Heavy metal pollution of ecosystem within the middle course of the jihlava river

The monitoring of the contents of heavy metal pollutants: total Hg,Pb,Cd,Cr,Ni,Cu and Zn in fish muscle,water,bottom sediments and zoobenthos was realised in May and July of 2007 on two localities: Vladislav,upstream the Dalešice and Mohelno dam reservoirs (Czech Republic),and Hrubšice downstream them. Samples of fish muscle were taken from chub (Leuciscus cephalus),barbel (Barbus barbus) and brown trout (Salmo trutta m. fario). Water,bottom sediments and zoobenthos samples were taken as representative ones from both localities. The samples were analysed with the apparatus AMA 254,AA-300 and SPECTR AA-30. In water of both sites there was found above-limit (0.1 μg/l) content of mercury (0.99 μg/l Hrubšice,2 μg/l Vladislav). The bottom sediments in Vladislav were most contaminated by Pb (120.21 mg/kg) and Cr (164.90 mg/kg) and in Hrubšice locality by Ni (90.66 mg/kg). High concentration of Pb (25.84mg/kg) in Vladislav and of Ni (240.90 mg/kg) and Cr (140.5 mg/kg) in Hrubšice was found in zoobenthos. In the point of view contents of heavy metals in fish muscle tissue,statistically significant (p 0.05) higher content of Hg was found in barbel and chub from Vladislav (0.15 5 ± 0.012 mg/kg and 0.163 ± 0.064 mg/kg) in comparison with Hrubšice (0.073 ± 0.03 5 mg/kg and 0.095 ± 0.082 mg/kg) as similarly as the concentration of Cd in chub (0.062 ± 0.140 mg/kg at Vladislav and 0.006 ± 0.002 mg/kg at Hrubšice),whereas the content of Ni in barbel was statistically significantly higher at Hrubšice (0.175 ± 0.042 mg/kg) compared to Vladislav (0.050 ± 0.017 mg/kg). The last significant difference was found in Pb concentrations,when fish from Hrubšice were more contaminated (concentrations 0.155 ± 0.048mg/kgin barbel and 0.182 ± 0.110mg/kg in chub) than the same species from Vladislav (contents 0.050 ± 0.017 mg/kg and 0.064 ± 0.005 mg/kg). In theme of consumption risk of the muscle tissue of fish by FAO/WHO,the Hg was limiting factor at both sites. In the locality Vladislav provisional tolerated weekly intake (PTWI) was 1.94 kg in barbel and 1.84 kg in chub. In the Hrubšice it reached 4.12 kg in barbel,3.15 kg in chub and 5.51 kg in brown trout.