Distribution of Heavy Metal Contents of Urban Soils in Sanya, China

A total of 44 topsoil samples (depth=0~20 cm)and 8 deep-soil samples (depth=150 ~ 200 cm) were collected from urban green space and roadside green belt in Sanya in order to : (1) get the total content of eight heavy metals (Hg, As, Cr, Ni, Cu, Pb, Cd and Zn) in urban soils in Sanya; (2) to identify the degree of heavy metal contamination by comparing with other studied cities; and (3) to determine the spatial distribution of heavy metals in different city functional zones and the vertical distribution in topsoil and deep-soil. Means of Hg, As, Cd, Cu, Cr, Ni, Pb and Zn concentrations of topsoil are 0.07, 3.53, 0.08, 3.71, 20.48, 7.05, 28.53 and 142.18 mg/kg, respectively. Except Zn, none heavy metals in samples exceeded the maximum concentration CEQSS ii (Chinese Environmental Quality Standard ii for Soils). With CEQSS I as a standard, Cu, Cr, Cd, As and Ni in topsoil were unpolluted, Pb and Hg were enriched in about 20% total samples, and Zn was worth the whistle in environment. Sanya is a clear city compared with many cities in the world. The study area had been classified into five functional zones according to its land use, and heavy metal enriched in order of roadside green belt > suburban area > commercial area > residential > landscaped area. Deep-soil enriched heavy metals compared with topsoil except Hg and As, and the content variation trend is consistent in different sample sites.