Dissipation,half-lives,and mass spectrometric identification of chlorpyrifos and its two metabolites on field-grown collard and kale

The persistence and fate of chlorpyrifos and its two metabolites, chlorpyrifos-oxon and the 3, 5, 6-trichloro-2-pyridinol (TCP) break-down product were investigated on kale and collard leaves under field conditions. A simultaneous extraction and quantification procedure was developed for chrorpyrifos and its two main metabolites. Residues of chlorpyrifos, chlorpyrifos oxon, and TCP were determined using a gas chromatograph (GC) equipped with an electron capture detector (GC/ECD). Chlorpyrifos metabolites were detectable up to 23 days following application. Residues were confirmed using a GC equipped with a mass selective detector (GC/MSD) in total ion mode. Initial residues of chlorpyrifos were greater on collard (14.5 µg g^?1) than kale (8.2 µg g^?1) corresponding to half-lives (T_1/2) values of 7.4 and 2.2 days, respectively. TCP, the hydrolysis product, was more persistent on collards with an estimated T_1/2 of 6.5 days compared to kale (T_1/2 of 1.9 days).     

Ambient Air Analyses Using Nonspecific Flame lonization and Electron Capture Detection Compared to Specific Detection by Mass Spectroscopy

Ambient air samples from various studies were analyzed for a specific set of trace-level volatile organic compounds by using a gas chromatograph (GC) equipped with a flame ionization detector (FID) in parallel with an electron capture detector (ECD). The samples were then reanalyzed on a second GC system equipped with a mass selective detector (MSD). GC-FID/ECD data were compared to the nominally correct GC-MSD data to determine the accuracy of the nonspecific detectors, which often do not differentiate the targeted compound from Interfering compounds. Qualitative accuracy (capability for correctly identifying compounds on the basis of retention time only) and quantitative accuracy (capability for correctly measuring the concentration of an identified compound on the basis of peak area) were evaluated. Data are presented on a per-compound basis to provide the combined typical results from air samples collected in three geographic regions: Kanawha Valley, WV; Los Angeles, CA, area; and Houston, TX.     

Evaluation of an Ion Selective Electrode Monitor for Total Oxidants

The iodide ion selective electrode has potential use for continuous monitoring of total oxidants in ambient air. Total oxidants are measured coulometrically or colorimetrically after oxidation of neutral buffered Kl solution (0.6-1.2M) to free iodine. On the other hand, the iodide electrode can measure much more dilute solutions (<10^-4M). The iodide electrode measures the disappearance of iodide from the absorbing solution. The detector is made from an iodide electrode, reference electrode, an expanded scale pH meter, and millivolt recorder. The iodide electrode shows a constant Nernstian —59 mv change per decade over a dilute solution range although the absolute voltage shows a drift of 1 mv/day. A continuous iodide electrode air monitor was set up and investigated for ambient monitoring. Operational parameters as air and solution flow rates and electrode parameters as response time at different iodide concentrations were investigated. Statistical comparison was made with a Beekman colorimetric total oxidant monitor and a prototype REM chemiluminescent ozone monitor. The iodide electrode monitor was shown capable of continuously monitoring oxidants in the atmosphere being sensitive to changes in ambient concentrations.     

A Continuous Quantitative Detection Method for Total Mercaptans,Organic Sulphides,H2S,and CS2 for Odouriferous Emissions

A monitoring system enabling detection and determination of the nature of odour nuisance caused by industrial emissions of volatile organic sulphur compounds is presented. The system consists of two continuous, highly sensitive detectors for sulphur compounds at the ppb-level. One of the detectors is equipped with a SO_x-scrubber and measures the total amount of non-S0₂ sulphur compounds. By the use of a newly developed scrubber retaining S0₂, H₂S and CS₂ the second detector monitors the presence of odorous mercaptans and organic sulphides in ambient air. Both these continuous detection signals are fed to a data processor which triggers air collection for the determination of the individual compounds by gas chromatographic analysis in the laboratory. The concept and operation, as well as the practical possibilities and applications of the system are explained     

Agricultural reuse of reclaimed water and uptake of organic compounds: pilot study at Mutah University wastewater treatment plant, Jordan

