribution of patches of forest > 60 years old, old-growth (> 100 years), and especially of old-growth pine forest (> 100 years), relative to the properties of plots with C. rufocanus, suggested that there are few forest patches left that are suitable for C. rufocanus. Our current results suggest that habitat fragmentation cannot be excluded as a contributing cause to the long-term decline of C. rufocanus in boreal Sweden.

The "local patch quality perspective" revealed the importance to C. rufocanus of a large patch of forest >60 yr old containing a lot of old-growth (pine) forest (>100 yr). In fact, at the landscape level, the frequency distribution of focal patches of forest >60 yr old and especially their content of old-growth pine forest (>100 yr), relative to the properties of plots with C. rufocanus, suggests that there are few forest patches left that are suitable for C. rufocanus in our study area. Our results strongly suggest habitat fragmentation as a contributing cause to the long-term decline of C. rufocanus.

Uncertainty is an important factor in ecological assessment, and has important implications for the ecological classification and management of lakes. However, our knowledge of the effects of uncertainty in the assessment of different ecological indicators is limited. Here, we used data from a standardized campaign of aquatic plant surveys, in 28 lakes from 10 European countries, to assess variation in macrophyte metrics across a set of nested spatial scales: countries, lakes, sampling stations, replicate transects, and replicate samples at two depth-zones. Metrics investigated in each transect included taxa richness, maximum depth of colonisation and two indicators of trophic status: Ellenberg’s N and a metric based on phosphorus trophic status. Metrics were found to have a slightly stronger relationship to pressures when they were calculated on abundance data compared to presence/absence data. Eutrophication metrics based on helophytes were found not to be useful in assessing the effects of nutrient pressure. These metrics were also found to vary with the depth of sampling, with shallower taxa representing higher trophic status. This study demonstrates the complex spatial variability in macrophyte communities, the effect of this variability on the metrics, and theimplications to water managers, especially in relation to survey design.

De befintliga bedömningsgrunderna för makrofyter (BGM) i sjöar har hittills ansetts som preliminära. Dessutom motsvarade de inte kraven enligt EUs Ramdirektiv för vatten med avseende på bl.a. typanpassningen och angivna gränser mellan olika klasser av ekologisk status. I det framlagda förslaget för revideringen av BGM i enlighet med EUs Ramdirektiv för vatten, lades stor vikt vid att utöka dataunderlaget av framför allt referenssjöar. Med hjälp av olika påverkanskriterier valdes 49 referenssjöar, dvs. sjöar som ansågs vara av hög ekologisk status. Som kriterier användes markanvändning, sjösänkning, koncentrationen av näringsämnen samt pH i vattenfasen. Baserad på artsammansättningen bland makrofyterna gjordes en klusteranalys-baserad typindelning i tre grupper. Dessa tre typologigrupper kunde skiljas åt med hjälp av främst två typologivariabler, nämligen Y-koordinat och h.ö.h. De tre typologigrupperna/regionerna var sjöar S om Limes norrlandicus (LN), sjöar N om LN men under högsta kustlinjen (HK) samt sjöar N om LN och över HK. För att bestämma sjöarnas ekologiska status, beräknades indikatorvärden längs Tot-P-gradienten för alla funna makrofytarter förutom helofyter. Indikatorvärdena viktades med arternas nischbredd längs Tot-P-gradienten. För varje sjö kunde på det viset ett medianindikatorvärde, ett trofiindex, beräknas. Dessa trofiindex översattes till en femgradig skala enligt Ramdirektivets krav, dvs. de fem klasserna av ekologisk status. Denna konvertering gjordes med hjälp av Tot-P halter som prefereras av makrofytarter som ansågs karakteristiska för respektive klass av ekologisk status. På grund av bristande dataunderlag kunde gränsvärden inte beräknas mellan klasserna otillfredsställande och dålig ekologisk status. Trots ett heterogent datamaterial som är insamlat i olika syften, under olika decennier och till och med sekler och med varierande metodik mm., anses det föreslagna systemet kunna tillämpas i enlighet med EUs Ramdirektiv för vatten. Föreliggande utredning understryker dock det stora behovet av kompletterande inventeringar samt av en revidering av undersökningsmetoden för inventering av makrofyter. Det föreslagna systemet bör verifieras med datamaterial som inte användes för den här redovisade bedömningen. Därefter bör en eventuell revidering genomföras.

1. We have limited knowledge of the effects of land use in general and of drainage ditching in particular on macrophyte communities in lakes. I quantified catchment land use, including drainage ditching, as well as water quality and the number of macrophyte species in 17 Swedish lakes in summer 2005.

2. Land use within 1 km of the studied lakes was analysed in a geographic information system. The following variables were included: areas of forests, mires, agricultural land and urbanization, length of drainage ditches (classified according to the use of the land they drained), and shortest distance from lake to an urban area. To extract and analyse general trends in the data sets, redundancy analysis was used.

3. Water quality was explained mainly by three land-use related variables: the lengths of agricultural, forest and mire ditches. The length of agricultural ditches was positively correlated with lake water conductivity, total dissolved solids, Ca, N and total organic carbon (TOC). The lengths of forest and mire ditches were positively correlated with lake water characteristics, especially TOC.

4. The number of species representing different macrophyte life forms was explained by three environmental variables: conductivity, and lengths of forest and agricultural ditches. The numbers of isoetids, nymphaeids, elodeids and total obligate hydrophytes were negatively correlated with length of forest ditches. In contrast, the number of lemnids and helophytes was positively correlated with conductivity and length of agricultural ditches. Furthermore, the number of isoetids was exponentially related (negatively) to lengths of agricultural and forest ditches, indicating a threshold response to drainage ditch length.

5. The results suggest that effects on water quality and macrophyte communities result from drainage ditching in the lake catchments rather than from land use itself. Given the total area of drainage-ditched land worldwide (millions of ha in Scandinavia alone), drainage ditching should be considered when evaluating environmental impacts on lake water quality and macrophyte occurrence and when determining reference conditions for catchment land use.

