Behaviour and assessment of bioavailability of organic contaminants in soil: relevance for risk assessment and remediation

Abstract. Soils contaminated with organic chemicals are now widespread in industrialized and developing countries, and the risk assessment and remediation of such contaminated sites is a priority. However, containment and remediation strategies are complicated in many cases by the range of contaminants present and the historical nature of the contamination. Research has increased our understanding of the behaviour of organic contaminants in soil and the factors that control their behaviour. There is a fundamental need to understand and, where possible, quantify the bioavailable fraction as well as the total concentration of contaminant present in soil: the bioavailable fraction is key to toxicity or biodegradation. To quantify these fractions, a large number of techniques have been employed, ranging from organic and aqueous based solvent extractions to the use of biota. Many studies have been carried out investigating the use of chemical techniques to describe bioavailability, which could be used in the assessment and remediation of contaminated land. The aim of this review is to consider the behaviour of organic contaminants in soil, highlighting issues of bioavailability, and then to discuss the relevance of the various methods for assessing risk and potential remediation of organic contaminants in soil.     

基于AHP筛选的有机污染土联合修复技术案例研究

为了研究联合修复技术在有机物污染场地中的筛选方法以及修复效果，以山西某搬迁遗留场地土壤修复工程为案例，本文提出了采用层次分析法（AHP）对常用的物理、化学、生物修复技术方法进行优选，最终确定“常温解吸+异位热脱附+填埋场覆土利用+水泥窑协同处置”的新联合修复模式，并且研究了该联合修复模式的处理效果及其对环境造成的影响。结果表明，AHP可用于有机污染场地修复最佳方案的筛选；采用该联合修复模式费用低、效果良好且未对周围环境造成影响。可见该联合修复模式能够有效地处理此类型场地污染土体。该修复模式的成功实施为类似污染场地土壤修复项目提供了借鉴和参考价值，并在一定程度上控制了土壤资源的流失。     

Application of a Balanced Scorecard System for Supporting Decision-Making in Contaminated Sites Remediation

This work introduces the development and application of a multi-goal evaluation procedure for assessing sets of remedial options that have previously been found technically suitable for managing a certain contaminated site. The construction of this decision support tool, in the form of a balanced scorecard, has followed a multi-attribute conception of the contaminated sites problem, identifying the most critical aspects considered by all stakeholders involved in contaminated sites management decisions. The developed tool has been checked in its formulation and application against an export benchmark of an Austrian remediation project. The performed evaluation allowed to identify and suggest a remedial option that best fitted the expectations of all stakeholders involved in the project. Furthermore, through the accomplishment of a sensitivity analysis it has been demonstrated that the system is stable and robust in terms of the chosen elicitation schemes, and that the preferences of the different stakeholders are influencing factors on the final result. The results and conclusions of this work present the benefits of implementing the developed balanced scorecard as a tool for supporting decision making in contaminated sites remediation projects.     

基于Web of Science数据库的污染场地可持续修复领域的文献计量分析

实现碳达峰、碳中和目标是我国经济社会深刻的系统性变革,“双碳”目标的提出将对我国土壤污染修复领域产生重要影响,并促进研发更多符合绿色可持续修复的新技术和新产品。为了解污染场地可持续修复领域的研究进展和发展动态,采用CiteSpace和VOSviewer科学图谱绘制软件对Web of Science数据库核心集中2000 ~ 2020年污染场地可持续修复领域的相关文献进行了计量分析,通过合作、共现和共被引等网络分析,探索该领域的研究热点和前沿趋势。结果表明:1）近年来世界范围内该领域发文数量总体呈增长趋势;2）该领域发文量前三的国家是美国、英国和中国;3）该领域的主要发文机构有清华大学、剑桥大学和中国科学院;4）Hou、Norrman和Rosen是该领域发文数量较多的研究人员;5）载文量较多的期刊有Science of the Total Environment、Journal of Environmental Management和Journal of Cleaner Production;6）目前污染场地多采用异位修复的方式修复,原位修复技术及各类耦合修复技术的研究将会增多;7）对土壤修复的可持续研究逐渐增多,地下水修复的可持续研究较少。制定科学合理的具有中国特色的污染场地可持续修复方法势在必行;降低污染修复全过程的环境影响和二次污染是响应碳减排号召的重要过程,环境友好型材料研发、绿色可持续修复技术的实施是污染场地可持续修复领域的重要措施。     

