Weathering Rate and Potential Ecological Effect in Soil Profile of a Typical Black Shale Area
The heavy metal elements rich in black shale are released into the environment due to weathering,resulting in the enrich-ment of heavy metals in the soil,forming a high geological background area of heavy metals.In order to understand the weathering and enrichment process and characteristics of heavy metals in the high geological background area of black shale,this study used PROFILE model to quantitatively calculate the chemical weathering rate of soil profile for the typical Cambrian black shale samples in western Zhejiang,and to evaluate the release rate of heavy metals.At the same time,the potential ecological effects of soil heavy metals in this area were evaluated.The results showed that the chemical weathering rate of soil ranged from 62.95 to 412.62 mmol/(m2·a),and the release rate of base cations(Ca2+,Mg2+,Na+and K+)ranged from 97.47 to 806.16 mmol/(m2·a).The content of carbonate in black shale soil has a great influence on the weathering rate.The average release rates of As,Cd,Cr,Cu,Hg,Pb and Zn in the soil of the study area are 31.25,18.79,135.65,65.14,0.15,28.02 and 367.35 mmol/(m2·a)respectively.The heavy metal concen-tration and base cations concentration(CBCt)had a significant impact on the release rates of heavy metals in soil,while the release rate of base cations(RBC)had a relatively small impact on the release rates of heavy metals.The average value of the comprehensive poten-tial ecological risk index of heavy metals in the study area is 961.89,and the potential ecological risk index of Cd is the highest,with a contribution rate of 53.44％-99.70％.
black shaleweathering rateheavy metalsecological effect
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