| 重庆市农地重金属基线值的厘定及其积累特征分析 |
| 摘要点击 2116 全文点击 746 投稿时间：2018-03-29 修订日期：2018-05-14 |
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| 中文关键词 土壤 农地 重金属 基线值 积累 |
| 英文关键词 soil agricultural land heavy metals baseline value accumulation |
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| 中文摘要 |
| 为了确定重庆市农地土壤重金属基线值，了解重金属积累情况，明确优先控制元素，本研究基于地球化学基线原理，根据分层抽样采集6个土壤类型的表层土样共214个；在严格质量控制下，测定各个样品As、Cd、Cr、Cu、Hg、Ni、Pb、Zn的含量.采用数理统计法、迭代剔除法和累积频率曲线法确定8种重金属的基线值，并应用地球化学基线因子污染指数法和地质累积指数法评估了重庆市农地土壤重金属积累状况.结果表明，重庆市农地土壤As、Cd、Cr、Cu、Hg、Ni、Pb、Zn的基线值分别为5.83、0.25、66.78、25.45、0.069、29.90、26.18、78.44 mg·kg-1.地球化学基线因子指数法评估表明土壤As、Hg、Zn积累最为突出，分别有14.65%、11.82%、3.88%样点达重度积累；地质累积指数法评估表明Cd、Cr、Cu、Ni、Pb超过93%的样点处于无积累，Hg、Zn、As轻度积累比例分别为26.60%、21.84%、21.21%，仅As和Zn有5.56%和0.49%的样点为中度积累.水稻土、紫色土与潮土、黄壤、石灰岩土相比重金属积累程度轻.渝东北大巴山石灰岩中低山区、渝东南武陵山石灰岩低山区As、Zn点位积累率较高，渝西窟窿丘陵台地区、渝中中高丘平行岭谷区Hg、As点位积累率较高.两种评估方法均表明重庆市农地土壤主要积累重金属为As，其次为Hg、Zn，应加强管理防范. |
| 英文摘要 |
| In order to understand the accumulation of heavy metals of agricultural land in Chongqing and make clear priority control elements, the soil heavy metal baseline values need to be determined. Based on geochemical baselines, a total of 214 surface soil samples of six soil types were collected according to stratified sampling. Under strict quality control, the As, Cd, Cr, Cu, Hg, Ni, Pb, and Zn content in each sample was measured. The baseline values of eight heavy metals were determined using mathematical statistics, iterative culling, and cumulative frequency curve methods. The accumulation of heavy metals in agricultural soils in Chongqing was evaluated using the geochemical baseline pollution and geological accumulation index methods. The mean baseline values of As, Cd, Cr, Cu, Hg, Ni, Pb, and Zn in agricultural land in Chongqing were 5.83, 0.25, 66.78, 25.45, 0.069, 29.90, 26.18, and 78.44 mg·kg-1, respectively, which agreed with the historical findings. Evaluation of the geochemical baseline pollution index method showed that the accumulation of As, Hg, and Zn in soil was the most prominent, with 14.65%, 11.82%, and 3.88% of the samples reaching severe accumulation, respectively. The proportions of moderate accumulation of As, Cd, Cr, Cu, Hg, Ni, Pb, and Zn were 12.12%, 6.50%, 3.79%, 6.50%, 15.27%, 5.29%, 5.45%, and 17.96%, respectively, of which As, Hg, and Zn were relatively large. The geological accumulation index indicated that more than 93% of the samples of Cd, Cr, Cu, Ni, and Pb were in a state of no accumulation. The proportions of mild accumulation of Hg, Zn, and As were 26.60%, 21.84%, and 21.21%, respectively. Only 5.56% and 0.49% of the samples had moderate accumulation of As and Zn. Different soil types have different properties. All soil types in the sample had different degrees of accumulation of the eight kinds of heavy metals. The accumulation of heavy metals in paddy and purple soils was lower than that in other soil types. For the soils of different geological and geomorphic types, the Ki values of As in the limestone middle and low mountain area of Daba Mountain in Northeast Chongqing and the low mountain area of the limestone of Wuling Mountain in Southeast Chongqing were relatively large; the rest were not significantly different, and all belonged to the non-accumulation and mild accumulation ranges. Both evaluation methods showed that the main accumulated heavy metals in agricultural land soil in Chongqing was As, followed by Hg and Zn, and management and prevention of the accumulation of these elements should be strengthened. |
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