Weathering And Pedogenesis Of Karst Catchments, Behavior Of Mineral Elements And Environmental Quality

Weathering and pedogenesis of rocks are important sources of mineral elements for ecological systems, and key processes of global biogeochemical cycling of mineral elements. Therefore, it is helpful for our learning biogeochemical cycling of mineral elements and its ecological and environmental effects, and of great importance for agricultural production and environmental protection to study behavior of mineral elements during weathering and pedogenesis of rocks and environmental quality. We took sedimentary rock-soil-plant-river systems in Wujiang Catchments as our study objects, and collected samples of rocks, soils, plants and stream water at several small watersheds. By measuring mineralogical and elemental composition and hosting phases of elements, we analyzed mineralogical and geochemical characteristics of karst catchments, studied material sources of pedogenesis, modes and controlling factors of weathering and pedogenesis in karst catchments. We also investigated behavior of mineral elements during weathering and pedogenesis and environmental quality. The purposes of the study are to set bases for further study on biogeochemical cycling of mineral elements in soil-plant systems in karst regions, to guide ecological and environmental protection and recovery, and agricultural application of mineral elements such as rare earth elements in karst regions. We also hope that the study can be helpful for geological dealing of nuclear wastes. From the above investigation, we have gained the following achievements and knowledge.(1) We put forward the concept of weak supergene elements and improved the evolution model of elements in weathering profiles before and after physical erosion.(2) Input from weathering and pedogenesis of underlying bedrocks is the major material source of soils distributed in regions dominated by silicate rocks. An obvious trend of leaching of silica and enrichment of aluminum can be observed during weathering and pedogenesis of silicate rocks.(3) Input from weathering and pedogenesis of carbonate rocks is the final material...