Environmental behavior and eco-toxicity of xylene in aquatic environments: A review

With the demand for chemicals and fuels increasing continuously, the occurrence of accidental leakage poses great risks to the aquatic environment. Xylene, a hazardous and noxious substance, has been major concerns with regard to heterogeneity and eco-toxicity towards aquatic organisms. This review focused on the ecotoxicological hazards of m-, o-, and p-xylene, as well as mixed xylene, on aquatic organisms. The mechanism of action of xylenes was also demonstrated in details. The purpose of this review was to further understand transfer and diffusion of toxicity on marine and freshwater organisms of xylene in the aquatic environment. Another aim was to screen sensitive biomarkers which were suitable for ecotoxicological assessment and monitoring in an aquatic system.

Can coastline plant species be used as biosamplers of emerging contaminants? - UV-filters and synthetic musks as case studies

Personal care products, an important class of emerging contaminants, have been frequently detected in different environmental matrices. Included in this category are synthetic musks compounds (SMCs) and UV-filters. Their occurrence in the coastal environment has been poorly studied. Therefore, this work aimed to verify whether five coastline plant species (Carpobrotus edulis, Cakile maritima, Medicago marina, Elymus farctus borealis-atlanticus and Euphorbia paralias) have the ability to accumulate 11 SMCs (cashmeran, celestolide, phantolide, galaxolide, tonalide, exaltolide, musk moskene, tibetene, ambrette, xylene and ketone) and 2 organic UVB filters (3-(4'-methylbenzylidene) camphor and octocrylene), functioning as biosamplers. To accomplish this task, a QuEChERS technique ("Quick, Easy, Cheap, Effective, Rugged, and Safe") was employed to extract the target compounds from the plant material collected in 15 beaches of Matosinhos and Vila Nova de Gaia (Portugal). The resulting extracts were analysed by gas chromatography-mass spectrometry. Limits of detection ranged from 0.02 ng g^-1 for celestolide and tonalide to 1.32 ng g^-1 for musk ambrette. The obtained recoveries were around 93% and relative standard deviation was generally less than 15%. SMCs were detected at levels ranging from 1.56 to 350 ng g^-1 dw and UV-filters from 2.9 to 264 ng g^-1 dw. Galaxolide and 3-(4'-methylbenzylidene) camphor were the synthetic musk and UV-filter detected in higher concentrations, respectively. Plants with higher water content accumulate better SMCs (hottentot-fig), while those with higher lipid content retain better the UV-filters (sea spurge).

Assessment of Surface Water Contamination from Coalbed Methane Fracturing-Derived Volatile Contaminants in Sullivan County, Indiana, USA

There is a growing concern over the contamination of surface water and the associated environmental and public health consequences from the recent proliferation of hydraulic fracturing in the USA. Petroleum hydrocarbon-derived contaminants of concern [benzene, toluene, ethylbenzene, and xylenes (BTEX)] and various dissolved cations and anions were spatially determined in surface waters around 15 coalbed methane fracking wells in Sullivan County, IN, USA. At least one BTEX compound was detected in 69% of sampling sites (n = 13) and 23% of sampling sites were found to be contaminated with all of the BTEX compounds. Toluene was the most common BTEX compound detected across all sampling sites, both upstream and downstream from coalbed methane fracking wells. The average concentration of toluene at a reservoir and its outlet nearby the fracking wells was ~2× higher than other downstream sites. However, one of the upstream sites was found to be contaminated with BTEX at similar concentrations as in a reservoir site nearby the fracking well. Calcium (~60 ppm) and sulfates (~175 ppm) were the dominant cations and anions, respectively, in surface water around the fracking sites. This study represents the first report of BTEX contamination in surface water from coalbed methane hydraulic fracturing wells.

