某石油泄漏场地土壤二甲苯空间分布的三维插值

为精确界定污染场地中污染物三维空间分布范围,本文以中国某石油储罐泄露污染场地为研究对象,采用最近邻点法、反距离加权法及克里金法3种三维空间插值模型,对场地中特征污染物二甲苯进行三维空间插值计算及污染分布表征,比较不同插值模型的计算精度,揭示场地中实际受污染土方量。结果表明,反距离加权法预测平均误差为4.94,均方根误差为14.11,其精度明显高于另外2种模型,界定的污染分布范围较符合实际污染情况,通过该方法进行插值后计算受污染土方量为666.2 m~3。研究结果对该类型污染场地污染物空间分布表征和修复治理决策制定提供科学依据。     

建立污染土壤修复标准的探讨

随着污染土壤修复技术的发展和污染土壤修复环境工程的实施,污染土壤修复标准的建立已成为检验污染土壤修复工程效果的瓶颈.我国现行的土壤环境质量标准已不能适应污染土壤修复效果评判的需要.本文在分析我国土壤环境质量标准不足的基础上,结合一些发达国家土壤修复标准以及我国土壤污染实际情况,提出建立污染土壤修复标准应从污染物的选择、分析检测方法、修复标准的分类、对地下水的保护和生态毒理学评价方面综合考虑.     

某焦化场地土壤中多环芳烃分布的三维空间插值研究

为准确界定污染场地土壤中多环芳烃在3维条件下的污染分布范围和受污染土方量,选择我国某焦化污染场地苯并(a)芘分布为研究对象,对比研究Krig-3D、IDW-Shepard、IDW-(Franke/Nielson)以及Nearest Neighbor 4种3维插值方法对界定污染范围的不确定性影响。结果表明,不同3维插值模型计算结果差异较大,交叉验证结果显示Krig-3D插值模型插值精度最高,插值结果能较真实地反映场地实际污染情况。通过修复目标对比确定进一步表明,基于4种插值模型计算所得的污染土壤土方量分别为8.51×105、5.62×105、7.12×105、1.09×106m3,选择合理的插值模型将对预测污染范围的不确定性产生重要影响。研究结果对分析污染范围和修复治理过程土方量确定提供重要参考。     

农田表层土壤镉的典型空间插值方法对比研究

空间插值对于土壤重金属空间分布和污染评价具有重要意义, 以广东省广州市某地区农田表层土壤重金属镉的调查监测结果为例, 选取具有代表性的反距离加权、径向基函数、普通克里金、简单克里金、泛克里金5 种空间插值方法, 进行空间插值及土壤等级划分, 比较不同插值方法结果精度, 分析不同插值方法结果差异。研究结果表明: 不同插值方法识别的土壤镉浓度空间分布特征和土壤等级划分存在差异, 主要体现在局部极值向外过渡区域存在较大不确定性, 其中径向基函数精度最高, 克里金插值法对数据存在“压缩”效应较强。因此, 在开展土壤重金属污染调查时应考虑土壤重金属样本数据特征和空间结构特征, 选择合适的插值模型, 并适当加大土壤重金属浓度过渡区域采样密度。     

北方农牧交错典型区土壤重金属空间分布及污染风险评价

随着农牧经济的快速发展, 大量重金属进入土壤, 使土壤结构和功能发生改变、土壤质量下降, 不仅影响农牧业的产量和品质, 最终会危及到人类的健康。选取北方农牧典型交错区扎鲁特旗作为研究区, 采集62个土壤表层(0-20 cm)样品, 测定了铜(Cu)和铅(Pb)两种重金属的含量, 采用简单克里金插值分析了重金属Cu和Pb含量的空间分布特征, 利用污染指数和潜在生态风险指数评价了重金属的污染及生态风险状况, 以及运用反距离权重插值法分析了潜在生态风险的空间分布特征。结果表明: 土壤Cu和Pb平均含量分别为24.28和19.54 mg·kg–1。Cu含量呈现由中心向四周辐射状递减, 其峰值主要分布于中部偏东位置, 低值主要分布于西北部区域; Pb含量呈现由西北向东南地区递增的趋势, 其区域变化较明显, 北部地区含量较少。农田Cu和Pb含量显著高于草地。土壤重金属含量的空间分布与年平均降水量、土壤有机碳、土壤容重有显著的相关性。Cu污染比较严重, Pb为轻度或中度污染, 综合潜在生态风险均在中等及以下, 风险区主要分布在中部。     