The residues of polynuclear aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), chlorinated benzenes (CBs) and phenols were investigated for soil, wastewater, groundwater and plants. The uptake concentration of these compounds was comparatively determined using various plant types: Zea mays L., Helianthus annus L., Capsicum annum L., Abelmoschus esculentus L., Solanum melongena L. and Lycopersicon esculentum L. which were grown in a pilot site established at Mutah University wastewater treatment plant, Jordan. Soil, wastewater, groundwater and various plant parts (roots, leaves and fruits) samples were extracted in duplicate, cleaned up by open-column chromatography and analyzed by a multi-residue analytical methods using gas chromatography equipped with either mass selective detector (GC/MS), electron capture detector (GC/ECD), or flame ionization detector (FID). Environmentally relevant concentrations of targeted compounds were detected for wastewater much higher than for groundwater. The overall distribution profiles of PAHs and PCBs appeared similar for groundwater and wastewater indicating common potential pollution sources. The concentrations of PAHs, PCBs and phenols for different soils ranged from 169.34 to 673.20 microg kg(-1), 0.04 to 73.86 microg kg(-1) and 73.83 to 8724.42 microg kg(-1), respectively. However, much lower concentrations were detected for reference soil. CBs were detected in very low concentrations. Furthermore, it was found that different plants have different uptake and translocation behavior. As a consequence, there are some difficulties in evaluating the translocation of PAHs, CBs, PCBs and phenols from soil-roots-plant system. The uptake concentrations of various compounds from soil, in which plants grown, were dependent on plant variety and plant part, and they showed different uptake concentrations. Among the different plant parts, roots were found to be the most contaminated and fruits the least contaminated.     

Petroleum hydrocarbons and polycyclic aromatic hydrocarbons in the surficial sediments of Xiamen Harbour and Yuan Dan Lake, China

Surficial sediments were sampled from nine stations in Xiamen Harbour and two stations in Yuan Dan Lake during April 2002. Sediment samples were extracted by organic solvents, separated by silica gel column chromatography and analyzed by gas chromatography-mass selective detector (GC-MSD). Selected ion monitoring was at M/Z=57 for petroleum hydrocarbons (PHCs) and individual M/Zs for each of the 15 typical polycyclic aromatic hydrocarbons (PAHs) and nine alkylated PAHs. The results showed that concentrations of PHCs and total PAHs in the sediments of Yuan Dan Lake were 1397 microg g(-1) (dry weight, dw) and 1377 ng g(-1) (dw), respectively. The ranges for PHCs and total PAHs in the sediments from Xiamen Harbour were 133-943 microg g(-1) (dw) and 98-309 ng g(-1) (dw), respectively. Shipping activities, industrial wastewater discharges, fuel oil spillage from ships and vehicles were the main sources of PHCs and PAHs in the Harbour. In addition, the widespread use of coal for industrial processes and domestic consumption accounted for the second largest source of PAHs in the sediments, while atmospheric transport and deposition of PAHs are also important.     

Bioremediation of industrial effluents containing heavy metals using brewing cells of <Emphasis Type="Italic">Saccharomyces cerevisiae</Emphasis> as a green technology: a review

The release of heavy metals into the environment, mainly as a consequence of anthropogenic activities, constitutes a worldwide environmental pollution problem. Unlike organic pollutants, heavy metals are not degraded and remain indefinitely in the ecosystem, which poses a different kind of challenge for remediation. It seems that the “best treatment technologies” available may not be completely effective for metal removal or can be expensive; therefore, new methodologies have been proposed for the detoxification of metal-bearing wastewaters. The present work reviews and discusses the advantages of using brewing yeast cells of Saccharomyces cerevisiae in the detoxification of effluents containing heavy metals. The current knowledge of the mechanisms of metal removal by yeast biomass is presented. The use of live or dead biomass and the influence of biomass inactivation on the metal accumulation characteristics are outlined. The role of chemical speciation for predicting and optimising the efficiency of metal removal is highlighted. The problem of biomass separation, after treatment of the effluents, and the use of flocculent characteristics, as an alternative process of cell–liquid separation, are also discussed. The use of yeast cells in the treatment of real effluents to bridge the gap between fundamental and applied studies is presented and updated. The convenient management of the contaminated biomass and the advantages of the selective recovery of heavy metals in the development of a closed cycle without residues (green technology) are critically reviewed.     

