【摘要】 为探明高地质背景区农田土壤与农作物系统中重金属富集与转运特征,通过对采自重庆黑色岩系高镉地质背景区的土壤和农作物样品进行分析,并与其他典型黑色页岩区域进行对比研究.发现研究区部分农田土壤pH极低; Cd、Cr、Ni和Zn显著富集.土壤样品Cd的超标率为100%,其次为Cr和Ni,91. 3%的土壤样品Cd污染级别为严重污染及以上.土壤Zn、Cu、Cr和Ni的残渣态占比为80%以上,Cd和Pb较低;弱酸提取态Cd占比27. 0%±6. 4%,Zn和Ni次之.黑色岩系母质风化导致研究区土壤重金属富集,Cd是区域内的特征污染元素,其生物有效性较高,并易于在农作物中富集. Cd的转运系数高于其他元素,农作物中Cd的富集和污染程度最高,特别是叶类蔬菜,平均Cd含量（干重）高达11. 5 mg·kg^-1,不适于种植和食用;部分农作物Cr超标,存在一定风险.因此,有必要对研究区农田土壤进行污染等级划分,实行科学管控,并进行农作物种植结构调整,以保障当地人群健康.更多还原

【Abstract】 In order to investigate the accumulation and transfer of heavy metals in agricultural soils and crops in an area with a high geochemical background of cadmium,soil and crop samples from a black shale outcropped area in Chongqing were collected and analyzed,and the results were then compared with those from other representative black shale outcropped areas. The results showed that some soil samples had a very low pH,and the metals Cd,Cr,Ni,and Zn were enriched. Cadmium concentrations in soil samples exceeded the safety limit,followed by Cr and Ni. Overall,91. 3% of soil samples were heavily to extremely polluted by Cd. The residual fractions accounted for more than 80% of the total metals,except for Cd and Pb. The weak acid soluble fraction of Cd accounted for 27. 0% ± 6. 4% of the total Cd,followed by Zn and Ni. The results demonstrate that weathering of black shales can result in elevated heavy metals in soils,and Cd is the primary contaminant in local soils. The high bioavailability of Cd and the high acidity of soils induced the enrichment of Cd in local crops. Cadmium has a higher transfer factor than other metals,and the crops were seriously polluted by Cd,particularly the leaf vegetables,which presented a high concentration of 11. 5 mg·kg^-1 based on dry weight,and thus,these vegetables are not suitable for cultivating as food stuff. In addition,the risks from Cr should be of concern as well.Therefore,it is recommended that countermeasures be carried out to address the pollution situation,for example,by classifying the pollution levels of agricultural soils and adjusting the planting structures accordingly to reduce the health risks to local inhabitants.更多还原