重金属污染土壤原位化学固定修复研究进展

重金属污染土壤原位化学固定修复是通过添加不同外源物质固定土壤中重金属元素,达到降低重金属迁移性和生物有效性的一种重要方法.由于操作方便和效果快速,使其在污染土壤治理过程中有着不可代替的作用,尤其对于耕作土壤中的面源污染.许多具有俘获土壤中重金属离子能力的自然物质和工业副产品如磷矿石、泥炭土、石灰和有机肥等都可用在实地的固定修复中.采用实验室评价和实地应用评价,一方面可以评估这些固定物质在土壤中对重金属离子的固定效率;另一方面可以评估重金属的溶出、释放和生物毒性等生态风险.本文对原位修复过程中采用的不同固定物质的来源和分类进行了概述,对化学固定过程的机理进行了探讨,同时阐述了重金属污染土壤化学固定修复应用过程中的实验室评价和实地应用评价方法,分析了化学固定修复的局限性并提出了今后的发展方向.     

某废弃采油井场周边土壤石油污染及微生物分布特征研究

以某废弃采油井井场做为研究对象, 对油井不同方位、距离和深度剖面土壤石油含量和物理化学性质进行测试, 并利用实时定量PCR 技术对场地细菌和真菌生物量展开调查, 以期能够为修复工作提供数据基础。结果显示, 该场地遭受了严重石油污染和盐碱污染。土壤细菌16S rDNA 和真菌ITS rDNA 定量调查结果显示, 细菌和真菌的生物量均高于普通土壤, 尤其石油含量与细菌16S rDNA 基因具有一定的正相关性, 土壤的生态系统的健康和稳定性变弱。通过土壤三氮的测定, 结合石油和微生物量的对比得出, 嗜油微生物大量生长导致了土壤硝化作用的减弱和NH4+的积累、土壤N 素的缺失和土壤健康及稳定性的减弱。因此, 有必要对该污染场地进行治理。基于分析数据, 提出了 一些该污染场地的修复建议。     

插值方法与样点数对县域土壤有效磷空间变异特征评价的影响

与欧美大规模农场经营不同,土地分散经营使我国县域土壤养分空间变异特征评价更加困难.本研究以安徽芜湖土壤有效磷为例,系统地评价插值方法与样点数对县域土壤养分空间变异特征评价准确性的影响.结果表明：局部多项式、普通克里格、简单克里格和析取克里格插值方法的评价效果优于反距离加权法、全局多项式、径向基插值和泛克里格等插值方法,考虑到实际操作简单,推荐用普通克里格方法进行县域土壤有效磷空间变异特征评价.随着参与空间插值样点数的增加,县域土壤有效磷空间变异特征预测的准确性增加,充分考虑评价的准确性和田间取样费用,建议县域土壤有效磷空间变异特征评价的适宜样点数应介于500～1000个.     