重金属污染土壤的螯合剂诱导植物修复研究进展

植物修复作为一种生态友好型原位绿色修复技术成为重金属污染土壤修复研究的热点。然而,目前最具有推广价值的超积累植物因生物量低、生长缓慢、对重金属的积累具有专一性等缺点,大大限制了植物修复技术在重金属污染尤其是复合重金属污染土壤治理方面的推广应用。利用生长速度快、生物量大的普通植物借助其它技术辅助的联合植物修复便成了有效可行的替代途径和研究焦点。近年来,金属螯合剂诱导的化学-植物联合修复技术备受关注。本文综述了螯合剂诱导植物修复技术的研究进展、修复机理和目前存在的问题,并对该项技术的未来研究方向给予了展望。     

基于绿色可持续理念的污染场地修复碳足迹研究进展

污染场地修复工程，以其短期、在较小空间尺度内产生高强度的能源消耗和碳排放而受到广泛关注。在全球环境变化及“双碳”政策背景下，污染场地的绿色可持续修复成为必然趋势。降低污染场地修复工程的碳排放水平，可以为减缓气候变化、实现修复行业的绿色发展提供重要支撑。然而，目前我国污染场地修复行业仍存在碳足迹评估技术研究不充分、绿色可持续修复理念贯彻不深入等问题。本文梳理了污染场地绿色可持续修复的发展历程和存在问题，以修复行为的碳足迹核算为着力点，综述了基于绿色可持续修复理念的碳足迹核算研究进展与案例分析，从场地、区域和宏观的不同尺度层面探究了污染场地修复评估方法体系中碳核算相关工作。在气候变化的全球背景下和“双碳”政策的国家背景下，污染场地碳足迹核算将为我国修复行业实现减污降碳、推进绿色低碳管理提供参考。     

土壤修复技术的可持续性评价——以原位稳定/固化技术和异位填埋技术为例

土壤修复技术的可持续性是评价土壤修复工程的可持续性和选择土壤修复技术的重要依据.本研究以上海某重大工程的污染场地土壤修复为例,运用多标准分析法(MCA),从人体健康、社会、能源消耗以及环境保护等角度,对两种典型的修复技术(原位稳定/固化,异地填埋)的可持续性进行综合分析和评价.结果表明,稳定/固化技术是一种较为经济且环境污染少的可持续的修复方法;填埋技术不仅经济成本较高,而且温室气体排放种类多,对社会的可持续发展较为不利.     

Biodegradation combined with ozone for the remediation of contaminated soils

The effectiveness of the SS-SBR (Soil Slurry – Sequencing Batch Reactor) process for the remediation of soils contaminated by several organic pollutants has been evaluated. Experimental tests have been performed on two different soils, a spiked one and an industrial aged soil. The spiked soil, artificially contaminated, has been prepared trying to simulate the pollution of an industrial aged soil in terms of number and kind of contaminants. PAHs (Polycyclic Aromatic Hydrocarbons) and phenols degradation has been particularly investigated because they are considered persistent and recalcitrant. Concerning the spiked soil, removal efficiencies higher than 95% in 6 to 9 weeks have been found for all the pollutants, except for five-rings PAHs; however, these compounds were partly removed in 11 to 13 weeks. Good results have been achieved also for the industrial aged soil with a maximum removal of about 80% in 7–8 weeks. To enhance the pollutants degradation, trying to obtain a faster remediation, the biological treatment has been combined with a chemical oxidation with ozone. The best degradation effectiveness of the combined process has been obtained applying the ozonation after few days of the biological treatment. Therefore, a combined biological and chemical treatment allowed to markedly improve the remediation of contaminated soils.     

An Expert Support Model for In Situ Soil Remediation

This article presents an expert support model for in situ soil remediation. It combines knowledge andexperiences obtained from previous in situ soilremediations. The aim of this model is to optimiseknowledge transfer among the various parties involvedin contaminated site management. Structured KnowledgeEngineering (SKE) has been used as a framework formodel development. This approach requires scrutinisingall relevant data to answer questions related to anin situ soil remediation operation. Moreover, itclarifies the roles of the different involved parties.The approach was applied to a chlorinated hydrocarbonpollution at a dry cleaner's. Use of the expertsupport model resulted in the development andselection of a new remediation technique.     

