我国污染场地土壤风险评估的局限性与发展

近些年来,为加强对污染场地土壤风险评估工作的贯彻落实力度,相关部门通过健全完善土壤环境监测网络以及构建评估体系标准,推进我国土壤环境生态友好发展。但是从整体上来看,随着我国工业产业化进程的不断推进,国内污染场地数量急剧增多,且污染程度复杂、种类多样,对我国污染场地土壤风险评估工作带来了一定难度。针对于此,本文主要对当前污染场地土壤风险评估局限性以及发展策略进行研究与分析,以供参考。

英美土壤污染生态风险评估技术体系研究及启示

随着经济的发展,人为活动产生的大量有害物质进入土壤,造成了严重的土壤污染问题。生态风险评估是预测风险源对生态系统产生风险的方法体系,其作为污染土壤生态风险管控及修复治理的重要依据,决定着是否需要采取风险管控和修复治理措施及目标。由于研究的侧重角度不同,出现了诸多生态风险评估技术体系。英美两国拥有多年的污染地块管理经验,生态风险评估相关技术导则完善、法规健全且配套技术成熟,借鉴其经验有助于管理者从生态系统角度更加科学地分析土壤污染对环境的影响。通过对我国土壤污染生态风险评估现状的分析,以及对美国超级基金生态风险评估技术体系和英国土壤污染生态风险评估技术体系的讨论,得出我国在构建本土化的土壤污染生态风险评估技术体系时需要注意的关键点:(1)构建层次化的生态风险评估技术体系;(2)开发从污染物暴露到产生生态效应整个过程的污染地块生态风险评估概念模型;(3)加强污染物与生态受体所受影响之间的因果关系分析;(4)提高生态风险评估过程的决策参与;(5)推动本土物种的毒理学研究。该文旨在推动我国土壤污染生态风险评估技术体系的构建,保障评估过程的顺利实施及后续污染土壤风险管控或修复治理工作的开展,促进土壤资源可持续安全利用。

典型工业搬迁地块土壤污染状况调查与风险评估

以北方某工业搬迁地块为研究对象,开展地块土壤污染状况调查和风险评估。采集地块内300件土壤样品和15组地下水样品进行检测,采用单因子污染指数法和内梅罗综合污染指数法进行数据分析评价。结果显示地块内地下水中污染物均未超标,土壤中有机污染物氯仿超标,采用单因子指数评价,重金属Pmax均小于1,未造成土壤污染,有机污染物中氯仿Pmax为11.93,造成土壤重度污染。采用内梅罗综合污染指数评价,地块内所有采样点位P综合max最大值氯仿为8.44,土壤的氯仿属于重度污染,地块内重度污染点位占比3.33%,中度污染点位占比3.33%,轻度污染点位占比1.67%,尙清洁的点位占比3.33%,清洁的点位占比88.33%。采用ArcGIS差值模拟分析,氯仿主要污染区域为生产三车间及其周边区域,污染深度0~5.5m范围。对地块开展进一步的风险评估,结果表明:地块内超标点位的污染物氯仿致癌风险范围为1.79E-06~2.40E-05,均大于1.00E-06,致癌风险不可接受,主要暴露途径是通过吸入室内空气中来自下层土壤的气态污染物影响人体健康。本研究对工业搬迁地块的土壤风险管控,特别是化工类的有机污染地块的管控提供科学指导和技术支撑。

伊河流域栾川-嵩县段土壤重金属污染调查及风险评估

为调查并评价伊河流域(栾川-嵩县段)土壤重金属元素污染状况,分别采用单因子指数法、综合因子指数法、潜在生态风险指数法对伊河流域(栾川-嵩县段)土壤重金属元素污染状况进行了评价。结果表明:除Cr元素外,栾川-嵩县段土壤中其他重金属元素特定pH值条件下,均超出风险筛选值点位;单因子污染指数评价结果表明,Cd元素对区域内土壤环境污染所产生影响最大;综合污染指数评价结果显示,调查区域范围内整体呈“轻度污染”表现;生态风险指数评价结果则表明,区域范围内土壤中As、Cr、Pb元素属“轻微危害”水平,Cd处于“很强危害”水平,Hg则处于“极强危害”水平。为此,提出了总体来看,伊河流域(栾川-嵩县段)土壤重金属元素污染等级处于可控范围,针对部分含量较高且危害程度较严重的金属元素,应及时开展专项治理。

