Concentration characteristics and geoaccumulation index assessment of soil heavy metals in tropical crops producing areas of Hainan Island

Investigation and assessment of pollution in heavy metals such as As，Hg，Pb，Cd and Cr in tropical crops producing areas of Hainan Island were carried out. The concentration characteristics of heavy metals were evaluated，and the degree of heavy metals pollution was evaluated by means of Geoaccumulation Index. The results showed that the background value of surface soil in Hainan was taken as the reference standard，and the ratio of As， Hg and Cr was 4.90，2.00 and 7.73 respectively. The pollution rate was 92.45%，85.53% and 71.70% respectively， which showed that human activities had caused a certain degree of pollution accumulation of As，Hg and Cr. The concentration of heavy metals such as As and Cr in some soil samples exceeded the secondary standard of national soil environmental quality standard. The pollution rate of As and Cr was 0.63% and 43.40% respectively. The Geoaccumulation Index indicated that some of the soils in the study areas were polluted by heavy metals. The main manifestation was the Cr pollution in Hongming，Dongchang，Nanhai，Donglu and Nanyang. The Geoaccumulation Index was 0.83，1.03，0.99，0.72 and 0.62 respectively.