多年冻土区石油污染土物理性质、石油迁移及修复现状

Physical Properties,Oil Migration and Remediation Status of Oil-Contaminated Soil in Permafrost Regions

随着多年冻土区石油资源的开发,石油污染问题日益严重。本文概述了多年冻土区石油污染土的物理性质和修复技术,以及石油污染物的迁移规律和模型。通过回顾相关研究发现:①在微观结构上,多年冻土区石油污染土平均孔隙度没有变化,但孔径增大,孔隙数量减少,各向异性程度降低。②土壤受到石油污染后,其导热率和冻结温度会显著降低,从而减少了土壤冻结成冰的分凝量和冻胀量。③位于多年冻土上部活动层的石油随冻融循环调控水分而发生迁移,而低渗透率的多年冻土层是有效阻止石油垂直迁移的天然屏障。④现有的石油迁移模型可分为两类:一是非水相流体在多孔介质中的渗流模型,二是非水相流体在多孔介质中的浓度分布模型。多年冻土区石油迁移模型的建立受多种因素的影响,特别是要考虑多年冻土区特殊的气候条件,如低温、淋滤和冻融循环等。⑤多年冻土区石油污染土壤的修复技术包括物理、化学和生物修复。其中,物理修复是应急首选,快速高效但成本较高;化学修复效果明显,但易造成二次污染;生物修复经济环保,但在多年冻土区受到诸多限制,且时效性长。总体而言,由于多年冻土区的石油污染场地的复杂性和多变性,单一的修复技术往往难以解决污染问题,联合使用物理、化学和生物修复方法是未来重要的发展趋势。

With the development of petroleum resources in permafrost regions,the problems of the oil pollution are becoming increasingly serious.Therefore,it is particularly important to study the oil pollution problems in permafrost regions.This article outlines the physical properties and remediation technologies of the oil-contaminated soils in permafrost regions,as well as the rules and models of oil migration in soil.A review of relevant studies found that:(1)In terms of microstructure,the average porosity of the oil-contaminated soil in permafrost regions did not change,but the pore diameter increased,the number of pores decreased,and the degree of anisotropy decreased.(2)After the soil was contaminated by petroleum,its thermal conductivity and freezing temperature were significantly reduced,thereby reducing the amount of ice segregation and freezing expansion when the soil was frozen.(3)The freeze-thaw cycle of the active layer above permafrost affects the migration of oil in the soil by controlling the direction of water migration.The low permeability permafrost is a natural barrier that effectively prevents the vertical migration of oil.(4)Existing petroleum migration models can be divided into two categories:one is the seepage model of non-aqueous phase fluid in porous media,and the other is the concentration distribution model of non-aqueous phase fluid in porous media.The establishment of oil migration model in permafrost regions is affected by many factors,especially considering the special climatic conditions in permafrost regions,such as low temperature,leaching,freezethaw cycles,etc.(5)Remediation technologies of the oil-contaminated soil in permafrost regions include physical chemical and biological remediation.Among them,the physical remediation is the first choice in emergencies,which is fast and efficient,but the cost is high;Chemical remediation has obvious effects,but may cause secondary pollution;Bioremediation is economical and environmentally friendly,but it is subject to many restrictions in permafrost areas and has a long timeliness.Overall,due to the complexity and variability of oil-contaminated sites in permafrost regions,it is often difficult to solve oil pollution problems with a single remediation technology.The combination of the physical chemical and biological remediation methods is the future development trend.