Soil mercury distribution and pollution in urban and suburbs of Guilin

By means of the systematically sampling, analysis and mapping in urban and suburbs of Guilin, the mercury distribution in the surface and bottom soil has been clarified, meanwhile the pollution sections and the pollution level also have been determined. Based on these works, with mercury analysis of the bedrock, factor analysis of heavy metal elements and heat release mercury method, the elementary study on the mercury source and the mercury phase states and the element association of pollution have been conducted.Mercury content in soil of this area is high in west and low in east horizontally, which is consistent to the district of the west (industrial and residential area) and the east (agricultural area). The high mercury pollution has emerged in the center of the west, which has affected the crops. In profile, the mercury content is high in horizon A and low in horizon B. In horizon A, the soil mercury content ranges from 76 × 10-9 to 5 822 ×10-9, and its geometric mean value is 341×10-9. In horizon B, the content ranges from 52. 3 × 10-9 to 1 210×10-9, and its geometric mean value is 240×10-9. The mercury pollution in horizon A distributes extensively and seriously, and part of the horizon B also has been polluted in degrees. In the non-polluted area, the geometric mean value is 204 ×10-9 in horizon A and 148 × 10-9 in horizon B, which is much higher than the nature content in the other area of our country. The weathering of the enriched-mercury carbonaceous shale in YangUan Stage, Lower Carboniferous is the chief factor to the high mercury background of this area, industrial manufacture and city living are the main source of mercury pollution, and aghcultural activities make the mercury pollution spread further.The factor analysis shows that Hg and Cr, Zn, Cu, Pb, Cd are isolated factors in non-polluted ana, and in polluted area, Hg and Cu, Pb form one factor. The mercury pollution is obviously related to Cu and Pb pollution. The main phase states of mercury are microthermal mercury(Hg2Cl2, HgCl2 and some organic mercury), the secondary are absorbed mercury, sulfide mercury and mesothermal mercury. The phase states of mercury are more complicated in horizon A than in horizon B, and more complex in polluted area than in non-polluted one.