垃圾填埋场地下水污染风险分级评价

为了更有针对性地解决垃圾填埋场造成的地下水污染问题,有利于分级管理及合理安排资源,构建包括垃圾填埋场特征、含水层脆弱性和受体暴露情况的风险评价指标体系,使用AHP（层次分析法）确定各指标的权重,采用加权求和的方法计算垃圾填埋场地下水污染风险指数,并将垃圾填埋场的地下水风险分为“低”“中”“高”三级,针对不同风险等级提出相应的管理建议.以北天堂垃圾填埋场的4个填埋地块为例,运用所构建的风险评价模型对其进行风险评价.结果表明:4个填埋地块的风险指数分别为5.307、5.845、7.001和7.413.位于东北部和北部的填埋地块1和2风险等级为“中”,位于西北部和南部的地块3和4风险等级为“高”.研究显示,通过垃圾填埋场地下水污染风险评价体系,可以识别出填埋场污染的关键环节,对风险等级为高、已经造成污染的填埋场污染提出有针对性的治理和修复措施,对风险等级为低和中的填埋场,制订相应的监测和管理方案,防止污染发生.      

简易垃圾填埋场地下水污染风险评价

对简易垃圾填埋场污染地下水的风险进行评价是开展地下水保护的重要手段. 基于对简易垃圾填埋场污染地下水的系统结构分析,构建了包括填埋场危险性、评价对象暴露性、包气带抗污性、含水层脆弱性以及地下水危害性等影响因素的地下水污染风险评价指标体系,确定了各评价指标的取值依据和取值范围(为1~10),采用层次分析(AHP)法确定了各评价指标的权重,并建立了综合指数风险评价模型. 以北天堂简易垃圾填埋场对北京市水源四厂地下水污染的风险评价为例,对该风险评价模型进行了验证. 结果表明,北天堂简易垃圾填埋场对北京市水源四厂地下水污染风险指数为7.455 6,污染风险等级较高,与有关研究结果相符,证实所建立的地下水污染的综合指数风险评价模型与指标体系合理.      

非正规垃圾填埋场土壤和地下水重金属污染特征与评价

为了解非正规垃圾填埋场土壤和地下水重金属污染状况,以江西乱石湾垃圾填埋场周边土壤和地下水为研究对象,对研究区进行采样分析,应用内梅罗综合污染指数法和美国环保局地下水健康风险评价模型对该垃圾填埋场土壤和地下水中重金属污染物进行含量特征分析与评价。结果表明,Cr(Ⅵ)、Cd、Cu、Pb重金属是填埋场土壤中的主要污染物,区域所有采样点的内梅罗综合污染指数平均值为2. 20,说明土壤受中度重金属污染; Cr(Ⅵ)是填埋场地下水的主要污染物,所有采样点的综合污染指数平均值为0. 89,说明地下水总体处于警戒线等级;致癌健康风险值在2. 32×10~(-4)～1. 69×10~(-3)/a之间,是国际委员会推荐值的4. 64～33. 8倍,致癌风险水平为Cr(Ⅵ)NiAsCd;非致癌健康风险值在2. 54×10~(-10)～9. 72×10~(-9)/a之间,致癌类重金属的个人年健康风险值是非致癌类重金属的10~5～10~6倍,说明该区域的致癌风险极大,应引起重视。     

基于过程模拟的地下水污染风险评价方法研究

通过对简易垃圾填埋场污染地下水过程的系统分析,提出了以抽水井作为保护目标进行地下水污染风险评价的方法,确定了地下水污染风险评价因子,建立了基于过程模拟的污染物迁移转化数学模型.以特征污染物Cl-的污染范围和程度划分了风险等级.利用构建的地下水污染风险评价方法,以我国北方某简易垃圾填埋场作为案例进行了地下水污染风险评价.结果表明,污染源与污染物迁移转化的共同作用决定了地下水污染范围和风险等级.地下水污染风险评价方法的建立为开展简易垃圾填埋场地下水污染有效监管提供了一种方法.     

