Influencing Factors of Elevated Levels of Potentially Toxic Elements in Agricultural Soils from Typical Karst Regions of China
Yubo Wen,
Yuanyuan Wang,
Wenbing Ji,
Ning Wei,
Qilin Liao,
Dingling Huang,
Xianqiang Meng,
Yinxian Song
Affiliations
Yubo Wen
School of Geographical Science, Nantong University, Nantong 226019, China
Yuanyuan Wang
Technology Innovation Center for Ecological Monitoring & Restoration Project on Land (Arable), Ministry of Natural Resources, Geological Survey of Jiangsu Province, Nanjing 210018, China
Wenbing Ji
State Environmental Protection Key Laboratory of Soil Environmental Management and Pollution Control, Nanjing Institute of Environmental Sciences, Ministry of Ecology and Environment, Nanjing 210042, China
Ning Wei
Key Laboratory of Surficial Geochemistry, Ministry of Education, School of Earth Sciences and Engineering, Nanjing University, Nanjing 210023, China
Qilin Liao
Technology Innovation Center for Ecological Monitoring & Restoration Project on Land (Arable), Ministry of Natural Resources, Geological Survey of Jiangsu Province, Nanjing 210018, China
Dingling Huang
Army Engineering University of PLA, Nanjing 210007, China
Xianqiang Meng
State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, China
Yinxian Song
Department of Geosciences, Faculty of Land Resource Engineering, Kunming University of Science and Technology, Kunming 650093, China
Agricultural soils originating from carbonate rocks within karst regions exhibit inherent high concentrations of potentially toxic elements (PTEs) due to geogenic processes. However, the influencing factors of the elevated levels of PTEs in the naturally contaminated karst regions remain inadequately comprehended. This research investigates the chemical compositions of 278 soils derived from carbonate rocks. Descriptive statistics, stepwise multiple regression, and the random forest (RF) method were applied to screen the significant factors that affect the distribution, migration, and enrichment of the PTEs in soils. Cadmium (Cd) and arsenic (As) are the most highly contaminated PTEs in the soils of the study area, and the average contents of Cd and As in soils are 11.5 and 2.92 times the national soil background value, respectively. The pollution risk ranking of PTEs is Cd > As > Cr > Zn > Pb > Cu > Ni > Hg, using the proportion exceeding the risk screening thresholds of agricultural land as the standard. Soil Fe2O3 and Mn contents, soil pH and total organic carbon (TOC) values, and weathering intensity (characterized using the chemical index of alternation, CIA) are the most important factors influencing the PTE levels in agricultural soils.
