Weathering of Carbonate Rocks by Biological Soil Crusts in Karst Areas  

作　　者：Ye Chen Bin Lian Zuoying Yin Yuan Tang 

机构地区：[1]Key Laboratory of Karst Environment and Geological Hazard Prevention, School of Chemistry and Chemical Engineering,Guizhou University [2]Jiangsu Key Laboratory for Microbes and Functional Genomics, Jiangsu Engineering and Technology Research Center for Microbiology, College of Life Science, Nanjing Normal University [3]Puding Karst Ecosystem Research Station, State Key Laboratory of Environmental Geochemistry,Institute of Geochemistry,Chinese Academy of Sciences

出　　处：《Journal of Earth Science》2014年第4期662-667,共6页地球科学学刊（英文版）

基　　金：supported by the National Key Basic Research Program of China (No. 2013CB956702);the National Natural Science Foundation of China (No. 41373078)

摘　　要：The weathering of carbonate rocks by biological soil crusts （BSC） in karst areas is very common. It is helpful to understand the weathering mechanisms and processes for avoiding karst rock-desertification. The weathering of carbonate rocks by BSC in karst areas, namely the expansion, contraction and curl resulting from environmental wetting-drying cycles, was investigated and ana- lyzed in this paper. The bulk density, area and thickness of BSC were determined and the weathering amount of limestone and dolomite per unit area of BSC was calculated as 3 700 and 3 400 g·m-2; the amount of biomass on the surface of limestone and dolomite was calculated as 1 146 and 1 301 g·m-2, respectively. Such an increased weathering amount was not only the result of chemical and physical weathering of BSC on carbonate rocks, but also the attachment and cementation of BSC to clay particles, dust-fall, sand particles, solid particles brought by strong air currents, wind and other factors in the surrounding environment, which may also be related to the special environment and the special time period. Based on the results obtained, a weathering mode of BSC is studied, and the mechanisms of weathering by BSC are discussed. In conclusion, we suggest that the mechanical force exerted by the expansion and constriction of gelatinous and mucilaginous substances through wetting and drying of BSC play a significant role in the physical weathering process of the carbonate substrates.The weathering of carbonate rocks by biological soil crusts （BSC） in karst areas is very common. It is helpful to understand the weathering mechanisms and processes for avoiding karst rock-desertification. The weathering of carbonate rocks by BSC in karst areas, namely the expansion, contraction and curl resulting from environmental wetting-drying cycles, was investigated and ana- lyzed in this paper. The bulk density, area and thickness of BSC were determined and the weathering amount of limestone and dolomite per unit area of BSC was calculated as 3 700 and 3 400 g·m-2; the amount of biomass on the surface of limestone and dolomite was calculated as 1 146 and 1 301 g·m-2, respectively. Such an increased weathering amount was not only the result of chemical and physical weathering of BSC on carbonate rocks, but also the attachment and cementation of BSC to clay particles, dust-fall, sand particles, solid particles brought by strong air currents, wind and other factors in the surrounding environment, which may also be related to the special environment and the special time period. Based on the results obtained, a weathering mode of BSC is studied, and the mechanisms of weathering by BSC are discussed. In conclusion, we suggest that the mechanical force exerted by the expansion and constriction of gelatinous and mucilaginous substances through wetting and drying of BSC play a significant role in the physical weathering process of the carbonate substrates.

关 键 词：biological soil crust DOLOMITE LIMESTONE weathering amount biomass. 

分 类 号：P512.1[天文地球—地质学] P588.245