|
(38-27) Sediment contamination assesment of the Keleti Irrigation Canal after heavy metal pollution. Keresztúri, Péter*,1, Kovács, Béla2, Lakatos, Gyula2, 1 College of Nyiregyhaza MMFK, Nyiregyhaza, Hungary2 University of Debrecen TTK, Debrecen, Hungary ABSTRACT- The dam of the settling pond of a mining company in Baia Borsa, Romania, burst on the 10th March, 2000, in consequence of heavy rainfall and snowmelt. About 20 tons of slurry contaminated with cyanide and heavy metals discharged into the creek Vaser, then through the stream Viso into the River Tisza. The pollution wave carrying cyanide, lead, copper and zinc, arrived in Hungary on 11th March. At the night of 11/12 March the maximum concentration of total lead and zinc was 2.9 mg/L, while that of the copper was 0.89 mg/L. On 13th March the pollution wave reached the upper lock end of the Keleti Irrigation Canal and due to the high flood level contaminated water seeped through the lock gate. The Keleti Irrigation Canal is the most important constructed watercourse in the Great Hungarian Plain. It gets the water supply from the River Tisza by gravity flow through a lock at Tiszavasvari. The upper reach of the canal supplies the wildlife of Hortobagy National Park and UNESCO Biosphere Reserve and about 50,000 people with drinking water. This study summarizes the results of the sediment quality measurements concentrating on the heavy metal pollution on the canal. Sediment samples were taken on 11 different sites downstream the keleti Canal from the biologically active zone (i.e., zero to about 15 cm depth) in April, 2000. The samples were analized by ICP-OES method and Pb, Cu have been measured. Results of the analysis show that heavy metals were deposited from the pollution wave enhancing the copper concentration of the sediment compared to the back ground data ( evaluated data on the same sites before the pollution).The copper concentratuons (mg/kg dry weight)were 76.0 (3.41) in 1999 and 105.0 (4.11)in 2000. And the lead concentrations were 68.0 (2.12) and 63.0 (3.24)accordingly. Each value represents the mean of the 11 examinated sites, standard deviations are in parentheses. We found the highest metal concentration of the sediment on those sites where the water flow velocity decreased and the suspended sediment settled in great amounts. We also summerize the long-term effects and dangers of the contamination such as potential effects on the drinking basis and the bioaccumulative effects of the heavy metals. Key words: copper, sediment , suspended-sediment, flow-velocity |
