The assessment of water quality contaminated with arsenic based on macroinvertebrates (Złoty Stok, Lower Silesia)

The quality of three water bodies: Czysty Potok, Mąkolnica and Trujący Potok was assessed in the commune Złoty Stok, which was contaminated with arsenic in the past, derived from the activity of an ancient gold mine, and caused illnesses of commune residents. In our studies, the arsenic concentrations slightly exceeded the norm values only in Trujący Potok, in the rest of the studied waters the arsenic content was very low. However, the results of biological studies based on macroinvertebrates suggest the significant influence of all examined sites on the water biocoenosis, since all waters were classified as low quality, based on the Margalef biodiversity index. The biotic index BMWP-PL which does not take the number of specimens into consideration, and because of that is less accurate, classified the waters of Trujący Potok as low ecological quality, but two remaining waters Czysty Potok and Mąkolnica were recognized as moderate waters. To summarize, the applied indices enable to determine the ecological state of waters, and hence to assess the impact of pollutants on the water biocoenosis. The presence of the arsenic was not the only factor affecting the poor quality of all waters; the human activity in this area also contributed significantly to the inferior condition of environment.