SUN Ziyuan1, WEN Xuefeng1, WU Pan1, LIU Hongyan1, LIU Yuansheng1, PAN Qiuzhu1, WEI Xiao1, 2，WU Shanshan1
（1. Guizhou University, Guiyang 550025, China；
2. Institute of geochemistry, Chinese academy of sciences,Guiyang 550002，China）
Abstract：The karst area in southwest China is a famous geochemical anomaly region of heavy metals. Besides human activities, the regional geological background could be another significant factor for which results in excessive heavy metals in soils. In order to figure out releasing rules and environmental effects of heavy metals during weathering and pedogenesis processes of rocks, investigations of excessive degrees and migration rules of heavy metals in representative weathering profiles of carbonate and clastic rocks in the Luodian County, Guizhou, were carried out using field surveys, geochemical analyses and mass balance calculations. The results show that, compared to clastic rocks, carbonate rocks have higher potential to release heavy metals, and that the amount of heavy metals released from carbonate rocks by either weathering or pedogenesis process is closely related to the weathered crust development degree. In the study area, concentrations of heavy metals in calcareous soil profiles exceed the national standards remarkably, especially of Cd and As. The enrichments of Cr and Ni in yellow soils are probably associated to the precipitation and enrichment of iron oxides during the development processes of weathering profiles. The difference of weathering rates caused by different lithology is probably the main reason for the difference of heavy metal leaching degrees between carbonate rocks and mudstone profiles. Moreover, the migrations of heavy metals in weathering profiles are controlled by their geochemical properties, parent rock types and development degrees of weathered crusts.
Key wards: calcareous soil, yellow soil, heavy metal element, element migration, Karst region
EARTH AND ENVIRONMENT Vol.47, No.1, Tot No.327, 2019, Page 50-56