Total Mercury in Lake Neusiedl, Austria

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Between May and September 2011 a total of 361 samples from water, sediment, macrophytes and fish tissues from the shallow, slightly alkaline Lake Neusiedl were measured for their total mercury content with cold vapour atomic absorption spectroscopy (CV-AAS). Hg content of surface water was below the LOD of 0.1 μg/L and the sediments displayed contents between 0.025 and 0.113 μg/g dw, significantly correlated with the proportion of organic components (fig 1). Although these results do not point to an anthropogenic pollution of the lake, considerable amounts of mercury could be measured in fish samples and macrophytes. Both investigated submerged plant species, namely Potamogeton pectinatus and Myriophyllum spicatum show a high potential for bioaccumulation of Hg, presenting mean values of 0.245 ± 0.152 and 0.298 ± 0.115 μg/g dw respectively. Compared to freshwater fish from other unpolluted sites high amounts of Hg could be measured (fig. 2). Biomagnification and significant differences could be observed when comparing muscle samples of the planctivorous fish species rudd Scardinus erythrophthalmus (n = 10, mean = 0.084 μg/g ww) with the piscivorous perch Perca fluviatilis (n = 21, mean = 0.184 μg/g ww) or pike-perch Sander lucioperca (n=9, mean = 0.205 μg/g ww) respectively. Significantly lower values were measured in the muscle of the piscivorous pike Esox lucius (n = 25, mean = 0.135 μg/g ww) in which a strong correlation between fish age and Hg content did not occur. In addition the muscle/liver ratio of Hg in pike was significantly lower compared to the other fish species, which points to a different Hg metabolism in pike, maybe under the specific saline alkaline conditions of this lake.