A Biomimetic Approach to the Detection and Identification of Estrogen Receptor Agonists in Surface Waters Using Semipermeable Membrane Devices (SPMDs) and Bioassay-Directed Chemical Analysis (12 pp)

Goal, Scope and Background Some anthropogenic pollutants posses the capacity to disrupt endogenous control of developmental and reproductive processes in aquatic biota by activating estrogen receptors. Many anthropogenic estrogen receptor agonists (ERAs) are hydrophobic and will therefore readily partition into the abiotic organic carbon phases present in natural waters. This partitioning process effectively reduces the proportion of ERAs readily available for bioconcentration by aquatic biota. Results from some studies have suggested that for many aquatic species, bioconcentration of the freely-dissolved fraction may be the principal route of uptake for hydrophobic pollutants with logarithm n-octanol/water partition coefficient (log Kow) values less than approximately 6.0, which includes the majority of known anthropogenic ERAs. The detection and identification of freely-dissolved readily bioconcentratable ERAs is therefore an important aspect of exposure and risk assessment. However, most studies use conventional techniques to sample total ERA concentrations and in doing so frequently fail to account for bioconcentration of the freely-dissolved fraction. The aim of the current study was to couple the biomimetic sampling properties of semipermeable membrane devices (SPMDs) to a bioassay-directed chemical analysis (BDCA) scheme for the detection and identification of readily bioconcentratable ERAs in surface waters. Methods SPMDs were constructed and deployed at a number of sites in Germany and the UK. Following the dialytic recovery of target compounds and size exclusion chromatographic clean-up, SPMD samples were fractionated using a reverse-phase HPLC method calibrated to provide an estimation of target analyte log Kow. A portion of each HPLC fraction was then subjected to the yeast estrogen screen (YES) to determine estrogenic potential. Results were plotted in the form of 'estrograms' which displayed profiles of estrogenic potential as a function of HPLC retention time (i.e. hydrophobicity) for each of the samples. Where significant activity was elicited in the YES, the remaining portion of the respective active fraction was subjected to GC-MS analysis in an attempt to identify the ERAs present. Results and Discussion Estrograms from each of the field samples showed that readily bioconcentratable ERAs were present at each of the sampling sites. Estimated log Kow values for the various active fractions ranged from 1.92 to 8.63. For some samples, estrogenic potential was associated with a relatively narrow range of log Kow values whilst in others estrogenic potential was more widely distributed across the respective estrograms. ERAs identified in active fractions included some benzophenones, various nonylphenol isomers, benzyl butyl phthalate, dehydroabietic acid, sitosterol, 3-(4-methylbenzylidine)camphor (4-MBC) and 6-acetyl-1,1,2,4,4,7-hexamethyltetralin (AHTN). Other tentatively identified compounds which may have contributed to the observed YES activity included various polycyclic aromatic hydrocarbons (PAHs) and their alkylated derivatives, methylated benzylphenols, various alkylphenols and dialkylphenols. However, potential ERAs present in some active fractions remain unidentified. Conclusions and Outlook Our results show that SPMD-YES-based BDCA can be used to detect and identify readily bioconcentratable ERAs in surface waters. As such, this biomimetic approach can be employed as an alternative to conventional methodologies to provide investigators with a more environmentally relevant insight into the distribution and identity of ERAs in surface waters. The use of alternative bioassays also has the potential to expand SPMD-based BDCA to include a wide range of toxicological endpoints. Improvements to the analytical methodology used to identify ERAs or other target compounds in active fractions in the current study could greatly enhance the applicability of the methodology to risk assessment and monitoring programmes.     

中美校车安全标准比较研究

为促进我国校车安全标准法规的发展,提高我国校车的安全技术水平,选择美国校车安全标准作为我国校车安全标准比较研究的对象,分别从校车的一般安全、主动安全和被动安全技术条件方面,将我国现已实施的校车安全标准和美国的校车安全标准进行比较。研究结果表明,我国校车安全标准和美国的校车安全标准之间存在一定差异,在应急出口、碰撞试验等方面还存在不足。根据研究结果,提出有关制定适合中国国情的校车安全标准和法规的建议。     

Solar tracking system – a review

The generation of power from the reduction of fossil fuels is the biggest challenge for the next half century. The idea of converting solar energy into electrical energy using photovoltaic panels holds its place in the front row compared to other renewable sources. But the continuous change in the relative angle of the sun with reference to the earth reduces the watts delivered by solar panel. In this context solar tracking system is the best alternative to increase the efficiency of the photovoltaic panel. Solar trackers move the payload towards the sun throughout the day. In this paper different types of tracking systems are reviewed and their pros and cons are discussed in detail. The results presented in this review confirm that the azimuth and altitude dual axis tracking system is more efficient compared to other tracking systems. However in cost and flexibility point of view single axis tracking system is more feasible than dual axis tracking system.     

