新型吸收剂净化吸收甲苯废气的实验研究

选择柠檬酸钠水溶液、Tween-20水溶液、檬酸钠-Tween-20混合水溶液、新型矿物油及新型矿物油-水作为研究对象,实验研究对比了几种吸收剂对甲苯废气的吸收效果。通过实验分析可知,檬酸钠水体系对甲苯废气吸收能力有限,加入盐类可小幅增强其水体系对于甲苯废气的吸收效果,其中Tween-20水溶液吸收剂对甲苯废气吸收率较柠檬酸钠水体系高;新型矿物油对甲苯废气有着较好的处理效果,吸收率最高可达97%,而新型矿物油-水混合吸收剂中单位体积新型矿物油对甲苯废气吸收率较新型矿物油吸收剂提高45%,且具有吸收效率高、分散性好、再生成本低的优点。     

应用表面活性剂-生物柴油微乳液去除污染土壤中多环芳烃

针对修复焦化厂高浓度多环芳烃污染土壤高成本的现实,采用以非食用性植物油、生物柴油、表面活性剂及其乳化合成的微乳液为淋洗剂,比较不同淋洗剂的淋洗效果。结果表明乳化合成的微乳液对焦化厂土壤中多环芳烃的总去除率高于单独使用表面活性剂为淋洗剂对土壤中多环芳烃的总去除率,说明生物柴油及植物油与表面活性剂乳化形成的微乳液对原污染土壤中的多环芳烃具有显著的增溶作用。1%TW-80和2.5%TW-80对土壤中多环芳烃总去除率分别为11%和14%;以2.5%TW-80为原料乳化合成的微乳液的淋洗去除率较以1%TW-80为原料乳化合成的微乳液高,总去除率分别为15%～30%和11%～18%;以生物柴油为原料乳化合成的微乳液的淋洗去除率较以植物油为原料乳化合成的微乳液高,分别为17%～30%和15%～23%,且对多环芳烃的去除率与其辛醇水分配系数(logKow)呈线性相关关系。     

生物法净化再生胶生产废气工业试验研究

在再生橡胶厂进行橡胶再生低浓度有机废气的生物法净化工业试验研究，对于甲苯浓度为300～1400mg/m^3的再生胶脱硫废气，在常温常压下以气体流量10～20m^3/h、循环液体喷淋量300～500L/h运行生物法废气净化装置获得了良好物净化效果。该装置连续运行100d的结果显示，其对再生胶废气中甲苯的净化效率可较长时间的保持在90%左右，废气经处理后可以实现达标排放，废气处理成本约为工厂再生胶产值的0.12%～0.14%，具有明显的技术先进性和经济合理性。     

水吸收法处理低浓度氮氧化物废气的中试研究

对水在中试规模下吸收低浓度的氮氧化物废气进行了研究。分别研究了喷淋密度、温度、压力、气速以及氮氧化物浓度对吸收效果的影响,结果表明,综合考虑各种因素,喷淋密度在20 m3/（m2·h）,水温在15℃以下,气速小于0.28 m/s,废气浓度在400 mg/m3左右时,氮氧化物的平均脱除率可以达到50%左右;同时,随着压力的增大,吸收效率也增加。     

中空纤维膜吸收甲苯气体

采用疏水性聚偏氟乙烯(PDVF)中空纤维膜为气液接触膜,n-甲酰吗啉(NFM)水溶液为吸收剂,研究了膜吸收技术分离甲苯/空气混合气的性能。考察了进气气体浓度、气体停留时间、吸收液体积分数和吸收液流量等诸因素对分离性能的影响。研究结果表明,膜吸收技术可以有效地分离甲苯/空气混合气,甲苯去除率可达90%;提高NFM吸收液的浓度和流量可同时增加甲苯的去除效率η和总传质系数K;气体停留时间的减小导致η降低,K反而增大;进气甲苯浓度的增加导致η下降,同时降低总传质系数K。     