西藏日喀则市生活垃圾填埋场地下水污染风险评价研究

污染区域地下水是填埋场存在的最大环境安全隐患,为掌握西藏日喀则市生活垃圾填埋场地地下水受污染风险大小,文章通过收集相关资料等方法,采用DRASTIC模型,结合填埋场自身特征对场区地下水含水层脆弱性和污染源污染风险大小进行评价。结果表明:日喀则市生活垃圾填埋场自身污染风险等级较高,场区所在地为地下水防污性能中等区域。文章可以为日喀则市生活垃圾填埋场地下水污染防治提供科学依据。     

基于迭置指数法的简易垃圾填埋场地下水污染风险研究

传统地下水风险评价DRASTIC模型常用于评价地下水含水层固有特性,体现了含水层自身对外界污染源的抵抗能力,但对环境污染源和地下水价值等相关要素考虑不足,使其评价结果存在一定的片面性。基于迭置指数法,结合地下水固有脆弱性7项评价指标和污染负荷危害性5项评价指标,对传统DRASTIC模型进行了改进,构建地下水污染风险评价综合指数计算模型,优化了地下水污染风险评价模型,并以我国西南某简易垃圾填埋场为实例,进行了地下水污染风险评价,运用ArcGIS空间分析获取研究区地下水污染风险评价12项评价指标和其综合指数的空间分布情况,以了解研究区地下水污染风险现状。结果表明:构建的地下水污染风险评价体系及评价模型可行,研究区内山区地下水受到污染的概率较小,地下水污染风险评价综合指数均小于4,河流附近与山谷平原区地下水污染风险评价综合指数增加,在简易垃圾填埋场周边地下水污染风险评价综合指数增至5.1。采用该评价模型能较全面地评价研究区地下水污染风险现状和抗污性能,可为区域地下水污染防治和地下水环境管理提供科学依据。     

基于指数分析和GIS方法的垃圾填埋场地下水环境影响分析

为合理评估垃圾填埋场的污染潜力及其对周边地下水环境的影响,以山东省某垃圾填埋场为例,采用LPI指数法和WQI指数法评估了垃圾填埋场渗滤液的污染情况和周围地下水的水质情况;利用GIS的空间分析等功能对污染影响分布进行评估;结合地下水数值模拟,以氨氮为典型特征污染物,计算分析了渗滤液污染物迁移扩散的规律。结果表明:研究区渗滤液的污染潜力较大,具有污染周围地下水的风险,目前周边地下水水质虽处于WHO和国家标准的限制内,水质状况良好,但随着渗滤液的渗漏,氨氮等污染物的污染区域会逐步扩散为羽毛状,水质将持续变差。预计到2025年,渗滤液将开始污染周边一处居民区的地下水并逐渐扩大范围,需采取相应的防渗措施对周边地下水进行防护。     

中国正规、非正规生活垃圾填埋场地下水中典型污染指标特性比较分析

本研究基于1991—2018年期间的相关报道,通过单因子和內梅罗指数法、地下水质量评分法等方法及SPSS 24.0和Origin 2017等分析软件分别对我国正规、非正规生活垃圾填埋场地下水中的主要污染指标进行了评价,通过累计污染负荷比法分别对其进行了识别,并分析了正规与非正规填埋场地下水的污染特征与差异,以期为我国不同类型的生活垃圾填埋场地下水污染的修复和治理提供指导.结果表明:我国正规生活垃圾填埋场地下水中已报道检出污染指标共计89种,非正规共计93种;其中在非正规填埋场地下水中,有机物、无机盐以及重金属污染指标的数量都较之正规的更多.正规、非正规生活垃圾填埋场地下水中普遍性、局部性和点源性的主要污染指标差异明显,虽然两种不同类型的填埋场地下水中均普遍存在有机物(高锰酸盐指数)、无机盐(氨氮、氯化物、硝酸盐氮)和重金属(铁)污染指标,但是在非正规填埋场地下水中还普遍含锰和砷,局部含汞;在正规填埋场地下水中,普遍含汞,局部含锰.同时,我国正规、非正规生活垃圾填埋场地下水质量综合评分F值分别为7.69和8.11,都属于极差级别,表明无论是正规还是非正规填埋场,其地下水都已受到了严重污染,其中非正规的污染程度明显高于正规的.因此,生活垃圾填埋场对地下水的污染应引起社会的关注,尤其应加强对非正规生活垃圾填埋场地下水污染的修复和治理.     

