污染土壤修复基准建立的方法体系、案例研究与评价

为了今后我国在国家层面上建立污染土壤修复基准系统，促进我国国家生态安全体系的建立，本研究对国外发达国家建立污染土壤修复基准的情况进行了系统详细的文献检索。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多方面综合考虑。并且以铅和乙草胺两种在我国东北地区普遍存在的污染物作为研究对象，首次开展区域水平上建立污染土壤修复基准方法和修复效果评判的尝试性研究。 通过农作物（小麦、大豆和白菜）发芽毒理实验，以食品卫生标准为反推基础的农作物毒物吸收实验，土壤动物毒理实验，生化水平毒理实验，土壤化学毒理实验和土壤酶学水平效应实验得出对土壤中主要组分和功能不产生影响，棕壤中乙草胺和铅浓度阈值。其基准不是所谓的不产生不良或有害影响的最大单一浓度或单一的无作用剂量，而是一个基于不同保护对象的多目标函数或一个范围值，所以对于不同的修复要求和保护对象确定乙草胺的修复阈值为0.4～12mg·kg-1，铅的修复阈值为3.98～793 mg·kg-1。 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（US EPA）最新的人类健康风险评价标准方法对冶炼厂废弃地块污染土壤进行评价的结果显示：冶炼厂厂区内土壤污染非常严重；无论是工业用地假设还是休闲用地假设，由无机Cu 造成的人类健康风险在整个风险中所占的比例最大；单纯依靠US EPA 的健康风险评价并不能正确指示出土壤的潜在风险。运用土壤酶、暴露在土壤环境中的陆生植物以及与土壤环境直接接触的无脊椎动物等可靠的生态毒理指标，来判定、评价污染土壤的修复效果是可行的。

重金属污染土壤的自养菌和异养菌淋滤修复研究

本文以冶炼厂和张士灌区土壤为修复对象，以镉、铅、锌、铜为目标污染物，在室内模拟实验条件下，利用自养菌-嗜酸性氧化亚铁硫杆菌和异养菌-黑曲霉淋滤技术修复重金属污染土壤。在考察自养菌和异养菌对重金属污染土壤修复效果的基础上，重点研究了溶解性有机质和耐酸性异养菌对淋滤修复的影响和机制，同时筛选确定替代蔗糖黑曲霉发酵产酸的廉价碳源。结果发现： 自养菌-氧化亚铁硫杆菌淋滤修复过程中，筛选鉴定嗜酸性氧化亚铁硫杆菌R2对甲酸、乙酸、丙酸、草酸、苹果酸和柠檬酸的耐受浓度分别为0.1、0.4、0.4、2.0、20和40 mmol/L，而高效液相色谱测定沈阳冶炼厂土壤和张士灌区土壤中低分子量有机酸浓度很低，其中草酸含量最高，分别仅为0.04mmol/L和0.149mmol/L，远低于氧化亚铁硫杆菌能耐受的有机酸浓度。同时土壤中溶解性有机质对氧化亚铁硫杆菌R2氧化Fe2+未产生抑制作用，而耐酸性异养微生物H1（红酵母菌）和H2（头孢霉）的加入对氧化亚铁硫杆菌R2淋滤去除重金属效果未产生明显促进作用，本研究中分离筛选的嗜酸性氧化亚铁硫杆菌R2可直接应用于污染土壤的生物淋滤修复。经过5d的生物淋滤，冶炼厂土壤中Cu、Zn和Cd的最高去除率分别为30.6%、58.4%和72%。 在一步黑曲霉生物淋滤过程中，当固液比5%（w/v）、接种量3%（v/v）和淋滤修复7d时，对冶炼厂土壤来说，Cu、Cd、Pb和Zn去除率分别为75.8%，100%，30.6%和26.1%；张士灌区土壤中分别为54%，71.8%，9.5%，18.7%。在二步黑曲霉生物淋滤过程中，当固液比10%（w/v）、接种量为2%（v/v）和黑曲霉发酵时间7d，淋滤2d时，冶炼厂土壤中四种重金属去除率分别为Cu 84%，Cd 75.5%，Pb30.5%和Zn10%；张士灌区土壤中Cu、Cd、Pb和Zn的去除率分别达到57%，94.8%，20.4%和17.5%。 异养菌-黑曲霉淋滤修复重金属污染土壤效果优于有机酸淋滤。与黑曲霉淋滤相比，在直接添加有机酸淋滤修复中，冶炼厂土壤中重金属去除率分别为Cu 46.4%，Cd 61.8%，Pb 30.2%和Zn 43.3%，张士灌区土壤中重金属去除率分别为Cu 44%，Cd 0%，Pb 0%和Zn 26.2%。 淋滤前后土壤中重金属形态分级结果表明，黑曲霉一步和二步淋滤修复能有效去除污染土壤中交换态、碳酸盐结合态部分重金属，并能显著降低氧化物结合态部分重金属，但对有机态和残余态部分重金属离子去除效果并不明显。 以树木落叶和农作物副产品作为廉价碳源实施黑曲霉淋滤实验表明：杨树叶、桃树叶、土豆皮和玉米芯产酸和去除重金属效果较好。杨树叶对冶炼厂土壤中重金属去除率分别为63.5% Cu、100% Cd、16.8% Pb和Zn 27%；桃树叶去除效果分别为Cu61.8%、Cd100%、14.6%Pb和28.5%Zn；土豆皮去除效果分别为61%Cu、100%Cd、10.6%Pb和34%Zn。这些廉价碳源的利用可降低污染土壤生物淋滤修复成本。 研究生物淋滤修复技术为重金属污染土壤处理与处置开辟了新途径。

