Accumulation and Sources of Heavy Metals in Agricultural Soil in A City Typical of the Yangtze River Delta, China

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National Natural Science Foundation of China (No.41877512) , the Environmental Protection Research Project of Department of Ecology and Environment of Jiangsu Province (No.2018013) and the National Science-technology Support Plan Projects (Grant No. 2015BAD05B04)

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    [Objective] Zhangjiagang City, located at the Yangtze River Delta, China, has experienced rapid economic development since the unfolding of the reform and opening up policy, and consequently the economic development has brought about a series of environmental problems that have aroused concerns among the society in recent years. For the purpose of scientifically managing soil resources and providing to decision-making support in the effort to control the heavy metal pollution problems from the source and to remedy contaminated farmland soils, this study was carried out to explore how heavy metals accumulate and to identify sources of the heavy metal pollutions in this city.[Method] Totally, a total of 188 sampling sites were set up for collection of samples of surface and subsurface soils in the study area, in the light of soil types, land uses, sampling homogeneity, and surrounding contamination conditions. Totals of the six elements, i.e. Cd, Hg, As, Pb. Cr, and Cu, soil pH, and soil organic matter in the samples were measured. Sources and driving factors of the heavy metal pollution in the soil were analyzed and identified with the aid of principal component analysis (PCA) and GeoDetector.[Results] Results show that:(1) In terms of accumulation degree, the six heavy metals follow a descending order:Hg > Cd > Cu > As > Pb > Cr; (2) With reference to the "Soil Environmental Quality Risk Control Standard for Soil Contamination of Agricultural Land (GB 15618-2018)", about 2.13%, 1.06% and 0.53%, respectively, of the farmland soils polluted with Cu, Cd and Hg had the elements exceed the criteria, while almost none of the farmland soils polluted with As, Pb, and Cr do. Pollution assessment with the Geo-accumulation index method shows that among the six heavy metal pollutants, Cd and Hg were the two major ones and detected in 12.83% and 21.28% of the sampling sites, respectively; (3) Performance of the GeoDetector shows that among all the nine factors (pH, soil organic matter, soil type, fertilization application rate, pesticide application rate, population density, GDP, distance from road, and industrial output) discussed in this study, fertilization and pesticide application rates as well as industrial output were the main factors contributing to spatial variation of the six pollutants, while population density, GDP and distance from road were the ones explaining spatial variation of Pb; and (4) As and Cr came mainly from agricultural and industrial activities, Cd and Hg came from soil parent materials in addition to agricultural and industrial activities, Cu in the surface soil came from agriculture, livestock breeding, and industrial activities, while Pb came mainly from agricultural, transportation and industrial activities.[Conclusion] In summary, the six heavy metals in the study area vary in accumulation characteristics. Agricultural and industrial activities are the major causes leading heavy metals pollution of the soil. Nevertheless, further researches should be carried out to figure out influences of social and transportation activities on accumulation of some certain heavy metals, such as Pb.

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WANG Xinkai, ZHANG Yanxia, HUANG Biao, XIE Enze, FAN Ya'nan, HU Wenyou, ZHAO Yongcun, QIU Yige. Accumulation and Sources of Heavy Metals in Agricultural Soil in A City Typical of the Yangtze River Delta, China[J]. Acta Pedologica Sinica,2021,58(1):82-91.

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  • Received:September 16,2019
  • Revised:March 09,2020
  • Adopted:April 29,2020
  • Online: October 30,2020
  • Published: January 11,2021