Several studies indicate a long-term decline in the numbers of voles in northern Fennoscandia. Altered land use and forest management practices have been proposed as possible causes of the decline. This doctorial thesis aimed to identify, on different spatial scales, landscape patterns that are important for the abundance of small mammals and that might be related to the decline. General trends and aspects of spatial habitat modelling were reviewed. Trapping data from three large extent monitoring programs were related to habitat factors on different spatial scales. For these analyses, a broad range of statistical and GIS (geographic information system) related methods was applied. On the microscale (trapping station, extent <= 10 m) and mesoscale (transect, length 90 m), structural habitat factors such as coarse and fine woody debris, umbrella vegetation and structural complexity of the forest floor were identified as important factors influencing small mammal abundance. Small mammal densities were related to the percentage landcover of vegetation types on the micro-, meso-, macro- (subarea/landscape, 1 x 1, 2.5 x 2.5 and 2 x 5 km) and regional scale (overall study area, 20 x 20 - 80 x 80 km). The spatial continuity (non- fragmentation) of old-growth pine forest patches on the landscape scale was positively related to the abundance of C. rufocanus, the species that showed the most pronounced long-term decline in numbers. The results of this thesis strongly suggest that altered land use might indeed be involved in the decline in numbers of voles in managed forest areas in northern Fennoscandia. To reveal and test responses of small mammals to changes in landscape patterns in more detail, this work proposes further application of large scale approaches. These approaches, e.g. the GIS-based prediction of the areas with currently high abundance of C. rufocanus can be tested by field sampling of the type applied in this thesis. Such approaches should consider the key aspects identified in the reviews on GIS-based habitat modelling, e.g. reconciling the scale of the population dynamics of small mammals with the scale (resolution and extent) of the input data, the application of different modelling approaches and the performance of sensitivity analysis.

The influence of forest age and structural habitat factors on species richness and the population dynamics of small mammals were evaluated. Small mammals were monitored both in old-growth and in immature managed forests, and habitat factors were recorded.Species richness and population dynamics of forest dwelling small mammal species were positively influenced by factors related to cover of vegetation in the field layer and to structural heterogeneity in the forest floor. In contrast, species richness and the overall abundance of Clethrionomys glareolus were negatively related to forest age. However, habitats in old forests were important refuges for the winter survival of C. glareolus and therefore may forest management practices, like clearcutting, enhance population fluctuations in this species. The contrasting effects of forest age indicate that population dynamics were primarily not related to the age of forests, but rather to habitat factors important to reproduction and survival of small mammals.

Vattenvegetation används nationellt och internationellt som indikator för att bedöma miljötillståndet, till exempel vattenkvalitet och naturvärden i sjöar och vattendrag. Det är av stor vikt att resultaten och analyserna från en makrofytinventering håller hög och tillförlitlig kvalitet. Den bedömning som grundar sig på kvalitetsfaktorn makrofyter kan få långtgående och kostsamma konsekvenser. Trots den stora mångfalden bland syften med makrofytinventeringar och tillgängliga inventeringsmetoder finns det i dagsläget ingen omfattande studie som har utvärderat olika inventeringsmetoder för makrofyter med avseende på en avvägning mellan syfte, karteringsmetodik, kvantifiering och resursbehov. Syftet med föreliggande utvärdering är att, baserat på en litteraturstudie och utvärdering av befintliga data, kunna rekommendera ett fåtal metoder för övervakningsinventering av sjöar för vidare fälttest. Utvärderingen bygger på en genomgång av relevant nationell och internationell litteratur, diskussioner med kollegor verksamma inom det europeiska interkalibreringsarbetet kring bedömningen av ekologisk status enligt Ramdirektivet för vatten, samt en utvärdering av tillgängliga men hittills icke utvärderade, svenska makrofytdata. Studien har avgränsats till övervakningsinventering enligt Ramdirektivet för vatten och bedömning av naturvärden. Den mest lovande metoden (enligt min bedömning) är krattning längs virtuella transekter med notering av täckningsgrad enligt en semikvantitativ skala. Metoden borde emellertid testas i minst 16 sjöar av olika biologisk och morfologisk karaktär. I ett antal sjöar (minst sex sjöar, t.ex. tre oligotrofa djupa och tre eutrofa grunda sjöar), bör krattmetoden jämföras med snorkling samt även med rutinventering med hjälp av dykning längs transekter. Dykningsmetoden är internationellt sett den mest använda övervakningsmetoden. För att undvika att de svenska data från en kommande miljöövervakningsmetod, baserad på krattmetoden, kommer att ifrågasättas, borde dykningsmetoden värderas mot krattningsmetoden. Hypotesen är att krattmetoden ger lika pålitliga resultat för bedömningen av vattenkvalitet enligt Ramdirektivet för vatten och bedömning av naturvärden som dykningsmetoden, i alla fall i de grunda sjöpartierna. Detta är dock bara ett antagande och bör verifieras med en gedigen fältstudie. Utvärderingen krävs för att kunna rekommendera krattmetoden baserat på vetenskaplig grund. Metoderna bör fälttestas under sommaren 2007, med fördel enligt faktorisk design, där hänsyn tas speciellt till sjöarnas trofistatus, bottensubstrat, sjödjup och sjöstorlek, samt med krav på att belägga effekten av antal undersökta transekter, olika typer av kratta, olika kvantifieringsmetoder, förhållandet mellan informationsvinst och resursbehov vid användning av olika karterings- och kvantifieringsmetoder.