Sources of Volatile Organic Compounds in a University Building

A total of 34 volatile organic compounds (VOCs) were measured in the indoor of laboratories, offices and classrooms of the Chemical Engineering Department of Hacettepe University in Ankara in 2 week-day passive sampling campaigns. The average concentrations ranged from 0.77 to 265 μg m^?3 at the different indoor sites, with the most abundant VOC found to be toluene (119.6 μg m^?3), followed by styrene (21.24 μg m^?3), 2-ethyltoluene (17.11 μg m^?3), n-hexane (10.21 μg m^?3) and benzene (9.42 μg m^?3). According to the factor analysis, the evaporation of solvents used in the laboratories was found to be the dominant source.     

利用PUF被动采样技术研究长三角城市群大气中多环芳烃的时空分布及来源

大气是环境污染研究领域重要的介质之一,大气被动采样技术在近10年来已发展成为主动大流量采样的重要补充手段.利用聚氨酯泡沫(polyurethane foam,PUF)被动采样技术在区域尺度上对长三角城市群大气中的多环芳烃(PAHs)进行监测.通过对31组采样点的研究发现,长三角城市群大气中PAHs的浓度在10.1～367 ng.m-3之间,苯并[a]芘(BaP)年平均浓度高达2.25 ng.m-3,超出GB 3095-2012规定限值两倍多.PAHs季节变化趋势为秋季>冬季>春季>夏季,秋冬季节长三角城市群大气中BaP的超标范围较大,其中冬季有明显的BaP排放.交通石油源、煤和生物质燃烧和焦炉排放源是该区域大气中PAHs的主要来源,贡献率依次为38.1%、42.4%和19.5%.     

Determination of VOCs in groundwater at an industrial contamination site using a homemade low-density polyethylene passive diffusion sampler

A home-made inexpensive passive diffusion bag （PDB） sampler, prepared by filling deionized water in low-density polyethylene （LDPE） tubes, was evaluated for volatile organic compounds （VOC） sampling in groundwater at industrial contamination sites. Impacts of environmentally relevant conditions on the sampling equilibration time and partitioning of VOCs between the sampler and the water sample were investigated. Sample salinity, agitation and temperature can influence the equilibration time, but generally sampling equilibration was obtained in 14 days under real field sampling of VOCs in groundwater. Both laboratory study and field testing in a contaminated site showed that the VOC concentrations in the developed sampler were equal to those in the water samples at equitibrium. Coupled with a purge and trap concentrator-gas chromatograph-mass spectrometer （P＆T-GC-MS）, the developed PDB sampler provided a low-cost sampling device for routine monitoring of VOCs in groundwater in wells, with LODs in the range of 2.9-10 μg/L. The proposed PDB was applied to determine VOCs in groundwater at an industrial contamination site, and the present results agreed well with those determined using conventional pump-and-sample monitoring. All the studied 13 VOCs were tested in the four wells in the industrial contamination sites, with their concentrations in the range of 12-73660 μg/L. In addition, while benzene and toluene were heavily contaminated up to a maximum concentration of 74000 μg/L and 6000 μg/L, respectively, 1,2,3-trichlorobenzene and bromobenzene had relatively low contamination levels （below 25 μg/L）.     

