The fate of endosulfan in water

Although the use of endosulfan to control cotton pests has declined, this insecticide still has widespread application in agriculture and can contaminate riverine systems as runoff from soil or by aerial deposition. The degradation of endosulfan in pure water at different pH values of 5, 7 and 9 and in river water from the Namoi and the Hawkesbury rivers of New South Wales (NSW), Australia, was studied in the laboratory. Endosulfan transformation into endosulfan sulfate in river water using artificial mesocosms was also investigated. The results show endosulfan is stable at pH 5, with increasing rates of disappearance at pH 7 and pH 9 by chemical hydrolysis. Incubation of endosulfan with river water at pH 8.3 resulted in the disappearance of endosulfan and the formation of endosulfan diol due to the alkaline pH as well as formation of endosulfan sulfate. Although the degradation of endosulfan by Anabaena, a blue-green alga, did not result in the transformation of endosulfan to endosulfan sulfate, we conclude that other microorganisms catalyzed the formation of the sulfate. Significant conversions of endosulfan into endosulfan sulfate were also reported from associated field studies using artificial mesocoms containing irrigation water from rivers inhabitated by micro-macro fauna. From these results, we conclude that the presence of endosulfan sulfate in river water cannot be used to distinguish contamination by runoff from soil from contamination by aerial drift or redeposition.     

Real-time measurements of jet aircraft engine exhaust

Particulate-phase exhaust properties from two different types of ground-based jet aircraft engines--high-thrust and turboshaft--were studied with real-time instruments on a portable pallet and additional time-integrated sampling devices. The real-time instruments successfully characterized rapidly changing particulate mass, light absorption, and polycyclic aromatic hydrocarbon (PAH) content. The integrated measurements included particulate-size distributions, PAH, and carbon concentrations for an entire test run (i.e., "run-integrated" measurements). In all cases, the particle-size distributions showed single modes peaking at 20-40nm diameter. Measurements of exhaust from high-thrust F404 engines showed relatively low-light absorption compared with exhaust from a turboshaft engine. Particulate-phase PAH measurements generally varied in phase with both net particulate mass and with light-absorbing particulate concentrations. Unexplained response behavior sometimes occurred with the real-time PAH analyzer, although on average the real-time and integrated PAH methods agreed within the same order of magnitude found in earlier investigations.     

Environmental diagnosis methodology for municipal waste landfills

A large number of countries are involved in a process of transformation with regard to the management of municipal solid waste. This process is a consequence of environmental requirements that occasionally materialise in legislation, such as the European Council Directive 31/99/EC on waste release in the European Union. In some cases, the remediation of old landfills can be carried out in compliance with environmental requirements; in other cases, it is necessary to proceed with the closure of the landfill and to assimilate it into its own environment. In both cases, it is necessary to undertake a diagnosis and characterisation of the impacted areas in order to develop an adequate action plan. This study presents a new methodology by which environmental diagnosis of landfill sites may be carried out. The methodology involves the formulation of a series of environmental indeces which provide information concerning the potential environmental problems of the landfills and the particular impact on different environmental elements, as well as information related to location, design and operation. On the basis of these results, it would be possible to draw up action plans for the remediation or closure of the landfill site. By applying the methodology to several landfills in a specific area, it would be possible to prioritize the order of actions required.     

Predictions of binary sorption isotherms for the sorption of heavy metals by pine bark using single isotherm data

The adsorption of three heavy metal ions by pine bark was studied. The study was divided into two parts; single component adsorption of the metals Cu2+, Cd2+ and Ni2+ and bisolute adsorption of the three binary systems Cu2+-Cd2+, Cu2+-Ni2+ and Cd2+-Ni2+. Extended Langmuir model, extended Freundlich model. Sips model and ideal adsorption solution theory (IAST) models were used to predict the equilibrium uptake for Cu2+, Cd2+ and Ni2+ in the binary diluted solutions using the single adsorption constants. The experimental data of single isotherm adsorption process were found to follow Langmuir isotherm model with less accuracy than Freundlich and Sips models. Whereas, the predictions of bisolute adsorption isotherms of the mentioned three systems, Cu2+-Cd2+, Cu2+-Ni2+ and Cd2+-Ni2+, showed good agreement with experimental data when using Extended-Langmuir, Extended-Freundlich and IAST. However, the only good fit of the Sips model was with the Cu2+-Cd2+ system.     