Assessing seasonal variation of synthetic musks in beach sands from Oporto coastal area: A case study

Synthetic musk compounds are widely used in the formulation of several cosmetics, personal care and household products. Due to their massive and widespread use, together with some health concerns, they are considered emerging pollutants and have been detected in different environmental compartments. This study focused on the evaluation of the concentration of synthetic musks (five nitro, five polycyclic and one macrocyclic musks) in beach sands, from Oporto coastal area (Portugal), contributing to the enhancement of the knowledge of levels, trends and behaviour of these compounds in this particular matrix. To accomplish this task, a QuEChERS methodology ("Quick, Easy, Cheap, Effective, Rugged, and Safe") coupled to gas chromatography-mass spectrometry (GC-MS) was successfully used to determine synthetic musks from beach sand. The chosen methodology proved to be suitable, achieving satisfactory results for precision (relative standard deviation values below 15%), accuracy (average recovery of 97%) and limits of detection (below 38 pg g^-1). Synthetic musks were detected in all 45 analysed samples, in concentrations ranging from 0.01 to 27 ng g^-1_dw. Tonalide (93%), exaltolide (89%) and galaxolide (76%) were the most commonly detected compounds, but also those detected in higher concentrations (up to 27 ng g^-1_dw). Musk ambrette, moskene, tibetene and xylene were not detected in any of the samples. Higher concentrations were as expected detected in the Summer (total average concentration of 9.21 ng g^-1_dw), namely in samples from Valadares Sul (29 ng g^-1_dw), Francelos (25 ng g^-1_dw) and Castelo do Queijo (25 ng g^-1_dw). The preliminary environmental risk assessment study based on the determination of hazard quotients revealed that the presence of analysed compounds (tonalide, galaxolide and musk ketone) seems to pose no risk to the studied environmental compartment.

Spatiotemporal description of BTEX volatile organic compounds in a Middle Eastern megacity: Tehran Study of Exposure Prediction for Environmental Health Research (Tehran SEPEHR)

The spatiotemporal variability of ambient volatile organic compounds (VOCs) in Tehran, Iran, is not well understood. Here we present the design, methods, and results of the Tehran Study of Exposure Prediction for Environmental Health Research (Tehran SEPEHR) on ambient concentrations of benzene, toluene, ethylbenzene, p-xylene, m-xylene, o-xylene (BTEX), and total BTEX. To date, this is the largest study of its kind in a low- and middle-income country and one of the largest globally. We measured BTEX concentrations at five reference sites and 174 distributed sites identified by a cluster analytic method. Samples were taken over 25 consecutive 2-weeks at five reference sites (to be used for temporal adjustments) and over three 2-week campaigns in summer, winter, and spring at 174 distributed sites. The annual median (25^th-75^th percentile) for benzene, the most carcinogenic of the BTEX species, was 7.8 (6.3-9.9) μg/m³, and was higher than the national and European Union air quality standard of 5 μg/m³ at approximately 90% of the measured sites. The estimated annual mean concentrations of BTEX were spatially highly correlated for all pollutants (Spearman rank coefficient 0.81-0.98). In general, concentrations and spatial variability were highest during the summer months, most likely due to fuel evaporation in hot weather. The annual median of benzene and total BTEX across the 35 sites in the Tehran regulatory monitoring network (7.7 and 56.8 μg/m³, respectively) did a reasonable job of approximating the additional 144 city-wide sites (7.9 and 58.7 μg/m³, respectively). The annual median concentrations of benzene and total BTEX within 300 m of gas stations were 9.1 and 67.3 μg/m³, respectively, and were higher than sites outside this buffer. We further found that airport did not affect annual BTEX concentrations of sites within 1 km. Overall, the observed ambient concentrations of toxic VOCs are a public health concern in Tehran.

Exposure profiles, seasonal variation and health risk assessment of BTEX in indoor air of homes at different microenvironments of a terai province of northern India

BTEX are known for their ability to deteriorate human health. A monitoring study was conducted at Gorakhpur, for a span of one year. BTEX were sampled by drawing air through activated charcoal tubes, using a low flow SKC model 220 pump. Samples were extracted with CS₂ followed by subjecting the aromatic fraction to GC-FID. The mean concentration of BTEX was highest at agricultural (54.3 μg m^-3) followed by industrial (18.2 μg m^-3), roadside (12.3 μg m^-3) and residential site (6.1 μg m^-3). Toluene levels were higher than benzene at all the sites except agricultural site, where benzene concentration exceeded toluene. Seasonal variation showed highest BTEX concentration during winters (32.56 μg m^-3) followed by monsoon (19.90 μg m^-3) and summers (14.44 μg m^-3). At each site, BTEX levels increased with decrease in temperature. Benzene and toluene levels were plotted against indoor temperature, which revealed a significant linear correlation (p < 0.001) for each plot. BTEX concentrations were compared between different sites using Student's t and Mann Whitney U tests. Value of integrated lifetime cancer risk (ILTCR) was higher than 10^-6 for benzene at all the sites, while for ethylbenzene, it was only higher at agricultural site. Cumulative hazard index (HI) was lower than 1.0 at all the sites.