工业大麻对重金属污染土壤的治理研究进展

由于工业、农业、废水处理、建筑和采矿等一系列人为活动造成土壤的污染程度日益严重,致使土壤不能用于粮食等作物生产.如何深入治理重金属污染土壤已成为当今研究的热点.由于传统的治理重金属污染技术非常昂贵,并存在二次污染的风险,促使研究者寻求新的治理技术.而植物修复技术以其价廉、清洁、不破坏环境、不会造成二次污染等特性逐步引起了学术界和政府部门的广泛重视.近年来,工业大麻以其优良的修复特性和利用价值已成为修复重金属污染土壤的候选植物之一.在此重点论述了重金属对工业大麻的影响及其在大麻不同部位的分布;工业大麻对重金属的吸收能力以及工业大麻对重金属污染土壤修复的优良特性,最后对工业大麻修复重金属污染土壤技术存在的不足等进行归纳总结,以便为工业大麻对重金属污染治理研究及耐重金属或超富集工业大麻品种的选育和栽培技术研究提供指导.     

修复土地再用生态风险评价方法研究

针对污染土壤的修复技术研究已经取得了很多重要的结果,但是对修复效果的评价研究却相对较少。实际上,在对污染土壤进行物理、化学以及生物修复后,再用前需要根据再用目的对可能残留的污染物或修复剂是否会产生生态安全和人类健康问题进行风险评价。本文着重从修复场地原位观察法、实验室模拟观察法、微宇宙法和现场经验与推导法四方面讨论了如何能够有效、灵敏地诊断污染物对生态系统产生的潜在危害,归纳了生态毒理学实验在评价修复土地再用风险中的作用;并对修复土地再用生态风险评价的发展前景进行了展望,提出了针对性的建议。     

沈阳某冶炼厂废弃厂区的人类健康风险评价

以沈阳某冶炼厂废弃厂区重金属污染监测为依据,采用美国环保局最新的人类健康风险评价标准方法对沈阳某冶炼厂废弃地块污染土壤进行了评价,并且假设未来该土地利用类型为工业用地(Ⅰ)或休闲用地(Ⅱ).评价结果显示:工业用地(Ⅰ)和休闲用地(Ⅱ)的累积非致癌风险指数分别为2.65×10-2和3.67×10-2;工业用地(Ⅰ)和休闲用地(Ⅱ)由呼吸摄入Cd造成的潜在致癌风险指数分别为4.48×10-9和7.30×10-10,不会对在该地区工作和休闲的人们造成身体健康上的伤害;无论是工业用地假设还是休闲用地假设,由无机铜造成的人类健康风险在整个风险中所占的比例最大;由美国环保局的人类健康风险评价方法反推得出的冶炼厂地块未来为工业用地的土壤修复目标值均小于我国工业企业土壤环境质量风险评价基准值.     

Uncertainty-based dynamic multimedia human health risk assessment for polycyclic aromatic hydrocarbons (PAHs) in a land oil exploitation area

With the increasing development of the petrochemical industry and the growing demand for oil, polycyclic aromatic hydrocarbons (PAHs) pollutions in the environment, especially in petroleum exploitation areas, are caused by the discharge of waste from the petroleum extraction process into an environmental system. This study aims to develop a new health risk assessment approach based on interval dynamic multimedia fugacity (IDMF) model and uncertainty analysis that could analyze the human exposure risk level for PAH contamination. The developed IDM health risk assessment (IDMHRA) approach is applied to assess previous, current, and future risks at a case study site in Daqing, Heilongjiang, China, from 1985 to 2020 for model validation. The human health risk assessment results show that 11 PAHs (NAP, ANT, FLA, PYR, BaA, CHR, BbF, BkF, BaP, IPY, and DBA) in the study site require further remediation efforts in terms of their unacceptable non-carcinogenic and carcinogenic risk. The results of risk source analysis reveal that soil media is the main risk pathway as compared with other exposure pathways. It can be seen that remediation process for soil contamination in the study site is urgently demanded. The assessment results demonstrate that the developed IDMHRA approach provides an effective tool for decision-makers and environmental managers to make remediation decisions in contaminated sites.     

