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Accumulation of Heavy Metals in the Macrozoobenthos of the Luda River, Bulgaria

ABSTRACT Heavy metals are among the most common environmental pollutants. Their long-term environmental chronic stress leads to negative impacts on the diversity and abundance of benthic invertebrates. The Luda River, a left tributary to the Struma River, flows through the north-western slopes of Pirin Mountain. An abandoned uranium mine is located in the upper parts of the watershed. The aim of this study was to assess the accumulation of heavy metals in the macrozoobenthos of the river. Four sites were sampled for river state assessment and from two of them additional macrozoobenthic samples were collected for heavy metal analysis in October 2011. In the lower reaches, the reduction of potential habitats, due to sand deposition, and the diversion of river waters showed stronger effect on the benthic communities than the abandoned mine. The benthic invertebrates bellow the mine were characterized with increased contents of Cr, Ni, Co, Zn, Cd, Pb and Cu. The results suggested that the metals accumulated in benthic organisms originate mostly from the water, whereas the accumulated Cd, Cu, Zn and Ni originate from the sediments. Supposedly, there is also biomagnification in the food web.