湘潭锰矿矿渣废弃地植被修复前的土壤诊断

Soil physical and chemical properties of the wasteland in Xiangtan manganese mine

对湘潭锰矿矿渣废弃地植被修复前的土壤进行了诊断分析。结果表明:湘潭锰矿矿渣废弃地土壤质地主要为粗砂土,土壤自然含水量与邻近非矿区杉木林对照地的差异显著,而土壤容重和土壤总孔隙度与邻近非矿区杉木林对照地的差异不显著。矿渣废弃地土壤的pH值平均为7·49,P和Ca的平均含量分别为1·01g/kg、4·41g/kg,都显著高于邻近非矿区杉木林对照地,而N含量却显著低于邻近非矿区杉木林对照地,土壤有机质、K和Mg平均含量与邻近非矿区杉木林对照地的差异不显著。矿渣废弃地的肥力综合指数为8,邻近非矿区杉木林对照地的为12,其中砾石百分含量、有机质含量、N含量、P含量成为了限制土壤肥力的主要因子。矿渣废弃地土壤中的Mn、Cu、Cd、Ni、Zn、Pb平均含量分别是邻近非矿区杉木林对照地的18·59、1·32、4·10、4·66、4·44倍和3·16倍。以邻近非矿区杉木林地土壤对照值、湖南省土壤重金属元素背景值和全国土壤重金属元素平均值作为评价标准,矿渣废弃地土壤6种重金属的综合污染指数分别为13·82、75·72和98·05,均远远超过了重污染等级,且以Mn、Cd的污染为最严重。

The restoration of the wasteland educed by the mining has become an important and interest issue because the wasteland not only occupied the vast tillable lands but also caused serious environment pollution. To provide necessary information for the restoration and management of the wastelands due to mining of Manganese, diagnosis of soil physical and chemical properties was conducted in a wasteland formed with the slag heaps in Xiangtan Manganese Mine, Hu＇ nan Province. A Chinese fir forestland located in the neighborhood of the wastelands but without the mining impacts was selected as a control site. The results showed that soil texture of the wasteland was mainly coarse sandy. Soil water content was significant lower in the wasteland （ 17.8 % ） than in the Chinese fir forestland （23.4%）. However no significant differences were found in soil volume weight and total capillary between the wasteland （1.45g/cm^3 and 45.24%, respectively） and that control site （ 1.42g/cm^3 and 42.34%, respectively）. The mean soil pH value in wasteland （7.49） was significantly higher than that in control site （5.45）. The average concentrations of P and Ca in the wasteland were 1.01g/kg and 4.41g/kg respectively, which were statistically higher than those in the Chinese fir forestland （0.43 g/kg and 0.66 g/kg respectively）. In contrast, average concentration of N was significant lower in wasteland （1.37g/kg） than in control site （2.28g/kg）. The differences in terms of the mean concentration of K and Mg, and soil organic matter content between the two land categories did not significant. The total soil fertility index was lower in the wasteland than in the Chinese fir forestland. It was found that the main factors limiting soil fertility in the wastelands were percentage of sandy grain （1 - 0.01mm）, soil organic matter content, soil concentrations of N and P. The concentration of Mn （7990.21mg/kg）, Cu （66.38mg/kg）, Pb （401.15mg/kg）, Zn （640.32mg/kg）, Cd （13.15mg/kg） and Ni （91.33mg/kg） in the wasteland were 18.59, 1.32, 4.10, 4.66, 4.44 and 3.16 times of those in the Chinese fir forestland, respectively. In comparison with the mean values of soil heavy metal elements recorded in the control site, Hu＇nan province and the national level, the syntheses pollution indexes of the six 6 heavy metal elements （Mn, Cu, Pb, Zn, Cd and Ni） in the wasteland were 13.82, 75.72 and 98.05, respectively, which all exceeded the heave pollution standard. On the individual element basis, the elements of Mn, Pb and Cd exceeded the heave pollution standard. Our research indicated that mining of Manganese result in serious environment pollution and tillable land degradation.