管式生物过滤器去除乙苯废气

生物过滤由于其良好的成本效益和环境友好性已经成为控制挥发性有机化合物(VOCs)含量和气味气体排放的常规技术。营养物质的均匀分布、生物膜和介质床内的气体流是成就一个性能优良的生物过滤器至关重要的因素。而由本实验室开发的管式生物过滤器(TBFs)已被证明具备此优势。本实验的管式生物过滤器以聚氨酯海绵作为填料,研究在不同有机负荷、气体停留时间(EBCT)、进气量和表面活性剂等条件下乙苯废气的去除效率(RE)。实验同时记录了管式生物过滤器启动阶段的表现。初期使附着在填料上的微生物暴露在浓度为40 mg/m3的乙苯废气中40 d,此时的气体停留时间为15 s,使微生物慢慢适应并逐步降解乙苯废气;然后连续地控制管式生物过滤器的入口乙苯浓度为40、80、120和160 mg/m3,以使有机负荷逐步升高。结果表明,乙苯去除效率随着有机负荷的增大而逐步减小。当气体停留时间从15 s增加到30 s和60 s,而有机负荷控制在38.60 g/(m3·h)时,乙苯废气去除效率略微增加。此外,随着进气量的增大乙苯废气的最大平均去除效率有所下降而此时的降解容量增大,这个过程中乙苯进气浓度保持不变。结果还表明,在营养液中加入聚乙二醇辛基苯基醚这种表面活性剂可以提高乙苯废气的去除效率。     

一种新型吸收剂吸收油气效果与影响因素分析

油气回收在倡导节约资源、保护环境的当今社会有着重要的意义。吸收法作为常见的油气回收手段,影响其吸收效果的关键因素之一是吸收剂的选用。分析了传统油气吸收剂的优缺点,在AbsFOV-97油气吸收剂基础上改进开发得到一种新型吸收剂,搭建了小试平台比较新型与传统吸收剂的吸收效果,并针对新型吸收剂,研究了影响吸收效果的因素,包括进塔油气浓度、吸收剂温度、吸收液喷淋量、进塔油气流量等,根据单因素小试实验设计了正交实验。结果表明,新型吸收剂回收率比改进前提高3.06%,进塔油气浓度为影响吸收效果的最大因素。     

水介质中微气泡臭氧化处理高浓度甲苯气体

高浓度挥发性有机物(VOC)气体高效处理技术是大气污染控制领域关注的重点。采用微气泡臭氧化在水介质中通过吸收-氧化过程对高浓度甲苯气体进行处理,考察微气泡臭氧化强化甲苯吸收-氧化去除性能、机理以及水介质pH对该工艺处理效果的影响。结果表明,微气泡能够强化甲苯气体在水介质中的吸收过程,氮气/甲苯微气泡在水介质中的甲苯去除率和吸收量均显著高于氮气/甲苯传统气泡,同时氮气/甲苯微气泡通过产生·OH氧化反应,使得平均甲苯氧化矿化率达到40.97%。微气泡臭氧化在水介质中对甲苯气体具有更高效的去除性能,臭氧/甲苯微气泡处理中甲苯平均去除率为97.08%,甲苯可被完全矿化而几乎无中间产物积累,其平均氧化矿化率为88.56%、平均臭氧利用率为82.54%、臭氧投加量与甲苯矿化量比值为1.26,处理性能显著优于臭氧/甲苯传统气泡处理。水介质pH对臭氧/甲苯微气泡处理甲苯气体具有一定影响,不同pH条件下甲苯气体去除率基本相当,但中性条件下甲苯氧化矿化率最高;碱性和酸性条件下甲苯氧化矿化率有所下降。微气泡臭氧化为高浓度VOC气体高效处理提供了新的解决途径。     

