Author/Editor		Kotnik, Jože; Horvat, Milena; Fajon, Vesna; Logar, Martina
Title		Geokemijski cikel živega srebra v Velenjskem jezeru
Type		članek
Source		In: Glavič P, Brodnjak-Vončina D, editors. Zbornik referatov s posvetovanja Slovenski kemijski dnevi 2000: 1. in 2. del; 2000 sep 28-29; Maribor. Maribor: FKKT,
Publication year		2000
Volume		str. 704-9
Language		slo
Abstract		Lake Velenje is located in one of the most polluted regions of Slovenia, the Šalek Valley. The major source of pollution is the coal-fired thermal power plant in Šoštanj (ŠTPP). Mass balance calculations in 1992 (Stropnik 1994) showed that around 630 kg of mercury are emitted into the atmosphere per year. In the past, dumping of coal ash directly into Lake Velenje and drainage water from the ash disposal site resulted in unique chemical characteristics of the lake water, such as very high pH (10-12) and a high concentrations of heavy metals. The introduction of a closed cycle ash transport system in 1995 resulted in a very fast recovery of the lake water quality. The aim of our study was to establish the sources, fate and distribution of mercury in Lake Velenje. In order to establish recent sources of mercury, total mercury and methylmercury concentrations were measured in various environmental samples (lake inflows, outflow, rainwater, sediments, etc.). Total mercury and methylmercury concentrations were measured at the surface and at different depths to establish mercury cycling, its transport and chemical transformations in the lake. The results show that the major sources of mercury in Lake Velenje are lake inflows and wet deposition. Total mercury and methylmercury concentrations in the water column are very low (total mercury: 0.2 - 2.7 ng/L; methylmercury: 20 - 86 pg/L) and can be compared to other non-contaminated freshwater lakes. These results suggest that the mercury emitted from the thermal power plant stacks has no or very little influence on the nearby sorroundings, but rather is subject of long range transport.
Descriptors		FRESH WATER WATER POLLUTANTS, CHEMICAL MERCURY POWER PLANTS METHYLMERCURY COMPOUNDS