Evaluation of sediment contamination by monoaromatic hydrocarbons in the coastal lagoons of Gulf of Saros, NE Aegean Sea

The concentrations and distribution of monoaromatic hydrocarbons (benzene, toluene, ethyl benzene and the sum of m-, p- and o-, xylenes) were determined in the sediments of coastal lagoons of the Gulf of Saros, using a static headspace GC-MS. The total concentrations of BTEX compounds ranged from 368.5 to below detection limit 0.6μgkg^-1 dw, with a mean value of 61.5μgkg^-1 dw. The light aromatic fraction of m-, p-xylene was the most abundant compound (57.1% in average), and followed by toluene (38.1%)>ethylbenzene (4.1%)>o-xylene (2.5%)>benzene (1.1%). The factor analysis indicated that the levels and distribution of BTEX compounds depend on the type of contaminant source (mobile/point), absorbance of compounds in sediment, and mobility of benzene compound and degradation processes. Point sources are mainly related to agricultural facilities and port activities while the dispersion of compounds are related with their solubility, volatility and effect of sea/saline waters on lagoons.

BTEX Emissions from the Largest Landfill in Operation in Rio de Janeiro, Brazil

The emission rates and the ambient air concentrations of benzene, toluene, ethyl benzene and xylenes (BTEX) were measured over the intermediate cover layer and atmosphere of the Seropédica landfill, Rio de Janeiro, Brazil. BTEX were sampled using coconut shell charcoal cartridges, followed by extraction with dichloromethane and analysis by gas chromatography with mass spectrometry. Thirteen samples were collected in areas with and without cracks in the cover layer, and six samples were collected from the ambient air. The average emission rates were 11.7, 492.2, 153.7, 67.2, and 21.7 µg m^- 2 day^- 1, respectively, for benzene, toluene, ethyl benzene, m + p-xylenes and o-xylene. No benzene concentrations above the detection limit were observed in ambient air samples. The average concentrations of toluene, ethyl benzene, m + p-xylenes and o-xylene in ambient air samples were 2.14, 1.35, 0.49 and 0.08 µg m^- 3, respectively. Higher emissions were found in locations containing larger cracks during the collection.

In vitro determination of transdermal permeation of synthetic musks and estimated dermal uptake through usage of personal care products

Synthetic musks, chemical constituents of personal care products, enter the human body through dermal contact. Elucidation of the mechanisms underlying transdermal permeation of synthetic musks should enhance our understanding of their uptake and distribution in human skin and allow accurate evaluation of associated human exposure. Here, the transdermal permeation dynamics and distribution of galaxolide (HHCB) and tonalide (AHTN) were investigated using an in vitro skin diffusion model. The transdermal permeation amounts of HHCB and AHTN increased rapidly during the first 6 h. The applied HHCB and AHTN amounts did not affect percutaneous absorption rates. HHCB and AHTN remained primarily in the stratum corneum, accounting for 70.0% and 70.3% of the totals during the 24-h period, respectively. The percutaneous absorption rate of both chemicals was ∼11%. HHCB, AHTN, musk ketone, musk xylene, and Musk-T were detected in 29 personal care products. The average total concentrations of the musks were 3990, 54.0, 17.7, and 9.8 μg g^-1 in perfume, shampoo, lotion, and shower gel, respectively. Among the four product categories, HHCB was dominant (57.4%-99.6%), followed by AHTN. The data clearly indicate that polycyclic and nitro musks are most commonly used in personal care products. The total estimated dermal intake (51.6 μg kg^-1_bw day^-1) was markedly higher than total dermal uptake (5.9 μg kg^-1_bw day^-1) when percutaneous absorption rates of the chemicals were added into the calculation. Uptake of HHCB and AHTN via dermal contact of personal care products was significantly higher than that from dust inhalation calculated according to earlier literature data.