表面活性剂对紫背浮萍吸收氮磷的影响

采用室内培养方法,以氨氮和总磷以及植物生长量作为观测指标,分别研究了阴离子型表面活性剂LAS、阳离子型表面活性剂CTMAB和非离子型表面活性剂Tween-80对紫背浮萍吸收氮磷及植株生长的影响。结果表明,无表面活性剂影响时紫背浮萍在模拟富营养化水体中生长良好并表现出很强的氮磷去除能力;LAS和CTMAB浓度低于1 mg/L时,紫背浮萍对总磷的吸收比对氨氮的吸收更易受影响;当浓度达到10 mg/L时,LAS和CTMAB的存在使紫背浮萍明显受到损伤,氮磷吸收率出现负值,而非离子型表面活性剂毒性相对最小,对紫背浮萍吸收氮磷的影响明显低于阴离子型和阳离子型的表面活性剂。     

混合型乳化液膜萃取分离处理工业化纤废水

为了去除工业化纤废水中的水溶性污染物,采用混合型乳化液膜法对废水样品进行了处理,以紫外吸收值和COD去除率为指标。结果表明,不同的表面活性剂、废水浓度、反应时间、液膜组成及处理工艺(包括内相酸浓度、油水比、乳水比)等对处理效果都会产生影响;其中T-152是最合适的表面活性剂,当体系pH=4,油内比为1∶1,乳水比为1∶3,废水初始COD为1 000 mg/L左右,表面活性剂的量:溶剂煤油的量:膜固定剂(TOA)三者体积比为5∶25 000∶1时,搅拌处理30 min,废水中紫外吸收光谱的最强吸收峰红移且峰强减小,COD的去除率达到96.5%,出水COD小于100 mg/L;处理后,废水的色度和浊度均得到显著降低,去除率达到98%以上,达到了排放要求。     

Patterns of volatile metabolites and nonvolatile trichothecenes produced by isolates of <Emphasis Type="Italic">Stachybotrys,Fusarium, Trichoderma,Trichothecium</Emphasis> and <Emphasis Type="Italic">Memnoniella</Emphasis>

We reported previously that trichodiene, a volatile trichothecene derivative, was produced by a Stachybotrys isolate, also known to produce highly cytotoxic, non-volatile, macrocyclic trichothecenes (satrotoxins). We investigated the relationship between the production of trichodiene and various non-volatile trichothecenes for several molds. Volatile metabolites were concentrated by adsorption on Tenax TA and analyzed by GC/MS, while non-volatile metabolites were separated by HPLC, derivatized and analyzed by GC/MS. Stachybotrys chartarum isolates producing macrocyclic trichothecenes secreted significantly larger amounts of trichodiene and other sesquiterpenes than isolates which only produced simple trichothecenes. The amounts of secreted trichodiene were relatively small in all cases. With the exception of Memnoniella, which excreted small amounts of sesquiterpenes, the other isolates produced varying amounts of sesquiterpenes, including trichodiene, as well as simple tricothecenes, no detectable trichodiene, but large amounts of griseofulvin derivatives. In Stachybotrys there is apparently a correlation between trichodiene and macrocyclic trichothecene production. In the remaining isolates, there was no simple relationship between trichodiene and non-volatile trichothecene synthesis. Trichodiene is produced in larger amounts by Stachybotrys isolates, which also produce satratoxins, but it will be difficult to utilize this metabolite to detect toxic isolates in buildings due to the relatively small amounts excreted.     

Radionuclides and trace elements in fish collected upstream and downstream of Los Alamos national laboratory and the doses to humans from the consumption of muscle and bone

