Unexpected response of high Alpine Lake waters to climate warming.

Over the past two decades, we have observed a substantial rise in solute concentration at two remote high mountain lakes in catchments of metamorphic rocks in the European Alps. At Rasass See, the electrical conductivity increased 18-fold. Unexpectedly high nickel concentrations at Rasass See, which exceeded the limit in drinking water by more than 1 order of magnitude, cannot be related to catchment geology. We attribute these changes in lake water quality to solute release from the ice of an active rock glacier in the catchment as a response to climate warming. Similar processes occurred at the higher elevation lake Schwarzsee ob Sölden, where electrical conductivity has risen 3-fold during the past two decades.

Factors governing the atmospheric deposition of polycyclic aromatic hydrocarbons to remote areas.

Polycyclic aromatic hydrocarbons (PAH) were measured in bulk atmospheric deposition collected in three remote areas of Europe during 1997-1998. Mean total PAH fluxes over a period of 18 months were 1560 +/- 750 and 1150 +/- 630 ng m(-2) mo(-1) in the Pyrenees and the Alps, respectively. In the Caledonian mountains (Scandinavia) the observed mean fluxes were 1900 +/- 940 ng m(-2) mo(-1) (6 month collection). Similar qualitative PAH compositions (p values <0.05) in the bulk atmospheric deposition have been observed between sites, which are dominated by the more volatile parent compounds. The main differences between lakes are related to the high molecular weight compounds. Atmospheric deposition of PAH to these remote sites appears to be independent of their concentrations in the atmosphere, which are similar between sites (in the range of 1.8-3.0 ng x m(-3)), being controlled mainly by particle deposition, followed by precipitation and air temperature. A multilevel regression model including these three variables accounted for 74% of the total variability in total PAH bulk deposition; however, the contribution of each variable in the model is compound and site-dependent. The deposition of high molecular weight PAH depends more on particle deposition and precipitation, whereas air temperature is the main factor controlling the deposition fluxes of the low molecular weight PAH.

Atmospherc deposition of organochlorine compounds to remote high mountain lakes of Europe.

Bulk deposition samples were taken near three mountain lakes located in the Pyrenees (Estany Redó), Alps (Gossenköllesee), and Caledonian Mountains (Ovre Neådalsvatn) for evaluation of the atmospheric deposition load of organochlorine compounds (OC), namely, polychlorobiphenyls (PCBs), hexachlorocyclohexanes (HCHs), hexachlorobenzene (HCB), and endosulfans, in the remote European high mountain areas. The compounds of present use in agriculture, namely, endosulfans and gamma-HCH, exhibit large differences in mean deposition fluxes between the three sites. They occur in large amounts in Estany Redó (340 and 430 ng m(-2) month(-1) for endosulfans and gamma-HCH, respectively), reflecting the impact of agricultural activities in southern Europe. This lake showed also the highest proportion of the more labile endosulfan isomers (alpha and beta = 82%) whereas only the most recalcitrant species, endosulfan sulfate, was found in Ovre Neådalsvatn. In contrast, the OC whose use is now banned exhibit a more uniform geographic distribution with deposition fluxes of 31-40, 30-100, and 1.4-15 ng m(-2) month(-1) for alpha-HCH, PCBs, and HCB. Both compounds of present and past use exhibit a clear seasonal pattern, with higher deposition in the warm periods, which is consistent with enhanced volatilization at higher temperatures. In the case of the agricultural pesticides it may also reflect higher use during application periods. The OC distributions in the atmospheric deposition of the three sites are rather uniform and highly enriched in compounds with volatilities larger than 0.0032 Pa. However, more than 90% of these compounds are not retained in the lake waters or sediments. Comparison of OC composition in atmospheric and sedimentary deposition evidences a selective trapping of the less volatile compounds. Trapping efficiencies increase at decreasing air temperatures of the lacustrine systems.