Urban roadside aromatic hydrocarbons in three cities of the Pearl River Delta,People's Republic of China

Urban roadside levels of benzene, toluene, ethylbenzene and xylenes (BTEX) were investigated in three typical cities (Guangzhou, Macau and Nanhai) in the Pearl River Delta Region of south China. Air samples were collected at typical ground level microenvironments by multi-bed adsorbent tubes. The BTEX concentrations were determined by thermal desorption–gas chromatography–mass selective detector (TD–GC–MSD) technique. The mean concentrations of benzene, toluene, ethylbenzene and xylenes were, respectively, 51.5, 77.3, 17.8 and 81.6 μg/m³ in Guangzhou, 34.9, 85.9, 24.1, 95.6 μg/m³ in Macau, and 20.0, 39.1, 3.0 and 14.2 μg/m³ in Nanhai. The relative concentration distribution pattern and mutual correlation analysis indicated that in Macau BTEX were predominantly traffic-related while in Guangzhou benzene had sources other than vehicle emission. In Nanhai, both benzene and toluene had different sources other than vehicle emission. The samples collected from Guangzhou showed that BTEX had significant higher concentrations in November than those in July.     

Speciation of non-methane hydrocarbons (NMHCs) from anthropogenic sources in Beirut,Lebanon

The chemical composition of emissions from the different anthropogenic sources of non-methane hydrocarbons (NMHC) is essential for modeling and source apportionment studies. The speciated profiles of major NMHC sources in Lebanon, including road transport, gasoline vapor, power generation, and solvent use were established. Field sampling have been carried out by canisters in 2012. Around 67 NMHC (C2 to C9) were identified and quantified by using a gas chromatograph equipped with a flame ionization detector. Typical features of the roadway emissions included high percentages of isopentane, butane, toluene, xylenes, ethylene, and ethyne. Gasoline evaporation profiles included high percentage of the C4–C5 saturated hydrocarbons reaching 59 %. The main compounds of the power generator emissions are related to combustion. Toluene and C8–C9 aromatics were the most abundant species in emissions from paint applications. Finally, the impact of the use of region-specific source profile is tackled regarding the implication on air quality.     

Effects of dimethoate on honey bee foraging

Collection by honey bees of sucrose solutions treated with dimethoate continued uninterrupted until 2.9–3.9 μg/bee had been accumulated. This self-limiting dose was 20–25 times the oral LD₅₀ for honey bees. Therefore a mean of 45 collection trips involving 1 ppm dimethoate or 11 trips involving 5 ppm was possible before foraging ceased. Losses in pollinator effectiveness and adult and larval mortality are likely to result from dimethoate contamination of nectar.     

Seasonal variation on size distribution and concentration of PAHs in Guangzhou city, China

Size distribution aerosol samples were collected at an urban location of Guangzhou in four seasons of 2003-2004 by a MOUDI (Micro-orifice Uniform Deposit Impactor). The particle loading (PM10: 80-397 microg m(-3)) was comparable with some other Asia cities; however, much higher than that of Western Europe and North America. Polycyclic aromatic hydrocarbons (PAHs) were measured by gas chromatography with mass selective detector (GC-MS). Seasonal effects on the size distribution of PAHs are presented. Bimode (accumulation and coarse mode) and unimode (accumulation mode) distributions were observed for low-molecule-weight and high-molecule-weight PAHs. A slight shift to larger particles was found for the accumulation mode in autumn and winter, compared with that of spring and summer. One explanation is that the longer aging process of PAHs in autumn and winter would result in volatilization from finer particles followed by condensation onto coarser particles. Another is there was mixing process of local emission with long-range transported aerosol in autumn and winter. The relative higher value of IcdP/(BghiP+IcdP) and lower value of BghiP/BeP in winter also give evidences to the mixing process. The level of PAHs concentration has been much elevated in recent years. This can be attributed to the fast growth of motor vehicle and energy consumption.     

