Organic pollutants in wild ducks from New York state: I. Interspecies differences in concentrations and congener profiles of PCBs and PCDDs/PCDFs

Wild ducks of three species, common mergansers (Mergus merganser americanus), gadwalls (Anas streptera), and mallards (Anas platyrhynchos), were collected near industrial sites in the Massena, NY area of the St. Lawrence River (SLR) in 1988/89 and 1994. Additional samples were collected in 1994 near a former polychlorinated biphenyl (PCB) capacitor plant at Fort Edward, NY (a mallard and two wood ducks (Aix sponsa)), and at control sites (common mergansers, mallards and wood ducks). On a lipid basis, PCB concentrations in liver tissue from the 1994 collection ranged from 0.1 mug/g in a control wood duck to 676 mug/g in a common merganser from the SLR area. However, the highest total polychlorinated dibenzofuran (PCDF) concentrations were found in liver and fat tissues of gadwalls and mallards collected near the SLR industrial sites (2.8-12 ng/g lipid). These two species bioaccumulated non-2,3,7,8-substituted PCDFs in addition to 2,3,7,8-PCDF isomers, whereas common mergansers preferentially bioaccumulated 2,3,7,8-substituted PCDFs. The mergansers from the SLR sites were the only specimens contaminated with polychlorinated dibenzo-p-dioxins (PCDDs), which were all 2,3,7,8-substituted. The PCB and PCDF congener patterns in the duck tissues appear to have been influenced by both sampling location and species trophic level.     

The behaviour of linear alkyl benzene sulphonate under direct discharge conditions in Vientiane, Lao PDR

Direct discharge of untreated sewage to surface waters is a common practice in many parts of the world. However, relatively little is known about the behaviour of synthetic organic pollutants under these conditions. This paper describes a sampling campaign designed to track changes in water quality in a surface water system in Vientiane (Lao PDR) receiving significant quantities of untreated waste water. The study was based on following in-channel transport using a fluorescent tracer injected as a pulse, with a focus on the anionic surfactant linear alkylbenzene sulphonate (LAS) and ammonia. Water samples were collected at a number of stations with sampling times estimated to coincide with solute time-of-travel. The reduction in LAS concentration with flow-time could be approximated by first-order kinetics with a half life of about 7 h. Free ammonia concentrations decreased more slowly than LAS and remained above the level believed to be toxic for sensitive aquatic species along the entire channel. Changes in the ratios of LAS alkyl chain homologues to total LAS concentrations suggest a preferential removal of longer chain lengths. The role of biodegradation in the removal of LAS was confirmed by the presence of LAS metabolites (sulphophenylcarboxylates, SPCs) which increased systematically (as a fraction of LAS remaining) with flow-time.     

Is phenol condensation one of the major pathways in the formation of polychlorinated dibenzofurans in municipal waste incinerators?: Model prediction vs. field observation

The role of phenol condensation pathways in the formation of polychlorinated dibenzofurans (PCDF) in a municipal waste incinerator was assessed by comparing predicted PCDF homologue and isomer patterns with those obtained from the incinerator. A two-phenol condensation model, dependent only on the distribution of phenols, was used to predict the distributions of PCDF congeners in the incinerator. Complete distributions of phenols and PCDF congeners were obtained from the incinerator. To quantify the degree of agreement between obtained isomer distributions and those predicted by the model, R-squared values from linear correlations were calculated for the dichlorinated- through hexachlorinated-isomers. They ranged from 0.001 to 0.1. Agreement between obtained and predicted PCDF isomers was very poor for all homologues, suggesting that phenol condensation pathways are unlikely to be the primary route in the formation of PCDF in the incinerator. However, dibenzofuran (DF) is likely to be produced from a condensation of two phenols. This paper shows the use of PCDF homologue and isomer patterns calculated by the two-phenol condensation model for testing PCDF formation mechanism attribution in a municipal waste incinerator.     