Distribution and health risk assessment of heavy metals in soil surrounding a lead and zinc smelting plant in Zanjan,Iran

One of the problematic issues in soil pollution studies is heavy metal particles which are produced by mines and smelting units and spread through wind action and/or runoff. Pollution and health risk assessment of cadmium, lead, zinc, copper, and nickel in soil around the lead and zinc smelting factory was carried out in Zanjan City, Iran. Contamination factor (Cf), pollution load index (PLI), geoaccumulation index (Igeo), hazard quotient (HQ), hazard index (HI), and carcinogenic risk were pollution and human health risk assessment metrics in this study. Based on the Iranian soil guideline value, soil samples in the studied areas were contaminated the least by copper and nickel and the most by cadmium. PLI results showed that soils near the production line were heavily or extremely heavily polluted. The results of Cf and Igeo showed that lead and zinc were the most important contaminants. Health risk assessment indicated that lead and cadmium in soil were the main contaminants, which pose both carcinogenic and non-carcinogenic risks to human health; carcinogenic risk levels were unacceptably high (above 1 × 10^?4). It can be concluded that mining and smelting activities degrade soil quality in this region and the soil pollution might be extended to farming areas.     

Chemical speciation and risks of heavy metals in sediment of urban wetlands in southeastern China

Dredging, remediation, and other management of sediment in polluted urban wetlands require the information of environmental risks associated with heavy metals (HMs). In this study, sediment samples collected from three typical wetlands in the urban area of Wenzhou City, China, were analyzed to evaluate their risks posed by five HMs. Sediments from an industrial area stored higher Cr and Cu but lower Cd and Pb than those from the residential and agricultural areas. The assessment by the pollution load index method indicated that all of the three study wetlands were polluted. An ecological risk index approach identified low risk for wetlands in forested and residential areas but high risk for wetlands in an industrial area as well as in mixed residential and agricultural area, which was also confirmed by the geo-accumulation index (I_geo) method. Furthermore, the ratio of the secondary phase and primary phase and risk assessment code methods recognized that Cd poses a high pollution risk. The results indicated that sediment pollution by HMs in urban wetlands is possibly a widespread problem in China and needs great attention.     

西北内陆盐湖盆地土壤重金属Cr、Hg、As空间分布特征及潜在生态风险评价

选取位于西北内陆的吉兰泰盐湖盆地为研究对象,按照表层(0—10 cm)、50 cm层(50—60 cm)和100 cm层(100—110 cm)分层土壤取样,系统采集了120个样品,测定了重金属Cr、Hg和As,以及主要化学成分的含量,以地统计学插值绘图揭示了吉兰泰盐湖盆地Cr、Hg和As的空间分布特征,以单因子指数法、内梅罗指数法和潜在生态风险指数法评价解析了盐湖盆地Cr、Hg和As的污染及生态风险状况,以统计相关检验和主成分分析法进行了盐湖盆地Cr、Hg和As的源分析。结果表明:1)盐湖盆地土壤中Cr、Hg、As总体具有相似的空间分布特征,Cr在西北部的巴音乌拉山、乌兰布和沙漠地区和西南台地地区的含量较高,Hg仅在西南低山台地地区、以及东北局部区域的含量较高,As在盐湖附近、东南贺兰山、巴音乌拉山西北部和乌兰布和沙漠地区含量较高;2)基于内蒙古土壤质量背景值,土壤污染分布次序为AsHgCr,其中Hg和As中度污染以上累计比重达到为45%,而Cr仅有7.5%的轻微污染;研究区无清洁土壤,仅有尚清洁土壤占2.5%,开始受到污染和中度污染以上土壤比重为50%和42.5%;土壤潜在风险次序为HgAsCr,Hg整体处于很强生态风险水平;轻微生态风险占到40%,由中度、强度到极强在20%以内,很强生态风险程度略超20%,大部地区处于轻微生态风险状况;3)基于国家土壤环境质量二级标准值,土壤中Cr、Hg、As无论是单因子污染、综合污染,还是潜在生态风险指数均未出现超标区域,不存在Cr、Hg、As污染或潜在生态风险,但相对内蒙古整个地区来说,盐湖盆地Cr、Hg、As含量较高;4)研究区土壤中Cr主要来源于土壤母质形成过程中的自然来源,Hg和As主要来源于工业排放、交通污染源等人类活动,均受到人类活动和自然环境变化的综合影响。     