Abstract

The purpose of this study was to determine radionuclide and trace element concentrations in bottom‐feeding fish (catfish, carp, and suckers) collected from the confluences of some of the major canyons that cross Los Alamos National Laboratory (LANL) lands with the Rio Grande (RG) and the potential radiological doses from the ingestion of these fish. Samples of muscle and bone (and viscera in some cases) were analyzed for ³H, ⁹⁰Sr, ¹³⁷Cs, ^totU, ²³⁸Pu, ^239,240Pu, and ²⁴¹Am and Ag, As, Ba, Be, Cr, Cd, Cu, Hg, Ni, Pb, Sb, Se, and Tl. Most radionuclides, with the exception of ⁹⁰Sr, in the muscle plus bone portions of fish collected from LANL canyons/RG were not significantly (p<0.05) higher from fish collected upstream (San Ildefonso/background) of LANL. Strontium‐90 in fish muscle plus bone tissue significantly (p<0.05) increases in concentration starting from Los Alamos Canyon, the most upstream confluence (fish contained 3.4E‐02 pCi g^‐1 [126E‐02 Bq kg^‐1]), to Frijoles Canyon, the most downstream confluence (fish contained 14E‐02 pCi g^‐1 [518E‐02 Bq kg^‐1]). The differences in ⁹⁰Sr concentrations in fish collected downstream and upstream (background) of LANL, however, were very small. Based on the average concentrations (±2SD) of radionuclides in fish tissue from the four LANL confluences, the committed effective dose equivalent from the ingestion of 46 lb (21 kg) (maximum ingestion rate per person per year) of fish muscle plus bone, after the subtraction of background, was 0.1 ± 0.1 mrem y^‐1 (1.0 ± 1.0 μSv y^‐1), and was far below the International Commission on Radiological Protection (all pathway) permissible dose limit of 100 mrem y^‐1 (1000 μSv y^‐1). Of the trace elements that were found above the limits of detection (Ba, Cu, and Hg) in fish muscle collected from the confluences of canyons that cross LANL and the RG, none were in significantly higher (p<0.05) concentrations than in muscle of fish collected from background locations.     

A History of Dry Cleaners and Sources of Solvent Releases from Dry Cleaning Equipment

Approximately 25, 000-35, 000 dry cleaning facilities currently operate in the U.S. The release of perchloroethylene and other solvents from these establishments represents a major source of soil and groundwater contamination. The manner in which dry cleaning solvents escape from dry cleaning plants is, for all practical purposes, identical for chlorinated and petroleum hydrocarbon solvents and is related to one of the following events: the catastrophic failure of a component of the dry cleaning system, the improper installation, operation or maintenance of the dry cleaning equipment or a combination of all of these causes. Acceptable customs, codes and regulations can also dictate what is authorized for operation of a dry cleaning facility in a particular community, geographic area during a particular time frame. Environmental litigation dealing with the origin of a solvent release from dry cleaners tends to focus on the design and manufacture of dry cleaning industry machines such as washers, washer extractors, tumblers, solvent filters, water separators, stills and spotting boards. A thorough analysis of the daily operations of dry cleaners often reveals that poor maintenance, failure to follow the manufacturer's instructions and the actions of the operator are the most likely causes of soil and groundwater pollution. In order to forensically evaluate the most probable origins of a solvent release and to examine issues regarding liability, a thorough understanding of the history of dry cleaning and a detailed analysis of the operation and maintenance of the dry cleaning equipment are necessary. The discovery of solvent plumes in the vicinity of dry cleaning plants may suggest that the solvent source is the dry cleaning plant; however, the presence of these plumes does not necessarily indicate that the dry cleaning equipment was defectively designed or manufactured. A thorough review of the type of equipment used over the life of the dry cleaning plant and verifiable solvent mileage records frequently indicates that operators of the plant have disposed of solvent and contaminated solids into the municipal sewer or on ground surfaces.     

Radionuclides in deer and elk from Los Alamos national laboratory and the doses to humans from the ingestion of muscle and bone