Under 1930-talet analyserade Gunnar Lohammar makrofytvegetationen och biogeokemin i 151 svenska sjöar. Detta material, kompletterat med data från återinventeringar ger en unik möjlighet att studera sambandet mellan makrofytvegetation, biogeokemi och markanvändning. Sommaren 2005 återinventerades 17 av Lohammar-sjöarna (åtta i Uppland och nio i Norrbotten) med målet att förstå de ovan nämnda sambanden samt förändringen i dessa. Makrofyterna visade tydliga preferenser längs de biogeokemiska gradienterna. Responsen längs gradienterna av isoetiderna och lemniderna var enhetlig inom respektive grupp medan arterna inom elodeiderna och flytbladsväxterna visade en varierad respons. Preferenserna kunde användas för att utveckla preliminära makrofytbaserade indikatorvärden. Dessa avvek från de befintliga engelska indikatorvärden som för närvarande används i Sverige. Både makrofytvegetationen, biogeokemin och markanvändningen har genomgått stora förändringar mellan 1930-talet - 2005. Generellt ändrades mellan 1930 - 2005 enbart antalet flytbladsväxter. Skillnaderna i makrofytabundansen visade sig dock främst mellan regionerna. Sjöarna i Norrbotten hade under 1930-talet ett större antal isoetider jämfört med Uppland, medan de uppländska sjöarna hade ett större antal lemnider. Skillnaderna mellan regionerna förstärktes mellan 1930 - 2005 och kan förklaras med ökade näringshalter i allmänhet och ökade tot-N halter i synnerhet. Näringshalterna (främst tot-N, men även tot-Na och konduktivitet) ökade både i Uppland och Norrbotten och förklarades med bl.a. ökad kvävedeposition och ökad användning av hushålls- och vägsalt. Tot-P halter förändrades inte signifikant mellan 1930 - 2005 men visade en koppling till respektive avrinningsområdets markanvändning, t.ex. avstånd till närmaste tätort. Makrofytabundans och sjöarnas biogeokemi påverkades av markanvändningen inom sjöarnas avrinningsområden och inom 1-km breda buffertzoner kring sjöarna. Anmärkningsvärt är det positiva sambandet mellan dikeslängd samt areal jordbruksmark och makrofytarter som föredrar näringsrika förhållanden. Makrofytabundans kunde förklaras med en kombination av markanvändning och sjöarnas biogeokemi. Den ökade hyggesarean under den studerade tidsperioden ledde antagligen till en minskning av arter som föredrar bl.a. näringsfattiga förhållanden och låga TOC-halter. Korrelationerna mellan näringsämnenas och spårmetallernas fraktionering tyder på att det antagligen är den biotillgängliga delen av ämnena som antagligen styr abundansen bland lemniderna. Resultaten visar effekterna av markanvändningen och dess förändring på både makrofyterna och biogeokemin. Resultaten borde anses som ett första steg för att bättre förstå kopplingen mellan markanvändning, makrofyter och biogeokemin.

Changes in forest landscape structure have been suggested as a likely contributing factor behind the long-term decline in the numbers of cyclic grey-sided voles (Clethrionomys rufocanus) in northern Fennoscandian lowland regions in contrast to mountain regions due to the absence of forest management in the mountains. This study, for the first time, formally explored landscape structure in 29 lowland (LF) and 14 mountain forest (MF) landscapes (each 2.5 × 2.5 km) in northern Sweden, and related the results to the cumulated spring trapping index of the grey-sided vole in 2002-2006. The grey-sided vole showed striking contrasts in dynamics close in space and time. The MF landscapes were characterized by larger patches and less fragmentation of preferred forest types. The grey-sided vole was trapped in all of 14 analyzed MF landscapes but only in three out of 29 of the LF landscapes. MF and LF landscapes with grey-sided vole occurrence were characterized by similar focal forest patch size (mean 357 ha, minimum 82 ha and mean 360 ha, minimum 79 ha, respectively). In contrast, these MF compared to the LF landscapes were characterized by larger patches of preferred forest types and less fragmented preferred forest types and by a lower proportion of clear-cut areas. The present results suggest that landscape structure is important for the abundance of grey-sided voles in both regions. However, in the mountains the change from more or less seasonal dynamics to high-amplitude cycles between the mid 1990s and 2000s cannot be explained by changes in landscape structure.

Several studies indicate a long-term decline in numbers of different species of voles in northern Fennoscandia. In boreal Sweden, the long-term decline is most pronounced in the grey-sided vole (Clethrionomys rufocanus). Altered forest landscape structure has been suggested as a possible cause of the decline. However, habitat responses of grey-sided voles at the landscape scale have never been studied. We analyzed such responses of this species in lowland forests in Västerbotten, northern Sweden. Cumulated spring densities representing 22 local time series from 1980-1999 were obtained by a landscape sampling design and were related to the surrounding landscape structure of 2.5×2.5 km plots centred on each of the 22 1-ha trapping plots. In accordance with general knowledge on local habitat preferences of grey-sided voles, our study supported the importance of habitat variables such as boulder fields and old-growth pine forest at the landscape scale. Densities were negatively related to clear cuts. Habitat associations were primarily those of landscape structure related to habitat fragmentation, distance between habitat patches and patch interspersion rather than habitat patch type quantity. Local densities of the grey-sided vole were positively and exponentially correlated with spatial contiguity (measured with the fragmentation index) of old-growth pine forest, indicating critical forest fragmentation thresholds. Our results indicate that altered land use might be involved in the long-term decline of the grey-sided vole in managed forest areas of Fennoscandia. We propose two further approaches to reveal and test responses of this species to changes in landscape structure.

There has been a long-term decline, causing frequent local extinctions, of cyclic grey-sided voles (Clethrionomys rufocanus) in northern Fennoscandia since 1971. Previous studies supported the hypothesis that altered landscape structure, especially in terms of forest patch area and fragmentation of oldgrowth forest, has contributed to the decline. Since those studies were based on cumulated vole time series data and static landscape structure, we now tested whether the long-term decline was related to a gradual change. We digitized landcover types (>0.25 ha) from aerial photographs within 6.25 km2 squares centred on each of the 27 sampling sites with 5 year intervals, starting in 1970. Because of clear-cutting, mean area of the patches of >35 year old forest that intersected the sampling sites decreased from 126 ha in 1970 to 44 ha in 2004. The main decrease in focal forest patch area occurred in 198085, coinciding with the major drop in vole numbers. Our results strongly suggest that long-term habitat fragmentation is involved in the current decline of grey-sided voles. However, climate change leading to warmer winters with a less stable snow cover is also thought to be of major importance, as indicated by a decrease in vole wintering success.

The grey-sided vole (Myodes rufocanus) is one of the keystone vole species for ecosystem functioning in boreal forests. In 1970-2008 there has been a long-term decline in the numbers of grey-sided voles within a 100×100 km2 study area in northern Sweden. Habitat destruction is regarded as a contributing factor to the decline. However, we have so far lacked knowledge on any spatiotemporal thresholds in landscape structure related to the decline. Here, we studied such thresholds in 16 5×5 km landscapes, systematically distributed within the study area. Local declines were most pronounced in the western (inland) part of the study area in 1980-85. At that time, the species already had gone extinct in the eastern (coastal) area. We related changes in landscape structure to the timing of the grey-sided vole declines. Landcover types (>0.25 ha) were digitized from aerial photographs within the 5×5 km landscapes with 5-yr intervals. The most pronounced changes in landscape structure were related to changes in forest age structure due to clear-cutting. Within the study area, there were significant geographical differences in the size distribution of clearcuts and forest patches. In 1970, the coastal in contrast to the inland study area, was characterized by more clear-cuts (766  versus 182) that were smaller (mean 5 ± 18 ha versus 13 ± 34 ha) but covered larger areas (sum 4077 ha versus 2325 ha). Spatio-temporal comparisons showed that the coastal landscape in 1970, when the vole was rarely found there, resembled the inland landscape in 1985. The main decrease in focal forest patch size in the inland occurred in 1980-85, coinciding with the major drop in vole numbers there. Our results suggest that spatio-temporal changes in landscape structure are important and contributing to declines in greysided vole abundance.

