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| Source apportionment and risk assessment of Cd and Hg pollution in farmland |
| Received:December 24, 2015 |
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| KeyWord:heavy metal pollution;risk assessment;source apportionment;bioavailability;planting structure adjustment |
| Author Name | Affiliation | E-mail | | LI Xia | MOE Key Laboratory of Pollution Processes and Environmental Criteria, College of Environmental Science and Engineering, Nankai University, Tianjin 300071, China | | | ZHANG Hui-ming | MOE Key Laboratory of Pollution Processes and Environmental Criteria, College of Environmental Science and Engineering, Nankai University, Tianjin 300071, China | | | XU Zhen | Tianjin Agricultural Environmental Protection Management Monitoring Station, Tianjin 300061, China | | | JIN Cong-ying | Tianjin Agricultural Environmental Protection Management Monitoring Station, Tianjin 300061, China | | | BAI Hong-tao | MOE Key Laboratory of Pollution Processes and Environmental Criteria, College of Environmental Science and Engineering, Nankai University, Tianjin 300071, China | | | WANG Lei | MOE Key Laboratory of Pollution Processes and Environmental Criteria, College of Environmental Science and Engineering, Nankai University, Tianjin 300071, China | | | ZHAO Zhen | MOE Key Laboratory of Pollution Processes and Environmental Criteria, College of Environmental Science and Engineering, Nankai University, Tianjin 300071, China | | | SUN Hong-wen | MOE Key Laboratory of Pollution Processes and Environmental Criteria, College of Environmental Science and Engineering, Nankai University, Tianjin 300071, China | sunhongwen@nankai.edu.cn |
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| Abstract: |
| Source apportionment and risk assessment are important two aspects for heavy metal pollution studies. In this study, levels of Cd and Hg in soil and agricultural products in a suburb of Tianjin were investigated. Their risk was evaluated by index methods and spatial distribution characteristics. Sources of Cd and Hg were studied by GIS-based space model and isotope ratio method. In addition, crops with low enrichment coefficients and high economic benefits were screened from various kinds of crops. Results showed that part of the investigated area suffered Cd and Hg pollution. Only 19% and 46% of the sites were Cd-and Hg-safe, respectively; whereas 36% and 17% were at warning and 26% and 19% at light pollution levels, respectively. Severely polluted sites were less than 10%. The percentages of polluted a gricultural products were 17% and 37% for Hg and Cd, respectively. In the studied area, Cd entered soil mainly via point sources and had high mobility; while Hg polluted soil primarily through non-point sources and existed largely as residue form. The heavy metal isotope ratio analysis revealed that soil Cd pollution was mainly from industrial waste and irrigation water and that Cd in agricultural products came most ly from soil. However, Hg pollution in soil resulted mainly from atmospheric deposit, organic fertilizer and irrigation water, and Hg in agricultural products was from soil and atmospheric dusts. The enrichment ability of heavy metals varied among crops, with the lowest enrichment found in melon and fruit vegetables, in which Cd and Hg content in fruits was safe. These results suggested that it is possible to pro duce safe agricultural products in slightly polluted farmland through adjusting planting structure, thus providing a practical way to control the hazard of heavy metal pollution in farmland. |
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