过一硫酸盐的化学氧化机理及在有机污染土壤修复中应用研究进展

基于过一硫酸盐(PMS)的高级氧化技术因反应快速高效、降解有机污染物效果优越,在环境修复领域拥有广阔的应用潜能。经过活化的PMS化学氧化技术在有机污染废水处理中被广泛应用,污染物的去除机制也在不断被发现并完善,其在有机污染土壤修复中也已得到应用。本文综述了PMS对有机污染物的化学氧化机制,分析了有机污染物降解的自由基和非自由基反应过程,探讨了不同活化方式(碱、过渡金属、碳基材料、辐射等)对PMS降解有机污染物的影响,阐述了PMS在有机污染土壤修复中的研究进展和存在问题,并进行了研究展望。     

生物质炭修复重金属及有机物污染土壤的研究进展

生物质炭是生物质原料在完全或部分缺氧条件下高温热解后的固体产物,它具有丰富的孔隙结构和较高的碳含量。该物质具有巨大的表面积和较强的阳离子交换能力等特殊性质,对受污染土壤中的重金属和有机物都具有很强的吸附能力,有效地降低这些污染物的生物有效性和在环境中的迁移,对改善土壤环境具有重大意义。近年来我国土壤污染严重,利用生物质炭修复受污染土壤的技术得到了广泛的关注。本文简述了生物质炭修复土壤污染的基本原理,探讨了与其他修复方法相比存在的优势,阐述了国内外近年来利用生物质炭修复污染土壤的研究进展,最后展望了今后需要进一步研究的领域。     

有机氯农药污染场地地下水抽水试验

伴随城市化进程和产业结构调整,我国出现许多污染场地亟待修复。通过某典型有机氯农药污染场地抽水试验论证抽出-处理修复方案应用于该污染场地地下水修复的可行性及获取抽出-处理工程设计所需要的参数,同时监测了特征污染物的浓度变化特征。该污染场地的地下水渗透系数为8.03 m·d-1,抽水井影响半径为117.1 m,长期抽水试验获得的单口井抽水量不低于170 m3·d-1,回灌速度达到7 m3·h-1。结果表明：该污染场地实施抽水是可行的,地下水量满足后续抽出-处理修复工程,可通过自来水回灌减缓修复过程抽水量下降趋势,但此过程也影响地下水的流动方向。同时,抽水过程可抽出大量的污染物,越靠近污染区域,抽提污染物的效果越明显;随着抽水的进行,污染物的浓度总体显现降低的趋势。此外,自来水回灌可稀释地下水中的污染物。     

Multi-criteria assessment tool for sustainability appraisal of remediation alternatives for a contaminated site

Purpose

In order to improve and support decision-making for the selection of remedial techniques for contaminated sites, a multi-criteria assessment (MCA) method has been developed. The MCA framework is structured in a decision process actively involving stakeholders, and compares the sustainability of remediation alternatives by integrating environmental, societal, and economic criteria in the assessment.

Materials and methods

The MCA includes five main decision criteria: remedial effect, remediation cost, remediation time, environmental impacts, and societal impacts. The main criteria are divided into a number of sub-criteria. The environmental impacts consider secondary impacts to the environment caused by remedial activities and are assessed by life-cycle assessment (LCA). The societal impacts mainly consider local impacts and are assessed in a more qualitative manner on a scale from 1 to 5. The performance on each main criterion is normalized to a score between 0 and 1, with 1 being the worst score. An overall score is obtained by calculating a weighted sum with criteria weights determined by stakeholders. The MCA method was applied to assess remediation alternatives for the Groyne 42 site, one of the largest contaminated sites in Denmark.

Results and discussion

The compared remediation alternatives for the site were: (1) excavation of the site followed by soil treatment; (2) in situ alkaline hydrolysis; (3) in situ thermal remediation; and (4) continued encapsulation of the site by sheet piling. Criteria weights were derived by a stakeholder panel. The stakeholders gave the highest weighting to the remedial effect of the methods and to the societal impacts. For the Groyne 42 case study, the excavation option obtained the lowest overall score in the MCA, and was therefore found to be the most sustainable option. This was especially due to the fact that this option obtained a high score in the main categories Effect and Social impacts, which were weighted highest by the stakeholders.

Conclusions

The developed MCA method is structured with five main criteria. Effect and time are included in addition to the three pillars of sustainability (environment, society, and economy). The remedial effect of remediation is therefore assessed and weighted separately from the main criteria environment. This structure makes interpretation of criteria scores more transparent and emphasizes the importance of effect and time as decision parameters. This also facilitated an easier weighting procedure for the stakeholders in the case study, who expressed a wish to weigh the remedial effect independently from the secondary environmental impacts.