Oil exploration activities: assessment of hazardous impacts on 'Golden silk' cultivation

Aliphatic-aromatic hydrocarbons and heavy metals (Cd, Cu, Co, Cr, Ni, Pb and Zn) were estimated in soil and leaf samples of Machilus bombycina (host plant of Antheraea assama silkworm) plantation along with atmospheric benzene, toluene and xylene (BTX) concentration near the oil exploration region of upper Assam, India, during the pre-monsoon and post-monsoon periods in six different sites. The results revealed higher aliphatic-aromatic hydrocarbons (ranging from 26.55 to 59.42 mg kg^-1) and heavy metal contaminations in all the six soil sampling sites during the pre-monsoon period while the trend was the opposite for the plant leaves. Polyaromatic hydrocarbons (9.85 mg kg^-1) were found in one soil sampling site near an abandoned oil well. The lead concentration in the soil showed values from 14.36 ± 1.5 to 96.5 ± 5.6 mg kg^-1 and found to be higher than the WHO limit in most of the samples. The aliphatic-aromatic hydrocarbon m-xylene was also found in M. bombycina plant leaves which could be traced due to crude oil. Cd and Pb concentrations in leave samples were found to be higher than the maximum allowable limit of 0.3 and 5.3 mg kg^-1, respectively. Principal component analysis of hydrocarbons in soil and leaves showed different clusters during the pre-monsoon and post-monsoon periods. The crude protein and total carbohydrate contents in the leaves were lower than those of uncontaminated samples which are an indication of a major disturbance to overall growth of plants. BTX concentration was found in the range of 119-198 μg m^-3 which indicates that atmospheric contamination in the studied area is causing the death of A. assama larvae.

The characteristics of BTEX concentration in various types of environment in the Baltic Sea Region, Lithuania

Benzene, toluene, ethylbenzene and xylene (BTEX) form an important group of volatile organic compounds (VOCs) affecting troposphere and posing risk to human health. The article examines the Mažeikiai area in the northern part of Lithuania where one of the largest Central European companies and the only oil refinery in the Baltic region (200,000 barrels/day) are close to the Baltic Sea. The research carried out mainly focuses on the following objectives: quantitative assessment of the amounts of BTEX occurring in the impact zone of the oil refinery and transport; estimation of background BTEX concentrations in the region; establishing the main sources of BTEX in the region researched and evaluation of impact of meteorological parameters on BTEX concentrations in different seasons. The passive measurement method was used for analysing VOCs (benzene (C₆H₆), toluene (C₇H₈), ethylbenzene (C₈H₁₀) and ortho-, meta- para-xylene (C₈H₁₀)). The research was carried out in 2010-2012. Its results showed that the average annual concentration of benzene was below the threshold value of 5 μg/m³. Within the measurement period, the average concentration of benzene fluctuated from 1.2 to 2.4 μg/m³, that of toluene varied from 1.3 to 3.5 μg/m³, that of ethylbenzene varied from 0.3 to 0.7 μg/m³ and that of xylene (calculated as para-, meta- and ortho-xylene) varied from 1.0 to 2.4 μg/m³. Compared to the established BTEX concentration, the actual background BTEX concentration in the urban area is two times higher. The seasonal analysis suggests that the highest values of benzene concentration are observed in the winter season.

Multivariate optimization for the simultaneous bioremoval of BTEX and chlorinated aliphatic hydrocarbons by Pseudomonas plecoglossicida

This study aimed to evaluate the effects of some major parameters on the cometabolic removal of cis-1,2-dichloroethylene (cis-DCE) and trichloroethylene (TCE), mixed with benzene, toluene, ethylbenzene, and xylenes, by an indigenous bacterial isolate Pseudomonas plecoglossicida. Such statistical methodologies as hierarchical cluster analysis heat map and principal component analysis were applied to better evaluate the effects of major parameters (soil pH, temperature, moisture, and cis-DCE/TCE concentrations) on the biological process. The bioremoval experiments were carried out in microcosms containing soil slurry, and the headspace concentrations of contaminants were analyzed by gas chromatography. The optimal bioremoval conditions for the mixture were soil water content >110%, pH 8-9, and temperature 15-20°C, while the cis-DCE/TCE concentration did not significantly affect the mixture bioremoval within the tested range (∼10mg per kg soil). Under the optimal conditions, benzene (97.7%), toluene (96.3%), and ethylbenzene (89.8%) were almost completely removed, while cis-DCE (24.5%), TCE (29.0%), m,p-xylene (36.3%), and o-xylene (29.6%) showed lower removal efficiencies. The obtained results would help to better design a remediation technology to be applied to the sites contaminated with mixed wastes, and the statistical methodologies used in this study appear to be very efficient and could serve as a template for optimization.