An improved microdesulphonation/gas liquid chromatography procedure for the determination of linear alkylbenzene sulphonates in U.K. rivers

An improved microdesulphonation/gas liquid chromatography (GLC) procedure is described for the specific determination of μg l⁻¹ levels of linear alkylbenzene sulphonates (LAS) in aqueous environmental samples including sewage, sewage effluent and surface waters. The LAS is concentrated from samples as its methylene blue complex by a large-scale solvent extraction and is then freed from potential interferences by a series of clean-up steps, i.e. ion-exchange chromatography, hydrolysis and solvent extraction, prior to its desulphonation with a concentrated phosphoric acid reagent. The resulting alkylbenzene hydrocarbons are recovered and quantitatively determined by a capillary GLC technique with the aid of internal standards (primary and secondary alkylbenzene sulphonate isomers) added at the initial concentration stage.The introduction of the clean-up stages, particularly a selective extraction of the LAS as the l-methylheptyl amine salt into hexane, has resulted in GLC traces that are free from major interferences and in which it is possible to readily identify LAS isomers on the basis of the relative retention times. The procedure has a limit of detection of less than 10 μg l⁻¹ LAS in a sample and allows the quantification of sub-μg l⁻¹ levels of individual isomers (C₉–C₁₅ homologues). The mean recovery of a C₁₂ LAS internal standard through the complete procedure is 91% for the environmental samples analysed.This procedure, together with a non-specific methylene blue colorimetric method (for determining anion surface active material), has been used in a monitoring exercise to establish the levels of LAS and methylene blue active substances (MBAS) in U.K. rivers and the River Rhine. A mean MBAS level of 0.15 mg l⁻¹ was found at the U.K. river sites selected (35 samples), of which only 26% on average was attributable to LAS by microdesulphonation/GLC analysis. However, the levels of LAS and its contribution to the total MBAS in rivers was found to vary with the nature of the sampling location, i.e. depending whether it was above, below or in the vicinity of a sewage effluent discharge. The distribution of the LAS isomers at these sites also showed differences that could be explained in terms of their relative biodegradabilities.     

Bacterial source tracking from diverse land use catchments by sterol ratios

Water samples from sites potentially impacted by septic tanks, cattle, sewage treatment plant (STP) and natural forests were collected at regular monthly intervals and within 48 h of rainfall events between October 2004 and June 2006. All samples (n=296) were analysed for faecal coliforms and faecal sterols including coprostanol, epicoprostanol, cholestanol, cholesterol and 24-ethylcoprostanol. Faecal sterol ratios were used to assign human and/or herbivore contamination sources and to estimate their percentage relative contributions in water samples. The catchments had significantly different profiles of designated contamination origins (p<0.05), which were consistent with land use patterns. The STP impacted site had the highest incidence of human contamination assignations and the highest mean levels of coprostanol, whilst the forested site had the highest incidence of uncontaminated samples and the lowest mean concentration of coprostanol. Coprostanol concentrations were not always correlated with faecal coliform counts.     

A seasonal study of the mecA gene and Staphylococcus aureus including methicillin-resistant S. aureus in a municipal wastewater treatment plant

The spread of methicillin-resistant Staphylococcus aureus (MRSA), in which the mecA gene mediates resistance, threatens the treatment of staphylococcal diseases. The aims were to determine the effect of wastewater treatment processes on mecA gene concentrations, and the prevalence of S. aureus and MRSA over time. To achieve this a municipal wastewater treatment plant was investigated for the mecA gene, S. aureus and MRSA, using real-time PCR assays. Water samples were collected monthly for one year, at eight sites in the plant, reflecting different aspects of the treatment process. The mecA gene and S. aureus could be detected throughout the year at all sampling sites. MRSA could also be detected, but mainly in the early treatment steps. The presence of MRSA was verified through cultivation from inlet water. The concentration of the mecA gene varied between months and sampling sites, but no obvious seasonal variation could be determined. The wastewater treatment process reduced the mecA gene concentration in most months. Taken together our results show that the mecA gene, S. aureus and MRSA occur over the year at all sites investigated.     

Mercury in ground water, septage, leach-field effluent, and soils in residential areas, New Jersey coastal plain