辽河油田采油井场污染土壤线虫群落特征研究

通过对辽河油田新老两个年限井场的污染状况开展调查研究，对比不同开采年限井场土壤石油总烃、重金属污染状况及线虫群落分布特征，为油田污染土壤评价和治理提供科学依据。研究结果表明，油田井场污染土壤的石油烃和重金属均高于对照，老井场的污染程度重于新井场。井场污染土壤石油总烃含量（TPHs）均随土层深度增加而降低，而重金属含量总体随土层深度增加而增加。与夏季相比，土壤有效态重金属含量有降低的趋势。 对照的苇田土壤线虫优势类群为植物寄生线虫，而井场污染土壤则为食细菌线虫，且其相对多度随污染程度加重而增加。井场污染土壤线虫属的数目显著减少，且随污染程度加重而减少。苇田土壤优势属为Helicotylenchus，井场污染土壤为Cuticularia。在重污染老井场土壤中发现Seinura线虫，且数量明显多于新井场，可能说明Seinura受长期污染而驯化。 井场土壤污染一定程度上促进了cp1线虫数量及相对多度增加，而对cp2、cp3-5线虫有明显抑制作用（尤其cp3-5线虫）。 井场和对照土壤线虫数量总体上均表现为随土层深度加深而减少的趋势，表层土壤夏季高于秋季，下层则表现出秋季高于夏季的趋势。 井场土壤污染导致线虫群落在属水平上的生物多样性以及丰富度和均匀度降低，且随污染程度加重而降低；优势度指数则表现为随污染程度加重而升高的趋势。两井场污染土壤线虫群落均受到高度干扰，趋于富集化，线虫种类趋于单一，稳定性下降。

稠油污染土壤高级氧化-生物耦合修复研究

稠油中的胶质和沥青质是导致稠油污染土壤难以彻底降解的关键要素，而目前传统的生物修复方法很难满足其处理要求。针对这一难题，本文研究了高级氧化-生物耦合修复方法处理稠油污染土壤，达到了使稠油中胶质和沥青质高效去除的目的。 本文采用蛭石模拟土壤，研究稠油污染土壤的高级氧化（臭氧、芬顿）-生物耦合处理方法。分析了氧化时间、水土比、污染土壤陈化时间和污染浓度对臭氧氧化效率的影响，以及H2O2加入量和H2O2/Fe2+摩尔比对芬顿预处理效率的影响；同时优化了高级氧化与微生物混合菌之间的耦合条件；并根据稠油成分的变化，探讨了稠油降解机制。 实验结果表明，模拟稠油污染土壤的最佳臭氧-生物耦合条件为：臭氧氧化30min，生物段采用混合菌1降解14d，此时，土壤中总石油烃、饱和烃、芳烃、胶质和沥青质的降解率分别为60.78%、65.59%、82.74%、26.61％；芬顿-生物耦合处理的最佳条件为：H2O2 加入量为27ml，H2O2与Fe2+的摩尔比为10：1，此时，模拟土壤中稠油总石油烃、饱和烃、芳烃、胶质和沥青质的降解率分别为35.41%，9.33%，49.82%，45.19%。 高级氧化预处理不仅能够减小生物段负荷，而且能够提高胶质和沥青质的生物可利用性，微生物可将胶质和沥青质降解为饱和烃、芳烃或其他物质，降解效率取决于预处理的程度。高级氧化-生物耦合处理降解效率高于单独采用氧化预处理、生物处理效率，因而高级氧化-生物耦合修复方法是一种可行的稠油污染土壤修复方法。