Point source attribution of ambient contamination events near unconventional oil and gas development

We present an analysis of ambient benzene, toluene, and xylene isomers in the Eagle Ford shale region of southern Texas. In situ air quality measurements using membrane inlet mobile mass spectrometry revealed ambient benzene and toluene concentrations as high as 1000 and 5000 parts-per-billion, respectively, originating from specific sub-processes on unconventional oil and gas well pad sites. The detection of highly variant contamination events attributable to natural gas flaring units, condensate tanks, compressor units, and hydrogen sulfide scavengers indicates that mechanical inefficiencies, and not necessarily the inherent nature of the extraction process as a whole, result in the release of these compounds into the environment. This awareness of ongoing contamination events contributes to an enhanced knowledge of ambient volatile organic compounds on a regional scale. While these reconnaissance measurements on their own do not fully characterize the fluctuations of ambient BTEX concentrations that likely exist in the atmosphere of the Eagle Ford Shale region, they do suggest that contamination events from unconventional oil and gas development can be monitored, controlled, and reduced.

Study of the effect of sample pressure on in situ BTEX chromatographs

In this paper, the influence of sample pressure on benzene measurements obtained with two automated in situ gas chromatographs is studied. The analysers were calibrated using a non-linear regression at 293 ± 1 K and 101.3 ± 0.2 kPa. A gas mixture of benzene in air (5 μg/m³) was produced and measured at calibration conditions. Subsequently, the sample pressure was changed to 80 and 110 kPa. Differences in readings were observed even though the pressure compensators were on, indicating incorrect performance of this tool. Further tests with two different benzene in air mixtures (5 and 40 μg/m³) at 80, 90, 105 and 110 kPa were also carried out. Results showed that the analysers take air from one or several unidentified inlets (apart from the sampling port) when the sampling pressure is lower than the atmospheric one. This is usually the case in air monitoring stations, so this phenomenon is particularly important as systematic biases could be affecting air quality data.

Statistical modeling of O3, NOx, CO, PM2.5, VOCs and noise levels in commercial complex and associated health risk assessment in an academic institution

Indoor Air Quality (IAQ) is considered to be of great concern due to its adverse impact on the human health nowadays. The presence of different air pollutants along with noise may aggravate the IAQ. The present study attempts to examine IAQ in terms of major criteria air pollutants (O₃, NOx=NO+NO₂, CO and PM_2.5) along with total volatile organic compound (TVOC), individual VOC and noise pollution in indoor and outdoor environment of a Commercial Shopping Complex (CSC) in Delhi. Real time measurements have been carried out for O₃, NOx, CO, PM_2.5, TVOC and noise while thirteen individual VOCs have been estimated using NIOSH method was performed using Gas Chromatograph. The study also aimed to find out the relationship among VOCs, source estimation using Principal Component Analysis. The observed results for the targeted pollutants were also compared with international and national recommended permissible values. The mean values of O₃, NOx, CO, PM_2.5 and TVOC are found to be 17.6/(15.0) ppb, 15.8/(14.1) ppb, 8.4/(1.9) ppm, 125.4/(74.6) μg/m³ and 412.5/(226.5) μg/m³ for indoor/(outdoor), respectively. Among the individual VOC, toluene was the most abundant followed by xylene-isomers and benzene. The noise pollution level in Indoor/outdoor were found to be 51.5/46.4dB which is below the guideline value (65dB) provided by the WHO. Most of the pollutants were found to have indoor sources. The different kinds of pollutants and noise may have synergistic effect and aggravate the health of the people working and visiting the CSC.

Investigation of outdoor BTEX: Concentration, variations, sources, spatial distribution, and risk assessment

