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(70-94) SEM/AVS Levels in Determination of the Ecotoxicity of Heavy Metals in Szamos and Tisza Rivers. Csengeri, István*,1, Lengyel, Péter1, Sándor, Zsuzsanna1, Oncsik, Mária1, Oncsik, Erzsébet1, Szabó, Pál1, Janurik, Endre2, Józsa, Vilmos1, Pekár, Ferenc1, 1 Research Institute for Fisheries, Aquaculture and Irrigation /HAKI/, Szarvas, Békés district, Hungary2 AQUACOPY BT., Szarvas, Békés district, Hungary ABSTRACT- Accompanied with the cianid spill into the rivers Szamos and Tisza in January-February, 2000, and during the heavy metal sludge spill into the River Tisza in March, 2000, high levels of heavy metals were loaded into the sediment of these riverine ecosystems. The potential ecotoxicity of the pollutions to the benthic invertebrate fauna were evaluated by measuring the simultaneously extracted metal (SEM) and acid volatile sulphid (AVS) levels. Based on the SEM/AVS ratios (ranging from 17.8±5.3 to 36.2±6.2, and 7.2±2.0 mekv kg-1 d.m.) and [SEM]-[AVS] values (from 11.1±0.6 to 21.3±0.7, and 4.51±0.58 mekv kg-1 d.m.), samples collected in October, 2000 had shown high probability of serious toxic effects of the spills to the benthic fauna in the main channels of the River Szamos and Tisza-to reservoir in the middle section of River Tisza, respectively. Due to the next year floods and sedimentation, the SEM/AVS ratios (from 2.4±0.2 to 3.6±0.6, and 1.9±0.5 mekv kg-1 d.m.) and [SEM]-[AVS] (from 3.7±0.2 to 9.7±1.8, and 1.7±0.5 mekv kg-1 d.m.) values had shown less severe toxicity in the samples collected at the same locations, respectively, in September, 2001. However, the values were still higher at many locations than the critical levels proposed by the US EPA. Values determined for the sediment in the horse-shoe lakes of the rivers were less or much less than those in the main channels depending on their locations in or out of the flooded areas. Demages in the benthic fauna were traced by the assessment of the biomass of the benthic invertebrates. The applied improved method of the SEM and AVS determinations was assumed as suitable and reliable method of the determination of potential ecotoxicity of heavy metals in the riverine ecosystems demaged by mine spills. Key words: heavy metal toxicity, cianid spill, benthos, SEM/AVS |