多氯联苯污染土壤的生态修复研究

本研究针对我国土壤PCBs的污染特点，初步探讨了含有PCBs的变压器油分析与测定，两种典型的机合修复过程和PCBs代谢产物的植物毒理三个方面的问题，得出如下结论：1．采用一种经过检验的新前处理方法，分析变压器油样中含有2种二氯联苯，4种三氯联苯，4种4氯联苯，3种5氯联苯，1种六氯联苯，共13种PCBs同类物，各同类物在ΣPCB中占的百分含量在1.2％-13.4％之间。2．采用KMnO4和好氧降解菌系拙合时，祸合方式不同，藕合效果不同，土壤介质不同锅合的效果也存在差异。3．模拟缺氧条件下，不含脱氯微生物啤酒厂污泥，在经过一定迟滞期后（4星期），存在脱氯情况，添加按计卜油醇可减少迟滞期，有明显的诱导作用。单独投加零价金属的脱氯效果与其化学性质和投加量有关，Fe。和zno辛禺合厌氧微生物的脱氯效果要好于两者单独的脱氯效果，其中Zn0耦合厌氧微生物的脱氯效果最好。4，在实验区间内，两种白菜的POD可与根伸长、发芽率一起作为CBA的生态毒理指标，且比根伸长和发芽率敏感，SOD和CAT则不适合。

污染土壤中多环芳烃的共代谢降解过程

The biodegradation of most PAHs with high molecular weight is carried out by means of cometabolism. The development of the theory about cometabolic degradation is reviewed in this paper, and the achievements on the cometabolic degradations of PAHs are also summarized. It is demonstrated that glucose, biphenyl, organic acids and mineral oil could be used as cometabolic substrate to enhance the degradation rate of PAHs, and there are complex interactions in the microbiological degradation process among different PAHs. Some low molecular PAHs could serve as cometabolic substrate, which could also be used to enhance the transformation rate of high molecular weight recalcitrant PAHs. To achieve the cometabolic degradation of the PAHs in the soils, the following problems must be solved: the screening out of efficient degradative strains, the selection of the appropriate cometabolic substrate, the addition of surfactant if necessary and the optimization of operational parameters with the contaminated soils. These problems are the important parts of the project for the cometabolic degradation of PAHs in the soils.

Polycyclic aromatic hydrocarbons (PAHS) (I): Toxicity, population exposure and involved foods

Food is one of the main exogenous sources of genotoxic compounds. In heated food products, polycyclic aromatic hydrocarbons (PAHs) represent a priority group of genotoxic, mutagenic and/or carcinogenic chemical pollutants with adverse long-term health effects. People can be exposed to these compounds through different environments and via various routes: inhalation, ingestion of foods and water and even percutaneously. The presence of these compounds in food may be due to environmental contamination, to industrial handling and processing of foods and to oil processing and refining. The highest levels of these compounds are found in smoked foods, in seafood which is found in polluted waters, in grilled meats and, to a lesser extent, in vegetable fats and oils. Lower levels of PAHs are found in vegetables and in cereals and its products.