The aim of this study was to measure BTEX (benzene, toluene, ethylbenzene, and xylenes) concentrations in the ambient air of Tehran, the capital of Iran, and investigate their seasonal variations, probable sources, spatial mapping, and risk assessment. The concentrations of BTEX were measured using a continuous monitoring device installed in seven stations around the city. Spatial mapping procedure was conducted using the inverse distance weighting (IDW) method. Monte Carlo simulation was used to assess the carcinogenic and noncarcinogenic risks imposed by BTEX. The highest and lowest annual mean concentrations of toluene and ethylbenzene were recorded as 16.25 and 3.63 μg m(-3), respectively. The maximum (6.434) and minimum (3.209) toluene/benzene (T/B) ratio was observed in summer and winter, respectively. The spatial distribution of BTEX pollution indicated that the highest concentrations were found along the major roads because of heavy traffic. Spearman's rank correlation coefficients and concentration ratios showed that BTEX were produced by the multiemission sources. The mean of inhalation lifetime cancer risk (LTCR) for benzene was 3.93 × 10(-7), which is lower than the limits recommended by the United States Environmental Protection Agency (US EPA) and the World Health Organization (WHO). The hazard quotient (HQ), noncarcinogenic risk index, for all BTEX compounds was <1. The obtained results showed no threat of BTEX concentrations to human health. However, as the concentrations of BTEX will increase due to the rapid growth of vehicles and industrial activities, much effort is required to control and manage the levels of these compounds in the future.

New family of biosensors for monitoring BTX in aquatic and edaphic environments

Benzene, toluene, ethylbenzene and xylenes (BTEX) contamination is a serious threat to public health and the environment, and therefore, there is an urgent need to detect its presence in nature. The use of whole-cell reporters is an efficient, easy-to-use and low-cost approach to detect and follow contaminants outside specialized laboratories; this is especially important in oil spills that are frequent in marine environments. The aim of this study is the construction of a bioreporter system and its comparison and validation for the specific detection of monocyclic aromatic hydrocarbons in different host bacteria and environmental samples. Our bioreporter system is based on the two component regulatory system TodS-TodT of P. putida DOT-T1E, and the PtodX promoter fused to the GFP protein as the reporter protein. For the construction of different biosensors, this bioreporter was transferred into three different bacterial strains isolated from three different environments, and their performance was measured. Validation of the biosensors on water samples spiked with petrol, diesel and crude oil on contaminated waters from oil spills and on contaminated soils demonstrated that they can be used in mapping and monitoring some BTEX compounds (specifically benzene, toluene and two xylene isomers). Validation of biosensors is an important issue for the integration of these devices into pollution-control programmes.

Determining exhaust fumes exposure in chainsaw operations

The objective of this study was to investigate the inhalation exposure of forest operators to polycyclic aromatic hydrocarbons (PAHs) and BTEX (benzene, toluene, ethylbenzene and total xylenes) contained in the exhaust fumes released from chainsaws and to suggest possible countermeasures. The study was carried out in four silvicultural treatments (coppice clearcut, conifer thinning, conifer pruning, and sanitary cut), using three types of chainsaw fuel (normal two-stroke petrol mix and two alkylate fuels). Eighty personal air samples were collected; IOM samplers combined with Amberlite XAD-2 sorbent tubes were used for collecting PAHs and Radiello^® samplers were used for BTEX. Results indicate that none of the four silvicultural treatments significantly affected the PAHs and BTEX inhalation exposure of forest workers. On the other hand, statistically significant differences were recorded in the inhalation exposure to PAHs and BTEX when using different fuel types. In particular, the inhalation exposure to PAHs and BTEX was generally one order of magnitude lower when using modern alkylate fuels as compared to the traditional oil and lead-free petrol mixture. The small, non-statistically significant differences in inhalation exposure recorded between the two alkylate fuels suggests that the two fuels might be equivalent in terms of quality. Our study indicates that while forest workers are exposed to PAHs and BTEX, the maximum values are generally well below accepted occupational exposure limits.

The relationship between solvent use and BTEX concentrations in occupational environments

Indoor air quality is an increasing concern; it causes significant damage to health because it is recycled in confined environments for extended periods of time. Among the pollutants found in these environments, benzene, toluene, ethylbenzene, and xylenes (BTEX) are known for their potential toxic, mutagenic, and carcinogenic effects. This study monitored the BTEX concentrations in paint, carpentry, and varnish workplaces and evaluated the potential to cause adverse health effects on workers in these environments. Twenty samples were collected in workplaces, 20 samples were collected outside the area, and eight samples were taken of the products used. Samples were collected using coconut shell cartridges, and chemical analyses were performed by gas chromatography with mass spectrometry. Toluene presented higher indoor concentrations and indoor and outdoor ratios, indicating that the paint and varnish workplaces had significant BTEX sources. The highest benzene and toluene concentrations were obtained from the paint workshop, and higher concentrations of ethylbenzene and xylenes were obtained in the varnish workshop. The highest non-carcinogenic risks were obtained for m + p-xylenes in the varnish work place, and the second highest non-carcinogenic risk was also determined for the same workshop.

