Earth Science Frontiers ›› 2022, Vol. 29 ›› Issue (4): 438-447.DOI: 10.13745/j.esf.sf.2021.11.2

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Parent rock type control on cadmium background in soil and sediment: An example from Guizhou Province

XIA Xueqi1,2(), JI Junfeng3, YANG Zhongfang1, LU Xinzhe2, HUANG Chunlei2, WEI Yingchun2, XU Changyan1,2, LIANG Zhuoying1   

  1. 1. School of Earth Sciences and Resources, China University of Geosciences (Beijing), Beijing 100083, China
    2. Technology Innovation Center of Ecological Evaluation and Remediation of Agricultural Land in Plain Area, Ministry of Natural Resources, Hangzhou 311200, China
    3. School of Earth Sciences and Engineering, Nanjing University, Nanjing 210023, China
  • Received:2021-03-02 Revised:2021-10-20 Online:2022-07-25 Published:2022-07-28

Abstract:

Cadmium (Cd) is one of the most concerned heavy metal pollutants in soil and sediment, and the accurate determination of its natural background values is of great significance in environmental management. However, due to the inherent concentration variability associated with bedrock types and elemental enrichment/depletion caused by weathering, Cd concentrations in surface soil and sediment vary greatly spatially. In some areas, Cd concentration may exceed the safety standard for agricultural land use (GB 15618-2018) under natural conditions. In this study, Guizhou Province, which has relatively complex bedrock types and high soil Cd variation, was selected as the study area. From the perspective of elemental migration from bedrock to soil, and based on geochemical survey data of the entire province, this study sought to investigate the link between bedrock and Cd concentrations in soil and sediment and develop classification schemes for endmember rock types and regions selected for Cd background measurements. The results showed that lithology was the key factor contributing to soil Cd variation, while limestone (relative to dolomite), basalt, diabase and carbonaceous shale contributed to high Cd background value in soil. Compared with the parent rock type, rock formation age had less influence on Cd background values. Through rigorous statistical analysis, the Cd background value and variance in soil were obtained for soils developed from relatively pure rock material. For soils developed from impure rock materials or from mixed geological units, the Cd background value may be affected by more than one endmember rock types.

Key words: soil, cadmium, geology, high background, heavy metal

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