Absorption of current use pesticides by snapping turtle (Chelydra serpentina) eggs in treated soil

Reptiles often breed within agricultural and urban environments that receive frequent pesticide use. Consequently, their eggs and thus developing embryos may be exposed to pesticides. Our objectives were to determine (i) if turtle eggs are capable of absorbing pesticides from treated soil, and (ii) if pesticide absorption rates can be predicted by their chemical and physical properties. Snapping turtle (Chelydra serpentina) eggs were incubated in soil that was treated with 10 pesticides (atrazine, simazine, metolachlor, azinphos-methyl, dimethoate, chlorpyrifos, carbaryl, endosulfan (I and II), captan, and chlorothalonil). There were two treatments, consisting of pesticides applied at application rate equivalents of 1.92 or 19.2 kg a.i/ha. Eggs were removed after one and eight days of exposure and analyzed for pesticides using gas chromatography coupled with a mass selective detector (GC-MSD) or high performance liquid chromatography (HPLC). Absorption of pesticides in eggs from soil increased with both magnitude and duration of exposure. Of the 10 pesticides, atrazine and metolachlor generally had the greatest absorption, while azinphos-methyl had the lowest. Chlorothalonil was below detection limits at both exposure rates. Our preliminary model suggests that pesticides having the highest absorption into eggs tended to have both low sorption to organic carbon or lipids, and high water solubility. For pesticides with high water solubility, high vapor pressure may also increase absorption. As our model is preliminary, confirmatory studies are needed to elucidate pesticide absorption in turtle eggs and the potential risk they may pose to embryonic development.     

改进GC/FID法连续观测大气中CO浓度

改进装配有氢火焰离子化检测器(即FID)的气相色谱仪(GC),可连续监测大气中痕量气体CO浓度.本系统采用单阀双柱反吹进样技术,优选前置柱能更有效地剔除杂质,提高了分析柱效率,保持色谱基线平稳,提高分辨率和定量分析的准确率.优化后的气路设计与色谱柱的改进,使GC/FID对CO的最低检出限达到10×10-9、精密度误差小于2%,准确度在±2%之内.将气相色谱与动态气体稀释仪耦合使系统能够自动进行工作曲线校准,系统自动采样、分析和标定,无需人员职守.对北京大气CO连续观测结果表明,北京大气CO浓度变化受气象要素与排放源双重控制.     

Optimization of a methodology for the determination of organochlorine pesticides in surface water by SPME-GC/MS

In the present work experimental conditions were optimized for the analysis of organochlorine traces in water matrix using solid-phase microextraction (SPME) followed by gas chromatography with mass selective detector. The parameters including time of exposure of the fiber in the aqueous sample, fiber type, agitation speed, pH, ionic forces, temperature of adsorption, and time of desorption were evaluated. The best conditions to analyze organochlorine were obtained by using higher than room temperature, agitation of the sample, extraction time of 40 min, and polyacrylate fiber.     

A calibrated source of N2O5

A calibrated source of N₂O₅ was developed for use in evaluating instruments designed to measure reactive odd-nitrogen species in the atmosphere. The desirable features of the source are the output of a very low mixing ratio of N₂O₅, the measurement of total reactive nitrogen NO_y in the source output, and the use of commercially-available detection and calibration equipment. N₂O₅ was derived from a solid crystalline sample at 192 K. Mixing ratios of N₂O₅ less than 2 ppmv (parts per million by volume) were produced in a small flow ( < 50 STPcc min⁻¹) of He carrier gas. This small flow was then diluted to obtain mixing ratios less than 50 ppbv (parts per billion by volume) in flows greater than 1 STPℓ min⁻¹. The N₂O₅ mixing ratio was determined with an accuracy of ± 15 % by using a thermal dissociator, calibrated NO/N₂ mixtures, and an NO chemiluminescence detector. The level of other reactive nitrogen species in the source output was determined with an Au catalytic converter and the NO detector.     

A study of polycyclic aromatic hydrocarbons in airborne particulate matter in central Taiwan

Two sampling sites in central Taiwan, at Hungkuang University (HKU) and Tunghai University (THU), were chosen to contrast the content of polycyclic aromatic hydrocarbons (PAHs) in the atmosphere from November 2000 to April 2001. PAHs that arise from incomplete combustion of organic materials, especially fossil fuels, are the major toxic pollutants in central Taiwan. This study aimed to analyse PAHs, by using a PS-1 sampler and a gas chromatograph/mass selective detector (GC/MSD), and to identify the major sources of PAHs. At the HKU sampling site, the primary emission sources are probably vehicles and coal burning, and vehicular emissions are the primary contributor at the THU sampling site.     

A comparison of the physical, chemical, and biological properties of sludges from a complete-mix activated sludge reactor and a submerged membrane bioreactor.