Physicochemical and mineralogical characteristics of soil/saprolite cores from a field research site, Tennessee

Site characterization is an essential initial step in determining the feasibility of remedial alternatives at hazardous waste sites. Physicochemical and mineralogical characterization of U-contaminated soils in deeply weathered saprolite at Area 2 of the DOE Field Research Center (FRC) site, Oak Ridge, TN, was accomplished to examine the feasibility of bioremediation. Concentrations of U in soil–saprolite (up to 291 mg kg–1 in oxalate-extractable Uo) were closely related to low pH (ca. 4–5), high effective cation exchange capacity without Ca (64.7–83.2 cmolc kg–1), amorphous Mn content (up to 9910 mg kg–1), and the decreased presence of relative clay mineral contents in the bulk samples (i.e., illite 2.5–12 wt. %, average 32 wt. %). The pH of the fill material ranged from 7.0 to 10.5, whereas the pH of the saprolite ranged from 4.5 to 8. Uranium concentration was highest (about 300 mg kg–1) at around 6 m below land surface near the saprolite–fill interface. The pH of ground water at Area 2 tended to be between 6 and 7 with U concentrations of about 0.9 to 1.7 mg L–1. These site specific characteristics of Area 2, which has lower U and nitrate contamination levels and more neutral ground water pH compared with FRC Areas 1 and 3 (ca. 5.5 and

Spectral induced polarization signatures of abiotic FeS precipitation

In recent years, geophysical methods have been shown to be sensitive to microbial-induced mineralization processes. The spectral induced-polarization (SIP) method appears to be very promising for monitoring mineralization and microbial processes. With this work, we study the links of mineralization and SIP signals, in the absence of microbial activity. We recorded the SIP response during abiotic FeS precipitation. We show that the SIP signals are diagnostic of FeS mineralization and can be differentiated from SIP signals from biomineralization processes. More specifically, the imaginary conductivity shows almost linear dependence on the amount of FeS precipitating out of solution, above the threshold value 0.006 gr under our experimental conditions. This research has direct implications for the use of the SIP method as a monitoring and decision-making tool for sustainable remediation of metals in contaminated soils and groundwater.

An arsenic-accumulating, hypertolerant brassica, Isatis capadocica

Isatis capadocica, a brassica collected from Iranian arsenic-contaminated mine spoils and control populations, was examined to determine arsenate tolerance, metabolism and accumulation. I. cappadocica exhibited arsenate hypertolerance in both mine and nonmine populations, actively growing at concentrations of > 1 mm arsenate in hydroponic solution. I. cappadocica had an ability to accumulate high concentrations of arsenic in its shoots, in excess of 100 mg kg(-1) DW, with a shoot : root transfer ratio of > 1. The ability to accumulate arsenic was exhibited in both hydroponics and contaminated soils. Tolerance in this species was not achieved through suppression of high-affinity phosphate/arsenate root transport, in contrast to other monocotyledons and dicotyledons. A high percentage (> 50%) of arsenic in the tissues was phytochelatin complexed; however, it is argued that this is a constitutive, rather than an adaptive, mechanism of tolerance.

The mechanistic basis of interactions between mycorrhizal associations and toxic metal cations

Mycorrhizal associations, including ericoid, arbuscular and ecto-mycorrhizas, are found colonising highly metal contaminated soils. How do mycorrhizal fungi achieve metal resistance, and does this metal resistance confer enhanced metal resistance to plant symbionts? These are the questions explored in this review by considering the mechanistic basis of mycorrhizal adaptation to metal cations. Recent molecular and physiological studies are discussed. The review reappraises what constitutes metal resistance in the context of mycorrhizal associations and sets out the constitutive and adaptive mechanisms available for mycorrhizas to adapt to contaminated sites. The only direct evidence of mycorrhizal adaptation to metal cation pollutants is the exudation of organic acids to alter pollutant availability in the rhizosphere. This is not to say that other mechanism of adaptation do not exist, but conclusive evidence of adaptive mechanisms of tolerance are lacking. For constitutive mechanisms of resistance, there is much more evidence, and mycorrhizas possess the same constitutive mechanisms for dealing with metal contaminants as other organisms. Rhizosphere chemistry is critical to understanding the interactions of mycorrhizas with polluted soils. Soil pH, mineral weathering, pollutant precipitation with plant excreted organic acids all may have a key role in constitutive and adaptive tolerance of mycorrhizal associations present on contaminated sites. The responses of mycorrhizal fungi to toxic metal cations are diverse. This, linked to the fact that mycorrhizal diversity is normally high, even on highly contaminated sites, suggests that this diversity may have a significant role in colonisation of contaminated sites by mycorrhizas. That is, the environment selects for the fungal community that can best cope with the environment, so having diverse physiological attributes will enable colonisation of a wide range of metal contaminated micro-habitats.