西藏日喀则市垃圾填埋场地下水环境质量评价

垃圾填埋场污染区域地下水是垃圾填埋场存在的最大环境安全隐患。长期以来,西藏地区生活垃圾几乎都采用卫生填埋的方式进行处理处置。为更好掌握西藏垃圾填埋场对地下水环境污染状况,为城镇用水安全、保障人群健康、环境污染防治提供可靠信息,以西藏日喀则市垃圾填埋场为研究对象,在3年现场采样收集数据的基础上,采用标准指数法、综合评价法和污染指数法对日喀则垃圾填埋场地下水环境质量进行了分析和评价。结果表明:2015—2017年,日喀则垃圾填埋场地下水评价因子中pH、总硬度、硝酸盐氮(NO_3~--N)、氟化物(F~-)、氯化物(Cl~-)、氨氮(NH_3-N)和铁(Fe) 7项指标明显高于其地下水环境背景值,其中,仅氨氮(NH_3-N)和铁(Fe)超出地下水质量Ⅲ类标准,氨氮(NH_3-N)综合污染等级为无污染,铁(Fe)为中等污染;地下水综合水质良好、污染现状为轻污染。     

中小城镇生活垃圾填埋场地下水环境质量评价研究

以安徽省某县生活垃圾填埋场为研究对象,对该填埋场4口监测井的地下水进行监测分析和综合评价,监测目标为总硬度、氨氮、铅、砷、汞等地下水常规监测项目。监测结果表明：填埋初期的生活垃圾填埋场,周边地下水中重金属物质多数未检出,但总硬度、溶解性总固体和无机盐等物质含量较高,部分点位的氨氮、硝酸盐超过地下水质量标准（GB／T 14848－1993）Ⅲ类标准,可见填埋场对周边地下水存在影响。     

Effects of two sludge application on fractionation and phytotoxicity of zinc and copper in the soil

The potential harm of heavy metals is a primary concern in application of sludge to the agricultural land. A pot experiment was conducted to evaluate the effect of two sludges on fractionation of Zn and Cu in soil and their phytotoxicity to pakchoi. The loamy soil was mixed with 0%, 20%, 40%, 60% and 80% (by weight) of digested sewage sludge (SS) and composted sludge (SC). The additions of both sludges caused a significant raise in all fractions, resulting in that exchangeable (EXCH) and organic bound (OM) became predominance of Zn and organic bound Cu occupied the largest portion. There was more available amount of Zn and Cu in SS treatments than SC treatments. During the pot experiment, the concentration of Zn in EXCH, carbonate (CAR) and OM and Cu in EXCH and OM fractions decreased in all treatments, so their bioavailability reduced. Germination rate and plant biomass decreased when the addition rate was high and the best yield appeared in 20% mixtures at the harvest of pakchoi. The two sludges increased tissue contents of Zn and Cu especially in the SS treatments. Zn in pakchoi was not only in relationship to ΔEXCH and ΔCAR forms but also in ΔOM forms in the sludge-soil mixtures. Tissue content of Cu in pakchoi grown on SC-soils could not be predicted by ΔEXCH. These correlation rates between Zn and Cu accumulation in pakchoi and variation of different fractions increased with time, which might indicate that sludges represented stronger impacts on the plant in long-term land application.     

Intraspecific differences in effects of co-contamination of cadmium and

A hydroponic experiment was carried out to study intraspecific differences in the effects of different concentrations of cadmium (Cd)(0-10 mg/L) and arsenate (As(V)) (0-8 mg/L) on the growth parameters and accumulation of Cd and As in six wheat varieties Jing-9428, Duokang-1, Jingdong-11, Jing-411, Jingdong-8 and Zhongmai-8. The endpoints of wheat seedlings, including seed germination,biomass, root length and shoot height, decreased with increasing the Cd and As concentrations. Significant differences in seed germination, biomass, root length, shoot height and the accumulation of Cd and As were observed between the treatments and among the varieties (p ＜ 0.05). The lethal dosage 50% were about 20, 80, 60, 60, 80 and 20 mg As/L for Jing-9428, Duokang-1, Jingdong-11,Jing-411, Jingdong-8 and Zhongmai-8, respectively, and the corresponding values for Cd were about 30, 80, 20, 40, 60 and 10 mg Cd/L, respectively. Among the six varieties, Duokang-1 was found to be the most resistant to Cd and As toxicity, and Zhongmai-8 was the most sensitive to Cd and As co-contamination. The resistance of the six varieties was found dependant on the seedling uptake of Cd and As. Duokang-1 was the most suitable for cultivation in Cd and As co-contaminated soils.     

