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| Titel |
Relationships between soil heavy metal pollution and enzyme activities in mining areas of northern Hunan province, Central South China |
| VerfasserIn |
Xue-Feng Hu, Ying Jiang, Ying Shu |
| Konferenz |
EGU General Assembly 2014
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250099245
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| Publikation (Nr.) |
 EGU/EGU2014-15002.pdf |
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| Zusammenfassung |
| Hunan province, Central South China, is a well-known nonferrous metal base in China. Mine
exploiting and processing there, however, often lead to heavy metal pollution of farmland.
To study the effects of mining activities on the soil environmental quality, four
representative paddy fields, the HSG, SNJ, NT and THJ, in Y county, northern
Hunan province, were investigated. It was found that the streams running through the
HSG, SNJ and NT are severely contaminated due to the long-term discharge of
untreated mineral wastewater from local indigenous mining factories. The stream at the
HSG, for example, is brownish red in color, with high concentrations of Cu, Zn,
Cd, Fe and Mn. The concentrations of Cu, Zn and Cd in all the stream water of
the HSG, SNJ and NT exceed the maximum allowable levels of the Agricultural
Irrigation Water Criteria of China. Correspondingly, the HSG, SNJ and NT are heavily
polluted by Cu, Zn and Cd due to the long-term irrigation with the contaminated
stream water. In comparison, both stream water and paddy fields of the THJ, far
away from mining areas, are not contaminated by any heavy metals and hence
regarded as a control in this study. The rice grain produced at the HSG, SNJ and
NT has a high risk of Cd contamination. The rate of rice grain produced in the
four paddy fields in Y county with Cd exceeding the safe level (Cd, 0.2 μg g-1)
specified by the National Standards for Rice Quality and Safety of China reaches
90%. Cd content in the rice grain is positively significantly correlated with that
in the paddy fields, especially with the content of diethylenetriaminepentaacetic
acid (DTPA) - extracted Cd, suggesting that the heavy metal pollution of paddy
fields has already posed a high risk to rice safety and human health. Soil enzyme
activities and microbial biomass are significantly inhibited by the heavy metal pollution
of the paddy fields. Microbial biomass C and N (MBC and MBN) at a severely
contaminated site of the HSG are only 31.6% and 64.4% of the controls; the activities of
dehydrogenase, urease, catalase, acid and neutral phosphatase and sucrase are only
25.2%, 49.3%, 52.4%, 94.7%, 53.2% and 87.8% of the controls. These microbial
parameters are mostly negatively significantly correlated with the contents of Cu, Zn,
Cd and Ni in the paddy fields, suggesting the toxic effects of the heavy metals on
microbial processes. Both the Principal Component Analysis (PCA) and Cluster
Analysis (CA) indicated that DH activity and MBC are the most sensitive to the
heavy metal pollution and could be used as eco-indicators of the environmental
quality of the paddy fields in the study areas. Acknowledgements: This work was
supported by the National Natural Science Foundation of China (No. 41130526). |
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