Methyl Tertiary Butyl Ether (MTBE) and Other Volatile Organic Compounds (VOCs) in Public Water Systems,Private Wells,and Ambient Groundwater Wells in New Jersey Compared to Regulatory and Human-Health Benchmarks

Potential threats to drinking water and water quality continue to be a major concern in many regions of the United States. New Jersey, in particular, has been at the forefront of assessing and managing potential contamination of its drinking water supplies from hazardous substances. The purpose of the current analysis is to provide an up-to-date evaluation of the occurrence and detected concentrations of methyl tertiary butyl ether (MTBE) and several other volatile organic compounds (VOCs) in public water systems, private wells, and ambient groundwater wells in New Jersey based on the best available data, and to put these results into context with federal and state regulatory and human-health benchmarks. Analyses are based on the following three databases that contain water quality monitoring data for New Jersey: Safe Drinking Water Information System (SDWIS), Private Well Testing Act (PWTA), and National Water Information System (NWIS). For public water systems served by groundwater in New Jersey, MTBE was detected at a concentration ≥10 μg/L, ≥20 μg/L, and ≥70 μg/L at least once in 30 (2%), 21 (1.4%), and five (0.3%) of sampled systems from 1997 to 2011, respectively. For private wells in New Jersey, MTBE was detected at a concentration ≥10 μg/L, ≥20 μg/L, and ≥70 μg/L at least once in 385 (0.5%), 183 (0.2%), and 46 (0.05%) of sampled wells from 2001 to 2011, respectively. For ambient groundwater wells in New Jersey, MTBE was detected at a concentration ≥10 μg/L, ≥20 μg/L, and ≥70 μg/L at least once in 14 (2.1%), 9 (1.3%), and 4 (0.6%) of sampled wells from 1993 to 2012, respectively. Average detected concentrations of MTBE, as well as detected concentrations at upper-end percentiles, were less than corresponding benchmarks for all three datasets. The available data show that MTBE is rarely detected in various source waters in New Jersey at a concentration that exceeds the State's health-based drinking water standard or other published benchmarks, and there is no evidence of an increasing trend in the detection frequency of MTBE. Other VOCs, such as tetrachloroethylene (PCE), trichloroethylene (TCE), and benzene, are detected more often above corresponding regulatory or human-health benchmarks due to their higher detected concentrations in water and/or greater toxicity values. The current analysis provides useful data for evaluating the nature and extent of historical and current contamination of water supplies in New Jersey and potential opportunities for public exposures and health risks due to MTBE and other VOCs on a statewide basis. Additional forensic or forecasting analyses are required to identify the sources or timing of releases of individual contaminants at specific locations or to predict potential future water contamination in New Jersey.     

环境水样中甲基汞的前处理和分析方法技术进展研究

环境水样中的甲基汞含量很低,但极易发生生物富集,且具有挥发性和高度的脂溶性,对神经系统造成不可逆的损害.而目前中国环境水样中的甲基汞检测标准滞后,且存在较大弊端,亟需更新.本文综述了前处理技术(液液萃取、固相萃取、固相微萃取、衍生化)和仪器技术(GC、GC-MS、HPLC-ICP-MS和CVAFS)等在检测环境水样中甲基汞的应用实例,论述了各种前处理技术和仪器分析方法的特点与不足,以期在分析环境水体中甲基汞的含量和前处理技术方面提供参考,并对未来的检测手段进行了展望.     

Ti/SnO2-Sb2O5/PbO2电极的制备及降解不同污染物性能研究

采用溶胶凝胶法和电沉积法分别制备了Ti/SnO2-Sb2O5/PbO2电极的中间层和表面活性层,并通过XRD和SEM对电极的中间层和表面活性层进行了相关表征.结果表明,制得的电极表面为β型PbO2,表面形貌均匀致密.同时,采用线性伏安扫描和交流阻抗测试对电极的电化学性能进行了测试.结果表明,电解液中污染物的存在可提高电极的析氧电位,中间层的制备可以有效提高电极的催化性能.另外,通过测定电极对苯酚、靛蓝胭脂红、甲基橙3种不同类型污染物的去除率、COD去除率,研究了该电极对不同类型有机物的降解规律.结果表明,在相同条件下该电极对靛蓝胭脂红的去除速率较高且所需电压最低,降解1 h时靛蓝胭脂红去除率即达100%,甲基橙降解3 h时其COD去除率高达55%.     

A comprehensive review on biodiesel production using Moringa oleifera oil

Biodiesel has emerged as one of the most promising renewable energy to substitute existing petroleum-derived diesel fuel being used in transportation sectors. Among the various feedstocks reported for biodiesel production, Moringa oleifera oil is becoming a promising replacement for conventional diesel fuel. Therefore, this work provides a comprehensive overview of the recent progress in biodiesel production from Moringa oleifera oil. The physicochemical properties, fatty acid composition of oil and methyl esters, oil extraction methods, esterification, and transesterification process, and purification methods employed in the biodiesel production have been discussed.     