Abstract

This paper summarizes radionuclide concentrations (³H, ⁹⁰Sr, ¹³⁷Cs, ²³⁸Pu, ^239,240Pu, ²⁴¹Am, and ^totU) in muscle and bone tissue of mule deer (Odocoileus hemionus) and Rocky Mountain elk (Cervus elaphus) collected from Los Alamos National Laboratory (LANL), Los Alamos, New Mexico, lands from 1991 through 1998. Also, the committed effective dose equivalent (CEDE) and the risk of excess cancer fatalities (RECF) to people who ingest muscle and bone from deer and elk collected from LANL lands were estimated. Most radionuclide concentrations in muscle and bone from individual deer (n = 11) and elk (n = 22) collected from LANL lands were either at less than detectable quantities (where the analytical result was smaller than two counting uncertainties) and/or within upper (95%) level background (BG) concentrations. As a group, most radionuclides in muscle and bone of deer and elk from LANL lands were not significantly higher (p<0.10) than in similar tissues from deer (n = 3) and elk (n = 7) collected from BG locations. Also, elk that had been radio collared and tracked for two years and spent an average time of 50% on LANL lands were not significantly different in most radionuclides from road kill elk that have been collected as part of the environmental surveillance program. Overall, the upper (95%) level net CEDEs (the CEDE plus two sigma for each radioisotope minus background) at the most conservative ingestion rate (50 lbs of muscle and 13 lbs of bone) were as follows: deer muscle = 0.22 mrem y^‐1 (2.2 μSv y^‐1), deer bone = 3.8 mrem y^‐1 (38 μSv y^‐1), elk muscle = 0.12 mrem y^‐1 (1.2 μSv y^‐1), and elk bone = 1.7 mrem y^‐1 (17 μSv y^‐1). All CEDEs were far below the International Commission on Radiological Protection guideline of 100 mrem y^‐1 (1000 μSv y^‐1), and the highest muscle plus bone net CEDE corresponded to a RECF of 2E‐06, which is far below the Environmental Protection Agency upper level guideline of 1E‐04.     

Leaching of seven pesticides currently used in cotton crop in Mato Grosso State—Brazil

This study aimed to evaluate the leaching of pesticides and the applicability of the Attenuation Factor (AF) Model to predict their leaching. The leaching of carbofuran, carbendazim, diuron, metolachlor, α and β endosulfan and chlorpyrifos was studied in an Oxisol using a field experiment lysimeter located in Dom Aquino – Mato Grosso. The samples of percolated water were collected by rain event and analyzed. Chemical and physical soil attributes were determined before pesticide application to the plots. The results showed that carbofuran was the pesticide that presented a higher leaching rate in the studied soil, so was the one representing the highest contamination potential. From the total carbofuran applied in the soil surface, around 6 % leached below 50 cm. The other pesticides showed lower mobility in the studied soil. The calculated values to AF were 7.06E-12 (carbendazim), 5.08E-03 (carbofuran), 3.12E-17 (diuron), 6.66E-345 (α-endosulfan), 1.47E-162 (β-endosulfan), 1.50E-06 (metolachlor), 3.51E-155 (chlorpyrifos). AF Model was useful to classify the pesticides' potential for contamination; however, that model underestimated pesticide leaching.     

Endosulfan in China 2—emissions and residues

Background, aim, and scope  Endosulfan is one of the organochlorine pesticides (OCPs) and also a candidate to be included in a group of new persistent organic pollutants (UNEP 2007). The first national endosulfan usage inventories in China with 1/4° longitude by 1/6° latitude resolution has been reported in an accompanying paper. In the second part of the paper, we compiled the gridded historical emissions and soil residues of endosulfan in China from the usage inventories. Based on the residue/emission data, gridded concentrations of endosulfan in Chinese soil and air have been calculated. These inventories will provide valuable data for the further study of endosulfan. Methods  Emission and residue of endosulfan were calculated from endosulfan usage by using a simplified gridded pesticide emission and residue model—SGPERM, which is an integrated modeling system combining mathematical model, database management system, and geographic information system. By using the emission and residue inventories, annual air and soil concentrations of endosulfan in each cell were determined. Results and discussion  Historical gridded emission and residue inventories of α- and β-endosulfan in agricultural soil in China with 1/4° longitude by 1/6° latitude resolution have been created. Total emissions were around 10,800 t, with α-endosulfan at 7,400 t and β-endosulfan at 3,400 t from 1994 to 2004. The highest residues were 140 t for α-endosulfan and 390 t for β-endosulfan, and the lowest residues were 0.7 t for α-endosulfan and 170 t for β-endosulfan in 2004 in Chinese agricultural soil where endosulfan was applied. Based on the emission and residue inventories, concentrations of α- and β-endosulfan in Chinese air and agricultural surface soil were also calculated for each grid cell. We have estimated annual averaged air concentrations and the annual minimum and maximum soil concentrations across China. The real concentrations will be different from season to season. Although our model does not consider the transport of the insecticide in the atmosphere, which could be very important in some areas during some special time, the estimated concentrations of endosulfan in Chinese air and soil derived from the endosulfan emission and residue inventories are in general consistent with the published monitoring data. Conclusions  To our knowledge, this work is the first inventory of this kind for endosulfan published on a national scale. Concentrations of the chemical in Chinese air and agricultural surface soil were calculated for each grid cell. Results show that the estimated concentrations of endosulfan in Chinese air and soil agree reasonably well with the monitoring data in general. Recommendations and perspectives  The gridded endosulfan emission/residue inventories and also the air and soil concentration inventories created in this study will be updated upon availability of new information, including usage and monitoring data. The establishment of these inventories for the OCP is important for both scientific communities and policy makers.     

