INFLUENCE OF HUMIC ACID AND SODIUM CHLORIDE ON THE UPTAKE OF MERCURY BY THE COMMON CARP (CYPRINUS CARPIO L.)

The aim of the experiment was to determine the distribution of mercury in six selected tissues (skin, fish scales, kidneys, muscle, liver and gills) of common carp (Cyprinus carpio L.) and its relationship to humic acid and sodium chloride when they are added. Carp fingerlings weighing 47.67 ± 4.61 g were exposed to a water solution containing a defined concentration of Hg2+ (1.5 μg/l) and increasing concentration of humic acid (0 mg/l, 1 mg/l, 5 mg/l) and sodium chloride (29 mg/l, 300 mg/l, 1 000 mg/l) in fish tanks for 72 hours. The concentrations of mercury in fish tanks were continuously monitored and adjusted to the required value during the whole experiment. The fish were not fed during the experiment and mercury accumulated in the carp tissues from the fish tank water only. The total mercury content in the water and in selected tissues was determined by the atomic absorption spectrometer AMA 254. The increased concentration of both humic acid and sodium chloride caused a reduction (humic acid: -65% to -96% (exception for muscle 2%); sodium chloride: -8% to 21%) of mercury accumulated in carp tissues.