Water samples were collected from domestic wells at an unsewered residential area in Gloucester County, New Jersey where mercury (Hg) concentrations in well water were known to exceed the USEPA maximum contaminant level (MCL) of 2,000 ng/L. This residential area (the CSL site) is representative of more than 70 such areas in southern New Jersey where about 600 domestic wells, sampled previously by State and county agencies, yielded water containing Hg at concentrations that exceed the MCL. Recent studies indicate that background concentrations of Hg in water from this unconfined sand and gravel aquifer system are <10 ng/L. Additional sampling was conducted at the CSL site in order to better understand sources of Hg and potential Hg transport mechanisms in the areas with Hg-contaminated ground water. At the CSL site, concentrations of Hg were substantially lower (although still exceeding the MCL in some cases) in filtered water samples than in the unfiltered water samples collected previously from the same wells. Surfactants and elevated concentrations of sodium, chloride, nitrate, ammonium, and phosphate in water from domestic and observation wells indicated septic-system effects on water quality; detections of sulfide indicated localized reducing conditions. Hg concentrations in septage and leach-field effluent sampled at several other households in the region were low relative to the contaminant-level Hg concentrations in water from domestic wells. Relations of Hg concentrations in leach-field effluent to iron concentrations indicate that reductive dissolution of iron hydroxides in soils may release Hg to the percolating effluent.     

Occurrence of phthalates and bisphenol A and F in the environment

Certain xenoestrogens, namely bisphenol A (BPA), bisphenol F (BPF), butylbenzyl phthalate (BBP), dibutyl phthalate (DBP), and di(2-ethylhexyl)phthalate (DEHP), were measured in various compartments (surface water, sediments, sewage treatment plant effluents, sewage sludge, dump water, liquid manure) in order to contribute to a better understanding of exposure to these compounds in different environments. Hundred and sixteen surface-water samples and 35 sediments from rivers, lakes and channels, 39 sewage effluents, and 38 sewage sludges were collected in Germany. Furthermore, ten liquid manure, two waste-dump and two compost-runoff water samples were also analysed. BPA measurements showed low concentrations from 0.0005 to 0.41 microg L(-1) in surface water, in sewage effluents from 0.018 to 0.702 microg L(-1), in sediments from 0.01 to 0.19 mgkg(-1) and in sewage sludge from 0.004 to 1.363mgkg(-1) dw. Measured concentrations of BPF were clearly lower than BPA in all environmental media. DEHP dominated the phthalate concentrations, which ranged from 0.33 to 97.8 microg L(-1) (surface water), 1.74 to 182 microg L(-1) (sewage effluents), 27.9 to 154 mgkg(-1) dw (sewage sludge) and 0.21 to 8.44 mgkg(-1) (sediment). DBP was found only in minor concentrations and BBP, only in a few samples in low amounts. Very high concentrations of BPA and phthalates were confirmed in waste dump water and compost water samples as well as in the liquid manure samples.     

Determination of phenol in the Bangsai River water of Bangladesh by gas chromatography-mass spectrometry

A simple, sensitive and rapid gas chromatography-mass spectrometry (GC-MS) method is proposed for the analysis of some environmentally important highly toxic phenols in water. The concentration level of phenol was determined in water at the sampling stations of Savar, Dhaka Export Processing Zone (DEPZ) and Bank Colony of the Bangsai River, Bangladesh. Water samples were collected from different depth of the sampling stations. The phenolic compounds were extracted with dichloromethane, which was further preconcentrated by evaporation. Different concentrations of toxic phenol were obtained in the river water at the various sampling stations. The concentration of highly toxic phenol was found in the range of 0.01–0.998 μg L⁻¹. This method could permit the analysis of water for phenol as well as phenolic derivatives with detection limit as low as 100 ng L⁻¹.     

Biological and functional responses of in situ bioassays with Chironomus riparius larvae to assess river water quality and contamination

Single species responses have the potential to measure impacts at earlier stages than more traditional methods based in community structure. This study evaluates a bioassay with biological (survival, development, growth) and functional (post-exposure feeding rate) responses of Chironomus riparius larvae to assess water quality and contamination in rivers. The bioassay with C. riparius third instar larvae was performed, in autumn and spring, in reference sites and in organic and metal contaminated sites in Portuguese rivers. Biotic, physical and chemical parameters were determined for each site. The relationship between both bioassays responses and biotic indices (IBMWP and IASPT) and the physical and chemical parameters of respective sites were determined. In general biotic indices were able to discriminate between contaminated and not contaminated sites although they demonstrated a poor ability to detect low level of metal contamination during autumn. IASPT was negatively related to ammonia concentrations in both seasons. No significant differences in survival and post-exposure feeding rate were found between sites. Development was inhibited in the most metal contaminated site during autumn, but pH and ammonia concentrations in water accounted for 82% of developmental variation during this season. Growth was highly inhibited in the most metal contaminated site during both seasons. In autumn, growth was also inhibited in the low metal contaminated site and, during this season, pH and Mn and Fe concentrations in water samples accounted for 97% of growth variation between sites. The results suggest that in situ bioassay with C. riparius larvae using growth as the endpoint is a responsive and suitable tool that can be used as bioindicator of metal pollution and to biomonitor water quality in metal contaminated rivers.     