Determination of Synthetic Musks in Surface Sediment from the Bizerte Lagoon by QuEChERS Extraction Followed by GC-MS

A new analytical method for the simultaneous determination of eight synthetic musks compounds (SMs) including five polycyclic musks (PCMs) and three nitro musks (NMs) was validated for sediment samples based on a simple QuEChERS (Quick, Easy, Cheap, Effective, Rugged and Safe) sample preparation procedure followed by gas chromatography-mass spectrometry (GC-MS). Good analytical performances were obtained for all the target compounds. For the validation of the method, internal calibration (IC) and internal calibration with QuEChERS (ICQ) were compared. Good linearity was obtained for both calibration methods with determination coefficients (R²) ranging between 0.990 for Musk Xylene (MX) and 0.999 for Tonalide (AHTN) with IC and between 0.991 for Musk Ketone (MK) and 0.999 for Traseolide (ATII) with ICQ. The repeatability ranges were 0.1 %-1.9 % with the IC and 0.1 %-2.6 % with the ICQ. The apparent recoveries obtained for SMs in the standard reference sediment (SRM1944) varied in the range of 70 %-98 % and 75 %-103 % in the sediment from the Bizerte Lagoon (Tunisia). The absolute recoveries ranged between 61 % and 92 % for the SRM1944 and between 61 % and 89 % in the sediment from the Bizerte Lagoon. The limits of detection (LOD) calculated for the two main compounds, Galaxolide (HHCB) and Tonalide (AHTN) were 0.3 and 0.1 ng g^-1 respectively. The LODs obtained for ADBI (Celestolide), AHMI (Phantolide), ATII (Traseolide), MM (Muks mosken), MK (Musk Ketone) and MX (Musk Xylene) were 0.08, 0.12, 0.03, 0.34, 0.11, 0.08, 0.10 and 0.15 ng g^-1 respectively. The levels of ∑SMs in surface sediments from the Bizerte Lagoon ranged from 1.4 to 4.5 ng g^-1, which are 1000 times lower that the predicted no effect concentration (PNEC) for marine organisms.

Determination of Xylene and Toluene by Solid-Phase Microextraction Using Au Nanoparticles-Thiol Silane Film Coupled to Ion Mobility Spectrometry

A simple, rapid and sensitive method for analysis of xylene and toluene was developed using the solid-phase microextraction (SPME) combined with ion mobilityspectrometry (IMS). Gold nanoparticles-thiol silane film (Au NPs-TSF) was applied as a newsorbent for SPME. Thiol silane film was formed on the surface of a stainless steel wire through incorporating Au nanoparticles during synthesis using sol-gel technique. The extraction properties of the fiber to xylene and toluene were examined, using a SPME device and thermal desorption ininjection port of IMS. The calibration graphs were linear in the range of 1.10-32.0 and 16.0-112.0 ppb for xylene and toluene, respectively. The detection limits for xylene and toluene were 0.7 and 8.0 ppb, respectively. The proposed method was applied without any considerable sample pretreatment and it was found to be simple enough to be strongly recommended for real sample analysis.

Occurrence and distribution of monocyclic aromatic hydrocarbons (BTEX) and the impact on macrobenthic community structure in Lagos lagoon, Nigeria

The widespread distribution of petroleum products arising from the rapid growth of the petroleum industry in Nigeria has resulted in the pollution of the environment through oil spills involving leakages from tankers, pipelines, tank farms, and dumping of waste petroleum products. The impacts and distribution of major toxic components (benzene, toluene, ethylbenzene, and xylene (BTEX)) of petroleum products in water and sediment samples collected from sampling stations in the Lagos lagoon was investigated over a 2-year period (February 2009-July 2010). The distribution of benthic communities in the different sampling stations of the Lagos lagoon was assessed. The determination of hydrocarbon levels in the samples showed that the levels of total hydrocarbon content (THC) in the water samples around the Atlas Cove and Apapa were high with values ranging from 2.03 to 31.38 mg/l and 4.04 to 22.89 mg/l, respectively. The highest value of total BTEX in the lagoon sediment was also recorded in the Apapa station (450.53 μg/kg), where oil depots and tank farm facilities are located. The study of the macrobenthic community structure showed that the species richness ranged from 1.57 to 2.02 in the reference station, Unilag, while in the Atlas Cove, Iddo, and Apapa stations, it ranged from 1.80 to 2.89, 1.95 to 3.03, and 1.86 to 2.95, respectively. The highest number of organisms (183) was recorded in the reference stations, while the least number (46) was recorded in Apapa. The main hydrocarbon pollution indicator species identified in the impacted aquatic stations were Nais eliguis and Heteromastus filiformis. The levels of hydrocarbon observed in the aquatic environment showed that there is widespread contamination as a result of petroleum product importation, storage, and distribution. The assessment of the monocyclic aromatic hydrocarbon and benthic community will therefore provide important tools for early detection, diagnosis, and management of hydrocarbon pollution in the Lagos lagoon.