The properties of sludges from a pilot-scale submerged membrane bioreactor (SMBR) and two bench-scale complete-mix, activated sludge (CMAS) reactors treating municipal primary effluent were determined. Compared with the CMAS sludges, the SMBR sludge contained a higher amount of soluble microbial products (SMP) and colloidal material attributed to the use of a membrane for solid-liquid separation; a higher amount nocardioform bacteria, resulting from efficient foam trapping; and a lower amount of extracellular polymeric substances (EPS), possibly because there was no selective pressure for the sludge to settle. High aeration rates in both the CMAS and SMBR reactors produced sludges with higher numbers of smaller particles. Normalized capillary suction time values for the SMBR sludge were lower than for the CMAS sludges, possibly because of its lower EPS content.     

Spatial and temporal distribution of polycyclic aromatic hydrocarbons (PAHs) in surface water from Liaohe River Basin,northeast China

Liaohe River Basin is an important region in northeast China, which consists of several main rivers including Liao River, Taizi river, Daliao River, and Hun River. As a highly industrialized region, the basin receives dense waste discharges, causing severe environmental problems. In this study, the spatial and temporal distribution of aqueous polycyclic aromatic hydrocarbons (PAHs) in Liaohe River Basin from 50 sampling sites in both dry (May) and level (October) periods in 2012 was investigated. Sixteen USEPA priority PAHs were quantified by gas chromatography/mass selective detector. The total PAH concentration ranged from 111.8 to 2,931.6 ng/L in the dry period and from 94.8 to 2766.0 ng/L in the level period, respectively. As for the spatial distribution, the mean concentration of PAHs followed the order of Taizi River > Daliao River > Hun River > Liao River, showing higher concentrations close to large cities with dense industries. The composition and possible sources of PAHs in the water samples were also determined. The fractions of low molecular weight PAHs ranged from 58.2 to 93.3 %, indicating the influence of low or moderate temperature combustion process. Diagnostic ratios, principal component analysis, and hierarchical cluster analysis were used to study the possible source categories in the study area, and consistent results were obtained from different techniques, that PAHs in water samples mainly originated from complex sources, i.e., both pyrogenic and petrogenic sources. The benzo[a]pyrene equivalents (EBaP) characterizing the ecological risk of PAHs to the aquatic environment suggested that PAHs in Liaohe River Basin had already caused environmental health risks.     

Analysis and fate of acephate and its metabolite,methamidophos, in pepper and cucumber

Abstract

Levels of acephate (Orthene^R) and its principle metabolite, methamidophos, in/on greenhouse‐grown pepper and cucumber fruits and leaves in relation to the applied methamidophos were monitored. Dislodgeable and total residues of acephate and methamidophos were determined by gas‐liquid chromatography equipped with a flame ionization detector (GC‐FID) and were confirmed by nitrogen phosphorus detector (GC‐NPD). The dissipation curves of the residues followed first‐order kinetics (R²> 0.96). Initial residues of acephate on fruits varied between pepper (15.12 ppm) and cucumber (2.16 ppm) . Total residues in fruits and leaves determined at intervals following application revealed the greater persistence of acephate on pepper fruits (half‐life [t_1/2] of 6 d) than on cucumber fruits (t_1/2 was 3.7 d) . T_1/2 values for the applied methamidophos were 4.7 and 5.3 d on pepper and cucumber fruits, respectively. Deacety‐lation of acephate (formation of its metabolite) was detectable 1 d following acephate treatment and reached a maximum of 2.05% of initial acephate residues 3 d after application on pepper fruits. On cucumber fruits, acephate metabolite reached a maximum of 2.12% one wk following application. No acephate residues were detected above the limit of detection of 0.001 ppm in pepper fruits 50 d following acephate application while its metabolite was detectable at that time (detectability limit was 0.0001 ppm).     

Solid-phase microextraction coupled with atomic emission spectroscopy--rapid screening for volatile chlorinated compounds

Solid-phase microextraction (SPME) coupled with atomic emission spectroscopy was evaluated as a rapid screening tool for volatile halogenated compounds in water samples. After extraction, the SPME fiber was introduced to the injector where the analytes were rapidly and efficiently desorbed. The analytes entered the detector over a short period of time and produced one well-defined analyte signal. Element selective responses were measured to confirm the presence and to roughly estimate the content of volatile compounds. The total time for extraction and detection was approximately 5 min, which makes this method a rapid and promising technique for determination of total amount of volatile halogenated compounds. The proposed technique may prove useful as a screening test in order to pinpoint the samples that need further assessment by capillary gas chromatography.