Distributions of arsenic and selenium in the Yangtze Estuary and its adjacent areas

One cruise of " Haijian 47 " was carried out in September 2004, to understand the behaviors of selenium and arsenic in the Yangtze Estuary and its adjacent areas. Selenium and arsenic species are determined by HG-AAS. Concentrations rang from 13.5 nmol'L-1 to 25.2 nmol· L for arsenic, under detection to 5.22 nmol·L^-1for As(III), 1.50 nmol·L^-1 to 5.70 nmol· L^-1 for selenium, with average of 17.9 nmol·L^-1, 1.76 nmol·L-1and 3.35 nmol·L^-1, respectively. Concentrations of arsenic and selenium decrease gradually from Yangtze Estuary to the East China Sea. The high concentration of arsenic appears mainly in the Yangtze diluted water area and the coastal water area of Jiangsu and Zhejiang, and the low values is present at the southeast part of study area showing the influence of the Kuroshio water. The data indicates that selenium did not behave conservatively in the estuary, but arsenic behaves conservatively. An important mobilization of selenium is observed from the river up to halfway in the estuary. Concentrations in the sediment range from 3.87 mg·kg^-1 to 13.1 mg·kg-1 for arsenic, 0.067 mg· kg^-1to 0.23 mg·kg^-1 for selenium. Yangtze input is the main source of arsenic and selenium in the sediment.