Heterogeneity of chlorinated hydrocarbon sorption properties in a sandy aquifer

Hydraulic conductivity and sorption coefficients for chlorinated hydrocarbons (chloroform, carbon tetrachloride and tetrachloroethylene) were evaluated for 216 sediment samples collected across a 15 m transect and a 21 m depth interval in a contaminated aquifer near Schoolcraft, Michigan. Relationships between hydraulic conductivity, linear sorption partition coefficients, grain size classes, and spatial location were investigated using linear regression analysis and geostatistical techniques. Clear evidence of layering was found in sorption properties, hydraulic conductivity and grain sizes. Conductivity correlated well with grain size, as expected, but sorption varied inversely with grain size, contrary to some previous reports. No significant correlation was found between sorption properties and hydraulic conductivity. This is likely due to the unexpected presence of small amounts of highly sorptive coal-like solids, which dominate the sorption behavior but have little effect on conductivity. The results demonstrate that recent findings regarding the high sorption capacity of coal materials found in soils can exert a controlling influence on contaminant transport. Designers of in situ remediation systems should be cautioned that 1) it is not reasonable to assume that sorption capacity and hydraulic conductivity are related, 2) sorption capacity and hydraulic conductivity are critical measurements for contaminant site characterization and subsequent transport modeling, 3) estimating sorption capacity from organic carbon measurement may lead to greater errors than performing sorption isotherms, and 4) it is more important to characterize vertical heterogeneity rather than horizontal heterogeneity because both sorption and hydraulic conductivity are correlated across longer distances in the horizontal plane.     

The chemical and biogenotoxic characterization of organic xenobiotics in aquatic sediment materials 1. The application and comparison of chemically non-specific and biogenotoxic methods

The aim of this work was to evaluate the Ames assay and mixed function oxidase (MFO)-Induct Test used in parallel with chemical group tests (ECD fingerprint and PAH estimation) for the characterization of the organic pollution of water sediment materials. Sediment materials were collected from “clean” and relatively heavily polluted locations in the Middle Adriatic Sea, and from some locations in continental Croatia polluted with wastewaters from different enterprises. Characterization of the organic extracts of the sediment materials investigated was performed chemically using UV spectrofluorometry for the determination polyaromatic hydrocarbons (PAH) and gas chromatography for the determination of volatile EC detector sensitive materials. Genotoxic analysis of the extracts was performed using the MFO-Induct Test and mutagenicity testing using the Standard Plate Incorporation Test as described by Maron and Ames with Salmonella typhimurium TA 98. Measurement of the BaPMO enzyme activity in the livers of carp treated i.p. with total extracts of the sediment investigated confirmed that the methanol extracts generally contained more inducing matter than the petroleum ether extracts. Ames assay showed that for all the samples following the elimination of the sulfur, there was an increase in the number of revertants in comparison to the control number, which indicates that the samples contained mutagenic substances. The larger doses of extracts generally demonstrated cytotoxicity, as evidenced by a reduced number of spontaneous revertants in the Salmonella/Microsome Test. Investigation of the correlation of the chemical parameters with the biological parameter showed that the induction of BaPMO exhibited a statistically significant correlation with the level of the ECD fingerprint of the petroleum ether sediment extract.     

Exploring the formation potential and optical properties of secondary organic aerosol from the photooxidation of selected short aliphatic ethers

Secondary organic aerosol (SOA) formation potential for six kinds of short aliphatic ethers has been studied. The size distribution, mass concentration, and yield of SOA formed by ethers photooxidation were determined under different conditions. The results showed that all six ethers can generate SOA via reaction with OH radicals even under no seed and NO_x-free condition. The mass concentration for six seedless experiments was less than 10 µg/m³ and the SOA yields were all below 1%. The strong increase in the SOA formation was observed when the system contained ammonium sulfate seed particles, while SOA yield decreased under the high-NO_x condition. SOA composition was analyzed using offline methods. Infrared spectra indicated that there are complex components in the particle-phase including carbonyls acid and aldehydes species. Moreover, the aqueous filter extracts were analyzed using ultraviolet-visible spectrometer and fluorescence spectrophotometer. For the fresh methyl n-butyl ether SOA, the largest absorption peak occurs at 280 nm and there exists slightly absorption in the 300–400 nm. Excitation-emission matrices display the distinct peak at excitation/emission = 470 nm/480 nm according to the fluorescence spectrum. These findings are important considerations of formation for ether SOA that can eventually be included in atmospheric models.     

The velocity of DNAPL fingering in water-saturated porous media: laboratory experiments and a mobile–immobile–zone model

Dense nonaqueous phase liquids (DNAPLs) are immiscible with water and can give rise to highly fingered fluid distributions when infiltrating through water-saturated porous media. In this paper, a conceptual mobile–immobile–zone (MIZ) model is presented to describe the structure of a DNAPL finger in water-saturated porous media and the velocity of finger propagation. A finger is composed of a finger body and a tip. The finger body has a mobile core and an immobile sheath. All the DNAPL within the tip of a finger is mobile. Lab experiments utilizing image analyses of a DNAPL (PCE) penetrating into water-saturated homogeneous glass beads were carried out in a two-dimensional transparent chamber. The results show that the fingers elongated almost linearly with time. The fingers did not grow laterally after the tip of the finger had passed. The average finger diameters were between 3.9 and 5.4 mm for PCE propagation in water-saturated glass bead porous media with mean particle diameters from 0.32 to 1.36 mm. The estimated mobile core diameters were 51–60% of the average finger diameters.     

