利用乡土树种修复重金属污染土壤的可行性分析

Feasibility Analysis of Using Native Tree Species to Remediate Heavy Metal Contaminated Soil

摘要: 为了说明利用乡土树种进行土壤重金属污染治理的可行性，本研究利用ICP-MS测定了酸枣、桂花、阴香、大叶女贞和拐枣等5种乡土树种的叶片及其根际土壤的重金属含量，采用单因子污染指数法、内梅罗污染指数法和地累积指数法对不同乡土树种根际土壤的重金属污染情况进行了评价，并对不同乡土树种叶片的重金属富集系数和富集能力进行了比较分析。结果表明：1) 研究区域土壤中的Mn、Cu、Zn、As、Cd、Pb等重金属元素含量远高于广西土壤和全国土壤的背景值，达到重度污染，其污染原因可能与矿物开采有关；2) 酸枣、桂花、阴香、大叶女贞和拐枣对重金属具有较强的耐性，虽然这些乡土树种叶片对重金属的富集系数较小，但其累积的重金属总量较大；3) 乡土树种生物量大，适应性强，对生境要求不高。因此，如能对其进行合理配置，再结合其他有效措施，利用乡土树种对土壤重金属污染进行治理是可行的。

Abstract: In order to illustrate the feasibility of using native tree species for soil heavy metal pollution con-trol, ICP-MS was used to determine the heavy metal content in leaves and rhizosphere soils of five native tree species, including Choerospondias axillaris, Osmanthus fragrans, Cinnamomum burmannii, Ligustrum lucidum and Hovenia dulcis. The single-factor pollution index method, Nemerow pollution index method and geoaccumulation index method were used to evaluate the heavy metal pollution in the rhizosphere soil of different native tree species, and the heavy metal enrichment coefficient and enrichment capacity of leaves of different native tree species were compared and analyzed. The results show that: 1) The content of heavy metal elements such as Mn, Cu, Zn, As, Cd, and Pb in the soil of the study area is much higher than the background value of the soil in Guangxi and the soil of the whole country, and has reached severe pollution. The cause of the pollution may be related to mineral mining. 2) Choerospondias axillaris, Osmanthus fragrans, Cinnamomum burmannii, Ligustrum lucidum and Hovenia dulcis have strong tolerance to heavy metals. Although the enrichment coefficients of these native tree species to heavy metals are small, the total amount of accumulated heavy metals is relatively large; 3) Native tree species have large biomass, strong adaptability and low requirements for habitat. Therefore, if it can be reasonably configured and combined with other effective measures, it is feasible to use native tree species to control soil heavy metal pollution.