Littoral interactions among sediment, water and macrophytes are poorly understood. In particular there is a gap in knowledge concerning the importance of macrophytes as sinks and sources of trace elements. Such knowledge is however central for, amongst others, explaining potential mechanisms behind the community structure of macrophytes and for the development of macrophyte-based indicator values. We studied the interactions between the three matrices (sediment, water and macrophytes) at 19 sampling sites in Storträsket, a 1.7 km2 boreal lake at the land uplift coast of Northern Sweden in summer 2008. The catchment of Storträsket was dominated  by coniferous forest of mainly the dwarf-shrub type and open wet mires. The upper sediment layers (0-6 cm) were dominated by fine detritus. Fine detritus dominated also the lower layers (>6 cm but ≤10 cm) at all but four of the studied localities where fine sediments (particle diameter <0.2 mm) dominated. Sediment and water element concentrations were related to element concentrations in the dominating macrophyte species, viz. Nuphar lutea (roots and leaves), Potamogeton natans (leaves) and Sparganium angustifolium (leaves) and to chlorophyll concentrations using uni- and multivariate statistics. We studied 27 major and trace elements. Estimations of abundance and biomass of N. lutea in eight bays was based on the evaluation of high resolution (2 cm) aerial photographs. The total biomass of N. lutea and standardized biomass (biomass per unit of area) differed significantly among bays. Also concentrations in all matrices as well as in chlorophyll showed significant spatial variation in the lake. N. lutea showed for several elements significant partitioning of elements between roots and leaves (e.g. Ca, K, Na, Fe, Pb, Zn). Correlations between element concentrations in sediment/water and in macrophytes were in general weak but significant for amongst others Si in water and leaves of P. natans and Co, Cu and Fe in water and roots of N. lutea. Interpreting correlations of elements between the sediment and macrophytes might in our study be impeded by potential incorporation of lithogenic material in extracellular macrophyte tissue. Our study identified especially N. lutea as a major sink (during vegetation period) and source (during autumn and winter) of several major and trace elements. Interactions between the matrices, chlorophyll concentrations and macrophyte community structure are further discussed as well as the implications of our results for the development of macrophyte-based indicator values.

It is important that legislation on water quality issues of freshwaters is not in conflict with nature conservation purposes. So far, it is however unknown how the assessment of ecological status according to for example the Water Framework Directive (WFD) of the European Community relates to the status of lakes according to the Habitat Directive (HD) or to national environmental objectives including, e.g., the protection of important wetland areas and red-listed species. We used lake macrophyte classification schemes of Norway, Sweden, and Finland and a total of 1,014 lakes to evaluate the possible conflict between these directives and national legislation. The classification schemes represent mainly trophic indices penalizing lakes with elevated phosphorous concentrations. In general, high ecological status according to the WFD did not mean high number of red-listed species or high status according to the HD or other national environmental objectives. In Sweden 78%, in Norway 47%, and in Finland 29% of lakes with red-listed species were classified as lakes of moderate or worse ecological status based on the macrophyte classification scheme. These lakes thus did not fulfill the demands of the WFD. Restoration of surface water toward fulfilling the demands requires in practice a reduction of the trophic status. This might potentially result in for example the loss of red-listed species. To avoid such potential conflicts, we primarily suggest revising the national quality assessment systems toward implicitly incorporating nature conservation aspects, e.g., the number of red-listed species in a multi-metric assessment system.

Recently, many member states of the European Union (EU) have finalised and implemented national systems for water quality assessment in lakes according to the EU Water Framework Directive (WFD). It is however unknown how the assessment of ecological status, according to the WFD, relates to the status of lakes according to the EU Habitat Directive (HD). High ecological status according to the WFD should mean high status according to the HD. To avoid any conflicts between different EU directives and national environmental objectives, surface waters protected as for example Natura 2000 sites should ideally show high ecological status according to the WFD. Also, high ecological status according to the WFD should imply the presence or potential for presence of red-listed species. Here, we studied the ecological status of 1014 Fennoscandian lakes (224 Norwegian, 491 Swedish and 299 Finnish lakes) according to the WFD and related it to the number of red-listed species per lake and to the status of the lakes as Natura 2000 areas. High ecological status according to the WFD did not mean high status according to the HD or according to national environmental objectives. In general, the number of red-listed species decreased with increased ecological quality ratios. In Norway 47%, in Sweden 78%, and in Finland 29% of lakes with red-listed species were classified as lakes of moderate or worse ecological status according to the WFD. In Sweden 39 of 68 studied Natura 2000 lakes had a moderate or poor ecological status according to the WFD. In Sweden and Norway, in contrast to Finland, macrophyte-based assessment systems are primarily a trophic index, i.e. penalising lakes with elevated phosphorous concentrations. The multimetric nature of the Finnish index probably contributes to the better agreement between the WFD assessment and the number of red-listed species in Finland compared to Sweden and Norway. In Sweden six of eight red-listed species occur in lakes with phosphorous concentrations considerably above reference conditions. Generally, it is assumed that biodiversity is favoured by intermediate nutrient concentrations. In addition, instead of phosphorous, Ca concentrations appear important for the occurrence of many redlisted species, especially for Charophytes. Rapid revision of the national indices is needed to increase compatibility between the two EU directives and to increase the agreement between the WFD and national environmental objectives.