Free ‐ living animals as indicators of environmental pollution by chlorinated hydrocarbons

As some species of game and free‐living animals promptly respond to ecosystem damage by a reaction that is easy to interpret, they are important ecological indicators in assessing the total contamination of the environment. Consumers of the highest order like predators, predatory and fish‐eating birds are among the most important bioindicators of environmental contamination by chlorinated hydrocarbons and PCB.

Data on chlorinated hydrocarbons and PCB levels were collected throughout 1988–1992 and obtained from 16 species of free‐living animals from 9 protected areas of Slovakia. Muscle tissue, liver, kidney and egg samples were examined for HCB, HCH isomers, DDT and its analogues, and PCB.

Levels of organic chlorinated contaminants reveal a decreasing tendency and thus cease to be a toxicologically important risk factor in game, with the exception of predatory birds, as significant values have been recorded in their eggs and reproductive organs.     

The interaction mechanisms of co-existing polybrominated diphenyl ethers and engineered nanoparticles in environmental waters:A critical review

This review focuses on the occurrence and interactions of engineered nanoparticles(ENPs)and brominated flame retardants(BFRs) such as polybrominated diphenyl ethers(PBDEs)in water systems and the generation of highly complex compounds in the environment.The release of ENPs and BFRs(e.g. PBDEs) to aquatic environments during their usage and disposal are summarised together with their key interaction mechanisms. The major interaction mechanisms including electrostatic, van der Waals, hydrophobic, ...     

多溴联苯醚好氧降解菌GH10的筛选及降解特性研究

从污水处理厂活性污泥中筛选得到一株多溴联苯醚好氧降解菌,命名为GH10.根据菌株形态特征、生理生化特性、16S rDNA基因序列及系统发育树分析,鉴定为长野雷夫松氏菌(Leifsonia shinshuensis).该菌能够利用十溴联苯醚作为唯一碳源生长,它对十溴联苯醚的降解率用HPLC法测定.十溴联苯醚质量浓度为10～50 mg/L时,降解效果较好,在十溴联苯醚初始质量浓度为50 mg/L、温度为30℃、摇床转速为150 r/min的条件下避光培养5d,菌株GH10对十溴联苯醚的降解率可达到59.24％.降解十溴联苯醚的最适条件为温度30℃,pH值7.0,接种量10％,相同条件下添加外加碳源葡萄糖可提高其降解率到90.08％.通过对十溴联苯醚降解动力学的模拟发现,添加外加碳源葡萄糖可以将十溴联苯醚的半衰期从3.91 d缩短至1.45 d.     

几种可利用多氯联苯和多溴联苯醚植物内生菌的分离及初步鉴定

采用PDA、NA以及高氏一号培养基,分别从毛白杨、绦柳、荻以及二穗短柄草植株内分离、纯化出37株内生菌,其中34株为细菌,3株为放线菌.以分离纯化得到菌株各自对应的营养培养基并添加不同浓度的污染物对获得的37株内生菌进行污染物的耐受筛选,发现24株分别对20 mg·L-1的aroclor1254和BDE209具有一定的耐受性.利用无机盐培养基并添加污染物作为微生物唯一碳源筛选,发现菌株CPY-4和菌株SGL-1可以在只提供4-BDE的无机盐培养基中存活,菌株CPY-4,SGL-1、菌株4、菌株13可以在提供BDE209和aroclor1254的无机盐培养基中存活.形态学观察和16Sr DNA序列同源性分析,初步确定菌株SGL-1为克雷伯氏菌属,菌株CPY-4为地衣芽胞杆菌,菌株4和菌株13为肠杆菌属.     

冷凝-催化燃烧法处理乙烯厂富含水蒸气的恶臭废气

采用冷凝-催化燃烧法处理乙烯厂富含水蒸气的恶臭废气,冷凝过程能够有效地脱除废气中的水蒸气、联苯和联苯醚,催化燃烧过程能够有效地脱除不凝气中的烃类化合物.催化燃烧反应器内装填Pr、Pd、Ce多组分蜂窝状催化剂,在床层空速为15900～40000h-4、反应器入口气温度为30～350℃的条件下,反应器入口气中总烃的体积分数为64.9×10-6～691.0×10-6时,出口总烃的体积分数可降至5.2×10-6～20.0×10-6,总烃的去除率为90%以上,处理后的气体符合国家排放标准.     

室内环境中持久性卤代有机污染物的人体暴露及潜在生殖健康影响

卤代持久性有机污染物(Hal-POPs),如多溴联苯醚(PBDEs)、多氯联苯(PCBs)、滴滴涕(DDT)等是环境中广泛存在的全球性有机污染物,同时它们又是内分泌干扰物,是威胁人类生殖健康的重要因素之一。由于人们每天约有80%以上的时间在室内度过,且室内环境是Hal-POPs人体暴露的主要来源之一,因此室内环境中Hal-POPs对人体内分泌系统的干扰作用及其机理等问题亟待研究,但目前这方面的研究很有限。本文通过综述Hal-POPs在室内环境中的赋存水平和在人体体内的负荷水平及其半衰期,探讨了其对人体内分泌系统尤其是男性生殖健康的影响情况及其可能的机理,并分析了目前研究的不足之处及研究前景,为进一步开展这方面的研究提供借鉴。