石油污染对土壤-植物系统的生态效应

伴随着石油的工业化生产和利用,石油污染已经成为一个严重的环境问题.本文从土壤、植物个体、植物群落与生态系统等层次对石油污染的生态效应进行了系统总结.含有多环芳烃(Polycyclic aromatic hydrocarbons,PAHs)、苯系物(Benzene、toluene、ethylbenzene和xylene,BTEX)等多种有毒物质的石油及其化工产品进入土壤-植物系统后会发生迁移.这不仅对土壤-植物系统的组成、结构、功能和服务产生影响,也会通过食物链危害人类健康.石油污染影响土壤水分状况、孔隙度等物理性质,土壤碳含量、养分含量等化学性质,以及土壤微生物群落组成和多样性、土壤酶活性等生物学性质.通常,石油污染会对大多数植物形成氧化胁迫,影响细胞膜透性,影响光合作用等生理活动,抑制植物生长,影响植物萌发、开花和结实.由于石油污染对植物个体的不同效应以及植物个体对石油污染的不同响应,石油污染对植物群落的影响存在3种基本模式,并最终导致植物群落生物量下降,物种多样性降低,植被盖度降低.进一步影响生态系统的生产力、稳定性和健康,最终危及生态系统的功能和服务.利用微生物、植物及其联合体菌根可以对石油污染物进行生物修复和降解,添加外源营养物质和通气等措施可以强化生物修复过程.应用植被指数和红边效应等遥感方法进行石油污染的生态效应监测具有较大的潜力.总之,如何把土壤-植物系统各水平上不同指标对石油污染物的响应与石油污染的生态效应联系起来,是目前石油污染生态效应研究的重点和难点之一.因此,亟需开展多尺度的系统研究,把室内控制实验、野外控制实验和野外调查有机地结合起来,构建多层次的石油污染标志物体系,全面认识石油污染对土壤-植物系统的生态效应,为石油污染的生态风险评价、治理和控制提供理论基础和实践指导.

Ecological Effects of Oil Pollution on Soil-Plant System

With industrial production and application of oil,oil pollution has become a worldwide and serious environmental problem.Ecological effects of oil pollution on soil,plant individuals,plant community and ecosystem are summed up systematically in this paper.There are many toxicants such as BTEX(benzene,toluene,ethylbenzene,and xylene) and PAHs(polycyclic aromatic hydrocarbons) in oils and petrochemicals.These oil pollutants transfer into the soil-plant system and affect the quality of underground water.Thus,oil pollution affects not only soil-plant system(including its composition,structure,function and service),but also human health through food chain.Oil pollution affects soil water condition,porosity and other physical properties;as well as soil carbon,nutrient and other chemical properties.It influences the composition and diversity of soil microbial community,soil enzymes and other biological properties.In most cases,oils pose oxidative stress to plants.Cell membranes are damaged by penetration of hydrocarbon molecules,leading to the leakage of cell contents.Oils usually reduce photosynthesis rates by destroying chloroplast membranes.Oil pollution often inhibits plant germination,growth,flowering and fruiting.However,low dose of oils may promote the growth of some plants.The effects of oil pollution on plant individuals can be classified into four categories: Promoting,no effect,sublethal and lethal.Correspondingly,plant responds in three ways(adaptation,tolerance and death).Thus,there are three basic patterns in which oil pollution affects plant community and finally reduces its biomass,species diversity and vegetation cover.The combination of the changes of plant community and the alternation of soil environment reduces the productivity,stability and health of ecosystem.Finally,functions and services of ecosystem are decreased by oil pollution.Oil pollutants can be biologically remediated and degraded by microorganisms,plants and mycorrhizae.These biological processes can be enhanced by nutrient addition and aeration.Vegetation indices,red edge effect and other remote sensing technologies are potential methods to monitor ecological effects of oil pollution.Overall,indices of different hierarchical levels in the soil-plant system respond to oil pollutants acutely or chronically.Linking these responses with ecological effects of oil pollution is one of the important and difficult issues in future researches.Therefore,multi-scaled and systematic researches should be carried out,and these researches should integrate indoor controlled experiments,outdoor controlled experiments and field investigations.With these researches,the system of hierarchical indices for ecological effects of oil pollution should be established to quantify the relationships between oil pollutants and indices of ecological effects.Then the ecological effects of oil pollution could be mechanically interpreted with simulations of some models,and the effects of oil pollution on soil-plant system could be comprehensively understood.These efforts will provide theoretical foundation and practical guidelines for ecological risk assessment,remediation and control of oil pollution.