广西某铅锌矿区土壤镉、铅、砷形态分布对水稻重金属的影响

Effect of Soil Cd,Pb,As and Their Fractions Distribution on Corresponding Heavy Metals in Rice Surrounding Lead-zinc Mines in Guangxi Province

【目的】探讨铅锌矿区周边土壤镉、铅和砷形态分布对水稻重金属影响,为当地土壤重金属修复治理提供参考。【方法】采集广西某铅锌矿区周边农田土壤和水稻根、茎、叶、籽粒等样品,分析土壤镉、铅和砷的全量和形态分布水稻重金属含量,通过单因素污染指数方法评价土壤重金属污染状况,通过富集系数评价水稻根、茎、叶、糙米对土壤重金属富集能力。【结果】水稻田土壤镉、铅和砷污染严重,土壤镉含量变化为0.42~2.68 mg/kg,平均值为1.52 mg/kg;铅含量变化为118~1180 mg/kg,平均值为472.59 mg/kg;砷含量为11.6~351.0 mg/kg,平均值为109.81 mg/kg。其中土壤镉主要以交换态和碳酸盐结合态为主;土壤铅以铁锰氧化结合态和有机物结合态为主;土壤砷以残余晶格态为主。土壤重金属的主要富集水稻根部位,其中水稻根富集土壤镉系数均大于1、富集铅系数介于0.38~3.53、富集砷系数均小于1,糙米镉和铅含量超标,砷未超标。【结论】铅锌矿区的周边土壤镉、铅、砷含量严重超标;水稻田土壤镉对农作物有一定风险;铅对农作物铅超标存在潜在危害;土壤砷主要残余晶格态为主;水稻籽粒镉全部超标、铅部分超标、砷不超标。

[ Objective ] To provide a reference for local soil heavy metal repair management, the eft）cts of Cd, Pb and As distribution charac- teristics on heavy metals contents in rice grown on the fields surrounding a lead-zinc mining area were assessed. [ Method] The soil, root, stem, shoot and rice grain samples were collected from fields around a lead-zinc mining zone in Guangxi, the content of Cd, Pb, As in sam- pies were analyzed and the fractions of Cd, Pb and As were tested with Tessier extraction method. The single factor pollution index method was used to evaluate soil heavy metal pollution, while enrichment factor was used to evaluate the enrichment ability of rice root, stem, leaf and brown rice. [ Result] The soil in the rice fields was seriously contaminated by Cd, Pb and As. The content of Cd ranged from 0.42 - 2. 68 mg/kg with an average value 1.52 mg/kg; the content of Pb ranged from 118 - 180 mg/kg with an average value 472.59 mg/kg; the range of As was 11.6 -351.0 mg/kg with an average value 109.81 mg/kg. Cd in the rice soil was dominated by exchanged and carbonate fraction; Pb was dominated by Fe-Mn oxides and organic fraction; As was dominated by residual fraction in soil. Bioaccumulation factors （BAF） of Cd, Pb and As in rice root was over 1 ; 0.38 - 3.53 ; less than 1 respectively. According to the Food Health Standards（ GB2762- 2017, the concentration of Cd, Pb exceeded the limits of standards but As in rice was within the threshold. [ Conclusion] The arsenic content of Cd, Pb and As in the surrounding soil of lead-zinc mine were seriously exceeded. Cd in paddy fields had certain risks to crops, while Pb had potentially harm to crops. The content of Cd in rice grain was exceeded, while Pb was partially exceeded, and the As was unexceeded.