Interactions between earthworms and arsenic in the soil environment:a review

Chemical pollution of the environment has become a major source of concern. In particular, many studies have investigated the impact of pollution on biota in the environment. Studies on metalliferous contaminated mine spoil wastes have shown that some soil organisms have the capability to become resistant to metal/metalloid toxicity. Earthworms are known to inhabit arsenic-rich metalliferous soils and, due to their intimate contact with the soil, in both the solid and aqueous phases, are likely to accumulate contaminants present in mine spoil. Earthworms that inhabit metalliferous contaminated soils must have developed mechanisms of resistance to the toxins found in these soils. The mechanisms of resistance are not fully understood; they may involve physiological adaptation (acclimation) or be genetic. This review discusses the relationships between earthworms and arsenic-rich mine spoil wastes, looking critically at resistance and possible mechanisms of resistance, in relation to soil edaphic factors and possible trophic transfer routes.

Arsenic uptake and speciation in the rootless duckweed Wolffia globosa

Duckweeds are a common macrophyte in paddy and aquatic environments. Here, we investigated arsenic (As) accumulation, speciation and tolerance of the rootless duckweed Wolffia globosa and its potential for As phytofiltration.

When grown with 1 mu M arsenate, W. globosa accumulated two to 10 times more As than four other duckweed or Azolla species tested. W. globosa was able to accumulate > 1000 mg As kg(-1) in frond dry weight (DW), and tolerate up to 400 mg As kg-1 DW. At the low concentration range, uptake rate was similar for arsenate and arsenite, but at the high concentration range, arsenite was taken up at a faster rate.

Arsenite was the predominant As species (c. 90% of the total extractable As) in both arsenate-and arsenite-exposed duckweed. W. globosa was more resistant to external arsenate than arsenite, but showed a similar degree of tolerance internally. W. globosa decreased arsenate in solution rapidly, but also effluxed arsenite.

Wolffia globosa is a strong As accumulator and an interesting model plant to study As uptake and metabolism because of the lack of a root-to-frond translocation

A review on completing arsenic biogeochemical cycle: Microbial volatilization of arsines in environment

Arsenic (As) is ubiquitous in the environment in the carcinogenic inorganic forms, posing risks to human health in many parts of the world. Many microorganisms have evolved a series of mechanisms to cope with inorganic arsenic in their growth media such as transforming As compounds into volatile derivatives. Bio-volatilization of As has been suggested to play an important role in global As biogeochemical cycling, and can also be explored as a potential method for arsenic bioremediation. This review aims to provide an overview of the quality and quantity of As volatilization by fungi, bacteria, microalga and protozoans. Arsenic bio-volatilization is influenced by both biotic and abiotic factors that can be manipulated/elucidated for the purpose of As bioremediation. Since As bio-volatilization is a resurgent topic for both biogeochemistry and environmental health, our review serves as a concept paper for future research directions.

High-affinity phosphate/arsenate transport in white lupin (Lupinus albus) is relatively insensitive to phosphate status

The development of proteoid roots under phosphorus deficiency by white lupin (Lupinus albus) may result in increased arsenate uptake, as arsenate is a phosphate analogue. This, together with its high biomass production, rapid growth and ability to survive in soils with low phosphate and nitrogen contents, low pH and high metal contents make them an interesting species to investigate with respect to revegetation, and possibly also for long-term phytoremediation, of arsenic contaminated soils. Kinetic parameters for arsenate uptake for P-deficient and P-sufficient plants, as well as for proteoid and nonproteoid roots were obtained. Down-regulation of arsenate uptake by phosphate, as well as phosphate/arsenate competition for P-deficient and P-sufficient plants was studied. Arsenate uptake was reduced by phosphate, but small differences were found between P-deficient and P-sufficient plants. Arsenate uptake by proteoid roots was higher than for nonproteoid roots of P-deficient plants, with higher V_max and similar K_m values. Down-regulation of the high affinity phosphate/arsenate uptake system by phosphate does take place but seems to be slower than in other plants. This study suggests that the low sensitivity of the phosphate/arsenate uptake system to regulation by phosphate may be related to the adaptations of white lupin to low P available environments. Such adaptation are absent in plants unable to develop proteoid roots.