| 宁夏供港蔬菜田土壤重金属分布特征及生态风险评价 |
| 摘要点击 977 全文点击 163 投稿时间：2023-07-05 修订日期：2023-09-05 |
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| 中文关键词 宁夏 供港蔬菜 土壤重金属 空间分布 生态风险评价 来源解析 |
| 英文关键词 Ningxia vegetables for Hong Kong soil heavy metals spatial distribution ecological risk evaluation source analysis |
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| 中文摘要 |
| 农田土壤重金属污染会影响蔬菜作物的生长发育及产量,同时也会影响蔬菜的品质与口感,长期以来通过食物链传递和富集,最终对人体健康造成一定危害.因此为探明宁夏多年多茬种植供港蔬菜后其土壤重金属分布特征,预测其生态风险,分析其污染形成原因,于2019~2021年连续3 a采集了477个宁夏供港蔬菜田表层土壤样本,分析As、Cd、Cr、Hg、Pb、Cu、Zn和 Ni 这8种重金属含量和分布特征,采用单因子污染指数法、内梅罗综合污染指数法、地累积指数法和潜在生态风险指数法对宁夏供港蔬菜田土壤重金属污染状况进行评价,利用Pearson相关分析和主成分分析法解析了宁夏供港蔬菜田重金属来源.结果表明,宁夏供港蔬菜田土壤中As、Cd、Cr、Hg、Cu和Zn含量均值高于宁夏土壤背景值,但8种重金属含量均低于国内农用地土壤风险筛选值；在空间分布上,As、Cr和Ni在研究区西北部、中部以及南部出现连片高值区,Pb、Zn、Cd、Hg和Cu在研究区西北部与南部出现高值响应；单因子指数法和内梅罗综合污染指数法表明,宁夏供港蔬菜田土壤整体处于清洁水平；地累积指数法结果显示研究区污染以Hg和Cd污染为主,污染区域主要集中在研究区西北部和南部；潜在生态风险指数显示Hg和Cd为主要风险元素,其中Hg以中等、较强和很强生态风险为主,分别占比44.65 %、44.65 %和1.26 %,Cd以中等、较强为主,占比65.83 %和3.56 %；综合Pearson相关分析和主成分分析表明,8种重金属污染来源可划分为3类,Ⅰ为自然源:Cu、Zn、Pb、As、Ni和Cr；Ⅱ为农业源:Cd；Ⅲ为工业源和农业源:Hg.综合来看,供港蔬菜田土壤重金属均无超标现象,土壤环境条件良好,宁夏供港蔬菜生产整体处于安全水平.研究结果可为宁夏供港菜田土壤安全利用和供港蔬菜安全生产、合理施肥、农艺运筹以及种植结构调整等提供帮助. |
| 英文摘要 |
| Heavy metal pollution in farmland soil can affect the growth, development, and yield of vegetable crops, as well as the quality and taste of vegetables, and can be continuously transmitted and enriched through the food chain, which ultimately poses a certain hazard to human health in the long term. Therefore, in order to investigate the distribution characteristics of soil heavy metals after years of multi-crop planting of vegetables supplied to Hong Kong, predict their ecological risks, and analyze the causes of pollution formation, 477 surface soil samples of vegetable fields supplied to Hong Kong in Ningxia were collected for three consecutive years from 2019 to 2021, and the contents and distribution characteristics of eight heavy metals, namely, As, Cd, Cr, Hg, Pb, Cu, Zn, and Ni were analyzed. The soil heavy metal pollution status of vegetable fields supplied to Hong Kong in Ningxia was evaluated using the single-factor pollution index method, Nemero's comprehensive pollution index method, land accumulation index method, and potential ecological risk index method, and the sources of heavy metals in vegetable fields supplied to Hong Kong in Ningxia were analyzed using the Pearson's correlation analysis and the principal component analysis method. The results showed that the mean values of As, Cd, Cr, Hg, Cu, and Zn in the soils of Ningxia's vegetable fields were higher than the background values of Ningxia soils, but the contents of all eight heavy metals were lower than the risk screening values of domestic agricultural soils; in terms of spatial distribution, As, Cr, and Ni showed contiguous high values in the northwestern, central, and southern parts of the study area, whereas Pb, Zn, Cd, Hg, and Cu showed high values in the northwestern and southern parts of the study area. The single-factor index method and the Nemero's comprehensive pollution index method showed that the soil of Ningxia's vegetable farmland for Hong Kong was at the clean level as a whole. The results of the ground accumulation index method showed that the pollution in the study area was mainly Hg and Cd pollution, and the pollution areas were mainly concentrated in the northwest and south of the study area. The potential ecological risk index showed that Hg and Cd were the main risk elements, among which Hg was dominated by moderate, strong, and very strong ecological risks, accounting for 44.65 %, 44.65 %, and 1.26 %, respectively, and Cd was dominated by moderate and strong risks, accounting for 65.83 % and 3.56 %. The comprehensive Pearson correlation analysis and principal component analysis showed that the pollution sources of eight heavy metals could be divided into three categories, namely, natural sources:Cu, Zn, Pb, As, Ni, and Cr; agricultural sources:Cd; and industrial and agricultural sources:Hg. From a comprehensive point of view, the heavy metals of the soil in the fields of vegetables supplied to Hong Kong had not exceeded the standard, and the environmental conditions of the soil were good, such that the production of vegetables supplied to Hong Kong by Ningxia was at a safe level overall. The results of the study can provide a theoretical basis for the safe utilization of soil in vegetable fields and the green production of vegetables supplied to Hong Kong in Ningxia, which were aimed to provide help for the safe production of vegetable fields supplied to Hong Kong, the rational application of fertilizers, agronomic planning, and the adjustment of planting structure. |
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