浙江省城市汽车站地表灰尘中重金属含量及其来源研究

为了解不同区域城市汽车站地表灰尘重金属的积累、有效性及其可能来源,在浙江省范围内选择了73个城市汽车站,采样并分析了地表灰尘颗粒组成及Pb、Zn、Cu、Cd、Cr、Ni、Hg、As、Se、Al、Fe、Mn和Co等元素的含量,用连续提取程序研究了地表灰尘中主要污染元素的化学形态.同时,应用相关分析、主成分分析和聚类分析等方法探讨了城市汽车站地表灰尘中重金属的可能来源及各城市汽车站地表灰尘组成的差异.颗粒组成分析结果表明,浙江省城市汽车站地表灰尘以粗颗粒组成为主,地表灰尘主要来源于车站附近的土壤、建筑、垃圾等,大气沉降对地表灰尘的贡献相对较小.与浙江省土壤背景值相比,Pb、Zn、Cu、Cd、Cr、Ni、Hg、As和Se等元素均有不同程度的污染,其平均含量分别为287.1、424.0、172.8、1.21、122.3、54.4、0.71、16.00和2.07mg·kg-1.因子分析将13个元素变量压缩为3个因子,可解释浙江省城市汽车站地表灰尘元素的来源:Pb、Zn、Cu、Cd、Cr和Ni主要与交通活动、工业污染等有关;Al、Fe、Mn和Co与当地成土母质等地质背景有关;Hg、As和Se等元素受交通污染、居民生活污染和工业污染等多重影响.根据地表灰尘元素组成的差异,可把城市汽车站分为5类.重金属元素化学形态研究表明,城市汽车站地表灰尘中不同元素的化学形态有较大的差异,有效性较高的元素为Zn、Mn和Cd,其次为Cu、Ni和Hg,而Pb、Cr和Fe的活性相对较低.     

我国城市不同功能区地表灰尘重金属分布及来源

为揭示城市不同功能区地表灰尘重金属的分布规律及污染来源,在文献调研的基础上,通过对多个省会城市主要功能区地表灰尘重金属数据的分析和比对,阐述了我国城市不同功能区地表灰尘中Cd、Cu、Pb和Zn的分布及累积差异,并探讨了不同功能区地表灰尘重金属的可能来源及影响因素.结果表明,工业区地表灰尘重金属含量最高,交通区地表灰尘重金属含量最低,商业区和居民文教区地表灰尘重金属含量处于中等水平.4种功能区之间地表灰尘重金属水平分异较大的元素是Zn和Pb,Cu和Cd在不同功能区地表灰尘中的含量差异较小.相对于城市土壤,工业区地表灰尘重金属累积最重,其它3个功能区地表灰尘重金属累积差异不明显,但相对而言,交通区地表灰尘重金属累积最轻.不同功能区地表灰尘累积程度差异最小的元素是Cd.     

城市土壤和地表灰尘重金属污染研究进展与展望

随着城市化和工业化的不断推进,城市土壤和地表灰尘重金属污染日趋严重,对城市环境和人类健康构成威胁,已成为国内外城市环境研究的热点问题.从重金属污染水平及其时空特征、污染源解析方法、生态和健康风险这3个主要方面,对国内外城市土壤和地表灰尘重金属研究成果进行了梳理和归纳.分析了当前研究存在的不足,并对未来研究进行了展望,即研究土壤和地表灰尘重金属在不同条件下的相互影响机制,通过丰富验证方法加强重金属来源解析模型结果的可靠性研究,加强来源驱动下重金属化学形态差异和地表灰尘短期累积污染过程的研究,完善暴露参数并深入探究重金属的化学形态对其生态和健康风险的影响,以提高风险预测水平.     

福州市公交枢纽站地表灰尘重金属含量、来源及其健康风险评价

城市地表灰尘中的重金属已成为城市环境和人类健康最重要的威胁之一. 为评价地表灰尘重金属的污染水平,研究了福州市公交枢纽站地表灰尘中的重金属质量分数、来源及其可能产生的健康风险. 结果表明:福州市公交枢纽站地表灰尘中w(Cr)、w(Cu)、w(Zn)和w(Cd)分别是福州市城区土壤的2.74、4.21、4.01和4.68倍. 灰尘中重金属Co、Ni和Mn主要来源于城市土壤,Cd、Pb和Cu来源于交通运输过程,Cr来源于城市土壤和交通运输,Zn主要来源于交通运输、城市生活污染和工业活动等复合污染源. 不同暴露途径的重金属暴露剂量和非致癌风险大小排序为消化道>皮肤接触>呼吸吸入. 地表灰尘中重金属非致癌总风险为儿童高于成人. 致癌重金属的暴露风险为Cd>Ni>Cr. 城市公交枢纽站地表灰尘中重金属污染受交通运输影响较大.      

