农田土壤重金属外源识别及安全利用技术筛选——以宜宾市筠连县部分区域为例

Source identification and screening of safe utilization methods of farmland soil heavy metals:Taking parts of Junlian county of Yibin as an example

【目的】基于农田土壤重金属污染外部来源途径的识别结果,筛选出钝化剂-低积累作物品种耦合的镉污染农田绿色修复与安全利用技术,以期为农田土壤重金属污染防控提供参考依据。【方法】以四川南部宜宾市筠连县部分乡镇为研究区域,监测该区域内大气沉降、肥料使用、灌溉水及底泥中重金属含量从而计算不同途径的农田土壤重金属输入通量,并选择具有代表性的JL镇利用大田试验开展钝化剂、重金属镉低积累蔬菜和水稻品种筛选。【结果】2019—2020年研究区域农田土壤中汞、砷、铅和锌的主要输入途径为大气沉降,所占比例分别为99.99%、75.88%、90.57%和84.82%;镉、铬和镍的主要输入途径为肥料,所占比例均为100.00%;铜的主要输入途径为灌溉水,所占比例为93.66%。JL镇镉污染农田土壤中施用铁锰肥钝化剂(硫酸亚铁750 kg/hm^(2)+硫酸锰75 kg/hm^(2))对降低水稻籽粒中镉的效果最佳,归因于土壤微量元素的补充对肥力的改善作用,而钝化剂复配(3000 kg/hm^(2))处理下水稻籽粒中镉含量最高。镉低积累蔬菜和水稻品种筛选结果表明九斤萝卜和川康优6276是该地区最适宜种植的蔬菜和水稻品种,收获后可食用部分重金属镉含量均符合食品安全国家标准。【结论】在研究区域除应选用符合国家标准的肥料并注意防控大气沉降污染外,同时建议推广使用铁锰肥、腐殖酸和磷肥钝化材料,并种植九斤萝卜蔬菜和川康优6276水稻品种以保障农产品质量安全。

【Objective】Based on the main input source of soil heavy metals pollution idenfitication and screening the most efficient immobilizing agent and low accumulation varieties of vegetable and rice for Cd contaminated soil,the study aimed to provide a reference for farmland soil heavy mtal pollution preventing and control.【Method】The expreriment was conducted to monitor heavy metals concentrations in atmospheric deposition,fertilizer,irrigation water and sediment and further calculated soil heavy metals input flux by these different pathways to find out the pollution source of soil heavy metals in some towns in Junlian county of Yibin,which was in the south of Sichuan province.Further field experiments were conducted to screen vegetables and rice varieties with lowest accumulation of Cd and the most efficient immobilizing agents in JL town.【Result】Hg,As,Pb and Zn in soil mainly came from atmospheric deposition,accounting for 99.99%,75.88%,90.57%and 84.82%,respectively.While Cd,Cr and Ni mainly came from fertilizer use,all accounting for 100%.Cu was mainly from irrigation water in the study area during 2019 to 2020,accounting for 93.66%.The application of iron manganese fertilizer(FeSO_(4)750 kg/hm^(2)+MnSO_(4)75 kg/hm^(2))had the best effect on reducing the Cd content in rice grains,mainly attributed to the improvement of soil microelement supplement on fertility,while the passivation material compounding(3000 kg/hm^(2))had the highest Cd content in rice grains.The screening results of low Cd accumulation of vegetables and rice varieties showed that Jiujing radish and Chuankangyou 6276 were the most suitable vegetable and rice varieties for planting in the Cd polluted soil in JL town with the Cd content in edible parts after harvest met the national food safety standard.【Conclusion】To ensure the quality and safety of crops,selecting fertilizers that meet national standards and controlling atmospheric decomposition are primary step.Besides the iron manganese fertilizer,humic acid and phosphorus fertilizer passivation agents are suggested to be used,and Jiujing radish and Chuankangyou 6276 varieties are recommended to be planted in the study area.