Evaluation of mercury methylation in fresh and pre dried sediments using ^(203)Hg radioisotope  

作　　者：J.R.Ikingura 1, H.Akagi 2, J.R.D.Guimaraes 3 (1. University of Dar es Salaam, P.O.Box 35052, Dar es Salaam, Tanzania 2. Nat. Inst. for Minamata Disease, 4058 Hama, Minamata, 867 Kumamoto, Japan 3. Lab. de Radioisotopos, Universidade Federal Do Rio 

出　　处：《Journal of Environmental Sciences》2000年第S1期66-75,共10页环境科学学报（英文版）

摘　　要：Mercury methylation rates in fresh and pre dried river sediments were determined in sediment water systems spiked with 203 HgCl 2 at a level of 0.75—0.95 ppm as Hg. At the end of the incubation period (21—38 days), methylmercury production in the fresh sediments was in the order of 3.0% to 13.75%, whereas in the pre dried sediments the methylation was much lower, at 0.6% to 3.9%. The highest methylation levels were generally recorded in the uppermost, 1 cm layer of the sediment column. Total mercury concentration in water in equilibrium with the 203 Hg spiked fresh sediments was in the range of 44.7 to 634 ng/L, whereas in equilibrium with the pre dried sediments the concentration was in the range of 19.5 to 34.5 ng/L. The proportion of methylmercury to total mercury in the water varied from 9.4% to 66.6% over the fresh sediments, and from 7.1% to 10.8% over the pre dried sediments. In the system consisting of water, sediment and sediment inverterbrates the concentrations of methylmercury were 8.61 to 15.69 ng/g in the sediment, 0.011 ng/ml in the water, and 9.22 to 40.69 ng/g in the inverterbrates. Methylmercury bioaccumualtion factors (BAFs) were in the order of 274 to 8087 relative to the water, and 0.25 to 7.31 relative to the sediment. These results provide further evidence for the tendency of methylmercury to accumulate in high concentrations in aquatic organisms, even at very low total mercury concentration in water.Mercury methylation rates in fresh and pre dried river sediments were determined in sediment water systems spiked with 203 HgCl 2 at a level of 0.75—0.95 ppm as Hg. At the end of the incubation period (21—38 days), methylmercury production in the fresh sediments was in the order of 3.0% to 13.75%, whereas in the pre dried sediments the methylation was much lower, at 0.6% to 3.9%. The highest methylation levels were generally recorded in the uppermost, 1 cm layer of the sediment column. Total mercury concentration in water in equilibrium with the 203 Hg spiked fresh sediments was in the range of 44.7 to 634 ng/L, whereas in equilibrium with the pre dried sediments the concentration was in the range of 19.5 to 34.5 ng/L. The proportion of methylmercury to total mercury in the water varied from 9.4% to 66.6% over the fresh sediments, and from 7.1% to 10.8% over the pre dried sediments. In the system consisting of water, sediment and sediment inverterbrates the concentrations of methylmercury were 8.61 to 15.69 ng/g in the sediment, 0.011 ng/ml in the water, and 9.22 to 40.69 ng/g in the inverterbrates. Methylmercury bioaccumualtion factors (BAFs) were in the order of 274 to 8087 relative to the water, and 0.25 to 7.31 relative to the sediment. These results provide further evidence for the tendency of methylmercury to accumulate in high concentrations in aquatic organisms, even at very low total mercury concentration in water.

关 键 词：mercury methylation rate METHYLMERCURY partitioning tropical river sediment 

分 类 号：X592[环境科学与工程—环境工程]