| A large number of lead-zinc mines distributed in upstream of the big huanjiang river, there was torrential rain and flood in June1999, much mill waste water runned into rivers,and leaded the big huanjiang riner gets serious heavy metal pollution.Now to research the soil pollution status and the features of conventional nutrients, microbial biomass and the relationship between the various indicators,make the farmland spatial distribution and the pollution degree of heavy metal pollution,and makes health and ecological risk assessment, provides a scientific basis in local environmental management and further land restoration. In this paper, the soil of the big hujiang river as the research object, throughing field survey sampling and laboratory analysis, describing the general characteristics of all the indicators classical statistics, use statistical methods to reveal the spatial distribution pattern of all the indicators and each single pollution index space distribution characteristics of heavy metals and to assess soil of the big huanjiang. The main conclusions are as follows:(1) The characteristics of conventional soil nutrients, the variation degree of available nutrients was biger than all nutrients in the study area, the variation of phosphorus and potassium were greater than nitrogen, this was likely to be available potassium had more reaction to the changes to a small area. Degree of variation of organic matter and pH were relatively lower. The study area soil nutrient variation difference was not big, TK and TP had good spatial continuity and space continuity of other indices were poorer. The variation of the TN is lowest among them. The fractal dimension D of all indicators were greater than1.9, indicating that their uniformity of the remaining indicators were good. The way and the different soil types had different contents. The average content of calcareous soil and red soil nutrients were similar, difference was not big.(2) The characteristics of the soil microbial quantity, the index variation coefficient of soil microorganisms were very big, MBC, MBC/MBN have intensity variation, reflected the height of the big huanjiang river basin habitat heterogeneity, in this study MBC, MBN showed a moderate spatial correlation, other indicators showed a strong spatial correlation, MBC/MBN of the spatial continuity was poorer, variation degree was higher. MBN spatial variation scale was larger, should expand the scope of study, in order to more accurate comprehensive reflect the spatial distribution of soil microbial biomass N. The amount of microbialin in different soil using the way and the different soil types had different contents. Microbial indicators had no marked difference, content was similar.(3) The big huanjiang river basin characteristics of soil heavy metals, each index of the coefficient of variation was very big. Pb, Ni, Cd, Cr and Zn had a strong spatial correlation charactor in the study area; The rest of indicators were medium spatial autocorrelation. Each index variation difference compared mark, Cu and Zn, Pb, As had a good space continuity, other indicators were poor. The impact of different use way and different soil types on soil heavy metal content of was not big.(4) The soil heavy metal pollution evaluation, only the average content of Zn, Cd was higher than soil background values, accumulation phenomenon was relatively common. As, Ni, Pb and Hg were main in light pollution, but Cd, Zn pollution was more serious. Through spatial distribution, the Cd and Zn pollution was most serious, the pollution of Cd largely scattered on the whole river basin. Heavy metal pollution was basically concentrated in hierarchical, and the downstream, less pollution. From the perspective of environmental and human health risk, As, Cd, Pb, Zn should be a priority control of heavy metal. |
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