Toxic effects of acetochlor, methamidophos and their combination on nifH gene in soil

Toxic effects of two agrochemicals on nifH gene in agricultural black soil were investigated using denaturing gradient gel electrophoresis （DGGE） and sequencing approaches in a microcosm experiment. Changes of soil nifH gene diversity and composition were examined following the application of acetochlor, methamidophos and their combination. Acetochlor reduced the nifH gene diversity （both in gene richness and diversity index values） and caused changes in the nifH gene composition. The effects of acetochlor on nifH gene were strengthened as the concentration of acetochlor increased. Cluster analysis of DGGE banding patterns showed that nifH gene composition which had been affected by low concentration of acetochlor （50 mg/kg） recovered firstly. Methamidophos reduced nifH gene richness that except at 4 weeks. The medium concentration of methamidophos （150 mg/kg） caused the most apparent changes in nifH gene diversity at the first week while the high concentration of methamidophos （250 mg/kg） produced prominent effects on nifH gene diversity in the following weeks. Cluster analysis showed that minimal changes of nifH gene composition were found at 1 week and maximal changes at 4 weeks. Toxic effects of acetochlor and methamidophos combination on nifH gene were also apparent. Different nifH genes （bands） responded differently to the impact of agrochemicals： four individual bands were eliminated by the application of the agrochemicals, five bands became predominant by the stimulation of the agrochemicals, and four bands showed strong resistance to the influence of the agrochemicals. Fifteen prominent bands were partially sequenced, yielding 15 different nifH sequences, which were used for phylogenetic reconstructions. All sequences were affiliated with the alpha- and beta-proteobacteria, showing higher similarity to eight different diazotrophic genera.     

EDTA-enhanced phytoremediation of lead contaminated soil by Bidens maximowicziana

Phytoremediation is a potential cleanup technology for the removal of heavy metals from contaminated soils.Bidens maximowicziana is a new Pb hyperaccumulator,which not only has remarkable tolerance to Pb but also extraordinary accumulation capacity for Pb.The maximum Pb concentration was 1509.3 mg/kg in roots and 2164.7 mg/kg in overground tissues.The Pb distribution order in the B. maximowicziana was:leaf>stem>root.The effect of amendments on phytoremediation was also studied.The mobility of soil Pb and the Pb concentrations in plants were both increased by EDTA application.Compared with CK(control check),EDTA application promoted translocation of Pb to overground parts of the plant.The Pb concentrations in overground parts of plants was increased from 24.23-680.56 mg/kg to 29.07-1905.57 mg/kg.This research demonstrated that B.maximowicziana appeared to be suitable for phytoremediation of Pb contaminated soil,especially,combination with EDTA.     

Distribution and ecological effect of mercury in Laogang landfill, Shanghai, China

Laogang landfill near Shanghai is the largest landfill in China, and receives about 10000 t of daily garbage per day, Samples of topsoil and plants were analyzed to evaluate mercury pollution from the landfill. For topsoil samples, there were significant correlations among total mercury （HgT）, combinative mercury （Hgc） and gaseous mercury （HgG）, and content of total organic carbon （TOC）, but, no significantly relationship was found between Hg content and filling time. Hg content changes in vertical profiles with time showed that the average Hgv of profiles 1992, 1996, and 2000 was similar, but their average HgG was quite different. HgT was significantly correlated with Hgc in profile 1992 and 2000, and Hgv was significantly correlated with Hg6 in profile 1996. HgG/Hgv ratio in profile samples decreased in the order of （HgG,/HgT）1992〉（HgG/HgT）1996〉〉（HgG/HgT）2000. A simple outline of Hg release in landfill could be drawn： with increasing of filling time, degradation undergoes different biodegradation, accordingly, gaseous mercury goes through small, more, and small proportion to total mercury. Distribution of Hg in plants was inhomogeneous, following the order of leaf〉root〉stem. The highest value of leaf may be associated with higher atmospheric Hg from landfill. Ligneous plants （e.g. Phyllostachys glanca, Prunus salicina and Ligustrum lucidum） are capable of enriching more Hg than herbaceous plants.     