水中总汞量的估测(摘要)

用现有的设备、以冷蒸汽无焰原子吸收法能快速测定低浓度的汞。但是,在测定前,必须将全部汞转化成有机态的汞,还必须去除能结合汞的有机物,而且需在没有汞挥发或吸附损失下进行。下面介绍用化学氧化法和光分解法获得的经验及其结果。     

微分脉冲极谱法测定砷(Ⅲ)、砷(Ⅴ)、和总无机砷

以微分脉冲极谱法完成了对砷(Ⅲ)、砷(Ⅴ)和总无机砷化学形态的测定。砷(Ⅲ)可直接在1M高氯酸或1M盐酸中测定。用煮沸的亚硫酸氢钠溶液将电活性低的砷(Ⅴ)预还原后,可在上述任何一种支持电解质中测定总无机砷。总无机砷与砷(Ⅲ)之差为砷(Ⅴ)。砷(Ⅴ)的浓     

高生长速率下高声学Q石英的生长

水热生长的合成石英中高的声损失严重地降低其可用性,特别是对于高频应用更是如此。早巳知悉,声损失是与碱性生长溶液中以(OH)~-形式进入晶格的间隙 H~ 有关的,H~ 则是为了补偿晶格中 Si~( 4)位置上存在的非正四离子(Fe~( 3)、Fe~( 2)、Cu~( 2)、Al~( 3))的。     

关于环境性致癌因素的探讨(摘译)

人与环境是一个互相作用的整体,环境因素有对人有利的一面和对人有害的一面。这些环境因素有生物的,物理的,和化学的。其中化学因素可由于化学物本身代谢、分解或降解而产生,有些化学因素对细胞可产生毒性反应,也就是致癌、致畸或致突变作用。许多化学因素来源于生产过程对空气、土壤、水和食物的污染。在自然界,大气中细胞毒性剂可来源于植物、微生物、或动物、昆虫的传播。大气中的气态和颗粒物质种类很多,例如有一氧化二氮、二氧化硫等化学排放物,硅酸盐、石棉、     

Alachlor and bentazone losses from subsurface drainage of two soils

Atrazine (6-chloro-N2-ethyl-N4-isopropyl-1,3,5-triazine-2,4-diamine) is frequently detected at high concentrations in ground water. Bentazone [3-isopropyl-1H-2,1,3-benzothiadiazin-4(3H)-one 2,2-dioxide] plus alachlor (2-chloro-2',6'-diethyl-N-methoxymethylacetanilide) is a potential herbicide combination used as a substitute for atrazine. Thus, the objective of this study was to assess the environmental risk of this blend. Drainage water contamination by bentazone and alachlor was assessed in silty clay (Vertic Eutrochrept) and silt loam (Aquic Hapludalf) soils under the same management and climatic conditions. Drainage volumes and concentrations of alachlor and bentazone were monitored after application. Herbicides first arrived at the drains after less than 1 cm of net drainage. This is consistent with preferential flow and suggests that about 3% of the pore volume was active in rapid transport. During the monitoring periods, bentazone losses were higher (0.11-2.40% of the applied amount) than alachlor losses (0.00-0.28%) in the drains of the silty clay and silt loam. The rank order of herbicide mass losses corresponded with the rank order of herbicide adsorption coefficients. More herbicide residues were detected in drainage from the silty clay, probably due to preferential flow and more intensive drainage in this soil than the silt loam. Surprisingly, herbicide losses were higher in the drains of both soils in the drier of the two study years. This could be explained by the time intervals between the treatments and first drainage events, which were longer in the wetter year. Results suggest that the drainage phases occurred by preferential flow in the spring-summer period, with correspondingly fast leaching of herbicides, and by matrix flow during the fall-winter period, with slower herbicide migration.