School of Chemical & Environmental Engineering, China University of Mining and Technology-Beijing, Beijing 100083, China; State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, China.
State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, China.
Sci Total Environ. 2021 Nov 1;793:148614. doi: 10.1016/j.scitotenv.2021.148614. Epub 2021 Jun 22.
Mining activities and high geological background are considered the important factors causing heavy metal(loid)s accumulation in rice fields of karst area. In this study, the contents, main sources, and the factors influencing bio-availability of heavy metal(loid)s were determined using conditional inference tree (CIT), random forest (RF), and geostatistical analyses with 105 soil samples collected from rice fields in karst area. Contamination by Cd, Hg, As, and Pb in soil was relatively serious in the study area in which the compound pollution was highly similar to that in the flooded area. CIT and RF effectively identified the contributions of natural and anthropogenic inputs of soil heavy metal(loid)s. Concentrations of Pb, As, and Hg were closely associated with human inputs whose cumulative contribution rates reached 68%, 87%, and 86%, respectively. Industrial activities (28%) and geogenic characteristics (44%) were primary sources of Cd accumulation. The soil pH, soil organic matter (SOM), distance from city center, the contents of heavy metal(loid)s in soil, and industry type were the most important factors influencing bio-availability of heavy metal(loid)s. Combined effect of multiple metals could not be ignored, in which As and Cd contributed over 80% to total non-carcinogenic risks for adults and children.
采矿活动和高地质背景被认为是导致喀斯特地区稻田重金属（类）积累的重要因素。本研究采用条件推断树（CIT）、随机森林（RF）和地统计分析，对采自喀斯特地区稻田的 105 个土壤样本中的重金属（类）含量、主要来源以及生物有效性的影响因素进行了测定。研究区域土壤中 Cd、Hg、As 和 Pb 的污染相对严重，其复合污染与淹水地区高度相似。CIT 和 RF 有效地确定了土壤重金属（类）的自然和人为输入的贡献。Pb、As 和 Hg 的浓度与人为输入密切相关，其累积贡献率分别达到 68%、87%和 86%。工业活动（28%）和地球化学特征（44%）是 Cd 积累的主要来源。土壤 pH 值、土壤有机质（SOM）、距市中心的距离、土壤中重金属（类）的含量和工业类型是影响重金属（类）生物有效性的最重要因素。多种金属的联合效应不容忽视，其中 As 和 Cd 对成人和儿童的非致癌总风险的贡献超过 80%。
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