High-resolution separation performance of poly(caprolactone)diol for challenging isomers of xylenes, phenols and anilines by capillary gas chromatography

Efficient separation of xylenes, phenols and anilines is a big issue in chemical and petroleum industries. This work presents the first example of employing poly (caprolactone) diol (PCL-Diol) as stationary phase for high-resolution gas chromatographic (GC) separations of these tough isomer mixtures. It showed medium polarity and stronger H-bonding basicity than H-bonding acidity. Impressively, PCL-Diol column exhibited extremely high resolving capability for the isomer mixtures of xylenes, cresols/xylenols, and toluidines/xylidines with good peak shapes. Moreover, it exhibited preferential retention for analytes of a linear alkyl chain, suggesting its shape fitting selectivity for specific analytes. In addition, its separation performance has good repeatability with RSD values on retention times below 0.01% for run to run (n=6), 0.67-0.80% for day to day (n=4) and 3.2-4.4% for column to column (n=4) repeatability, respectively. Furthermore, it was applied for the determination of isomer impurities in real samples, showing good potential for practical use. This work demonstrates the advantageous high-resolution separation performance for challenging isomers and shows its promising future of PCL-Diol-based materials in separation science.

Kinetics and equilibrium partitioning of dissolved BTEX in PDMS and POM sheets

Passive sampling of volatile organic chemicals from soil and groundwater is primarily important in assessing the status of environmental contamination. A group of low molecular weight pollutants usually found in petroleum fuels, benzene, toluene, ethylbenzene, and xylenes (BTEX) was studied for its kinetics and equilibrium partitioning with single-phase passive samplers using polydimethylsiloxane (PDMS) and polyoxymethylene (POM) as sorbing phase. PDMS (1 mm) and POM (0.076 mm) sheets were used for sorption of BTEX and concentrations were analyzed using GC-FID. The equilibrium absorption and desorption of PDMS in water was achieved after 120 min while POM sheets absorbed up to 35 days and desorbed in 7 days. The kinetic rate constants in PDMS is higher than in POM up to 3 orders of magnitude. Logarithms of partition coefficient were determined to be in the range of 1.6-2.8 for PDMS and 2.1-3.1 for POM. The results indicate that POM is a stronger sorbent for BTEX and has slower equilibration time than PDMS. The partitioning process for both polymers was found to be enthalpy-driven by measurement of K d values at varying temperatures. K d values increase at low temperature and high ionic strength conditions. Presence of other gasoline components, as well as dissolved organic matter, did not significantly affect equilibrium partitioning. A good 1:1 correlation between the measured and the predicted concentrations was established on testing the potential application of the constructed PDMS sampler on natural soils and artificial soils spiked with gasoline-contaminated water.

BTX in urban areas of eastern Spain: a focus on time variations and sources

Seasonal and daily cycles of BTX were studied in a non-industrialized city (Alicante) and an urban area near an oil refinery plant (Castellón) in order to evaluate the influence of different sources on time variations. Lower levels were observed in summer than in winter at both locations due to higher dispersion conditions and photochemical removal of BTX during the summer season. Daily patterns showed seasonal differences and were controlled by traffic emissions and the evolution of the mixing layer height, with no influence of the petroleum refinery plant in the city of Castellón. The results of the conditional bivariate probability function suggest that the influence of this source on BTX concentrations was limited to point impacts. At both sites, benzene exhibited a different behavior from toluene and xylenes, most likely due to its significantly lower chemical reactivity.