用煤矸石合成4A沸石分子筛处理氨氮废水

以煤矸石为原料，采用碱熔一水热法合成4A沸石分子筛。由于煤矸石中铝、硅主要以高岭土形式存在，其活化过程是合成4A沸石分子筛关键环节。为提高4A沸石分子筛钙离子的交换能力，增加对模拟废水氨氮的去除率，实验考察了碳酸钠与煤矸石质量比、活化温度、活化时间、晶化温度和晶化时间对4A沸石分子筛钙离子交换能力的影响，同时也考察了模拟废水的pH、4A沸石分子筛加入量及吸附时间对氨氮去除率的影响。结果表明，最佳工艺条件为，碳酸钠与煤矸石质量比为0．9、活化温度为800％、活化时间1．5h、晶化温度90％和晶化时间3h。合成4A沸石分子筛的钙离子交换能力为310mg／g，在pH为6的100mL模拟氨氮废水中加入6g4A沸石分子筛吸附40min后，废水中氨氮的去除率达到86％。通过最佳工艺条件合成4A沸石分子筛，在处理氨氮废水方面具有一定的应用前景。     

4A沸石分子筛处理中低浓度氨氮废水

利用天然沸石、采用水热合成法制备4A沸石分子筛,用XRD和SEM进行了表征。通过考察吸附剂用量、pH、共存金属阳离子、吸附时间、氨氮废水初始浓度、温度对吸附性能的影响,结合动力学方程、吸附等温线、热力学函数等研究了吸附性能和机理。结果表明,当4 g/L的4A沸石分子筛在废水pH值为4~8的条件下对中低浓度氨氮吸附120min后,去除率可达88%;废水中共存单一金属阳离子(Pb2+、Cu2+、Ca2+和Mg2+)浓度大于100 mg/L时,对中低浓度的NH+4有强烈的竞争吸附;氨氮的吸附过程较好地符合准二级动力学方程、Freundlich模型,是一种混乱度增加、自发的放热过程。     

斜发沸石处理氨氮废水

以斜发沸石为吸附剂处理氨氮废水,研究了斜发沸石粒径、反应时间、废水pH、废水氨氮初始浓度、斜发沸石用量对吸附的影响,分析了斜发沸石的吸附动力学和热力学特征。结果表明,在298 K下,当斜发沸石用量为7 g/100 mL,沸石粒径小于74μm,废水氨氮初始浓度为200 mg/L,pH为7,吸附时间为3 h时,废水中氨氮的去除率可达到92.71%,斜发沸石吸附氨氮符合拟二级动力学方程。在温度为298~318 K之间时,吸附等温线更好地符合Freundlich方程。在此基础上,热力学计算发现,ΔH00、ΔG00、ΔS00,表明氨氮在斜发沸石上的吸附是自发吸热过程,以物理吸附为主。     

4A沸石去除水中Pb2＋的研究

在静态条件下，研究了4A沸石对废水中Pb2＋的吸附性能，并探讨了影响吸附的因素。实验表明：当温度为30℃，废水pH为5～6，0．01g4A沸石对100mg／LPb2＋溶液10mL吸附20min，Pb2＋的去除率可达到99％以上。在实验研究条件下，4A沸石对Pb2＋的吸附符合Langmuir和Freundlich等温吸附方程，相关系数为0．9819和0．9998。经计算，4A沸石对Pb2＋的饱和吸附量为125mg／g。4A沸石吸附水中Pb2＋达到吸附平衡的时间较短；溶液pH值的变化对吸附效果影响不显著；温度从室温略微升高，Pb2＋的去除率略有增大。吸附在4A沸石上的Pb“可回收利用，处理后的4A沸石可以再生，且重复使用性能较好。     

4A沸石去除水中Pb~(2+)的研究

在静态条件下,研究了4A沸石对废水中Pb2+的吸附性能,并探讨了影响吸附的因素。实验表明:当温度为30℃,废水pH为5~6,0.01 g4A沸石对100 mg/LPb2+溶液10 mL吸附20 min,Pb2+的去除率可达到99%以上。在实验研究条件下,4A沸石对Pb2+的吸附符合Langmuir和Freundlich等温吸附方程,相关系数为0.9819和0.9998。经计算,4A沸石对Pb2+的饱和吸附量为125 mg/g。4A沸石吸附水中Pb2+,达到吸附平衡的时间较短;溶液pH值的变化对吸附效果影响不显著;温度从室温略微升高,Pb2+的去除率略有增大。吸附在4 A沸石上的Pb2+可回收利用,处理后的4A沸石可以再生,且重复使用性能较好。     

