RESUMEN
The abundance and properties of small standing water bodies (SSWB) is globally not well known for their ecological importance is undervalued and their detection suffers from technical limitations. In the current study, we used a combination of GIS-based methods (satellite, orthophoto, ground validation) to evaluate regional estimates of standing water body (SWB) inventories in two geographically different parts of Europe - France, and Estonia. In our study the SWBs surface area threshold limit was 0.00001 km2, exceeding the limits of previous studies (>0.002 km2). The total number of SWBs in Estonia is 111 552 (2.5 per km2) and in France 598 371 (1.1 per km2). Our estimates show that the median size of SWBs in Estonia and France is 0.0003 km2 and 0.0007 km2 respectively, meaning that most of the SSWBs are not included in the global inventories, and their number is therefore underestimated. SSWBs (area below 0.01 km2) form a significant share of the total shoreline length of SWBs, 70.3% in Estonia and 58.8% in France. As nearshore areas are often very productive with diverse habitats, the SSWBs hold a crucial role in maintaining biodiversity. Our results provide quantitative evidence that SSWBs are vital and abundant landscape elements, freshwater resources, and habitats that should not be ignored in global inventories.
RESUMEN
The distribution of 11 individual polycyclic aromatic hydrocarbons (PAHs) was analysed in a (210)Pb dated sediment core from the deepest area of Lake Peipsi and in four surface sediment samples taken from littoral areas. According to the concentrations in the core three groups of PAHs may be distinguished: (1) relatively stable concentrations of PAHs within the whole studied time interval; (2) very low concentrations in sediments accumulated before intensive anthropogenic impact (from 19th century up to the 1920s) following a slight increase and (3) an overall increase in PAH concentrations since the 1920s up to the present. Comprehensive analysis of PAHs in the core and monitoring data obtained in the 1980s together with the lithology of sediments show that an increase of anthropogenically induced PAHs correlates well with the history of fuel consumption in Estonia and speaks about atmospheric long-distance transport of PAHs. The continuous increase of PAH concentrations since the 1920s do not support the earlier hypothesis about the dominating impact of the oil shale fired power plants near the lake, because their emissions decreased significantly in the 1990s. The concentration of PAHs in the deep lake core sample correlates well with the content of organic matter, indicating absorption and co-precipitation with plankton in the sediment.