陇东黄土高原油污土壤环境因子对场地生态修复的季节响应

目的]探讨陇东黄土高原地区油污土壤场地修复过程中土壤环境因子对季节变化的响应机制,为油污土壤植物微生物联合生态修复的推广应用提供参考。方法]利用陇东适生植物"金盏菊"联合土著石油降解菌剂开展为期285d的场地原位修复试验,采用常规方法测定不同季节土壤理化特性、酶活性和微生物群落特性等环境指标。结果](1)场地修复过程中土壤TPHs降解率在夏(24.62%±3.96%)秋(29.93%±1.94%)两季明显高于春(3.82%±0.91%)冬(9.24%±0.87%)两季;(2)季节变化和强化处理对油污土壤酶活性和理化特性存在显著交互效应(p0.05)。土壤pH值、含盐率和有机质含量在秋季明显降低(p0.05),而土壤速效养分均在夏秋含量最高(p0.05);(3)春季土壤微生物群落Evenness指数偏低(p0.05),夏季Richness指数明显增加(p0.05),Shannon-Wiener指数在夏秋两季明显高于其他季节(p0.05);(4)NMDS排序结果显示,夏秋两季分异于其他季节主要与土壤微生物群落Richness指数(r2=0.706 3,p=0.002)和速效磷(r2=0.615 7,p=0.005)有关;(5)低温季节影响土壤TPHs降解率的因素主要是土壤理化特性和土壤酶活性的叠加效应(54%),而夏秋两季土壤理化特性、土壤酶活性和土壤微生物特性三者的共同作用可解释土壤TPHs降解率变异的74%。结论]土壤微生物群落Evenness指数和土壤酶活性偏低是造成春冬两季土壤TPHs降解率偏低,而土壤微生物群落ShannonWiener指数、Richness指数、速效磷含量和生物强化处理有效化水平是陇东地区夏秋两季土壤TPHs降解率明显增加的主要环境因素。

Seasonal Responses of Soil Environmental Factors to In-Situ Ecological Remediation of Crude-Oil Contaminated Soil in Eastern Gansu Province of Loess Plateau

Objective] To explore the mechanism of seasonal responses of soil environmental factors to in-situ ecological remediation of crude-oil contaminated soil in Eastern Gansu Province of the loess plateau, in order to provide reference for the popularization and application of ecological restoration of soil plant microorganisms.Methods] A combined remediation experiment using the indigenous crude-oil degradation bacteria agent and the native plant (Calendula officinalis) as materials had been conducted for in-situ ecological remediation of crude-oil contaminated soil for 285 days. The changes and seasonal responses to the in-situ ecological remediation of soil physicochemical property, enzyme activity and microbial-community property were investigated using conventional methods.Results] (1) Soil TPHs degradation rate in summer (24.62%±3.96%) and fall (29.93%±1.94%) were higher than those in spring (3.82%±0.91%) and winter (9.24%±0.87%) during the process of in-situ ecological remediation. (2) There were obvious interactions between remediation treatment and seasonal variation with regard to soil physicochemical property and enzyme activity (p<0.05). Soil pH value, salt content and organic content were lower and soil nutrient were higher in fall in comparison with that of other seasons (p<0.05), respectively. (3) Evenness index of soil microbial community was less in spring (p<0.05), and its richness index was higher in summer (p<0.05), as well as the Shannon-Wiener index was higher in summer and fall (p<0.05). (4) Nonmetric multidimensional scaling analysis suggested that the seasonal difference of soil TPHs degradation rate was strongly affected by the richness index (r²=0.706 3, p=0.002) and soil available phosphous (r²=0.615 7, p=0.005). (5) Variation partitioning analysis revealed that the most important combined environmental factor to determine the degradation rate of soil TPHs in cold season (spring and winter) was the interaction between soil physicochemical properties and enzyme activity (54%). However, 74% of the soil TPHs variation in warm season was explained by soil physicochemical property, enzyme activity and soil microbial community property.Conclusion] The low soil TPHs degradation rates in spring and winter were resulted from the low evenness index of soil microbial community and low soil enzymes activity; while richness index and the Shannon-Wiener index of soil microbial community, soil available P and ecological remediation effectiveness all resulted to the high soil TPHs degradation rate in summer and fall.