Determination of methyl tert-butyl ether (MTBE) in Chinese fuels by gas chromatography/mass spectrometry and gas chromatography/flame ionization detector

A method was developed to determine the concentration of methyl tert-butyl ether(MTBE) in gasoline,diesel and heating oil by gas chromatography(GC) with mass spectrometry(GC-MS) or flame ionization detection(FID). The diluted gasoline was directly injected into the GC, and the complete separation of MTBE from co-eluting hydrocarbons was not required. GC/MS or GC/FID method can be used to analyze MTBE in different concentration range and have good consistency.     

甲醇燃料发动机排气中的亚硝酸甲酯和硝酸甲酯的分析

为了测定使用甲醇燃料的发动机排气里的亚硝酸甲酯(MeONO)和硝酸甲酯(MeONO_2)含量,建立了色谱分析方法。本方法的最小检测限MeONO为20ppb,MeONO_2为50ppb。对自制的MeONO和MeONO_2进行了质谱鉴定,并对所制备的一定浓度的样品进行了稳定性考察。应用本方法测定了甲醇机排气中的MeONO含量为5ppm—250ppm,MeONO_2含量为<50ppb。     

A semipermeable membrane equilibrator for halomethanes in seawater

An equilibrator for sampling the partial pressures of halomethanes in seawater was designed and built, incorporating semipermeable membrane tubing to carry the gas phase. The equilibrator was tested for its ability to equilibrate chloromethane, bromomethane, iodomethane, and CFC-11. The residence time required for these halomethanes to equilibrate in the tubing (30 to 60 s) was determined experimentally. In a laboratory test, concentrations calculated from equilibrator measurements and based on published solubility values were found to differ by 6% to 16% from concentrations measured with a purge-and-trap apparatus, but uncertainties in the solubility values are likely to contribute significantly to the differences. In a comparison at sea, no significant difference was found between the semipermeable membrane equilibrator and another, more conventional equilibrator, except a 1.3% difference for CFC-11. This study demonstrates the feasibility of using semipermeable membranes in this and related applications.     

氯吡嘧磺隆和镉复合对斑马鱼肝脏的影响

为了探究污染物镉和氯吡嘧磺隆复合污染对非靶标生物斑马鱼的毒性作用,通过急性毒性试验,获得镉和氯吡嘧磺隆对斑马鱼的LC50.以LC25作为0水平,设置9个处理组进行试验,检测不同处理组斑马鱼96 h死亡率、斑马鱼肝脏中CAT、MDA和羧酸酯酶CarE.检测结果表明,镉和氯吡嘧磺隆对斑马鱼存在交互作用,当水体中镉浓度为3....     

磁场强化铁碳微电解降解甲基橙的研究

铁碳微电解技术因其操作简单、生态环保和经济高效等优势,常被用于印染废水的治理研究,但该技术存在COD去除率低和适用p H范围窄的问题。为了克服以上问题,引入磁场强化技术。通过批试验,系统考察了初始p H、初始甲基橙浓度、转速和温度等对磁场强化铁碳微电解去除甲基橙过程的影响。研究结果表明:磁场能够显著提升铁碳微电解去除甲基橙和COD的效率,且拓宽了p H的适用范围。结合SEM、XRD和电化学技术表征,阐明了磁场强化铁碳微电解去除甲基橙的机理是磁场能够加速铁碳微电解的腐蚀,产生大量二价铁,从而强化还原去除甲基橙。本研究提出了一种新的强化铁碳微电解高效去除污染物方法。     

催化臭氧氧化染料溶液的研究

采用催化臭氧化技术降解染料废水,以甲基紫溶液为目标污染物,研究了过渡型金属离子的类型,Fe2+的浓度,溶液初始pH值,染料浓度和正丁醇等因素对其降解率的影响。实验结果表明:臭氧氧化甲基紫溶液的过程中,加入一定浓度的过渡型金属离子对甲基紫的去除具有促进作用;当臭氧浓度为16 mg/L,一定浓度范围内,Fe2+催化臭氧化的效果随着浓度的增加而增加,但Fe2+浓度为13 mg/L时,甲基紫的降解率下降;在酸性范围时,pH值增大其降解率会减小;染料浓度增加,甲基紫的降解率减小,但是其绝对降解值会增加;正丁醇的加入抑制氧化反应的进行,甲基紫的降解率下降,说明催化臭氧化过程中有羟基自由基产生。染料降解过程符合一级反应动力学规律。