Impact of spiked concentrations of Cd,Pb, As and Zn in growth medium on elemental uptake of Nasturtium officinale (Watercress)

This study is aimed at investigating the impact of water quality on the uptake and distribution of three non-essential and toxic elements, namely, As, Cd and Pb in the watercress plant to assess for metal toxicity. The plant was hydroponically cultivated under greenhouse conditions, with the growth medium being spiked with varying concentrations of As, Cd and Pb. Plants that were harvested weekly for elemental analysis showed physiological and morphological symptoms of toxicity on exposure to high concentrations of Cd and Pb. Plants exposed to high concentrations of As did not survive and the threshold for As uptake in watercress was established at 5 ppm. Translocation factors were low in all cases as the toxic elements accumulated more in the roots of the plant than the edible leaves. The impact of Zn on the uptake of toxic elements was also evaluated and Zn was found to have an antagonistic effect on uptake of both Cd and Pb with no notable effect on uptake of As. The findings indicate that phytotoxicity or death of the watercress plant would prevent it from being a route of human exposure to high concentrations of As, Cd and Pb in the environment.     

Butyltin compounds in sediment and fish from the Polish Coast of the Baltic Sea

Concentrations of mono- (MBT), di- (DBT), and tri-(TBT) butyltin compounds were measured in eggs, liver, and muscle of nine species of fish from four regions of the Baltic Sea - the Firth of Vistula, the Gulf of Gdańsk, Puck Bay, and the mouth of the Vistula River. The overall concentration ranges among all the fish sampled from the four sites were: < 7 to 79 ng/g for MBT, 6 to 1100 ng/g for DBT, 7 to 3600 ng/g for TBT, and 16 to 4800 ng/g for total BTs, on a wet wt basis. The highest concentration of total BTs was found in herring liver from the Firth of Vistula (4800 ng/g, wet wt) and in roach muscle from Puck Bay (3300 ng/g, wet wt), while the least concentration was found in burbot eggs and liver from the Vistula River (39 and 32 ng/g, wet wt, respectively). TBT was the major form of BTs present in most samples analyzed. Sediment samples collected from shipyards in the Gulf of Gdańsk contained butyltin concentrations ranging from 1.2 to 46 μg/g (dry wt) for MBT, 2.0 to 42 μg/g for DBT, and 2.6 to 40 μg/g for TBT. As with the fish, the majority of the BTs in sediment were present as TBT, which suggested recent exposure of the aquatic environment of the region to TBT.     

Malathion-induced sublethal toxicity on the intestine of cricket frog (Fejervarya limnocharis)

The effect of malathion [diethyl(dimethoxythiophosphorylthio)succinate] at sublethal concentration (0.006 ppm) on intestinal parameters of cricket frog (Fejervarya limnocharis) was studied for 24 hrs to 240 hrs of exposure and remarkable histopathological alterations were observed. The study on intestinal parameters revealed acute pathological conditions in the intestinal wall. The toxic effect became evident as the cytoplasm of the cells disintegrated and the cells became empty and vacuolated. The cell membranes were also ruptured. Degenerative changes of the absorptive surface (villi) of the intestine in the different periods of exposure were pronounced. Severe atrophic nature (necrotic mucosa) of the intestine began from 48 hrs onwards to 96 hrs of exposure.