In northern Scandinavia there are indications of a long-term decline in the abundance of the three dominant vole species, Clethrionomys glareolus, Clethrionomys rufocanus and Microtus agrestis, since the 1970s. One explanation proposes that intensified clear-cutting has created even-aged and homogeneous forest stands with poor overall conditions for survival and reproduction of the voles. 2. We investigated the relationship between forest age and structural habitat factors and its implications for the species richness and abundance of small mammals. In particular, we assessed the population dynamics of C. glareolus, a forest-dwelling species with rather general habitat requirements. 3. Extensive snap-trapping of small mammals was conducted during 1998-2000 on 24 study sites in boreal forests in northern Sweden. Trapping was carried out along transects running from immature forests of six age classes (0-50 years) into adjacent reference sites (> 100 years). At each trapping station we recorded 14 habitat variables that were reduced to three principal components (PCs). The PCs were related to late successional traits, such as forest age and cover of tree layers (PC1), cover of tall vegetation in the field layer (PC2) and structural heterogeneity in the forest floor (PC3). 4. The species richness of small mammals, as well as the total abundance of C. glareolus, was positively influenced by tall vegetation (PC2) and structural heterogeneity (PC3) but not by late successional traits (PC1). The youngest forests had higher scores for both PC2 and PC3 compared with older forests. 5. The youngest forests also had the highest species richness and total abundance of C. glareolus. This was associated with a generally higher rate of change in numbers of C. glareolus during summer in the youngest forests compared with adjacent reference sites. In contrast, survival during winter was lower in the youngest forests. We found this result to be consistent with a source-sink scenario where young individuals, primarily born in old forest stands in early summer, migrate into younger forests to breed, but where the probabilities for winter survival are poor. 6. Our study demonstrates that both the species richness of small mammals and the population dynamics of C. glareolus are influenced to a great extent by structural habitat factors that are altered by common forest management practices in northern Sweden. In order to conserve species richness of small mammals and to minimize population fluctuations of C. glareolus in northern Scandinavia, we outline forest management practices that will provide heterogeneous environments, such as leaving logging residues on site after forest harvesting.

Plant strategies under succession were evaluated for communities on rising seashores of the northern Gulf of Bothnia, Sweden, representing sites of primary succession. The succession could not be explained by Grime's CSR model. Early successional stages were neither characterized by high incidence of ruderals as proposed for secondary successions, nor by the dominance of stress tolerators, as proposed for primary successions. Short-lived species were almost totally absent. Instead, the shore habitat was characterized by species with an ability to tolerate and vegetatively recover from disturbance. The way in which different species experience one and the same form of stress or disturbance is an important reason why the classification on the basis of stress and disturbance seems to be insufficient to explain the course of this succession. Dominants of early and late successional stages differed with respect to root system, breeding system, leaf longevity and growth form (graminioid, herb).

It has previously been concluded that the stable Si isotopes are fractionated during geochemical and biogeochemical elemental transfers, such as weathering and precipitation of clays and biogenic Si, which has opened up the possibility of using Si as a tracer in natural terrestrial ecosystems. Furthermore, quantification of the biogenic impact on the biogeochemical Si cycle has attracted significant scientific interest since biological control has been suggested. Previous observations of seasonal variations in the dissolved Si isotopic pattern further imply that high-frequency riverine sampling during main hydrological events might provide important information about natural processes governing the fluvial biogeochemical Si cycle.Therefore, temporal variations in the isotopic composition of riverine dissolved Si were investigated for the Kalix River, Northern Sweden, the largest pristine river system in Europe, based on high-frequency sampling during a period of 25 weeks from early April to early October 2006. Temporal variations spanning 0.4‰ for δ29Si and 0.8‰ for δ30Si of dissolved Si in the Kalix River were observed during the period, suggesting that the riverine dissolved Si input to the oceans cannot be considered to have a constant Si isotopic composition even on a short time scale.The results implicate biogeochemical Si-cycling via formation and dissolution of biogenic silica as processes significantly affecting the dissolved Si transport in boreal systems during April to early October. The Si budget in the river system appeared to be controlled by relative Si enrichment during high discharge events and relative Si depletions in the subarctic mountainous and lake dominated areas. The Si enrichments and depletions were accompanied by decreasing and increasing riverine δ29Si and δ30Si, respectively. These isotope variations can be explained by release of plant derived silica, depleted in heavier Si isotopes, during the spring snowmelt. Further, increased volumetric contribution from the headwater and losses of dissolved Si due to biogenic silica formation by diatoms in the subarctic lakes at a later period are expected to be responsible for the preferential losses of lighter isotopes, as further verified by land cover analysis

Interest in quantifying the biogenic impact on the terrestrial biogeochemical Si cycle has increased significantly since biological control has been suggested. Previous observations of isotopic fractionation of Si during biogeochemical and geochemical processes imply that seasonal dissolved Si isotopic patterns in rivers have the potential for use in extracting information about the riverineand terrestrial biogeochemical Si cycles.Therefore, variations in the isotopic composition of dissolved riverine Si were investigated for the Kalix River, Northern Sweden, one of the largest pristine rivers in Europe, based on high-frequency sampling during a period of 25 weeks from early April to early October 2006. Temporal variations spanning 0.4. for δ29Si and 0.8. for δ30Si of dissolved Si in the Kalix River were observed during the period, suggesting that the riverine Si input to the oceans cannot be considered to have a constant Si isotopic composition even on a short time scale. The results implicate biogeochemical Si-cycling via formation and dissolution of biogenic silica as major processes controlling the Si transport in boreal systems. The Si budget in the river system appeared to be controlled by relative Si accretions during high discharge events and relative Si depletions in the subarctic mountainous and lake dominated areas. There were also temporal variations in Si isotopic composition with accretion (relative Si contribution), accompanied by depletion of the heavier Si isotopes, while the opposite trend was observed during periods of riverine Si depletion. These isotope variations can be explained by release of plant derived silica, depleted in heavier Si isotopes, during the spring snowmelt. Further, increased volumetric contribution from the headwater and losses of Si due to biogenic silica formation by diatoms in the subarctic lakes at a later period are expected to be responsible for the preferential losses of lighter isotopes. These conclusions are further verified by land cover analysis.