以粉煤灰为原料制备高纯度NaP型分子筛

以工业固体废弃物粉煤灰为原料,经分级处理后提取其中的硅铝元素(Na_2SiO_3和NaAlO_2),通过水热合成法制备高纯度NaP型分子筛。考察了硅铝比、水硅比、晶化时间和晶化温度对NaP型分子筛制备的影响,采用XRD、SEM、FTIR和DTA-TG对NaP型分子筛的晶型、形貌、热稳定性进行分析表征,并考察了NaP分子筛对Cu~(2+)的吸附性能。实验结果表明,当H_2O/Si为120、Si/Al为1.0,晶化温度为115℃、晶化时间9h时,可得到高纯度NaP型分子筛。合成的NaP型分子筛可有效地吸附Cu~(2+),温度升高有助于分子筛吸附能力的提升,当吸附温度为45℃,吸附120min时,Cu~(2+)的最大去除率可达98.3%。     

粉煤灰合成NaX型分子筛的表征及其对Fe~（2＋）离子的吸附研究

以高温碱熔融处理粉煤灰合成了NaX型沸石分子筛,考察了不同水热晶化温度对产物结果的影响,用粉末XRD、XRF、SEM和FT-IR等手段对产品进行了表征,结果表明,以粉煤灰为原料用水热合成法合成微孔分子筛时,在晶化温度为90℃时能得到晶形较好的NaX型分子筛。同时考察了NaX分子筛的用量、时间和pH值等因素对Fe2＋离子的吸附影响,在25 mL Fe2＋离子浓度为2×103 mg/L的溶液中,当吸附剂用量为0.2 g,吸附时间为2 h,吸附效率达到最大值（36.41%）,而随着溶液pH值的升高其吸附效率显著增大。     

斜发沸石对城市污水处理厂二级出水中氨氮的处理效果研究

通过静态实验,研究天然斜发沸石去除城市污水处理二级出水中氨氮的性能。研究结果表明,投加量越大,沸石对废水中氨氮的去除率越高,但是吸附容量越低;沸石对氨氮的去除具有短时间内快速吸附,然后缓慢平衡的特点;粉末状沸石对氨氮的去除效果明显好于颗粒状沸石;pH对氨氮去除率有显著影响,pH值为6时,沸石对氨氮的去除率最高。NaCl和NaOH溶液对沸石的改性具有明显的效果,HCl溶液对沸石的改性作用不明显。     

复合分子筛去除水中氟化物的研究

通过使用复合分子筛对模拟含氟水进行静态吸附实验,研究了复合分子筛对水中氟化物的吸附性能,并分析了吸附过程中温度、pH值和停留时间等因素对分子筛除氟效率的影响。结果表明,用80 g粒径0.9 mm的分子筛处理150 mL浓度为5 mg/L的模拟含氟水,分子筛的除氟效率达到90%以上,而同样条件下天然沸石和改性涂铁沸石的去除率分别为23.35%和80.69%。分子筛的除氟效率随着温度呈现先上升后下降的趋势,50℃时去除效率达到最高,为92.7%;在弱酸性条件下的去除率比碱性条件要高,在pH=4时去除率最大,为91.8%;停留时间初始阶段与去除率保持正相关,在45 min后反应达到平衡。分子筛的吸附速率符合二级动力学方程dqe/dt=k(qe-qt)2,吸附等温线符合Langmuir方程。     

沸石法工业污水氨氮治理技术研究

本文研究了斜发沸石法去除工业污水中氨氮的方法，通过沸石对NH4^ 的全交换容量、吸附和洗脱工艺条件对去除氨氮效果影响的试验，确定了处理氨氮废水的工艺流程和适宜参数。结果表明，在废水浓度pH＝7的条件下，沸石对铵的平均全交换容量达到12.96mg/g沸石，且交换容量随pH值的增大而降低；高速低温有利于吸附，低速高温有利于洗脱；处理后污水氨氮含量低于50mg/L，达到了国家排放标准。本研究可为治理氨氮废水技术开发提供了一定的技术依据。     

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.     

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 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.     

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.     

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.     

Nitrogen leaching and acidification during 19 years of NH₄NO₃ additions to a coniferous-forested catchment at Gårdsjön, Sweden (NITREX)

The role of nitrogen (N) in acidification of soil and water has become relatively more important as the deposition of sulphur has decreased. Starting in 1991, we have conducted a whole-catchment experiment with N addition at Gårdsjön, Sweden, to investigate the risk of N saturation. We have added 41 kg N ha⁻¹ yr⁻¹ as NH₄NO₃ to the ambient 9 kg N ha⁻¹ yr⁻¹ in fortnightly doses by means of sprinkling system. The fraction of input N lost to runoff has increased from 0% to 10%. Increased concentrations of NO₃ in runoff partially offset the decreasing concentrations of SO₄ and slowed ecosystem recovery from acid deposition. From 1990-2002, about 5% of the total N input went to runoff, 44% to biomass, and the remaining 51% to soil. The soil N pool increased by 5%. N deposition enhanced carbon (C) sequestration at a mean C/N ratio of 42-59 g g⁻¹.     

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.