典型铅锌企业周边农田重金属富集植物筛选

Screening of accumulating plants in farmland surrounding typical lead and zinc smelting enterprises

  • 摘要: 为探究有色金属企业周边农田重金属污染状况, 筛选修复与安全利用优势植物, 本研究在河南省济源市某铅锌冶炼企业周边农田开展调查, 探明研究区土壤重金属污染特征, 并选用17种重金属富集植物, 开展田间试验, 比较其生物量及重金属含量、富集系数、提取量及去除率等, 建立适合研究区的土壤重金属污染植物修复技术模式。结果表明, 试验区土壤镉(Cd)、铅(Pb)存在超标情况, 超标率Cd>Pb, 污染物主要分布在0~20 cm耕作层, 属典型的轻、中度Cd、Pb污染农田土壤。试验区主要农产品小麦籽粒Cd、Pb超标率为100%, 部分样品As超标, 玉米籽粒符合标准。17种富集植物生物量和对重金属的富集能力差异较大, 籽粒苋生物量最高, 达29 598 kg∙hm−2, 是遏蓝菜的46.61倍, 体内重金属Cd、Pb、As含量分别为2.90~30.90 mg∙kg−1、7.81~93.07 mg∙kg−1、3.76~22.90 mg∙kg−1。不同植物对土壤中重金属的去除率存在明显差异, 籽粒苋、冬油菜‘中油千斤旱’、向日葵‘S606’表现出良好的Cd、Pb提取修复潜力, 对土壤中Cd的去除率均高于1.90%。此外, 油菜和向日葵可进一步加工生产食用油、饲料或有机肥料, 实现边修复边生产, 应用前景较好。在研究区采用籽粒苋-冬油菜轮作和向日葵单作两种修复模式均能达到较高的修复效果, 具备一定的推广应用潜力。

     

    Abstract: As one of the most important lead (Pb) and zinc (Zn) smelting production bases in China, the heavy metal content in the farmland surrounding the enterprises in Jiyuan City of Henan Province seriously exceeded the national standard due to the backward technology and large pollutant discharge. In order to explore the characteristics of heavy metal contamination in farmland around Pb and Zn smelting enterprises in Jiyuan City, select the dominant plants for remediation and safe utilization of heavy metal-contaminated farmland, and establish a preliminary remediation model, field experiments were conducted on farmland surrounding Pb and Zn smelting enterprises in Jiyuan City. The study included investigating the characteristics of cadmium (Cd), Pb, and arsenic (As) pollution in soil, analyzing the heavy metal content in main agricultural products, selecting 17 kinds of heavy metal-accumulating plants for field cultivation, and studying their biomass, heavy metal contents, bioconcentration factor, extraction amount, and remediation efficiency. The results showed that the average content of Cd, Pb, and As in soil was 2.22 mg·kg−1, 173.1 mg·kg−1 and 18.38 mg∙kg−1, respectively, which were mainly distributed in the cultivated layer. Among them, the content of Cd and Pb exceeded the risk screening values in the Environmental Quality Standard for Soils (GB 15618—2018), and the single factor pollution index reached 3.71 and 1.02, respectively. In terms of the wheat and maize cultivated on the contaminated farmland, the content of Cd, Pb, and As in maize seeds did not exceed the values in the National Food Safety Standards (GB 2762—2022), but the Cd and Pb content in wheat seeds exceeded the standards, while the exceeding rates both reached 100%. In plant cultivation experiments, the biomass and heavy metal enrichment capacities of the 17 kinds of accumulating plants differed significantly. The biomass of Amaranthus hypochondriacus was the highest, reaching 29 598 kg·hm−2, which was 46.61 times that of Noccaea caerulescens (635 kg·hm−2). The contents of Cd, Pb, and As in the 17 plant species were 2.90−30.90 mg·kg−1, 7.81−93.07 mg·kg−1, and 3.76−22.90 mg·kg−1, respectively. The bioconcentration factors of Cd, Pb, and As were 1.31 to 13.92, 0.05 to 0.54, and 0.20 to 1.24, respectively. Helianthus annuus ‘S606’ had the largest Cd, Pb, and As comprehensive bio-concentration index of 2.3. Combining plant biomass and enrichment capacity, 17 plant species showed clear differences in the removal efficiency of contaminated soil. Cluster analysis showed that Amaranthus hypochondriacus, Brassica napus ‘Zhongyou 1000’, and Helianthus annuus ‘S606’ had higher Cd and Pb accumulation and remediation capacities in soil. The removal efficiency of these three species was higher than 1.90% for Cd and 0.07% for Pb, showing a promising potential for remediation of Cd and Pb-contaminated soils. In addition, Brassica napus and Helianthus annuus can be further processed to produce edible oil, feed, or fertilizer, which can bring economic benefits while remediating soil. In conclusion, the farmland surrounding the Pb and Zn smelting enterprise in Jiyuan City was typically light to moderately contaminated with Cd and Pb. In response to this situation, two technical modes of heavy metals-contaminated farmland remediation were proposed: Amaranthus hypochondriacus-Brassica napus rotation remediation mode and Helianthus annuus monoculture remediation mode. Both modes can achieve high remediation efficiency and were viable and extendable.

     

/

返回文章
返回