Abstract:

This study aimed to analyze the correlation between the dominant plant species in Pb-Zn wasteland and rhizosphere soil microbes, soil physical and chemical properties and soil enzyme on the basis of vegetation survey and determination of heavy metal content in eastern Guangdong Province, provide the scientific basis for soil environmental quality assessment in mining area and guide the rehabilitation and reconstruction of the mine ecosystem. The microbe amount, enzyme activity, physical and chemical properties in rhizosphere soil of three dominant plant in Bingcun Pb-Zn mining wasteland, Mei County, Guangdong Province were measured by conventional experimental methods and analyzed in comparison with those in non-rhizosphere and non-contaminated soil, the results showed that: (1) the heavy metal contents of soil in this wasteland tailings soil were much higher than the national soil quality standard value, and the polluted degree reached above the level 3 pollution. The different capacities to absorb heavy metals of three dominant plants, Neyraudia reynaudiana, Vitex negundo, Rhus chinensis, growing in the contaminated regions, resulted in different heavy metal contents of the rhizosphere soil. (2) the alkali N content, available K, and pH value of rhizosphere and non-rhizosphere soil in contaminated region were lower than those in non-contaminated regions, but the available P content was higher; in non-contaminated regions, there were no significant differences in alkaline N and available K content between these three plants, but in the contaminated regions, the alkaline N content of N. reynaudiana was significantly higher than that of V. negundo and R. chinensis, the available K content of V. negundo was lower than that of N. reynaudiana and R. chinensis. The available P content of rhizosphere soil for these three plants in contaminated regions was lower than that of non-rhizosphere soil, but was lower in non-contaminated areas. The pH value of rhizosphere soil in contaminated and non-contaminated areas of N. reynaudiana, was higher than that of V. negundo and R. chinensis, and higher than that of the non-rhizosphere soil. (3) in non-contaminated regions, the actinomycetes was the most in rhizosphere and non-rhizosphere soil for three plant, followed by bacteria, fungi was the least; the total microbe amount of rhizosphere soil for N. reynaudiana was more than that for other plants; in the contaminated regions, the bacteria, fungi, actinomyces of rhizosphere soil were less than those of non-rhizosphere soil; the total microbe amount of rhizosphere soil for R. chinensis was larger than for other plants. In most cases, whether in contaminated or non-contaminated regios, the enzyme activity of rhizosphere soil were significantly higher than that of non-rhizosphere soil for the three plant; in the contaminated area, the activity of invertase, polyphenol oxidase, urease, phosphatase of rhizosphere soil were higher than those in non-contaminated areas for the three plant. (5) due to being influenced by plant species, study area, the nature (single or combined pollution) and the and extent of pollution, there presented complex correlation between soil microbes, nutrients (alkaline solution of N, available K, quick-P) and enzyme activity.