羟基磷灰石–植物联合修复对Cu/Cd污染植物根际 土壤微生物群落的影响

针对江西贵溪Cu、Cd重金属污染土壤,通过田间试验,比较无机生物材料羟基磷灰石及3种植物(海州香薷、巨菌草、伴矿景天)与羟基磷灰石联合修复对土壤总Cu、Cd的吸收及对活性Cu、Cd的钝化吸收能力差异。采用磷脂脂肪酸(PLFA)分析法,比较不同修复模式对土壤微生物群落结构的影响,以评估土壤微生态环境对不同修复措施的响应。研究结果表明:羟基磷灰石的施加可显著提高土壤pH,并有效钝化土壤活性Cu、Cd含量,但对土壤总Cu、Cd的含量影响较小。植物与羟基磷灰石的联合修复在显著降低土壤活性Cu、Cd(P0.05)的同时,减少了植物根际土壤总Cu、Cd的含量(P0.05)。不同修复措施对土壤微生物群落组成影响差异明显。单独施加羟基磷灰石与土壤真菌群落呈显著正相关,使土壤真菌生物量提高,从而引起真菌/细菌(F/B)的升高。植物与羟基磷灰石的联合修复可有效缓解土壤真菌化的趋势,其中巨菌草与羟基磷灰石的联合修复可有效提高土壤革兰氏阳性、革兰氏阴性细菌生物量及多样性,降低F/B值,从而降低土壤真菌病害的风险。不同植物根系活性代谢引起有机质的积累促进植物与羟基磷灰石处理中根际有机碳含量显著提高。聚类增强树(Aggregated boosted tree,ABT)分析结果表明:不同修复模式是影响土壤微生物群落的重要因素,其次土壤pH和Cu的含量及活性也是改变重金属污染区域微生物群落的因子。该研究从微生物群落结构角度解释了植物与羟基磷灰石联合修复对土壤微生态体系的作用,为开展Cu、Cd等重金属污染地植物与无机生物材料的联合修复方式的筛选及实施提供可靠的理论依据。

Effects of Combined Remediation of Hydroxyapatite-Plants on Rhizosphere Microbial Community of Cu/Cd Contaminated Soil

Via field experiments, the different effects of inorganic biological material hydroxyapatite and the combined remediations of three kind of plants (Elsholtzia Splendens, Pennisetumsp, Sedum plumbizincicola) with hydroxyapatite on the absorption of soil total Cu and Cd, the passivation and absorptive ability for available Cu amd Cd derived from Cu and Cd contaminated soils in Guixi was compared. PLFA method was used to study the effects of different remediations on soil microbial community, aiming to assess the response of soil micro-ecological environment to various remediations. The results showed that the application of hydroxyapatite increased soil pH value significantly and passivate available Cu and Cd in soil, while had little influence on total Cu and Cd contents in soil. The combined remediations of plants and hydroxyapatite not only reduced soil available Cu and Cd significantly (P<0.05), but also decreased soil total Cu and Cd contents in plant rhizosphere (P<0.05), mainly due to plant tissues absorption and fixation for metals, particularly the aboveground fractions. The effects of different remediations were significantly different on the composition of soil microbial community, sole hydroxyapatite application was positively correlated with soil fungi community and increased soil fungi biomass, which increased fungi/bacteria ratio, while the combined remediation of plant and hydroxyapatite could alleviate the trend of soil fungi enrichment effectively, the combined remediation of Pennisetumsp and hydroxyapatite increased the biomass and diversity of soil Gram positive and Gram negative bacteria and decreased F/B ratio, thus reduced the risk of soil fungi diseases. In addition, organic matter accumulation caused by different plants root metabolism significantly improved rhizosphere organic C of the combined remediation treatments. ABT analysis indicated that different remediations were most important influential factor on soil microbial community, other factors included soil pH value, the content and availability of Cu. The above results explained the combined remediation of plant and hydroxyapatite on soil micro-ecosystem from the perspective of microbial community composition, thus can provide reliable theory bases for the screening and conducting of combined remediation of plant and inorganic biological materials in Cu and Cd contaminated regions.