QuestionsDo high-resolution (sub-decimetre) aerial images taken with unmanned aircraft systems (UASs) allow a human interpreter to recognize aquatic plant species? Can UAS images be used to (1) produce vegetation maps at the species level; and (2) estimate species abundance? LocationOne river and two lake test sites in northern Sweden, middle boreal sub-zone. MethodsAt one lake and at the river site we evaluated accuracy with which aquatic plant species can be identified on printouts of UAS images (scale 1:800, resolution 5.6 cm). As assessment units we used homogeneous vegetation patches, referred to as vegetation stands of one or more species. The accuracy assessment included calibration and validation based on field controls. At the river site, we produced a digital vegetation map based on an UAS orthoimage (geometrically corrected image mosaic) and the results of the species identification evaluation. We applied visual image interpretation and manual mapping. At one of the lake sites, we assessed the abundance (four-grade scale) of the dominating Phragmites australis and produced a cover map. ResultsWe identified the species composition of vegetation stands at the lake and the river site with an overall accuracy of 95.1% and 80.4%, respectively. It was feasible to produce a digital vegetation map, albeit with a slight reduction in detail compared to the species identification step. At the site for abundance assessment, P. australis covered 20% of the total lake surface area, and 70% of the covered area had cover ≤25%. ConclusionsThe tested UAS facilitates lake and river vegetation identification and mapping at the species level, as well as abundance estimates

Quantifying plant biomass and related processes such as element allocation is a major challenge at the scale of entire riparian zones. We applied sub-decimetre-resolution (5 cm) remote sensing using an unmanned aircraft system (UAS) in combination with field sampling to quantify riparian vegetation biomass at three locations (320-m river stretches) along a mining-impacted boreal river and estimated the amounts of Cd, Cu, and Zn stored in the dominant species. A species-level vegetation map was derived from visual interpretation of aerial images acquired using the UAS and field sampling to determine species composition and cover. Herbaceous and shrub biomass and metal contents were assessed by combining the vegetation maps with field sampling results. Riparian zone productivity decreased from 9.5 to 5.4 t ha-1 with increasing distance from the source of contamination, and the total amount of vegetation-bound Cd and Zn decreased from 24 to 0.4 and 3,488 to 211 g, respectively. Most Cu was stored at the central location. Biomass and metal contents indicated large variation between species. Salix spp. comprised only 17% of the total dominant-species biomass but contained 95% of all Cd and 65% of all Zn. In contrast, Carex rostrata/vesicaria comprised 64% of the total dominant-species biomass and contained 63% of all Cu and 25% of all Zn. Our study demonstrates the applicability of UAS for monitoring entire riparian zones. The method offers great potential for accurately assessing nutrient and trace element cycling in the riparian zone and for planning potential phytoremediation measures in polluted areas

Over the past three decades in boreal Sweden, there has been a long-term decline of cyclic sympatric voles, leading to local extinctions of the most affected species, the grey-sided vole (Clethrionomys rufocanus). We monitored this decline by snap-trapping on 58 permanent plots spread over 100 km2 in spring and fall from fall 1971-2003. The reason for the decline is largely unknown, although a common major factor is likely to be involved in the decline of C. rufocanus and of the coexisting voles. However, here we deal with the reasonability of one complementary hypothesis, the habitat fragmentation hypothesis, which assumes that part of the decline of C. rufocanus is caused by habitat (forest) destruction. There was considerable local variation in the decline among the 58 1-ha sampling plots, with respect to both density and timing of the decline; however, all declines ended up with local extinction almost without exception. Local declines were not associated with habitat destruction by clear-cutting within sampling-plots, as declines started about equally often before as after clear-cutting, which suggested that habitat destruction outside sampling plots could be involved. In a multiple regression analysis, local habitat preference (LHP; expressed as a ratio of observed to expected number of voles trapped per habitat) together with two habitat variables in the surrounding (2.5×2.5 km2) landscape matrix explained 56% of the variation among local cumulated densities of C. rufocanus and hence of local time-series. LHP was positively correlated and explained 31% of the variation, while connectivity among clear-cuts was negatively correlated and proximity among xeric-mesic mires was positively correlated and explained additional 16% and 9%, respectively. Even if the overall decline cannot be connected to local clear-cutting on sampling-plots, clear-cutting and hence habitat fragmentation/destruction in the surrounding landscapes potentially influenced grey-sided vole numbers negatively.

1. Suppression of wildfires in boreal landscapes has become widespread and has seriously affected many fire favoured species. However, little is known about the response of organism assemblages to large wildfires in regions with a long history of effective fire suppression, such as Scandinavia.2. We studied the short-term effects of a >1600 ha wildfire on beetle assemblages in northern Sweden. The first summer after fire, beetles were sampled in 12 sites using 36 large window traps, half in old pine forest stands in the burned area and half in similar, but unburned control stands. The entire beetle assemblage and eight subgroups were analysed: saproxylics, non-saproxylics, moderately fire favoured, strongly fire favoured, fungivores, predators, cambium consumers and red-listed species.3. Species composition differed markedly between burned and unburned forests in all nine groups. Furthermore, beetle abundance was higher in the burned area for the entire assemblage and for saproxylics, both groups of fire favoured species, predators and cambium consumers. Species number was higher only for non-saproxylics, strongly fire favoured species and cambium consumers.4. Our results show that wildfire has rapid and strong effects on a wide range of beetles. However, we only trapped two individuals of fire-dependent beetles, which may suggest a lack of such species in the region, possibly due to >100 years of fire suppression. At the regional scale, the studied wildfire may potentially increase the abundance of these beetles after a longer period of reproduction in the burned area.

Many northern lakes are regulated to enhance hydropower production and flood protection. This bears hydromorphological pressures which are important factors causing lowered ecological status. Water level fluctuation triggers erosion on the shoreline and, depending on fluctuation range, also affects species composition or disappearance of sensitive aquatic macrophytes. We developed a water leveldrawdown index (WIc) for Nordic lakes using macrophytedata from 73 lakes with varying water level fluctuation in Finland, Norway and Sweden. The index is based on the ratio between sensitive and tolerant macrophyte species. The sensitive and tolerant species are identified based on a percentile approach, analysing the presence or absence of species along the winter drawdown range. The index correlates well with winter drawdown in Finnish and Norwegian lakes with strongest correlations with winter drawdown in storage lakes (lakes regulated for hydroelectric power and with a considerable winter drawdown). The WIcindex is applicable in low alkalinity, oligotrophic and ice-covered lakes, and is suggested to be a useful tool to identify and designate heavily modified water bodies in Nordic lakes according to the European Water Framework Directive.