某有机化工污染场地土壤与地下水风险评估

以江苏某有机化工污染场地为例,采用美国RBCA(risk based corrective action)风险评估软件,并依据我国《污染场地风险评估技术导则》(征求意见稿)对模型中的参数进行了本土化设定,开展了典型有机化工类场地土壤与地下水的人体健康与水环境风险评估。结果表明:研究场地土壤污染相对较轻,局部区域存在风险或危害,最大值分别为5.44×10 5和54;地下水污染相对严重,有6个点位存在不同污染物的风险或危害商超标,其中,1,2-二氯乙烷的最大致癌风险高达0.174,氯苯的最大非致癌危害商高达20 586。与保护人体健康的修复目标值相比,保护水环境的值要更为保守。由此,仅基于健康风险的修复仍然可能存在水环境风险,应当予以重视。

污染场地土壤污染调查与风险评估研究

由于城市规模的不断扩大,一些企业尤其是大型的工业化企业,在搬迁之后容易对当地的土壤造成一定的污染。在企业搬迁的过程中,由于某些原材料具有一定的污染性,一旦发生事故将会对当地的土壤造成一定的影响。对于此,需要专业工作人员,对当地的土壤污染环境进行调查,并且对其风险进行评估,才能保证人民群众的居住安全。

我国南方某典型有机化工污染场地土壤与地下水健康风险评估

以某典型有机化工污染场地为例,开展了多层次健康风险评估,推算了土壤与地下水的筛选值和修复目标值,确定了污染修复范围及修复量。结果表明：土壤与地下水均存在不同程度的有机污染,关注污染物氯仿、四氯化碳、苯、氯苯在0~1 m的土壤修复目标值分别为0.03、0.05、0.35、6.51 mg/kg;1~3 m的土壤修复目标值分别为0.07、0.30、0.90、13.49 mg/kg;3~5 m的土壤修复目标值分别0.14、0.46、1.69、20.45 mg/kg;5~9 m的土壤修复目标值分别为0.25、0.79、2.99、36.27 mg/kg,地下水修复目标值分别为0.32、0.51、3.43、21.80 mg/L。土壤中氯仿、四氯化碳、氯苯的超标点位随深度增加而增多,其风险或危害随之增大;地下水污染区域集中,GW6号点位4种污染物均超标,其中氯仿污染最严重,致癌风险高达1.11×10–3,非致癌危害商为9.8。

土壤污染风险分层评估方法在氯代烃深层污染场地中的应用

以某氯代烃污染的纺织工业场地为例,对比分析土壤污染风险分层评估和不分层评估结果。该场地在最大超标深度19m范围内存在杂填土、粉质粘土、砂质粉土、淤泥质粉质黏土、淤泥质黏土、黏土等6类土层,风险评估结果表明:在不分层评估的计算方式下,粘土层中的污染水平仍存在超风险的情况,超风险深度达19m;在对各类土层分层评估的计算方式下,土壤中污染物的风险控制值的计算结果随着土层深度的增加显示出不同程度的升高,粘土层中的污染水平已不超风险,超风险深度降低至16 m,超风险区域的土壤方量也有显著降低。根据土层性质及分布深度的不同,对深层污染场地进行分层风险评估,可更加精准地刻画污染超风险范围,同时可有效降低污染土壤的修复成本和周期。

土壤污染风险评估研究现状综述

当前,我国正面临严峻的土壤污染,全国10%以上的耕地已受重金属污染,因此,对土壤污染风险进行全面评估势在必行。本文分析了土壤污染风险评估的重要性,论述了土壤污染风险评估的主要内容,并提出了土壤污染风险评估的具体应用建议,以期全面改善我国土壤环境,进一步提升土壤污染治理效果,构建人与自然和谐发展的生态格局。

