Emissions and distribution of methyl bromide in field beds applied at two rates and covered with two types of plastic mulches

A field experiment was conducted to compare two plastic mulches and two application rates on surface emissions and subsurface distribution of methyl bromide (MBr) in field beds in Florida. Within 30 minutes after injection of MBr to 30 cm depth, MBr had diffused upward to soil surface in all beds covered with polyethylene film (PE) or virtually impermeable film (VIF) and applied at a high rate (392 kg/ha) and a low rate (196 kg/ha). Due to the highly permeable nature of PE, within 30 minutes after injection, MBr volatilized from the bed surfaces of the two PE-covered beds into the atmosphere. The amount of volatilization was greater for the high rate-treatment bed. On the other hand, volatilization of MBr from the bed surfaces of the two VIF-covered beds were negligible. Volatilization losses occurred from the edges of all the beds covered with PE or VIF and were greater from the high rate-treatment beds. Initial vertical diffusion of MBr in the subsurface of the beds covered with PE or VIF was mainly upward, as large concentrations of MBr were detected from near bed surfaces to 20 cm depth in these beds 30 minutes after injection and little or no MBr was found at 40 cm depth. The two VIF-covered beds exhibited greater MBr concentrations and longer resident times in the root zone (0.5-40 cm depth) than corresponding PE-covered beds. Concentrations of MBr in the root zone of the high rate-treatment beds were 3.6-6.1 times larger than the low rate-treatment beds during the first days after application. In conclusion, VIF promoted retention of MBr in the root zone and, if volatilization loss from bed edges can be blocked, volatilization loss from VIF-covered beds should be negligible.     

纳米零价铁对衰减停滞期氯代烃污染地下水的实地修复

在处于衰减停滞期的氯代烃污染场地,进行了液相纳米零价铁(nZVI)的现场制备,并针对目标含水层完成了nZVI的2次原位注入.监测结果表明,nZVI的原位注入可有效削减高浓度的氯乙烯(VC)且减缓其向下游的迁移.在第2次注入nZVI后期,在距注入井lm的上游和下游监测井中,氯代乙烯整体呈现降低的趋势;而上游监测井中的氯代乙烷则发生显著反弹;在距注入井2m的下游监测井中,各氯代烃均发生持续降解.总铁浓度变化结果表明,原位注入过程促使部分nZVI短期内向上游发生了定向迁移,导致注入初期上游监测井中氯代烃的削减程度高于下游监测井.乙烯浓度的大幅升高(由1490μg·L-1增加至4110μg·L-1)印证了距注入井2 m的下游监测井中脱氯反应最为显著且彻底,可推测下游适量nZVI的引入有效刺激了含水层优势微生物的协同降解.nZVI原位注入可作为以VC污染为主的衰减停滞期地下水修复的有效手段.以上研究结果可为实际场地大规模治理修复提供参考.     

浅谈环境监管人员如何解读渎职司法解释研究

文章结合两高关于渎职司法解释,探讨环境监管人员的依法履职。首先简明扼要地阐述了《解释》关于滥用职权罪、玩忽职守罪的定罪量刑标准等9个方面的内容,并就失误、失职、渎职和徇私舞敝的概念进行了分析与鉴别,最后重点论述了环境监管人员在环境监管与应急管理工作中环境监管失职罪、滥用职权罪、玩忽职守罪以及企业涉嫌污染环境罪的定义、主体、时效等适用《解释》的情况,并对环境污染经济损失认定和涉嫌犯罪案件的移送进行了探讨。     

Process safety data management program based on HAZOP analysis and its application to an ethylene oxide/ethylene glycol plant

HAZOP analysis is a process hazard analysis method that has been widely applied both within and outside the chemical processing industries. This paper presents a design method for a process safety data management program for petrochemical plants based on HAZOP analysis and demonstrates the steps of application involved in building a process safety data management system for an ethylene oxide/ethylene glycol production plant. Firstly, the production data files and relevant documents of the plants should be classified and stored in the program database as reference documents and treatment schemes for coping with abnormal situations should be collected and summarized as guidance documents. Secondly, the HAZOP analysis method is employed to identify all the dangerous deviations possibly existing in the production process of the ethylene oxide/ethylene glycol plant. Then, the relationships among the deviations, the reference documents and the guidance documents should be considered and evaluated. Finally, each dangerous deviation will be given a corresponding reference document and guidance document. The reference documents and guidance documents stored in the expert system can be utilized to help operators solve the corresponding technical problems and cope with abnormal situations. The process safety data management program will contribute to the identification, analysis and resolution of operation problems. When an abnormal situation occurs, according to the deviations exhibited in the system, the necessary reference documents and guidance documents will be quickly consulted by the operators, and an appropriate decision will be made to address the abnormal situation. Therefore, by using the process safety data management program, plant security and human safety in the petrochemical industries will be improved.     

