粤东铅锌尾矿区3种优势植物根际土壤微生物的活性研究

Study on the Microbial Activity of Rhizosphere Soil for Three Dominant Plant in Pb-Zn Wasteland in Eastern Guangdong Province

为了在植被调查和重金属含量的测定基础上,分析粤东铅锌尾矿区优势植物与根际土壤微生物、土壤理化性质和土壤酶之间的相关性,为污染矿区土壤环境质量评价提供科学依据,并指导矿区生态系统的恢复和重建。采用常规实验方法对广东梅县丙村铅锌尾矿废弃地的3种优势植物根系土壤的微生物数量、酶活性以及理化性质进行测定,并与非根际土壤和非污染土壤比较分析。结果表明:(1)该尾矿土壤重金属含量远高于国家土壤质量标准值,在三级污染以上。在污染区生长的类芦、黄荆、盐肤木3种优势植物,很可能由于其重金属的吸收能力不同,导致根际土壤中重金属含量不同。(2)污染区根际和非根际土壤的碱解N、速效K含量、pH值低于非污染区,但速效P含量要高;在非污染区,根际土壤的碱解N与速效钾含量在3种植物之间无显著差异,但在污染区,类芦的碱解N含量显著高于黄荆和盐肤木,黄荆的速效K含量低于类芦和盐肤木。在污染区,3种植物的根际土壤速效P含量均低于非根际土壤,但在非污染区反而要低。在污染区和非污染区,类芦的根际土壤pH值均高于黄荆和盐肤,且高于非根际土壤。(3)在非污染区,3种植物的根际土壤及非根际土壤中,均是放线菌最多,细菌次之,真菌最少;类芦的根际土壤微生物数量最多;在污染区,根际土壤细菌、真菌、放线菌数量均低于非根际土壤;盐肤木的根际土壤微生物数量最多。(4)绝大多数情况下,无论是污染区还是非污染区,3种植物根际土壤酶的活性均显著高于非根际土壤;污染区3种植物的根际土壤蔗糖酶、多酚氧化酶、脲酶、磷酸酶的活性均高于非污染区。(5)由于受植物种类、研究地域、污染性质(单一污染或复合污染)及程度的影响,土壤微生物数量、养分(碱解N、速效K、速效P)、土壤酶活性之间呈现非常复杂的相关关系。

This study aimed to analyze the correlation between the dominant plant species in Pb-Zn wastelandand 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 basisfor 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 andnon-contaminated soil. The results showed that： 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. 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. ehinensis, the available K content of V. negundo was lower than that of N. reynaudiana and R. ehinensis. 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. ehinensis, and higher than that of the non-rhizosphere soil. Innon-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, aetinomyces 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. Due to being influenced by plant species, study area, the nature （single or combined pollution） and the extent of pollution, it presented complex correlation among soil microbes, nutrients （alkaline solution of N, available K, quick-P） and enzyme activity.