非洲菊对陇东地区油污土壤的生态修复

Phytoremediation of crude oil-contaminated soils using a wild ornamental plant Gerbera jamesonii in eastern Gansu Province of the Loess Plateau

为评估非洲菊(Gerbera jamesonii)在陇东地区对石油污染物生物降解的潜力,研究植物应对不同油污浓度胁迫的生长和根际土壤环境响应,本研究分析了非洲菊应对4种油污浓度(1%、3%、5%和7%)胁迫时的植物生长指标、土壤环境指标以及土壤总石油烃(total petroleum hydrocarbons,TPH)、烷烃和芳烃的降解率和降解速率。结果显示:1)土壤TPH、烷烃和芳烃降解率随油污浓度的增加而逐步降低,但其降解速率在油污浓度为5%时最高;2)非洲菊株高、根长和出苗率均随油污浓度的增加而逐渐降低(P<0.05),重度污染(7%)对其地上部生物量有显著抑制作用(P<0.05),而中度污染(3%和5%)对其地上部和地下部生物量有显著促进作用(P<0.05);3)当油污浓度<5%时,非洲菊通过增加土壤脱氢酶、地下部及地上部生物量和土壤微生物多样性来提高土壤TPH降解率,且非度量多维尺度(non-metric multidimensional scaling,NMDS)分析结果显示,植物生物量、土壤酶活性和微生物特性的彼此间共同效应是决定土壤TPH降解率的主要环境因素,而重度污染对非洲菊植物体生物量的抑制作用是导致其土壤TPH降解率显著降低的关键因素。综上所述,5%油污浓度应设为非洲菊耐受力阈值浓度,且在该浓度下非洲菊可确定为具备油污土壤修复潜力的良好植物品种。

In order to verify whether Gerbera jamesonii can biodegrade the crude oil-contaminated pollutants in the east part of the Loess Plateau,we studied the response of plant growth index and rhizosphere soil environmental index under different soil total petroleum hydrocarbons(TPH)concentrations stress.The plant growth index,rhizosphere soil environmental index,as well as removal and degradation rates of soil TPH,alkane and aromatic hydrocarbon under different soil TPH concentrations(1%,3%,5%,and 7%)were investigated by conventional methods.We found that removal rate of soil TPH,alkane,and aromatic hydrocarbon were decreased with the increase in soil TPH concentration and achieved its highest degradation rate in the soil TPH up to 5%(P<0.05).Besides,plant height,root length,and germination rate of the G.jamesonii were similarly decreased with the increase in soil TPH concentration(P<0.05).Moreover,the soil TPH at 7% could significantly inhibit its biomass above the ground,but both biomasses above and under the ground were significantly promoted when the soil TPH was up to 5%(P<0.05).Next,at the soil TPH less than 5%,its removal rate was improved by the increase in soil dehydrogenase activity,biomasses above and under the ground as well as soil microbial diversity.Nonmetric multidimensional scaling(NMDS)analysis showed that combined action of plant biomass,soil enzyme activity,and soil microbial community could be the main factors that determine the soil TPH removal rate.Meanwhile,when the soil TPH was up to 7%,severe inhibition of the plant biomass of G.jamesonii was the key factor leading to the significant reduction of soil TPH removal rate.All the results indicated that soil TPH concentration at 5% should be determined as the threshold tolerance concentration of Gerbera jamesonii,when it is applied to the ecological restoration of crude oil-contaminated soil.In conclusion,we propose that the adaptable plant of eastern Gansu Province of the Loess Plateau,G.jamesonii,is a superior plant variety with the ability for crude oil-contaminated soil restoration when soil TPH concentration is less than 5%.