环保型棉纺织品耐久阻燃系统

本文介绍两类环保型棉纺织品耐久阻燃系统，一类是无卤锑系统，另一类是无甲醛或低甲醛系统。前一类包括磷氮系膨胀型阻燃剂、有机磷酸酯及多元醇磷酰氯；后一类包括低甲醛的磷氮系、磷酸酯-膦酸酯齐聚物-低甲醛含量树脂复合系统、烷基氨基磷酸酯-氯化铵加合物、多羧酸酯等。后两者系无甲醛配方。     

城市污水处理厂进水浓度偏低原因分析及对策研究

城市污水处理厂进水浓度偏低是南方地区许多城市面临的共同问题,既影响废水主要污染物COD的减排成效,制约水环境质量的改善,也在一定程度上造成城市污水处理工程的投资浪费.以张家界市中心城区污水处理厂为例,通过现场勘测与监测分析,考察了管网渗漏、雨污合流、地表水渗入、管网反坡和管网颗粒物沉积等因素,探究造成该市城市污水处理厂进水浓度偏低的主要原因,并在此基础上提出有针对性的对策建议,供管理部门参考.     

Long-term evaluation of activated carbon as an adsorbent for biogas desulfurization

ABSTRACT

In this study, granular activated carbon (GAC) was used as an adsorbent for biogas desulfurization. Biogas containing 932–2,350 ppm of H₂S was collected from an anaerobic digester to treat the wastewater from a dairy farm with about 200 cows. An adsorption test was performed by introducing the biogas to a column that was packed with approximately 50 L of commercial GAC. The operation ceased if the effluent gas had an H₂S concentration of over 100 ppm. The GAC was replaced by a given weight of new GAC in a subsequent test. According to the results, for H₂S concentrations in the range of 932–1,560 ppm (average±SD = 1,260 ± 256 ppm), 1 kg of the GAC yielded biogas treatment capacities of 568 ± 112 m³ and H₂S adsorption capacities of 979 ± 235 g. For the higher influent H₂S concentrations of 2,110 ± 219 ppm, the biogas treatment and H₂S-adsorption capacities decreased to 229 ± 18 m³ and 668 ± 47 g, respectively. An estimation indicated a requisite cost of US$16.5 for the purification of 1,000 m³ of biogas containing 2,110 ppm of H₂S. This cost is approximately 5% of US$330, the value of 1,000 m³ of biogas.     

Acute toxicity of benzene derivatives to the tadpoles (Rana japonica) and QSAR analyses

Acute lethal toxicity (the negative logarithm of molar concentrations of 12 h acute median lethal, expressed as 12 h-log1/LC50) of 46 benzene derivatives to Rana japonica tadpoles was determined. 1-octanol/water partition coefficient (logKow)-dependent models were developed to study the toxicity of different categories chemicals. In an effort to model all chemicals, response surface analyses and stepwise multiple regression analyses were performed and successful models were obtained. A general and robust QSAR model was achieved with the combined application of variables reflecting hydrophobicity, electric property, and molecular size respectively (12h-log1/LC50 = 0.393logKow - 0.428Elumo + 0.0110Vol. + 1.362 n = 51, r2 = 0.834) using stepwise multiple regression analyses. Because of strong dissociation of carboxyl group greatly decreasing their observed toxicity, using logDow in instead of logKow the quality of the models is greatly improved. The conventional r2 and cross-validation r2(CV) were 0.914 and 0.785, respectively, indicating that QSAR was both internally consistent and highly predictive.     

Atmospheric volatilization and distribution of (Z)- and (E)-1,3-dichloropropene in field beds with and without plastic covers

The fumigant 1,3-dichloropropene (1,3-D) is considered to be a potential replacement for methyl bromide when methyl bromide is phased out in 2005. This study on surface emissions and subsurface diffusion of 1,3-D in a Florida sandy soil was conducted in field beds with or without plastic covers. After injection of the commercial fumigant Telone II by conventional chisels to field beds at 30cm depth which were covered with polyethylene film (PE), virtually impermeable film, or no cover (bare), (Z)- and (E)-1,3-D rapidly diffused upward. Twenty hours after injection, majority of (Z)- and (E)-1,3-D had moved upward from 30 cm depth to the layer of 5-20 cm depth. Downward movement of the two isomers in the beds with or without a plastic cover was not significant. (Z)-1,3-D diffused more rapidly than (E)-1,3-D. Virtually impermeable films (VIF) had a good capacity to retain (Z)- and (E)-1,3-D in soil pore air space. Vapor concentrations of the two isomers in the shallow subsurface of the field bed covered with VIF were greater than that in the two beds covered with polyethylene film (PE) or no cover (bare). In addition, VIF cover provided more uniform distribution of (Z)- and (E)-1,3-D in shallow subsurface than PE cover or no cover. Virtually impermeable film also had a better capability to retard surface emissions of the two isomers from soil in field beds than PE cover or no cover.     

利用化学混凝法处理钻井污水实验研究

采用化学混凝法对江汉油田钻井污水进行了室内处理实验。实验结果表明,污水处理时所选絮凝剂的种类、加入量、加入顺序、温度和加入后的沉降时间等都会影响处理效果。采用单一无机化学药剂,沉降速度较慢,故考虑将无机和有机药剂复配使用,即利用先加无机药剂后再加入有机药剂的顺序处理该油田钻井废水。该实验结果为油田钻井污水无害化处理提供了基础资料。