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| Ecological risks of heavy metals and the relationship between sources and sinks in an abandoned mining area of Guangxi Zhuang Autonomous Region |
| Received:November 19, 2020 |
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| KeyWord:multimedia sample;heavy metals;source analysis;ecological risk;source-sink flux |
| Author Name | Affiliation | E-mail | | MAO Zhi-qiang | College of Environment, Hohai University, Nanjing 210098, China
State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China | | | TIAN Kang | State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China | tiank@issas.ac.cn | | LIU Ben-le | State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China | | | ZHANG Xiao-hui | College of Environment, Hohai University, Nanjing 210098, China
State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China | | | BIAN Zi-jin | State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China | | | HUANG Biao | State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China | | | YUAN Xu-yin | College of Environment, Hohai University, Nanjing 210098, China | | | WU Long-hua | State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China | | | LUO Dong-yuan | Scientific Research Academy of Guangxi Environmental Protection, Nanning 530022, China | ivanldy@163.com |
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| Abstract: |
| To explore the influence of an abandoned mining area on the surrounding environmental media, quantify the contributions of heavy metals(HMs) in farmland soils, and estimate the source and sink fluxes of HMs, a typical polymetallic abandoned mining area and its downstream area in Nandan County, Guangxi Zhuang Autonomous Region were selected as the study areas. A total of 151 samples of tailings(16), farmland soils(113), and river sediments(22) were collected, and 9 typical HMs(Cr, Ni, Cu, Cd, Zn, As, Sn, Sb, and Pb) were determined in these multimedia samples. The pollution statuses of the HMs were assessed using the geo-accumulation index and potential ecological risk index(RI). The source apportionment of HMs in farmland was explored using an absolute principal component multiple linear regression and the relative importance of the variables. The source and sink fluxes of HMs were also calculated in the study area. The results showed that the geometric means of the HM contents in tailings and sediments(except for Cr and Ni) were significantly higher than those in farmland soils, and those in the three media exceeded the background values. Cr and Ni in the farmland soils mainly originated from natural sources. Cu, Cd, Zn, As, Sn, Sb, and Pb in the farmland soils of the upstream area mainly originated from upstream abandoned mine tailings. In farmland soils of the downstream area, Cu, Sn, Sb, and Pb mainly originated from downstream abandoned dressing plant tailings(contributions of 85.11%, 92.04%, 64.15%, and 57.57%, respectively), whereas Cd, Zn, and As mainly originated from upstream abandoned mine tailings(contributions of 59.28%, 59.61%, and 93.81%, respectively). The main pollution elements in the farmland soils and sediments in the study areas were Sn and Sb. The farmland soils and sediments exhibited relatively high ecological risks in both areas(RI>300), and the main ecological risk factors were Cd, As, and Sb. Farmland soils were major sinks of HMs because the input fluxes of Cu, Cd, Zn, As, Sn, Sb, and Pb in the upstream and downstream farmland soils were 132, 3, 1 348, 302, 139, 149 kg·hm-2, and 238 kg·hm-2 and 36, 2, 746, 177, 271, 211 kg·hm-2, and 455 kg·hm-2, respectively. In conclusion, the tailings as the main sources of HMs still contain a large amount of HMs and have a high potential to release HMs. Thus, more attention should be paid to the source-sink relationships of HMs in multimedia samples in abandoned polymetallic mining areas. Relevant departments should strengthen the pollution prevention and risk management of HMs according to the pollution status of different media and regions and ensure tailing control. |
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