Changes in sample collection and analytical techniques and effects on retrospective comparability of low-level concentrations of trace elements in ground water

Ground-water sampling techniques were modified to reduce random low-level contamination during collection of filtered water samples for determination of trace-element concentrations. The modified sampling techniques were first used in New Jersey by the US Geological Survey in 1994 along with inductively coupled plasma-mass spectrometry (ICP-MS) analysis to determine the concentrations of 18 trace elements at the one microgram-per-liter (microg/L) level in the oxic water of the unconfined sand and gravel Kirkwood-Cohansey aquifer system. The revised technique tested included a combination of the following: collection of samples (1) with flow rates of about 2 L per minute, (2) through acid-washed single-use disposable tubing and (3) a single-use disposable 0.45-microm pore size capsule filter, (4) contained within portable glove boxes, (5) in a dedicated clean sampling van, (6) only after turbidity stabilized at values less than 2 nephelometric turbidity units (NTU), when possible. Quality-assurance data, obtained from equipment blanks and split samples, indicated that trace element concentrations, with the exception of iron, chromium, aluminum, and zinc, measured in the samples collected in 1994 were not subject to random contamination at 1 microg/L. Results from samples collected in 1994 were compared to those from samples collected in 1991 from the same 12 PVC-cased observation wells using the available sampling and analytical techniques at that time. Concentrations of copper, lead, manganese and zinc were statistically significantly lower in samples collected in 1994 than in 1991. Sampling techniques used in 1994 likely provided trace-element data that represented concentrations in the aquifer with less bias than data from 1991 when samples were collected without the same degree of attention to sample handling.     

Detection of Cryptosporidium spp. and Giardia duodenalis in surface water: A health risk for humans and animals

The objective of the present study was to determine the degree of contamination by Cryptosporidium spp. and Giardia duodenalis in a river basin in a livestock farming area in Galicia (NW, Spain). Water samples (50 l) were collected at 22 points in the main basin (including 5 recreational areas), and at the source and mouth of the 3 most important rivers and at the mouth of a smaller, secondary river. Faecal samples were collected from dairy cattle selected at random from 18 herds farmed in the area. A total of 139 neonatal calves, 480 heifers and 697 cows were sampled. The prevalence, intensity of infection and the risk associated with the spread of infection by both enteropathogens were determined. Water and faecal samples were collected in spring, summer, autumn and winter of 2007. The species and genotypes of these parasites present in the water samples were identified. In both water and faecal samples, more parasitic stages were collected in spring and summer than in autumn and winter. In spring, Cryptosporidium spp. oocysts were detected in 33 (9.4%) cows from 13 (72.2%) herds, and G. duodenalis cysts were detected in 56 (16.0%) cows from 15 farms (83.3%); the intensity of infection ranged from 5 to 7895 G. duodenalis cysts per gram of faeces. Infective stages of Cryptosporidium spp. and G. duodenalis were also detected in respectively 26 (89.6%) and 27 (93.1%) water samples, in spring. The mean concentrations of parasites ranged from 2 to 1200 Cryptosporidium spp. oocysts per litre and from 2 to 400 G. duodenalis cysts per litre. Cryptosporidium parvum, C. andersoni, C. hominis and assemblages A-I, A-II, E of G. duodenalis were detected. The presence of both protozoans must be monitored in cattle, in sources of water used for recreational purposes and in artificial waterways used by farmers (water channels, animal drinking water and drainage systems).     

Differential tracing of oily waste and the associated water mass by tagging with rare earths

A method was developed for tagging oily waste with dysprosium and the associated fresh water with samarium. Neutron activation analysis permitted determination of rare earth concentrations as low as 40 ng l⁻¹ in 15-ml water samples. Shipboard sampling procedures were developed that allowed measurement of the three-dimensional distribution of the spreading wastes and associated water. The method was applied in two field experiments that involved tracing oily wastes and polluted water from the Indiana Harbor Canal (IHC) into Lake Michigan.For a summer, floating-plume experiment, about 1400 shipboard samples were collected. Employment of the dual-tracer technique led to the following results: (1) after artificial mixing into the water column by a passing ship, the tagged oil did not immediately resurface, and (2) there were no distinguishable differences between the movement of the oil and water over 4 km of travel.During a winter, sinking-plume experiment, 1200 lake-water samples were collected from a boat and from the raw-water intakes of Chicago's South Water Filtration Plant (SWFP). These data provided positive evidence of the intake of IHC effluent and oily waste at the SWFP. The different tracers for the oily waste and underlying water gave evidence of separate pathways to the SWFP, reflecting differing transport modes for surface and near-bottom waters.     

