| Abstract | 1. We carried out a coordinated survey of mountain lakes covering the main ranges across Europe (including Greenland), sampling 379 lakes above the local tree line in 2000. The objectives were to identify the main sources of chemical variability in mountain lakes, define a chemical classification of lakes, and develop tools to extrapolate our results to regional lake populations through an empirical regionalisation or upscaling of chemical properties.
2. We investigated the main causes of chemical variability using factor analysis (FA) and empirical relationships between chemistry and several environmental variables. Weathering, sea salt inputs, atmospheric deposition of N and S, and biological activity in soils of the catchment were identified as the major drivers of lake chemistry.
3. We tested discriminant analysis (DA) to predict the lake chemistry. It was possible to use the lithology of the catchments to predict the range of Ca2+ and SO(4)2- into which a lake of unknown chemistry will decrease. Lakes with lower SO(4)2- concentrations have little geologically derived S, and better reflect the variations in atmospheric S loading. The influence of marine aerosols on lakewater chemistry could also be predicted from the minimum distance to the sea and altitude of the lakes.
4. The most remarkable result of FA was to reveal a factor correlated to DOC (positively) and NO(3)- (negatively). This inverse relationship might be the result either of independent processes active in the catchment soils and acting in an opposite sense, or a direct interaction, e.g. limitation of denitrification by DOC availability. Such a relationship has been reported in the recent literature in many sites and at all scales, appearing to be a global pattern that could reflect the link between the C and N cycles.
5. The concentration of NO(3)- is determined by both atmospheric N deposition and the processing capacity of the catchments (i.e. N uptake by plants and soil microbes). The fraction of the variability in NO(3)- because of atmospheric deposition is captured by an independent factor in the FA. This is the only factor showing a clear pattern when mapped over Europe, indicating lower N deposition in the northernmost areas.
6. A classification has been derived which takes into account all the major chemical features of the mountain lakes in Europe. FA provided the criteria to establish the most important factors influencing lake water chemistry, define classes within them, and classify the surveyed lakes into each class. DA can be used as a tool to scale up the classification to unsurveyed lakes, regarding sensitivity to acidification, marine influence and sources of S. |
| Text | 179122 2009 10.1111/j.1365 2427.2009.02296.x ISI Web of Science WOS 000271710100003 chemical classification lakewater chemistry mountain lakes regionalisation upscaling Regionalisation of chemical variability in European mountain lakes Camarero L. 1 ; Rogora M. 2 ; Mosello R. 2 ; Anderson N.J. 3 ; Barbieri A. 4 ; Botev I. 5 ; Kernan M. 6 ; Kopacek J. 7 ; Korhola A. 8 ; Lotter A.F. 9 ; Muri G. 10 ; Postolache C. 11 ; Stuchlik E. 12 ; Thies H. 13 ; Wright R.F. 14 1 Limnological Observatory of the Pyrenees Centre d Estudis Avanc¸ats de Blanes CSIC, Blanes, Spain 2 CNR Institute of Ecosystems Study, Verbania Pallanza, Italy 3 Geological Survey of Denmark Greenland GEUS Copenhagen GeoCenter, Copenhagen, Denmark 4 Laboratorio Studi Ambientali, SPAA, Paradiso Lugano, Switzerland 5 Institute of Zoology, BAS, Sofia, Bulgaria 6 Environmental Change Research Centre Department of Geography, University College London, London, UK 7 Hydrobiological Institute AS CR, Ceske Budejovice, Czech Republic 8 Environmental Change Research Unit ECRU , Department of Biological and Environmental Sciences, University of Helsinki, Helsinki, Finland 9 Laboratory of Palaeobotany and Palynology, Utrecht University, Utrecht, The Netherlands 10 National Institute of Biology, Ljubljana, Slovenia 11 Department of Systems Ecology, University of Bucharest, Bucharest, Romania 12 Hydrobiological Station Velky Palenec, Institute for Environmental Studies, Charles University, Blatna, Czech Republic 13 Institute of Ecology, University of Innsbruck, Innsbruck, Austria 14 Norwegian Institute for Water Research, Oslo, Norway 1. We carried out a coordinated survey of mountain lakes covering the main ranges across Europe including Greenland , sampling 379 lakes above the local tree line in 2000. The objectives were to identify the main sources of chemical variability in mountain lakes, define a chemical classification of lakes, and develop tools to extrapolate our results to regional lake populations through an empirical regionalisation or upscaling of chemical properties. 2. We investigated the main causes of chemical variability using factor analysis FA and empirical relationships between chemistry and several environmental variables. Weathering, sea salt inputs, atmospheric deposition of N and S, and biological activity in soils of the catchment were identified as the major drivers of lake chemistry. 3. We tested discriminant analysis DA to predict the lake chemistry. It was possible to use the lithology of the catchments to predict the range of Ca2 and SO 4 2 into which a lake of unknown chemistry will decrease. Lakes with lower SO 4 2 concentrations have little geologically derived S, and better reflect the variations in atmospheric S loading. The influence of marine aerosols on lakewater chemistry could also be predicted from the minimum distance to the sea and altitude of the lakes. 4. The most remarkable result of FA was to reveal a factor correlated to DOC positively and NO 3 negatively . This inverse relationship might be the result either of independent processes active in the catchment soils and acting in an opposite sense, or a direct interaction, e.g. limitation of denitrification by DOC availability. Such a relationship has been reported in the recent literature in many sites and at all scales, appearing to be a global pattern that could reflect the link between the C and N cycles. 5. The concentration of NO 3 is determined by both atmospheric N deposition and the processing capacity of the catchments i.e. N uptake by plants and soil microbes . The fraction of the variability in NO 3 because of atmospheric deposition is captured by an independent factor in the FA. This is the only factor showing a clear pattern when mapped over Europe, indicating lower N deposition in the northernmost areas. 6. A classification has been derived which takes into account all the major chemical features of the mountain lakes in Europe. FA provided the criteria to establish the most important factors influencing lake water chemistry, define classes within them, and classify the surveyed lakes into each class. DA can be used as a tool to scale up the classification to unsurveyed lakes, regarding sensitivity to acidification, marine influence and sources of S. 54 Published version Articolo pubblicato 9_FreshBiol_2009_.pdf Articolo in rivista Blackwell Scientific Publications. 0046 5070 Freshwater biology Print Freshwater biology Print Freshw. biol. Print michela.rogora ROGORA MICHELA rosario.mosello MOSELLO ROSARIO TA.P02.014.002 Impatto dei cambiamenti globali sugli ecosistemi acquatici |
