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  • 1.
    Andersson, Per
    et al.
    Stockholms Universitet.
    Torssander, P.
    Stockholms Universitet.
    Ingri, Johan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Sulphur isotope ratios in sulphate and oxygen isotopes in water from a small watershed in central Sweden1992In: Hydrobiologia, ISSN 0018-8158, E-ISSN 1573-5117, Vol. 235-236, no 1, p. 205-217Article in journal (Refereed)
    Abstract [en]

    During 1988-89 water samples for sulphur and oxygen isotope measurements were collected in the Lake Mjösjön watershed (7.3 km2), central Sweden. Samples included: precipitation, throughfall, lakewater, shallow groundwater and inlet and outlet streams. The δ34S of sulphate in precipitation ranged from + 6.41‰ in winter to + 3.88‰ in summer, the higher winter values attributed to seasonal differences in the kinetic and equilibrium isotope fractionation during oxidation of atmospheric sulphur dioxide to sulphate. The δ34S in rain samples and in pine and spruce throughfall were similar, indicating no gain of sulphur from the trees. In the inflowing stream, the δ34S value increased as discharge decreased, from + 5.57‰ in spring to + 26.21‰ in summer, indicating bacterial sulphate reduction. The fluctuations in the inlet water were damped by the lake and in the outlet water, only a small decrease in the δ34S value during spring discharge was observed. During winter 1988-89, the near surface waters in the lake showed the same δ34S as snow indicating that meltwater governs the isotopic composition. During the winter, the δ34S in the near bottom waters increased while oxygen decreased due to bacterial sulphate reduction in the sediments. This also caused an increase in the alkalinity in the near bottom waters. Based on the δ18O data the water within the watershed is derived largely from meteoric water. During spring discharge, meltwater governs the inflow and outflow stream while additional groundwater influences occurred during the drier period. Most sulphur is derived from atmospheric deposition and the δ34S in sulphate increased during passage through the watershed due to bacterial sulphate reduction.

  • 2.
    Dudley, Bernard J.
    et al.
    Centre for Ecology and Hydrology, Bush Estate, Penicuik.
    Dunbar, Michael
    Centre for Ecology and Hydrology, Wallingford, Oxon.
    Penning, Ellis
    Deltares, Delft.
    Kolada, Agnieszka
    Institute of Environmental Protection - National Research Institute, Warsaw.
    Hellsten, Seppo K.
    Finnish Environment Institute (SYKE), University of Oulu.
    Oggioni, Alessandro
    Institute for Electromagnetic Sensing of the Environment CNR - IREA, Via Bassini.
    Bertin, Vincent
    Irstea, UR REBX, 50 Avenue de Verdun.
    Ecke, Frauke
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Søndergaard, Martin
    Institute of Bioscience, Aarhus University.
    Measurements of uncertainty in macrophyte metrics used to assess European lake water quality2013In: Hydrobiologia, ISSN 0018-8158, E-ISSN 1573-5117, Vol. 704, no 1, p. 179-191Article in journal (Refereed)
    Abstract [en]

    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.

  • 3.
    Ecke, Frauke
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Hellsten, Seppo
    Finnish Environment Institute (SYKE), University of Oulu.
    Mjelde, Marit
    Norwegian Institute for Water Research (NIVA), Trondheim.
    Schlacke, Sabine
    Research Centre for European Environmental Law, Faculty of Law, University of Bremen.
    Potential conflicts between environmental legislation and conservation exemplified by aquatic macrophytes2010In: Hydrobiologia, ISSN 0018-8158, E-ISSN 1573-5117, Vol. 656, no 1, p. 107-115Article in journal (Refereed)
    Abstract [en]

    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.

  • 4.
    Mjelde, Marit
    et al.
    Norwegian Institute for Water Research (NIVA), Trondheim.
    Hellsten, Seppo
    Finnish Environment Institute (SYKE), University of Oulu.
    Ecke, Frauke
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    A water level drawdown index for aquatic macrophytes in Nordic lakes2013In: Hydrobiologia, ISSN 0018-8158, E-ISSN 1573-5117, Vol. 704, no 1, p. 141-151Article in journal (Refereed)
    Abstract [en]

    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.

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