Emissions and environmental implications of mercury from artisanal gold mining in North Sulawesi,Indonesia

In artisanal gold mining practiced in North Sulawesi Island, Indonesia, gold is separated from ore by the use of mercury, which forms an amalgam with gold. All related processes are undertaken with a low level of technical knowledge and skills, no regulation, and with disregard for the safety of human and environment health. The situation is generating serious potential health and environmental risks in the area. As part of an ongoing monitoring program, total mercury concentrations were examined in water, bottom sediment and fish samples from three main rivers in Talawaan Watershed, which receives drainage from gold mining practices. Monitoring began in May-June 2000, almost 2 years after artisanal gold mining had begun. At that time, the mercury concentration in the sediment was generally low, except in places close to the gold processing plants. In the present study, a more systematic sampling and analysis was conducted in May-June 2001. Bottom surface sediments, water, and fish samples were collected at 12 sites along the three main rivers in the watershed. In addition, one site outside the watershed was sampled to serve as a control. Sample collections were conducted in three phases in duplicate, with two-week intervals between each phase. The mercury concentration observed in this study indicated that an increase took place along the three main rivers in the watershed. Solutions to this problem must be formulated as soon as possible in order to avoid a major health, economic, and ecological disaster arising from the continuing discharge of Hg. The present study proposes that mercury dispersion occur downstream of the mining.     

Microdistribution patterns of macroinvertebrate communities upstream and downstream of organic effluents

The present study analyses the distribution patterns of macroinvertebrate communities in four microhabitats (riffles, glides, leaf litter and bank roots) upstream and downstream of two waste water treatment plant (WWTP) effluents in northern Spain rivers. Macroinvertebrate communities were analysed in November 2006 by taking 5 samples from each of the microhabitats under unaffected (upstream WWTP) and affected (downstream WWTP) conditions, respectively. Water velocity, depth, substrate coarseness and hydraulic stress by means of the Froude number were also estimated at all sampling locations.Under unaffected conditions, the abundance and presence/absence of certain macroinvertebrate taxa were mainly determined by hydraulic characteristics (water velocity and Froude number) and feeding resource availability. However, neither macroinvertebrate richness nor abundance were neither significantly correlated with hydraulic stress nor substrate coarseness, although the number of macroinvertebrate taxa increased in microhabitats with high structural complexity. Macroinvertebrate abundance increased downstream of both WWTPs, while macroinvertebrate richness was not adversely affected by the organic enrichment of water. The structure and composition of macroinvertebrate communities occurring in riffles was similar under unaffected and affected conditions, while communities from leaf litter and submerged bank roots showed important changes above and below the WWTPs, indicating that they are probably the most appropriate communities for water quality assessment.     

Occurrence and seasonal variations of Giardia in wastewater and river water from Al-Jinderiyah region in Latakia,Syria

ABSTRACT

This study investigates the occurrence and concentration of Giardia cysts in wastewater and river water samples in Al-Jinderiyah region, Latakia, Syria. A total of 120 samples were collected between October 2016 and October 2017 from influent and effluent of Al-Jinderiyah Waste Water Treatment Plant (WWTP) and from three contaminated river water sites. Samples were concentrated and subjected to microscopic examination. The results show that the concentrations of cysts ranged from 0 to 297 cysts/L in wastewater samples. The overall removal efficiency of cysts in the activated sludge WWTP was 84.35%. The concentrations of cysts ranged from 0 to 128.52 cysts/L in river water samples. The highest concentration in river water was recorded near the raw wastewater discharge point. Seasonal variations of Giardia cysts concentration were significant, and the highest concentrations were recorded in the rainy season. The results suggest that Giardia may pose a public health risk in the studied region.     