典型石油烃污染场地土壤与地下水环境风险评估

由于石油烃污染场地有显著不同于其它类型污染场地的特征,故以探讨石油烃类污染场地土壤和地下水环境风险评估一般方法为目的,选取某典型石油烃污染场地,对土壤和地下水进行采样分析,得出了该污染场地主要关注污染物为总石油烃。且土壤和地下水中总石油烃均存在超标现象,通过对超标点位进行分析判断原厂石油烃的排放源为生产车间、潜在排放源为罐区,场地污染的主要原因可能是油罐发生泄漏;对土壤和地下水中总石油烃的非致癌危害商与非致癌风险控制值表征,计算结果表明:石油烃污染物已对土壤造成污染,并迁移至地下水,该污染场地可能对居住地人群造成健康风险。

基于SPOT5的密云水库上游土壤侵蚀风险空间格局分析

基于SPOT5-10 m多光谱数据提取研究区的植被覆盖与土地利用/土地覆盖,利用1∶5万DEM数据提取研究区坡度信息,采用中华人民共和国水利部部颁标准评价研究区的水蚀风险等级,并与第二次全国土壤侵蚀遥感（Landsat TM）调查数据进行对比分析。结果表明：（1）从整体上看,区域的侵蚀状况有所好转,侵蚀面积减少了84.10km2,但极强度侵蚀面积增加了6.68 km2,剧烈侵蚀增加了0.03 km2。（2）从空间分布看,大于1 700 m的高程带侵蚀面积最小,500~800 m高程带的侵蚀面积最大;小于5°和大于35°的坡度带侵蚀面积最小,而15°~25°坡度带侵蚀面积最大。研究结果可以作为基础数据,为管理部门进行治理决策依据。

某地块土壤中镍污染现状调查

工业企业搬迁遗留场地变更为居住、商业等用地,其土壤污染物类型、种类繁多,且因地而异。本文对某地块土壤中镍污染现状进行了初步调查检测,检测结果表明该地块土壤受到镍的污染较大,需进行风险评估和土壤修复后,才能用于居住或商业等建设用地。

土壤环境风险评估的法理重述与制度改良

在我国缺失专门性土壤污染防治法律的状况下,《环境保护法》、单行环境法、行政法规和部门规章、地方立法以及技术规范是土壤环境风险评估制度的规范依据。通过对现有法律规范和技术规范的梳理,可以发现我国土壤环境风险评估制度存在一些缺失和不恰当。应当基于对土壤环境风险根源和土壤风险评估制度逻辑的剖析,改良现有的土壤环境风险评估制度。在程序层面应当保障程序正当和广泛的利益相关者参与,同时土壤环境风险评估实体内容也应当延展至生态风险评估。

基于HERA土壤分层风险评估的SVE修复方案优化

以新疆某石油炼化污染场地为研究对象,将场地土壤划分为4层,选取石油烃(C5~C7)为目标污染物,基于HERA (health and environmental risk assessment)软件开展土壤分层风险评估。结果表明:各土壤层的危害风险均超过可接受水平,修复目标值分别为161.20、182.58、316.75、450.24 mg·kg^-1。根据风险评估结果,提出场地土壤气相抽提(soil vapor extraction,SVE)修复方案,抽提井数量为20口,抽提流量为0.36 m3·min^-1,苯的去除量为56.71 kg·d^-1,需要147 d将场地土壤中污染物的浓度降低到修复目标值以下。依据土壤层风险评估结果和土壤污染羽分布不同,优化了SVE抽提井井深和井筛深度设置,相对于寻常SVE修复设计,可降低修复成本,提高修复效率,预防过度修复,形成了一套基于HERA风险评估的SVE修复方案设计体系。

Chemical Criteria to Assess Risk of Phosphorus Leaching from Urban Soils

Soils from urban and suburban areas are normally enriched with phosphorus (P). Sixteen urban soils with a wide range of total P concentrations under typical urban land uses were sampled and analyzed for extractable P concentrations using water, sodium bicarbonate and citric acid. Meanwhile the soils were artificially leached in columns and P concentrations in the leachates were determined. With linear regression a two-stage linear relationship was found to exist between concentrations of P in the leachates …

Soil heavy metal(loid)s and risk assessment in vicinity of a coal mining area from southwest Guizhou, China