Previous research [1] has suggested that the boron (B) isotope system has a potential to be used as a tracer for detecting historic wood fire events. It was hypothesized that highly elevated B concentrations in sediments of a lake, accompanied by an enrichment of 10B, were a result of an urban wood fire event in the 19th century. The δ11B decrease in these sediments exceeded 9 ., coinciding with a peak in the B concentration.To evaluate this hypothesis, seasonal isotopic pattern of boron (B) was investigated during spring and summer 2007 in a small stream draining a boreal forest area which was severely burnt in a major forest fire in the summer of 2006. Dissolved (< 0.22 µm) boron concentrations of the burnt area were significantly higher compared to a non-burnt reference stream, while 11B/10B ratios were significantly lower. Dissolved δ11B differences between the reference and the burnt area stream were found to be -9 to -22 .. We interpret the elevated B concentrations, accompanied by enrichment of 10B, in the burnt stream as wood and plant ash leaching of biogenic B from the burnt forest by surface run-off. Our results suggest that a boreal forest fire event significantly increases the leached amount of isotopically lighter B in the dissolved phase of stream run-off.[1] Peltola & Åström (2006), Appl. Geochem. 21 (2006) 941-948.

An analytical method allowing multi-element characterization by external calibration, osmium (Os) concentration determination by isotope dilution (ID) and 187Os/188Os isotope abundance ratio measurement from a single sample preparation was developed. The method consists of microwave-assisted, closed-vessel acid digestion of small (0.01-0.4 g dry weight) biological samples spiked with Os solution enriched in a 190Os isotope followed by concentration and Os isotope ratio measurements using double-focusing, sector field inductively coupled plasma mass-spectrometry (ICP-SFMS) operated with methane addition to the plasma and solution nebulization (SN) sample introduction. For samples with Os content below 500 pg, complementary analysis using gas-phase introduction (GPI) on the remaining sample digests was performed. The use of disposable plastic lab ware for sample digestion and analysis by SN ICP-SFMS circumvents Os carry-over effects and improves the sample throughput and cost-efficiency of the method. For a 0.1 g dried sample, Os method limits of detection (MLODs) of 2 pg g -1 and 0.2 pg g-1 were obtained using SN or GPI, respectively. Long-term reproducibility of 187Os/188Os isotope abundance ratio measurements using the GPI approach was better than 1.5% RSD for our in-house control sample (moose kidney) with an Os concentration of approximately 5 pg g-1. Os data for several commercially available reference materials of biological or plant origin (not certified for Os) are presented. The method was used in the large scale bio-monitoring of free-living bank voles from an area affected by anthropogenic Os emissions.

Intensive Cu-Ni and Fe mining and smelting in northwestern Russia constitutes a potential risk of pollution in the Kola River. We assessed the degree of pollution along the Kola River by means of overall water quality evaluation and analyses of metals in water samples (dissolved and particulate fractions) and aquatic mosses. The observed pollutant levels were compared with those in unpolluted reference rivers. The results indicate relatively low overall contamination in the Kola River, although Cu and Ni levels are elevated relative to the reference data. Furthermore, PCA ordination models identified clear metal concentration patterns along the river. Al, Cd, Co, Fe, Pb and Zn exhibited an almost continuous increase from the headwaters to the river mouth, whereas As, Ba, Cu, Mn, Mo and Ni showed their highest concentrations in the headwaters, close to the mining areas, relatively low concentrations in the middle parts of the river and elevated concentrations at the river mouth. Bryophyte analysis appeared to be a more sensitive tool for metal pollution assessment than metal concentrations in water.

Defining the overall ecological status of lakes according to the Water Framework Directive (WFD) is to be partially based on the species composition of the aquatic macrophyte community. We tested three assessment methods to define the ecological status of the macrophyte community in response to a eutrophication pressure as reflected by total phosphorus concentrations in lake water. An absolute species richness, a trophic index (TI) and a lake trophic ranking (LTR) method were tested at Europe-wide, regional and national scales as well as by alkalinity category, using data from 1,147 lakes from 12 European states. Total phosphorus data were used to represent the trophic status of individual samples and were plotted against the calculated TI and LTR values. Additionally, the LTR method was tested in some individual lakes with a relatively long time series of monitoring data. The TI correlated well with total P in the Northern European lake types, whereas the relationship in the Central European lake types was less clear. The relationship between total P and light extinction is often very good in the Northern European lake types compared to the Central European lake types. This can be one of the reasons for a better agreement between the indices and eutrophication pressure in the Northern European lake types. The response of individual lakes to changes in the abiotic environment was sometimes represented incorrectly by the indices used, which is a cause of concern for the use of single indices in status assessments in practice.

Aquatic macrophytes are one of the biological quality elements in the Water Framework Directive (WFD) for which status assessments must be defined. We tested two methods to classify macrophyte species and their response to eutrophication pressure: one based on percentiles of occurrence along a phosphorous gradient and another based on trophic ranking of species using Canonical Correspondence Analyses in the ranking procedure. The methods were tested at Europe-wide, regional and national scale as well as by alkalinity category, using 1,147 lakes from 12 European states. The grouping of species as sensitive, tolerant or indifferent to eutrophication was evaluated for some taxa, such as the sensitive Chara spp. and the large isoetids, by analysing the (non-linear) response curve along a phosphorous gradient. These thresholds revealed in these response curves can be used to set boundaries among different ecological status classes. In total 48 taxa out of 114 taxa were classified identically regardless of dataset or classification method. These taxa can be considered the most consistent and reliable indicators of sensitivity or tolerance to eutrophication at European scale. Although the general response of well known indicator species seems to hold, there are many species that were evaluated differently according to the database selection and classification methods. This hampers a Europe-wide comparison of classified species lists as used for the status assessment within the WFD implementation process.

Osmium tetroxide (OsO4) is one of the most toxic air contaminants but its environmental effects are poorly understood. Here, for the first time, we present evidence of osmium uptake in a common herbivore (bank vole, Myodes glareolus) in boreal forests of northern Sweden. Voles (n = 22) and fruticose arboreal pendular lichens, the potential main winter food source of the vole, were collected along a spatial gradient to the west of a steelwork in Tornio, Finland at the Finnish-Swedish border. 187Os/188Os isotope ratios increased and osmium concentrations decreased in lichens and voles along the gradient. Osmium concentrations in lichens were 10,000-fold higher than those in voles. Closest to the steelwork, concentrations were highest in kidneys rather than skin/fur that are directly exposed to airborne OsO4. The kidney-to-body weight ratio was higher at the two localities close to the steelwork. Even though based on a small sample size, our results for the first time demonstrate that osmium is taken up, partitioned, and accumulated in mammal tissue, and indicate that high kidney-to-body weight ratios might be induced by anthropogenic osmium.