Characterization, identification of ambient air and road dust polycyclic aromatic hydrocarbons in central Taiwan, Taichung

The concentrations of ambient air polycyclic aromatic hydrocarbons (PAHs) were measured simultaneously in an industrial area (Taichung Industrial Park, TIP) and suburban area (Tunghai University, THU) in central Taiwan, Taichung. A total of samples were collected simultaneously at the two sites between August 2002 and March 2003. Particle-bound PAHs (p-PAHs) were collected on quartz filters and gas-phase PAHs (g-PAHs) on glass cartridges using polyurethane foam sampler, respectively. Both types of samples were extracted with dichloromethane/n-hexane mixture (50/50, v/v) for 24 h, then the extracts were subjected to gas chromatography/mass spectrometric analysis. Moreover, the roadside dust particle PAHs composition were also collected and analyzed at TIP, THU and traffic road sampling sites. The five main road lines in Taichung City were selected as traffic road sampling sites. Correlation studies between PAHs concentrations and meteorological parameters were revealed that temperature has greater effects (P>0.6) than other meteorological parameters such as wind speed, relative humidity and atmospheric pressure on g-PAHs and p-PAHs. PAHs sources were resolved by using principal component analysis and diagnostic ratios. The major sources of PAHs were combustion, traffic vehicle exhaust (diesel and gasoline engine), incinerator and industrial stationary sources at both sampling sites in central Taiwan.     

Accumulation of zinc, cadmium and lead by field populations of Lemanea

A study has been made of the concentrations of zinc, cadmium and lead in populations of the red alga Lemanea growing in fast-flowing rivers in Britain, France. Germany, Ireland and Sardinia (Italy). The sites were selected to provide a wide range of aqueous concentrations of these metals. Many of the sites are influenced by past or present mining activities and Lemanea was found at aqueous concentrations of zinc up to 1.16 mg 1⁻¹. In contrast to previous studies with filamentous green algae, no evidence could be found to support the hypothesis that populations differ genetically in their ability to tolerate these heavy metals. Samples of alga consisted of pooled 2 cm long terminal tips of filaments detached from approx. 1 cm² rock surface. Significant positive correlations were found between the logarithm of the mean concentration of zinc, cadmium and lead in four such samples collected from within 10 m reaches at 59 sites and the logarithm of the concentration of each metal in both unfiltered and filtered water. The enrichment ratios for each metal decreased with increasing aqueous metal concentrations. Although the aqueous concentrations of the three metals were strongly intercorrelated, differences in the ratio of metal concentrations were reflected in the composition of Lemanea filaments. The results suggest that high levels of calcium (and/or magnesium) result in decreased uptake of zinc. Intensive sampling from a single population showed that part of the zinc content of filaments is sensitive to short-term fluctuations in concentrations in the surrounding water. In the particular population studied this was about 20%; a similar percentage could be eluted in the laboratory with EDTA. Transplants of Lemanea were made between reaches with different aqueous concentrations of zinc and in all cases the zinc concentration in filament tips increased or decreased to stabilise at a concentration similar to that in filaments native to the reach. It is suggested that chemical analyses of natural or transplanted populations of Lemanea could provide a valuable aid in monitoring contamination of rivers by zinc, cadmium or lead.     

Occurrence and determination of a herbicide benthiocarb in rivers and agricultural drainages

The occurrence and determination of a herbicide, benthiocarb, 4-chlorobenzyl N,N-diethylthiolcarbamate (Saturn^®) in rivers and agricultural drainages was investigated. Benthiocarb residues were detected in water samples when it has been applied to rice paddies, after rice seedling transplantation, in concentrations of between 10.00 and 0.11 μg/l. These residues entered into rivers and agricultural drainages as a result of overflows from rice paddies. However, benthiocarb residues could not be found in water samples after the termination of its application to rice paddies, suggesting that the applied benthiocarb might be degraded by microbial and physico-chemical actions such as photochemical reactions occurring on the soil surface. Benthiocarb residue levels were higher in longer rivers than in agricultural drainage. The contribution of rainfall to the benthiocarb concentrations was shown. Benthiocarb in water was extracted with n-hexane and identified by a gas chromatography using a flame photometric detector (sulphur filter 394 nm) and a combined gas chromatography-mass spectrometry-computer system. The minimum detectable amount of benthiocarb in water sample by gas chromatography was 0.56 ng and about 100 ng of benthiocarb could be identified by a gas chromatography-mass spectrometry-computer system.