克拉玛依市地表灰尘重金属空间分布特征与来源解析

从新疆典型石油城市-克拉玛依市采集52个地表灰尘样品,分析其中As、Cd、Cr、Cu、Pb和Hg等6种重金属元素的含量,采用污染负荷指数法（PLI）评价地表灰尘中重金属元素污染水平,基于GIS技术与地统学理论,分析重金属元素含量空间分布格局,利用多元统计分析法,讨论地表灰尘中重金属元素的主要来源。结果表明：克拉玛依市地表灰尘中As、Cd、Cu、Pb和Hg等元素平均含量分别为新疆土壤背景值的1.61、1.75、1.50、1.23和2.94倍。地表灰尘中Hg呈现中度污染,As、Cu、Cr和Pb呈现轻度污染,Cd呈现轻微污染。从空间分布结果来看,克拉玛依市地表灰尘重金属元素含量及污染高值区主要分布于研究区西北部。从污染来源来看,研究区地表灰尘中Hg、As、Pb和Cd等元素主要受到人为污染源的影响,Cu与Cr主要受到土壤地球化学特征的控制。     

安徽省城市地表灰尘重金属污染及人体健康风险评价

本研究收集了安徽省合肥、蚌埠、芜湖、淮南、安庆、铜陵和宿州7个城市地表灰尘重金属含量的数据,分别采用地累积指数法、美国环境保护署(USEPA)人体健康风险评价法对地表灰尘重金属污染程度和人体健康风险水平进行评价。结果表明,所研究的安徽省7个城市地表灰尘中Pb、Cd、Cr、Zn和Cu平均含量分别为123.73±81.70、5.34±6.54、96.40±37.36、941.03±1 007.39和269.77±441.59 mg/kg,均高于安徽省土壤环境背景值。地累积指数法评价结果显示,安徽省城市地表灰尘Cr为轻度污染, Pb为中度污染,Zn为重度污染,Cd和Cu为严重污染。人体健康风险评价结果表明,安徽省城市地表灰尘重金属对儿童存在着明显的非致癌健康风险,对成人产生的非致癌健康风险不明显。重金属Cd和Cr致癌风险在安全范围内,不会对人群产生明显的致癌效应。手-口摄入是人体暴露于地表灰尘产生健康风险的主要途径,在同一暴露途径下儿童所遭遇的健康风险高于成人,儿童更容易受到地表灰尘中污染物的危害。     

淮南市不同功能区叶面尘和地表灰尘中重金属分布特征、来源及健康风险评价

以淮南市叶面尘及对应地表灰尘为研究对象,采集了6个不同功能区的石楠叶面尘和相应地表灰尘,研究了Cr、Cu、Zn、Pb、As、Ni、V的分布特征及其来源,并采用美国EPA人体暴露风险评价模型,对不同功能区、不同暴露途径的儿童重金属致癌和非致癌健康风险进行评估.结果表明:淮南市叶面尘中重金属含量显著高于地表灰尘,叶面尘主要污染元素为Zn、Pb、Cu、As、Ni,地表灰尘中主要污染元素为Cu、Zn、Pb.不同功能区重金属来源存在差异,商业交通区、经济开发区和煤炭运输区,交通排放是其主要来源,文教区、公园绿地、居住区来源较为复杂,除来自于交通排放,还可能来自于工业排放、燃煤燃烧、炊事活动和公共设施的磨损.叶面尘和地表灰尘中Ni、As、Cr的致癌风险均小于安全阈值,地表灰尘中非致癌总风险为0.58,叶面尘为1.36,超出了安全阈值1.0,已经对儿童健康构成危害,手-口摄入是主要暴露途径;各功能区叶面尘重金属非致癌风险除煤炭运输区外,均大于1.0,排序为:文教区公园绿地居住区经济开发区商业交通区煤炭运输区,地表灰尘均小于1.0,排序为:公园绿地经济开发区文教区商业交通区煤炭运输区居住区.叶面尘中重金属的非致癌风险排序为:AsPbCrVNiCuZn,地表灰尘为:AsCrPbVCuNiZn.     