Växtsamhällen på stränder av landhöjningskusten i norra Bottenviken, som representerar lokaler med primärsuccession, undersöktes på sin struktur. Grimes triangelmodell för växtstrategier under successionen, liksom teorier om en vid nischbredd av tidiga successionsarter och av reducerad nischöverlappning bland växtarter som tillhör samma släkte testades. Dessutom söktes efter växtegenskaper i litteraturen, för att gruppera arterna i olika guilds. Guilds användes för att illustrera successionsprocessen.Vegetationen i tio transekter placerade på olika strandtyper studerades från några centimeter under medelvattenståndet till flera meter in i busk- och trädzonen. Växternas täckningsgrad (%) värderades, växternas höjd mättes och 16 miljövariabler undersöktes.Genom att analysera värdena med Canonical Correspondence Analysis var det möjligt att visa skillnader och likheter mellan transekterna baserade på växtarternas täckningsgrad. Höjd över havet visade sig att ha den största betydelsen för växternas fördelning när miljöfaktorerna inkluderades i ordinationen. Korrelationsanalys visade att höjden över havet var signifikant korrelerad med flera andra undersökta miljöfaktorerna.Grimes modell gällde inte för denna typ av samhälle. Tidiga successionsstadier karakteriserades inte av en hög förekomst av kortlevande växter. En klassifikation baserad på stress, produktivitet och störningar verkar vara otillräcklig för att förklara successionsförloppet och växternas realiserade nischer. Reducerad nischöverlappning av växter som tillhör samma släkte kunde inte påvisas. Tvärtom, i de tre fall där signifikanta skillnader upptäcktes hade växter som tillhör samma släkte en större överlappning mellan varandra i jämförelse med referensarter. Nischbredden var inte större för tidiga successionsarter i jämförelse med sena arter. Arternas responsbredd var större för markfaktorer än för höjden över medelvattenytan.Nästan inga kortlivade arter hittades. Olika former och intensitet av störningar förorsakar kanske ett lågt fortbestånd av dessa arter genom att hindra en lyckosam reproduktion. Tidiga och sena successionsarter skilde sig beträffande rotsystemet, pollinationssättet, bladens livslängd och växtformen (graminoid, örtartad). Detta indikerar att det är inte bara växtarterna som ändrar sig under successionsförloppet utan även växtstrategier. Det tidiga successionsstadiet karakteriserades av rhizomatous-graminoid guild, det sena stadiet av summergreen-forb guild.

Four metal speciation and fractionation techniques – DGT (diffusive gradients in thin films), 1-kDa ultrafiltration, 0.22-µm membrane filtration and aquatic moss – were simultaneously applied to a small, contaminated freshwater stream in northern Sweden to investigate differences and similarities between the methods regarding trace metal speciation and their dependence on geochemical water properties. The investigated metals comprise Al, Cd, Co, Cu, Fe, Mn, Ni, and Zn. The normal DGT devices with Chelex cation exchanger were used. Shoots from the aquatic moss Fontinalis antipyretica L ex Hedw. were collected in a non-polluted brook and transplanted to the sampling site for exposure. It was evident that 0.22-µm membrane filtration, 1-kDa ultrafiltration and DGT generally measured different metal fractions where <1-kDa ultrafiltered concentrations were lower than DGT labile concentrations which in turn were lower than <0.22-µm concentrations. The differences between DGT and <1-kDa concentrations indicate the occurrence of labile colloids discriminated by ultrafiltration. Strong correlations between DGT and <1 kDa concentrations were found for Al, Cu, Cd, Co and Zn. Despite a rigorous sample cleaning, retention of particulate matter on the moss samples was revealed by a significant correlation between metal concentrations in moss and particulate Fe. Generally, elevated trace metal concentrations were found in moss exposed at the sampling site compared to reference moss from the non-polluted brook. No significant correlations were found between DGT-labile concentrations and moss concentrations.

The efficiency of biogeochemical mapping for identifying acid sulphate soils (AS soils) was studied by sampling and analysing water, transplanted aquatic moss (Fontinalis antipyretica) and leaves of the vascular plant Calamagrostis purpurea at two sites in a stream in northern Sweden with AS soils in its drainage area. One upstream sampling station (Mårtsmarken) was situated in an area dominated by till, and a downstream station (Persraningen) was situated in an area where AS soils are common. Metal contents in F. antipyretica and C. purpurea at these sites were compared to those in water (both unfiltered samples, and samples subjected to 0.22 μm membrane filtration and 1 kDa ultrafiltration to obtain data on metal speciation and its effects on uptake). Oxidation of sulphides with associated increases in acidity and release of metals were clearly reflected by differences in the water samples. At Persraningen the pH was lower than at Mårtsmarken, and the unfiltered concentrations of Al, Ca, Cd, Co, Cu, K, Mg, Mn, Ni, P, S, Sr, Y and Zn were higher. At the upstream station, Mårtsmarken, the suspended fraction was an important carrier of Fe and P, and the colloidal concentrations were higher than or similar to the dissolved concentrations for all determined elements except Na and K. At Persraningen the low pH resulted in changes of speciation, so that the dissolved concentrations were higher than the colloidal concentrations for most elements. For Al, As, Cr, Cu, Pb and Y, the dissolved and colloidal concentrations were similar. For Fe, the colloidal concentration was usually higher than the dissolved concentration, and suspended Fe was detected. Aluminium, Cr, Cu, Fe and Y concentrations were significantly higher in Fontinalis antipyretica at Persraningen than at Mårtsmarken. In addition, concentrations of Al and Fe in C. purpurea were significantly higher at Persraningen. Our results highlight the potential of biogeochemical mapping for predicting the occurrence of AS soils. A limitation is the strong pH dependence of the uptake of metals in the aquatic mosses resulting in that only a few of the elements typically occurring at high concentrations in waters draining AS soils are enriched in the macrophytes. A combination of maps showing both absolute concentrations and elemental ratios would be useful for this, including not only ratios of previously suggested utility (e.g. Y:Pb and Ni:Pb), but also others, such as Y:Ca, Al:Ca, Cu:Ca, Y:Mg, Al:Mg and Cu:Mg. © 2014 AAG/The Geological Society of London.