添加钝化剂对猪粪好氧堆肥过程中理化特性的影响

以猪粪和玉米秸秆粉为堆肥原料,通过添加不同用量的重金属钝化剂(粉煤灰、风化煤或膨润土)进行90d的好氧堆肥,研究钝化剂的种类和添加比例对堆肥理化特性的影响.结果表明:所有处理的堆体温度均能迅速升至近70℃,并维持在55℃以上超过一周;随着堆肥时间的延长,各处理堆体含水量逐渐降低,并在90d后达到30%左右,但添加膨润土能减少一次发酵期水分的损失;添加风化煤会导致堆体pH呈现较强的碱性,而添加膨润土会显著提高堆体EC值;随着堆制时间的延长,堆体Cu、Zn全量逐渐增加,但DTPA提取态Cu、Zn所占的比例则逐渐减小;对照处理和添加风化煤的各处理中,雪里蕻种子的发芽率最终均达到90%以上,GI约1.0左右;而在添加膨润土和粉煤灰的各处理中,到90d堆肥结束,发芽率最高仅达80%,仅有2.5%和5.0%添加比例(质量分数,下同)的处理中GI大于0.5,且GI的增加趋势随着膨润土和粉煤灰的添加比例增加而降低.研究表明,钝化剂的添加比例和种类对猪粪好氧堆肥中堆体温度和含水率变化无显著影响;虽然堆肥过程添加重金属钝化对堆肥重金属Cu、Zn有良好的钝化作用,但对堆体的pH和EC影响较为剧烈,对雪里蕻种子的根系生长也有一定的影响.在堆肥中应合理选择钝化剂的种类和添加比例.     

极性有机化合物整合采样技术在水环境有机污染物监测中的应用

极性有机化合物整合采样技术(Polar organic chemical integrative samplers,POCIS)适用于极性有机污染物的采集,随着新型极性有机污染物的不断出现,该技术已经引起了科学家的广泛关注.本文概述了几种常用的被动采样装置,重点介绍了POCIS采样器的一般结构、富集原理、环境因素如流速、温度、pH、溶解性有机质、盐度及膜的污染等对采样速率的影响,讨论了针对极性物质检测的质量控制和保证以及性能参考物质,综述了POCIS在水环境有机污染物监测中的应用.最后,本文对POCIS的应用前景进行了展望.     

Fe^0钝化膜的生物还原及其脱氮除磷

微生物的异化Fe（Ⅲ）还原是一种能够利用Fe（III）作为末端电子受体在无氧条件下氧化有机物的产能过程。结合这一特性，考察了在兼性厌氧／严格厌氧条件下Fe^0钝化膜作为Fe（111）源时的生物还原能力以及对N、P等营养元素的去除效果。结果表明，严格厌氧条件下微生物异化Fe（Ⅲ）还原能力较好，富集培养至7d，累计Fe（II）浓度达到最大，最大产生速率为98．69mg／（L·d），同时TP去除率高达97．1％以上。而体系对NH4-N、TN的去除相对滞后，培养至13d，去除率开始增大，最终分别达到86．6％和76．1％。这为装填有海绵铁＋聚氨酯泡沫载体的SBBR中填料的原位再生问题提供了解决思路。     

Air concentrations of currently used herbicides and legacy compounds in the Canadian prairies,subarctic, and arctic

Passive air samplers were installed in the summers of 2005 and 2007 for 90 days at four locations in the agricultural region of the Canadian Prairies and at five locations in the Canadian Subarctic and Arctic. The presence and masses of ten currently used herbicides and three legacy compounds in the polyurethane foam disks were quantified. Herbicides 2,4-D, bromoxynil and MCPA were detected at all locations in the Canadian Prairies and in both years because these herbicides are widely applied to control broadleaf weeds in cereal crops that are an integral part of Prairie agricultural production systems. MCPA was also detected at one location in the Arctic in 2007. The detection of the other seven herbicides in the 2 years combined ranged from no detections (atrazine only) to five detections for the relatively volatile herbicides trifluralin and triallate. Triallate was the only other herbicide detected in the Arctic (2005). Legacy compounds were either not detected (alachlor) or at levels near their detection level (γ-HCH and α-HCH). γ-HCH and α-HCH were more frequently detected in 2005 than in 2007 indicating that their concentrations in Canadian air have decreased over time. γ-HCH, widely used as an insecticide in Prairie oilseed production until 2002, was detected at larger concentrations in the Canadian Prairies than in the Subarctic and Arctic. α-HCH, a manufacturing by-product in technical HCH prior to 1971 in Canada, was not detected in the Canadian Prairies but was at detectable levels in the Subarctic and Arctic as the Arctic Ocean is reported to be a major source of α-HCH to the atmosphere. We conclude that some of the most widely used herbicides in Canadian agriculture today are commonly present in the air in regions where they are applied and that a portion of these herbicides may be traveling as parent molecules to the Canadian Arctic. To the authors’ knowledge, this is the first evidence of the presence of MCPA and triallate in Arctic air samples, perhaps because previous research has seldomly monitored for currently used herbicides in this region.