城市土壤重金属污染来源研究

随着城市工业化和城市化进程的不断深入,人们越来越关注城市土壤重金属污染的问题.本文介绍了城市土壤的概念,城市土壤重金属污染的特征及其危害.重点从工业、交通、大气沉降、农用物资等自然和人为污染来源,探讨城市土壤重金属污染来源的种类和特点,并提出了城市土壤重金属污染的生物效应与食品安全、土壤重金属迁移转化规律、同位素地球化学示踪方法和城市土壤数据库建设等方面的研究展望,以期为城市土壤重金属污染的相关研究、环境改善管理和决策提供参考依据.     

开封周边地区地表灰尘砷、汞背景值及其应用

在开封市周边地区采集96个地表灰尘样品和49个表土样品,用冷原子荧光法测定样品As、Hg含量,计算灰尘和土壤As、Hg背景值,并以开封城市地表灰尘为例,用地积累指数法(Igeo)和污染负荷指数法(PLI)分别开展基于灰尘和土壤背景值的污染评价.结果表明,开封市附近地区地表灰尘As、Hg背景值分别为8.04 mg·kg-1和22.37μg·kg-1,低于其土壤背景值,也低于我国潮土背景值.同一地区灰尘As、Hg背景值小于土壤,这主要与灰尘和土壤的有机质含量、颗粒大小、农业生产活动有关.基于灰尘背景值的开封城市地表灰尘As、Hg的Igeo和PLI,都大于基于我国潮土背景值的Igeo和PLI.因此,多数学者应用我国潮土背景值开展灰尘污染评价,其污染程度实质上被低估了.     

上海城市土壤和地表灰尘重金属污染现状及评价

应用空间插值方法研究了上海城市土壤和地表灰尘中重金属污染的含量水平和空间分布特征,并采用潜在生态危害指数法对样品中重金属的潜在生态危害进行了评价.结果表明,上海城市土壤和地表灰尘中的重金属均极显著地超过上海土壤背景值,其中土壤和灰尘中的铅分别是背景值的37倍和174倍.城市土壤和地表灰尘的潜在生态危害指数分别为244.69和1004.03,分别达到中等生态危害和很强生态危害.     

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.     

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.     

Degradation of metabolites accumulated of benzo[a]pyrene by coupling Penicillium Chrysogenum with KMnO4

Several main metabolites of benzo[a]pyrene （BaP） formed by Penicillium chrysogenum, Benzo[a]pyrene-1,6-quinone （BP 1,6- quinone）, trans-7,8-dihydroxy-7,8-dihydrobenzo[a]pyrene （BP 7,8-diol）, 3-hydroxybenzo[a]pyrene （3-OHBP）, were identified by high-performance liquid chromatography （HPLC）. The three metabolites were liable to be accumulated and were hardly further metabolized because of their toxicity to microorganisms. However, their further degradation was essential for the complete degradation of BaP. To enhance their degradation, two methods, degradation by coupling Penicillium chrysogenum with KMnO4 and degradation only by Penicillium chrysogenum, were compared; Meanwhile, the parameters of degradation in the superior method were optimized. The results showed that （1） the method of coupling Penicillium chrysogenum with KMnO4 was better and was the first method to be used in the degradation of BaP and its metabolites; （2） the metabolite, BP 1,6-quinone was the most liable to be accumulated in pure cultures; （3） the effect of degradation was the best when the concentration of KMnO4 in the cultures was 0.01% （w/v）, concentration of the three compounds was 5 mg/L and pH was 6.2. Based on the experimental results, a novel concept with regard to the bioremediation of BaP-contaminated environment was discussed, considering the influence on environmental toxicity of the accumulated metabolites.     

Impact of atrazine and nitrogen fertilizers on the sorption of chlorotoluron in soil and model sorbents

Sorption of chlorotoluron in ammonium sulfate, urea and atrazine multi-solutes system was investigated by batch experiments. The results showed application of nitrogen fertilizers to the soil could affect the behavior of chlorotoluron. At the same concentration of N, sorption of chlorotoluron decreased as the concentration of atrazine increased on the day 0 and 6 in soil, respectively. The sorption of chlorotoluron increased from 0 to 6 d when soils were preincubated with deionized water, ammonium sulfate and urea solution for 6 d. That indicated incubation time was one of the most important factors for the sorption of chlorotoluron in nitrogen fertilizers treatments. The individual sorption isotherms of chlorotoluron in rubbery polymer and silica were strictly linear in single solute system, but there were competition sorption between pesticides or between pesticides and nitrogen fertilizers. That indicated the sorption taken place by concurrent solid-phase dissolution mechanism and sorption on the interface of water-organic matter or water-mineral matter.     

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.     

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.     

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.     

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.