E. Valkova1*, V. Atanasov1, K. Velichkova2, G. Kostadinova3, M. Tzanova1
1Department of Biochemistry, Microbiology and Physics, Faculty of Agriculture, Trakia University, 6000 Stara Zagora, Bulgaria 2Department of Biology and Aquaculture; Faculty of Agriculture, Trakia University, 6000 Stara Zagora, Bulgaria
3Department of Applied Ecology and Animal Hygiene, Faculty of Agriculture, Trakia University, 6000 Stara Zagora, Bulgaria
Abstract. Chromium (Cr) is heavy metal often found in aquatic ecosystems due to its widespread use in households and industry. Reaching toxic levels in water, chromium may cause a violation of many metabolic processes in hydrobionts. The aim of the present study was to investigate and assess the Cr concentration levels in water, sediment, aquatic plants and meat of common carp from different surface water bodies in a region of Bulgaria with high anthropogenic impact. International standards of ISO and BSS for sample preparation of water, sediment, aquatic plants and meat of common carp analysis were used. Concentration of Cr in the analyzed samples was determined by atomic adsorption spectrometry. It was found that the Cr levels: a) in surface water varied from 0.012 mg/l in monitoring point (MP-5) to 0.043 mg/l in MP-6, all concentrations exceeded the maximum admissible concentration (MCA) – 8 μg/l (0.008 mg/l) for Cr (VI) according to Regulation No 4-H (2012) for characterization of surface water, from 1.5 times in MP 5 to 5.38 times in MP 6; b) in sediment ranged from 20.7 mg/kg in MP 1 to 199.9 mg/kg in MP 4, which are lower than the MCA for cultivated soil – 200 mg/kg dry soil according to Regulation No 3/01.08.2008 concerning norms for admissible content of harmful substances in the soil, from 1 time in MP 4 to 9.6 times in MP 1; c) in aquatic plants varied from 6.021 mg/kg in MP 3 to 23.2 mg/kg in MP 6; d) in common carp meat were between 0.11 mg/kg in MP 5 and 0,16 mg/kg in MP 3, which is lower than the MCA (0.3 mg/kg) for maximum permissible quantities for contaminants in food (Regulation No 31, 2004), from 0,37 times in MP 5 to 0.53 times in MP 3. Cr accumulation was not observed in the tested common carp meat samples, which most probably is due to its accumulation in organs with active metabolism (gills, liver); e) proportions of accumulation of Cr in the trophic chain are different for the different units – water/sediment (1040 – 12 129 times more), aquatic plants/water (207 – 1011 times more) and meat of common carp/water (9.1 – 12.1 times more).