Screening site contamination usina pathway exposure factors

Radian Corporation conducted an investigation of 29 waste sites at an air force base in New Mexico in partial fulfillment of the RCRA operating permit requirements for the facility. The contract required that the investigation be conducted under the Installation Restoration Program (IRP/CERCLA). In an effort to satisfy both RCRA and CERCLA requirements, a hybrid approach was taken for the risk assessment. Site contaminants ranged from petroleum and unconventional fuels to solvents, pesticides, and PCBs. A screening method was developed to classify the level of contamination at each of the 29 sites based on soil and groundwater sampling results. Under this method, sites were classified as “dirty,”; “clean,”; or “borderline.”; Dirty sites did not require a full‐scale risk assessment because some form of remedial action would be necessary. However, clean sites and borderline sites required a full‐scale risk assessment. For clean sites, the risk assessment served as justification for no further action; for borderline sites, the risk assessment determined whether or not remedial action would be required. The screening method used previously developed multipathway and multimedia models for estimating potential human exposure to environmental contaminants in the air, water, and soil through inhalation, ingestion, and dermal contact routes. Pathway exposure factors (PEFs), which combined information on human physiology, behavior patterns, and models of environmental transport, were used to determine the relationship between the concentration of environmental contaminants and human exposure. The PEF converts concentrations in environmental media to lifetime‐equivalent chronic daily intakes (CDI). Three exposure pathways contributing the greatest proportion of the risk were considered for screening these sites: (1) incidental ingestion of soil; (2) dermal contact with soil; and (3) ingestion of water. This project demonstrated that a screening approach could be used effectively to limit the number of full‐scale risk assessments required for a multisite investigation.     

草原矿区土壤环境损害基线评估判定的应用研究——以内蒙古草原矿区为例

草原生态环境损害评估鉴定中,土壤基线是重要的评价标准。如何确定土壤基线,寻找适宜的基线判定方法,进而判定草原土壤的受损害程度,已成为草原生态系统损害评估鉴定、生态系统保护及修复工作中的关键。基于科学、务实、准确的原则,对内蒙古2个草原矿区土壤的总有机质（TOM）、N、P、K含量进行采样分析,采用历史数据法、参考点位法和统计点位法来判定土壤基线。结果表明,胜利矿区土壤养分均值与参考点位法基线值差异较小,采矿对胜利矿区土壤养分含量未见直接的影响。宝日希勒矿区土壤中TOM含量均值明显低于3种方法得出的基线值,N、K均值与参考点位法基线值相似,P均值位于3种基线值之间。可见采矿对宝日希勒矿区土壤中TOM的含量造成了直接影响,对N、P、K含量未见直接的影响。最适宜该地区的方法取决于样本质量和评估尺度,建议以参考点位法为主,历史数据法和统计点位法作为验证工具,3种方法共同使用。     

Development & application of Conceptual Framework Model (CFM) for environmental risk assessment of contaminated lands

