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现代地质 ›› 2020, Vol. 34 ›› Issue (05): 917-927.DOI: 10.19657/j.geoscience.1000-8527.2020.068

• 地球化学 • 上一篇    下一篇

西南重金属高背景区农田系统土壤重金属生态风险评价

唐瑞玲1(), 王惠艳1,2, 吕许朋3, 徐进力1, 徐仁廷1,2, 张富贵1,2,4()   

  1. 1.中国地质科学院 地球物理地球化学勘查研究所,河北 廊坊 065000
    2.中国地质调查局 土地质量地球化学调查评价研究中心,河北 廊坊 065000
    3.云南省地质调查院,云南 昆明 650216
    4.成都理工大学 地球科学学院,四川 成都 610059
  • 收稿日期:2020-01-20 修回日期:2020-08-12 出版日期:2020-10-28 发布日期:2020-10-29
  • 通讯作者: 张富贵
  • 作者简介:张富贵,男,博士,高级工程师,1980年出生,沉积学专业,主要从事土地质量调查和生态地球化学工作。Email: zhangfugui@igge.cn
    唐瑞玲,女,硕士,工程师,1985年出生,地球化学专业,主要从事分析测试的工作。Email: tangruiling@igge.cn
  • 基金资助:
    中国地质调查局地质调查项目(DD20190522);中央级公益性科研院所基本科研业务费专项(AS2020J07)

Ecological Risk Assessment of Heavy Metals in Farmland System from an Area with High Background of Heavy Metals, Southwestern China

TANG Ruiling1(), WANG Huiyan1,2, LÜ Xupeng3, XU Jinli1, XU Renting1,2, ZHANG Fugui1,2,4()   

  1. 1. Institute of Geophysical and Geochemical Exploration, Chinese Academy of Geological Sciences, Langfang, Hebei 065000, China
    2. Research Center of Geochemical Survey and Assessment on Land Quality, China Geological Survey, Langfang, Hebei 065000, China
    3. Yunnan Institute of Geological Survey, Kunming, Yunnan 650216, China
    4. College of Earth Sciences, Chengdu University of Technology, Chengdu, Sichuan 610059, China
  • Received:2020-01-20 Revised:2020-08-12 Online:2020-10-28 Published:2020-10-29
  • Contact: ZHANG Fugui

摘要:

西南地区是我国典型重金属高背景区,在重金属高背景区开展生态风险评价对保障粮食安全有重要意义。采集云南省重金属高背景区土壤表层(0~20 cm)样品242件,农作物及对应的根系土样品74件,分析土壤和农作物样品中8种重金属(Cd、Cr、As、Hg、Pb、Cu、Zn、Ni)含量以及土壤中重金属赋存形态。研究发现,受地质背景因素影响,Cd、Cr、Cu、Hg、Ni和Zn含量平均值均超过云南省土壤背景值,Cd、Cu和Ni含量平均值均超过农用地土壤污染风险管控标准规定的筛选值,土壤pH值多呈酸性,有机质含量较低。土壤中As、Cr、Cu、Ni、Pb和Zn主要以残渣态形式存在,生物有效性低,是由地质背景引起的;Cd残渣态占比较低,生物有效组分较高,Cd元素的地累积指数分布显示,Cd受人为污染和地质背景交互叠加的影响,是研究区污染风险最高的重金属元素。Hg来源较为复杂,全量较低,污染风险较小。研究区大宗粮食作物(马铃薯和玉米)重金属含量均不超标,生物富集系数(BCF)均小于0.03,粮食作物较安全,生态风险较低。黄烟中Cd含量远远超过目前初步制定的安全限量标准,BCF为3.13,说明烟草特别能富集Cd,存在一定的生态风险。表层土壤重金属潜在生态风险指数(RI)统计结果显示,土壤重金属RI贡献降序依次为Cd(73.71)>Hg(57.40)>Cu(25.25)>Ni(8.76)>As(7.39)>Cr(4.15)>Pb(4.04)>Zn(2.0),Cd和Hg是研究区最重要的风险元素,但均以中等生态危害为主,很强生态危害分布面积较小,研究区生态风险整体较低,风险可控。

关键词: 土壤重金属, 农作物, 农田系统, 生态风险评价, 高背景

Abstract:

Southwestern China contains high metals (HMs) background, and ecological risk assessment on HMs is important to ensure food security.A total of 242 soil samples (0-20 cm) and 74 sets of rhizosphere soil and crop samples were collected from high-HM background area in Yunnan Province. We analyzed the concentrations of Cd, Hg, Pb, As, Cu, Zn, Ni and Cr in the soil and crop samples, as well as the chemical forms of heavy metals in soil. The results show that most soil samples are acidic (low pH) and low organic matter (OM) content, and the mean Cd, Cr, Cu, Hg, Ni, and Zn contents in the topsoil all exceed the soil background value in Yunnan Province. The average Cd, Cu, and Ni contents are remarkably higher than the screening value specified in the soil contamination risk in agricultural land (GB 15618-2018). Speciation analysis indicates that the HMs (Cr, As, Pb, Cu, Zn, and Ni) mainly exist in the residual form, with low bioavailability and source from the background geology. Cd has a high bioavailability ratio. Distribution of geo-accumulation index (Igeo) of Cd shows that Cd is affected by the superposition of anthropogenic pollution and background geology, and represents the highest pollution risk in the study area. Mercury has a complex source with a low volume and low pollution risk. The HMs concentrations of the staple crops in the study area do not exceed the standard, and the bioconcentration factor (BCF) is below 0.03, thus the food crops are safe for consumption and ecological risks are low. The Cd concentration in tobacco far exceeds the preliminary safety limit standard, and the BCF is 3.13, indicating that tobacco can concentrate much Cd, and affect human health and pose ecological risks. The potential ecological risk index (RI) shows that the descending order of Cd>Hg>Cu>Ni>As>Cr>Pb>Zn, with the contribution ratios of 40.33%, 31.41%, 13.81%, 4.79%, 4.04%, 2.27%, 2.21%, and 1.13%, respectively. Mercury and Cd are the main source of risk because of their high toxicity coefficient.Both Hg and Cd present moderate risk, and the strong risk area is small. The overall ecological risk is low and the risk is controllable in the study area.

Key words: soil heavy metal, crops, farmland system, ecological risk assessment, high background area

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