SMALL MAMMAL POPULATIONS AND COMMUNITY UNDER CONDITIONS OF EXTREMELY HIGH THALLIUM CONTAMINATION IN THE ENVIRONMENT

Studies were carried out in the vicinity of a zinc smelter in southern Poland, 50 km northwest of Krakow, where the previous measurements,vi th another bioindication method revealed huge thallium levels in the e nvironment. The mammals (106 individuals in total) were captured in fo ur wooded areas situated 1.5 to 2.5 km in various directions from the plant and in two reference sites, located far from industrial emission sources. Very high Tl levels were found in livers and kidneys of all mammals examined from the two areas nearest the smelter. Bank voles we re the most loaded (maximum Tl in kidneys, 34.27 mu g/g dry mass; in l ivers, 14.53 mu g/g; values from unpolluted areas were below the detec tion limit, 0.07 mu g/g). A distinct decrease in the amount of hair-a characteristic of thallium poisoning-was observed in several individua ls. The extreme case was a wood mouse with the rear half of its body a lmost entirely hairless (!). Densities of single populations and the w hole community were very low, up to 4.8 individuals/ha, including inse ctivores. Numerical proportions between species were changed in compar ison to unpolluted areas. The age structure was deformed, with a dispr oportionate small participation by young generations. Among the males studied, only sexually inactive individuals were found. The condition of populations and the community of small mammals living here was much worse compared with data from the surroundings of other zinc smelters . (C) 1998 Academic Press