     

Model experimental study on the migration behavior of heavy metals in electrokinetic remediation process for contaminated soil

Recently in Japan, like in other industrialized countries, treatment of contaminated soil or ground has become an important issue in redeveloping such areas as old factories, mining sites, and other polluted sites. In these cases, measures such as a construction of cut-off walls and disposal to controlled waste disposal sites have been so far taken. But, the treatment of contaminated soils has become more difficult nowadays. Therefore, remediation of contaminated soil by removal or extraction of contaminants is necessary and various methods have been developed and applied in many countries. Authors have tried to develop an electrokinetic remediation method for soil contaminated with heavy metals and some basic and pilot scale experiments have been carried out. In this paper, the results of a model experiment using an artificial soil contaminated with Cu or Ph or Cr are presented as follows. i) In the electrokinetic process, migration of water to the cathode by electroosmosis, migration of ions to the cathode or anode by electrophoresis and electrolysis of water occur spontaneously. ii) Upon DC loading, Cu and Pb migrate to the cathode and accumulate as oxides or hydroxides near the cathode but are not removed from contaminated soil. However, in the case of Cr contaminated soil, Cr in the form of Cr(VI) migrates to the anode and is removed from soil through the drainage water. iii) After DC loading for 2 weeks, the concentration of exchangeable cations and composition of soil changed drastically while the CEC and clay mineralogy did not change appreciably.     

An Empirical Model for Estimating Remediation Costs at Contaminated Sites

A model for estimating the remediation costs at contaminated sites is developed, in which the predictor variable is a composite of surface, subsurface, and contaminant risk factors. Calibration of the model is performed at 83 sites in an urbanized watershed with diverse surface geology in southeastern Michigan. These test sites exhibited different extents of contamination, including some where only soil was contaminated, and others where soil and groundwater were contaminated. The model was then applied to 79 sites with multiple contamination extents within different watersheds in North America, Europe, Australia, and Africa. The results indicate a very high correlation between the estimated and actual remediation costs at these sites. This model thus has the potential for providing reliable estimates of remediation costs across a broad array of soil and groundwater contamination scenarios, including dense nonaqueous phase liquid (DNAPL) contamination in sandy soil and lead in clay soil.     

客土改良技术及其在砷污染土壤修复中的应用展望

砷是一种毒性很强且对人体健康威胁很大的金属元素,土壤砷污染与修复长期以来受到各国政府和科学家的广泛关注。客土改良技术是污染土壤修复中较常用和有效的方法之一,近年来逐渐受到关注。本文在简述土壤中砷来源及其危害的基础上,重点对近年来该技术在土壤改良及污染土壤修复中的应用进行了系统整理,并以此为基础,比较了砷污染土壤的物理、化学及生物修复的效果。结合我国部分地区耕地砷污染较严重的现状,认为客土改良技术见效快、改良较彻底、且具有较高的实用性。同时,论文还对客土技术在砷污染土壤修复中的研究重点及应用前景等进行了展望。     

重金属污染农田土壤化学钝化修复的稳定性研究进展

化学钝化修复是一种应用广泛的重金属污染农田土壤修复方法,但钝化修复只是暂时降低了土壤中重金属的移动性和生物有效性,随着时间的推移被固定的重金属有可能重新释放到土壤中,因此钝化修复重金属污染土壤的稳定性是重金属污染土壤原位钝化修复成功的关键。本文探讨了钝化修复剂的种类、修复机制、修复稳定性的影响因素以及修复稳定性的研究方法,深入分析了钝化修复稳定性的研究现状和存在问题,并提出今后应加强钝化修复稳定性机制和修复稳定性预测模型的研究,建立和完善科学的钝化修复稳定性的研究方法。     

固定/稳定化土壤修复技术的应用与优化分析

固定/稳定化技术是污染土壤修复的常用方法之一,具有费用低、无毒、综合效益好等优点,非常适合我国典型土壤污染区的修复。本文介绍了固定/稳定化方法的作用原理与修复材料,分析了此技术的适用范围及优缺点。文章归纳了近年来固定/稳定化技术在污染土壤修复中的应用成功案例,并结合我国土壤污染的实际状况和修复需求,从加强工程技术与装备研发、优化费用结构和发展环境友好型固定/稳定化技术等角度,提出了固定/稳定化技术应用的优化建议。     

工业污染场地修复技术的筛选——以福建省泉州市某工业污染场地为例

[目的]探究最适合的工业污染场地修复技术,为类似污染场地修复技术的筛选及工程应用提供参考。[方法]以福建省泉州市某工业污染场地为例,结合场地的规划及位置特点总结出修复技术筛选矩阵,采用层次分析法和逼近理想解排序法构建了污染场地修复技术筛选的指标体系进行筛选。[结果]该方法筛选结果与研究场地的实际筛选结果相符。结合场地的规划及所处位置特点场地特点构建的筛选矩阵更能反映出场地的实际需求,同时层次分析法(AHP)和逼近理想解排序法(TOPSIS)结合运用于修复技术筛选,既可以克服层次分析法在不易定量化指标上的主观性,又可以避免逼近理想解排序法对评价指标权重的忽视。[结论]采用层次分析法和逼近理想解排序法可有效筛选最优的污染场地修复技术。