赣南钨矿区土壤重金属空间分布及其形态研究

发布时间：2018-05-28 22:27

本文选题：重金属污染 + 空间分布　；参考：《江西理工大学》2015年硕士论文

【摘要】：矿产资源的开采、加工使得各种伴生重金属元素释放于地表环境,已经成为土壤重金属污染的重要来源,严重影响矿区土壤生态系统。为了研究钨矿区土壤重金属的污染现状,采集矿区土壤样品。用ICP-AES测定土壤重金属(Pb、Cr、Mn、Zn、Cu、Cd)总量,以国家土壤二级标准评价其污染程度,运用BCR三步连续提取法分析重金属的形态分布特征及影响因素,采用Kriging插值法分析表层土壤重金属的空间分布特征和重金属的来源,并测定表层土壤脲酶、过氧化氢酶、蔗糖酶的活性,进一步验证土壤重金属的污染状况。研究结果表明重金属在土壤中存在累积现象,其中上层最严重,其次是中层。上层土壤Pb、Cr、Cu、Zn、Cd平均含量分别是国家土壤二级标准的2.264、1.06、1.326、0.647、17.7倍,中层土壤Pb、Cr、Cu、Zn、Cd平均含量分别是国家土壤二级标准的1.228、0.923、0.942、0.416、14.33倍。下层土壤虽然还是存在重金属污染,但程度较轻。六种重金属的空间相关性很强,最优拟合模型都是高斯模型,Cd的拟合模型精确度最高。土壤重金属的空间分布表明,土壤重金属来源于尾矿库堆积的尾矿砂中重金属的迁移。土壤中的元素Pb、Mn是以可还原态、残渣态为主,元素Cr是以可氧化态、残渣态为主,元素Cu、Zn、Cd以残渣态为主。除Cr外,Pb、Mn、Cu、Zn、Cd酸溶态含量在表层土壤最高,最活泼,生物有效性最大。土壤重金属的形态与阳离子交换量、p H值、重金属总量有一定的关系。土壤酶活性低于对照样,土壤脲酶、过氧化氢酶、蔗糖酶分别是对照的24.27%-93.29%、14.26%-95.63%和10.56%-97.57%。逐步多元回归法分析表明,在Pb、Cr、Mn、Zn、Cu、Cd复合污染条件下,矿区土壤不同酶活性表现出抑制或者激活作用,但各重金属元素对不同的酶活性的影响系数是不一样的,蔗糖酶对复合重金属污染最为敏感。土壤酶活性的指标能较好地反映钨矿矿区土壤重金属复合污染状况。
[Abstract]:Mining and processing of mineral resources have resulted in the release of various associated heavy metal elements into the surface environment, which has become an important source of soil heavy metal pollution and has seriously affected the soil ecosystem of mining areas. In order to study the pollution status of heavy metals in the soil of tungsten ore area, the soil samples of mining area were collected. ICP-AES was used to determine the total amount of heavy metal in soil, and the pollution degree was evaluated by the national soil secondary standard. The speciation and distribution characteristics and influencing factors of heavy metals were analyzed by BCR three-step continuous extraction method. The spatial distribution and source of heavy metals in surface soil were analyzed by Kriging interpolation method. The activities of urease, catalase and sucrase in surface soil were determined to further verify the pollution status of heavy metals in soil. The results showed that the accumulation of heavy metals in soil was the most serious in the upper layer and the second in the middle layer. The average content of Pb ~ (2 +) Cr ~ (2 +) Cu ~ (2 +) Zn ~ (2 +) ~ (2 +) in the upper soil was 17.7 times that of the national soil secondary standard, respectively, and the average content of Pb ~ (2 +) Cr ~ (2 +) Cu ~ (2 +) Zn ~ (2 +) in the middle soil was 1.228 ~ (0.923) ~ (0.942) ~ (0.416) 14.33 times of the second grade national soil standard, respectively. Although heavy metal pollution still exists in the lower soil, the degree of heavy metal pollution is relatively light. The spatial correlation of six heavy metals is very strong, and the best fitting model is the Gao Si model with the highest accuracy. The spatial distribution of heavy metals in soil indicated that the heavy metals in soil originated from the migration of heavy metals in tailings. In soil, the elements of Pb ~ (2 +) mn are mainly reducible and residual, Cr is oxidable and residual, and Cu ~ (2 +) Zn ~ (+) CD is residuals. In addition to Cr, the acid soluble content of PbHMnMnCuN ZnN CD in the topsoil was the highest, the most active, and the bioavailability was the greatest. The speciation of heavy metals in soil is related to the cation exchange capacity (pH) and the total amount of heavy metals. Soil urease, catalase and sucrase activity were 24.27-93.29% and 10.56% -97.57%, respectively. The results of stepwise multivariate regression analysis showed that the enzyme activities of different soils in the mining area were inhibited or activated under the combined pollution of PbPb-Cr-MnMnZn-Cu-Cu and CD, but the influence coefficient of heavy metal elements on different enzyme activities was not the same. Sucrase is most sensitive to complex heavy metal pollution. The index of soil enzyme activity can well reflect the complex pollution of heavy metals in the soil of tungsten mining area.
【学位授予单位】：江西理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X53;X753

【参考文献】