高浓度大气CO_(2)对铅污染刺槐幼苗根际土壤有机化合物和微生物特性的影响

Effection of Elevated Atmospheric CO_(2) on the Organic Compounds and Microbial Properties in Rhizosphere Soil of Robinia Pseudoacacia L.Seedlings with Pb Contamination

采用开顶箱气室内设置盆栽试验,研究高浓度大气CO_(2)耦合土壤Pb污染对刺槐幼苗根际土壤有机化合物和微生物特性的影响。结果表明:1)高浓度大气CO_(2)条件下,刺槐根际土壤TOC、DOC、MBC、总糖、酚酸、氨基酸和有机酸含量增加,细菌、真菌、放线菌和FDA活性升高,除L-天门冬酰胺酶外,脲酶、脱氢酶、转化酶、β-葡萄糖苷酶有所提高,土壤pH值无显著变化。2)Pb污染条件下,土壤TOC、总糖、氨基酸、有机酸含量及L-天门冬酰胺酶活性升高,而DOC、MBC、酚酸含量和脲酶、脱氢酶、转化酶、β-葡萄糖苷酶活性降低,细菌和真菌数量略有降低(4.06%和4.53%),放线菌和FDA下降趋势较大(12.86%和10.89%)。3)与单独Pb污染相比,高浓度大气CO_(2)耦合Pb污染(ECO_(2)+Pb)总体提高了土壤有机化合物含量和土壤微生物特性,冗余分析(RDA)表明,总糖、酚酸、MBC和pH值是影响根际土壤微生物特性的主要因子,土壤有机化合物与微生物特性之间具有显著的相关关系。综上表明,高浓度大气CO_(2)能够提高根际土壤有机化合物含量,从而缓减Pb污染对刺槐幼苗根际微环境胁迫效应。

The effects of elevated atmospheric CO_(2)concentration and Pb contamination on organic compounds and microbial characteristics in rhizosphere soil of Robinia Pseudoacacia L.seedlings are investigated via open-top chambers combing with pot experiment.The results show that:1)Elevated atmospheric CO_(2)increased the concentration of TOC,DOC,MBC,total souble sugars,phenolic acids,amino acids,and organic acids inrhizosphere soils,leading to an increase in the activity of bacteria,fungi,actinomycetes and FDA.Except for L-asparaginase,the activities of urease,dehydrogenase,invertase,andβ-glucosidase are enhanced,while the pH of soil has little change under elevated CO_(2)concentration.2)With Pb contamination,the concentrations of TOC,total souble sugars,amino acids,organic acids,and L-asparaginase increase,but the DOC,MBC,phenolic acid concentration,urease,dehydrogenase,invertase,andβ-glucosidase activity are in decline.The number of bacteria and fungi declines slightly(4.06%and 4.53%,respectively),by contrast,that of actinomycetes and FDA drops largely(12.86%and 10.89%,respectively)under Pb stress.Comparing with Pb contamination,ECO_(2)+Pb contamination enhances soil organic compounds and microbial characteristics.Redundancy analyses(RDA)show that the total souble sugars,phenolic acids,MBC,and pH are the principle influence factors for rhizosphere microenvironment.The soil organic compounds are closely related to soil microbial characteristics.The results show that the increased organic compounds under elevated atmospheric CO_(2),which is the major factor for relieving the impact of Pb contamination on the rhizosphere microenvironment of Robinia Pseudoacacia L.seedlings.