Total concentrations of arsenic, lead, cadmium, mercury, nickel, chromium, and copper in the soils from near a coal mine area in southwest Guizhou, China, were measured to evaluate the level of contamination, and the potential ecological risks posed by the heavy metals were quantitatively estimated. Results reveal that all heavy metals/metalloid exceeded the background values for soil environmental quality of heavy metals in Guizhou area. Geo-accumulation index(I_(geo)) showed that arsenic had the highest contamination level(I_(geo)=4) among the seven heavy metals/metalloid, and the contamination levels of mercury and lead were also relatively high(I_(geo)=3). Pearson correlation and cluster analysis identified that mercury, copper and arsenic had a relationship, and their presence might be mainly related to mining activity, coal and oil combustion, and vehicle emissions. Improved Nemerow index indicated that the overall level of heavy metal contamination in the studied area ranged from moderately–heavily contaminated to heavily contaminated level. Potential ecological risk index(R_I) analysis manifested that the whole ecological risk level ranged from high degree to very high degree(325.30≤R_I≤801.02) in the studied soil samples, and the potential ecological risk factors (E_r^i) of heavy metals/metalloid were as follows: Hg > As > Cd > Pb > Cu > Ni > Cr, and the E_r^i of Hg and As reached very high risk grade.

Risk Assessment of Nitrogen Discharge from a Coastal Watershed

Probabilistic risk assessment （PRA） uses probability theory to quantify the probability of occurrence of an event. In this study, PRA was conducted for the discharge of excess nitrogen （N） from an agricultural （Jiulong River） watershed in Southeast China. Using fault tree analysis, a type of PRA, the probability of occurrence of excess N discharge into the river during a runoff event was evaluated both qualitatively and quantitatively. Land use maps, soil maps, fertilizer use records, and expert opinions were used to determine probabilities of individual events within the fault tree and to calculate the overall probability of excess N discharge during a runoff event. Qualitative analysis showed that the risk of excess N discharge was mainly related to crop and livestock practices in the watershed. Proper management of tillage, fertilizer, and manure was necessary to control N releases. Quantitative assessment results indicated that alternative practices including reduction of fertilization, installation of vegetative strip buffer around the pig farms, and installation of more riparian buffers along the Jiulong River could reduce the likelihood of N discharge through runoff.

Assessment of Soil Erosion Risk in Albania

Albania results are a country with high quantitative level of soil erosion in Europe and elsewhere based on different studies. The amount of soil eroded from the surface water erosion is from 20-40 t/ha/year and in extreme cases results up to 100 t/ha/year from the deepest erosion. This preliminary study will identify the more specific places in order to do more details analyses in the future to take protection measures in highly sensitive places with high erosion risk. This will be a quantitative assessment of places with different level of erosion risks. Further on these results will be generalized at the level of main water basins of Albania. The following main elements of soil erosion assessment are evaluated in this study which include the land cover, slope and density of the hydrologic net.

Ecological Risk Assessment of Combined Pollution of Heavy Metals and Pesticides in Urban Soils

Urban soil is the main component of urban ecological systems and the key risk receptor from urbanization. Heavy metal and green pesticide pollutions in urban soils have been widely reported with the expanding of urbanization. Since urban soil pollution comes from various resources, application of integrated thinking and methods is needed in ecological risk assessment of urban soil pollution. This paper synthetically reviewed the combined pollution of heavy metals and pesticide, and ecological risk assessment, and then proposed some research trends and areas in the future that are required to carry out intensively according to the present situation of environmental pollution and international research fronts.

A Fuzzy-based Methodology for an Aggregative Environmental Risk Assessment of Restored Soil

Environmental risks pertaining to contaminated soils have been well studied,while little attention has been paid to the risks of the soils after remediation. In this study,a concept model developed based on fuzzy set theory was applied to evaluate the uncertainties of three risk indicators,namely,plant growth,groundwater safety and human health,of a restored site that had been previously polluted by heavy metals. The concept model classified the grade and importance of risk factors by an 11-level ranking system and was able to yield a comprehensive risk result rather than multi-risk results for complex risk indicators. Modeling results showed that the risks to the three indicators were effectively reduced after the remediation. Moreover,great sensitivity of the risks was found related to the weight distribution among the three risk indicators. In general,the risks of both polluted and restored soils to the environment were in the order of groundwater safety > plant growth > human health. The model was proved to solve the problems of multi-risk results due to complex risk indicators that previously encountered by other researchers,which made it helpful in decision-making and management of restored soils.