Arsenic uptake by arbuscular mycorrhizal maize （Zea mays L.） grown in an arsenic-contaminated soil with added phosphorus

The effects of arbuscular mycorrhizal (AM) fungus (Glomus mosseae) and phosphorus (P) addition (100 mg/kg soil) on arsenic (As) uptake by maize plants (Zea mays L.) from an As-contaminated soil were examined in a glasshouse experiment.Non-mycorrhizal and zero-P addition controls were included.Plant biomass and concentrations and uptake of As,P,and other nutrients,AM colonization,root lengths,and hyphal length densities were determined.The results indicated that addition of P significantly inhibited root colonization and development of extraradical mycelium.Root length and dry weight both increased markedly with mycorrhizal colonization under the zero-P treatments,but shoot and root biomass of AM plants was depressed by P application.AM fungal inoculation decreased shoot As concentrations when no P was added,and shoot and root As concentrations of AM plants increased 2.6 and 1.4 times with P addition,respectively.Shoot and root uptake of P,Mn,Cu,and Zn increased,but shoot Fe uptake decreased by 44.6%,with inoculation, when P was added.P addition reduced shoot P,Fe,Mn,Cu,and Zn uptake of AM plants,but increased root Fe and Mn uptake of the nonmycorrhizal ones.AM colonization therefore appeared to enhance plant tolerance to As in low P soil,and have some potential for the phytostabilization of As-contaminated soil,however,P application may introduce additional environmental risk by increasing soil As mobility.     

Enzymatic oxidation of aqueous pentachlorophenol

The influence of the nonionic surfactant Tween 80 on pentachlorophenol （PCP） oxidation catalyzed by horseradish peroxidase was studied. The surfactant was tested at concentrations below and above its critical micelle concentration （CMC）. Enhancement of PCP removal was observed at sub-CMCs. The presence of Tween 80 in the reaction mixture reduced enzyme inactivation which occurred through a combination of free radical attack and sorption by precipitated products. A simple first-order model was able to simulate time profiles for enzyme inactivation in the presence or absence of Tween 80. At supra-CMCs, the surfactant caused noticeable reductions in PCP removal, presumably through micelle partitioning of PCP which precluded the hydrophobic PCP molecule from interacting with the enzyme.     

Decomposition of alachlor by ozonation and its mechanism

Decomposition and corresponding mechanism of alachlor, an endocrine disruptor in water by ozonation were investigated. Results showed that alachlor could not be completely mineralized by ozone alone. Many intermediates and final products were formed during the process, including aromatic compounds, aliphatic carboxylic acids, and inorganic ions. In evoluting these products, some of them with weak polarity were qualitatively identified by GC-MS. The information of inorganic ions suggested that the dechlorination was the first and the fastest step in the ozonation of alachlor.     

基于综合水质标识指数和对应分析法的校园河道水质评价

以三峡大学的校园河道求索溪为研究对象,利用综合水质标识指数法确定求索溪水质类别,分析其水质时空变化规律,并利用对应分析法得出求索溪中不同监测点的主要污染因子.研究结果表明:求索溪整体的综合水质标识指数为7.423,整体水质为劣V类(地表水环境质量标准GB 3838-2002)且黑臭.从时间变化来看,求索溪4月份的水质最差,5月份次之,4、5月份所有监测点的水质都劣于V类且黑臭;8月份水质最好,水质为Ⅳ类;从空间分布来看,8个监测点综合水质标识指数均超过6.0,水质为劣V类,其中6号监测点的水质相对最好,监测点3号的水质相对最差;对应分析法得出求索溪的整体水体污染程度受总氮因子的影响最大,其次为总磷.该研究拟为求索溪及类似校园河道的水环境治理研究提供基础依据和参考.     

Potential of plant polyphenol oxidases in the decolorization and removal of textile and non-textile dyes

In this study an effort has been made to use plant polyphenol oxidases; potato （Solanum tuberosum） and brinjal （Solanum melongena）, for the treatment of various important dyes used in textile and other industries. The ammonium sulphate fractionated enzyme preparations were used to treat a number of dyes under various experimental conditions. Majority of the treated dyes were maximally decolorized at pH 3.0. Some of the dyes were quickly decolorized whereas others were marginally decolorized. The initial first hour was sufficient for the maximum decolorization of dyes. The rate of decolorization was quite slow on long treatment of dyes. Enhancement in the dye decolorization was noticed on increasing the concentration of enzymes. The complex mixtures of dyes were treated with both preparations of polyphenol oxidases in the buffers of varying pH values. Potato polyphenol oxidase was significantly more effective in decolorizing the dyes to higher extent as compared to the enzyme obtained from brinjal polyphenol oxidase. Decolorization of dyes and their mixtures, followed by the formation of an insoluble precipitate, which could be easily removed simply by centrifugation.