Dumping sites are the most common types of contaminated lands as they pollute the environment. Environmental management of contaminated sites cannot be delivered effectively and efficiently without robust holistic & integrated risk assessment. Previous studies reveal the absence of a risk assessment model that holistically integrates all essential factors progressively and categorically. The study aimed to develop a holistic & integrated Conceptual Framework Model (CFM) for environmental risk assessment and to apply developed CFM on real-world existing Mahmood Booti Open Dumping Site (MBODS). CFM developed in this study had three main tiers i.e., baseline study, hazard identification & exposure assessment, and risk estimation. For the application of CFM, baseline data were collected and assessed. Water, leachate & soil samples were collected within 1000 m across the site and analyzed for physio-chemical parameters and heavy metals to estimate risk. Results of applied CFM depicted that Physico-chemical analysis of leachate, water, and soil revealed significant pollution levels. Heavy metal analysis exhibited that Ni, Pb, Mn, and Cr levels exceeded the allowable limits of the “World Health Organization” in leachate, water, and soil samples. It also revealed the existence of metals at the source (dumping site itself), pathway, and receptor of the dumping site. Eⁱ_r value for Ni, Pb and Cd from the study area manifested a serious probable risk to ecological integrities. Results for PERI from dumpsite demonstrated a serious ecological risk. It can be concluded that although Mahmood Booti dumping site has been at post-closure stage, it is a momentous source of hazardous toxic contaminants to the nearby inhabitants. The work presented in this paper may reproduce repeatedly to create site-specific risk assessment models of other contaminated lands in a cost-effective, consistent and cohesive manner. Application of CFM at Mahmood Booti Dumping site described detailed risk assessment which helps further in risk management.     

Applying Mental Models to Qualitative Risk Assessment at the Tar Creek Superfund Site

Re-suspension of heavy metal residuals generated by former mining activities conducted at the Tar Creek Superfund site may result in exposures of nearby residents. Currently, remediation and mitigation activities include removal of yard soil containing high concentrations of heavy metals, removal of selected chat piles, and providing assistance for families with young children. Although these are important activities to reduce potential risks to Tar Creek residents, a qualitative assessment of the site that uses mental models identifies other potential contaminants of concern, transport, and exposure pathways that may require further investigation. Mental models structure judgments about hazards and risk by visually representing a contaminated site through the use of influence diagrams. A mental model was applied to the Mayer Ranch area of the Tar Creek Superfund site in Ottawa County, Oklahoma, to support a qualitative assessment of the health risks from heavy metals exposure. Documents were reviewed to develop influence diagrams illustrating the processes, interactions, and potential exposures that could subject a hypothetical individual recreating at Mayer Ranch to various health risks. The diagrams were modified to reflect expert judgments. The mental model includes four influence diagrams: source term, fate, and transport processes that may influence human health risks due to exposure to heavy metals; natural wetland processes that could remove heavy metals; net alkaline constructed wetland processes that could remove heavy metals; and potential future impacts from the removal of sediment and land development that could increase risk. Policies, regulations, and technologies that could most reduce the probability of exposures can be determined and evaluated by focusing on the environmental transport pathways and contaminants that pose the greatest potential risks and determining the difference between the risks. Also evident are the knowledge gaps with respect to the processes within wetlands.     

Antibiotic resistance in surface water ecosystems: Presence in the aquatic environment,prevention strategies,and risk assessment

Antibiotic-resistant bacteria (ARB) have gained increased notoriety due to their continued detection in environmental media and consequently their threat to human and animal health. The continuing spread of antibiotic resistance throughout the environment is of growing environmental and public health concern, making it difficult to treat harmful resistant diseases. This paper examines the presence of antibiotics, ARB, and antibiotic-resistant genes (ARGs) in aquatic environments; the effectiveness of current water treatment strategies to remove them; and risk assessment methods available that can be used to evaluate the risk from antibiotic resistance. Antibiotics, ARB, and ARGs have been reported at varying levels in wastewater treatment plants, hospital wastewater, irrigation water, recreational water, and drinking water. There are many different water treatments capable of reducing antibiotic resistance (including chlorination, UV, and ozone); however, no one method can fully eliminate it with much variation in the reported effects. Risk assessment models can be used for interpreting field data into the risk to human health from antibiotic resistance. Currently, there is no gold standard risk assessment method for evaluating antibiotic resistance. Methods in this area need further development to reflect evolving risk assessment methodologies and dynamic data as it emerges.