Volatile Halogenated Organic Compounds Research Articles

Size‐Selective Capture of Fluorocarbon Gases and Storage of Volatile Halogenated Organic Vapors with Low Boiling Points by Molecular‐Scale Cavities of Crystalline Pillar[n]quinones

AbstractFluorocarbon gases are regarded as one of the largest contributors to serious environmental problems such as ozone‐depletion and global warming, and thus, the development of reclamation technologies is in great demand for reducing emission of such harmful compounds. So far, porous materials such as zeolites, activated carbons, and metal‐organic frameworks (MOFs) have been examined as solid‐state absorbents for fluorocarbon gases. However, such porous materials often suffer from a lack of size‐selectivity in fluorocarbon gas uptakes due to the large‐sized cavities (>1 nm). Herein, it is reported that macrocyclic pillar[n]quinones (P[n]Q, n = 5 or 6) in crystalline state show size‐selective uptake for fluorocarbon gases owing to their molecular‐scale cavities (<1 nm). The P[n]Q also show uptake behaviors for volatile halogenated organic compounds (VHOCs), which are highly toxic. Interestingly, the volatilities of VHOCs within the 1D channels of P[5]Q are drastically reduced compared with those of the bulk VHOC solvents. Experimental results and computational analyses revealed that the excellent storage abilities of the crystalline P[n]Q are a synergic result of their electron‐deficient macrocyclic scaffolds and the basic carbonyl oxygen atoms on their rims.

Electron Donation from Boron Suboxides via Strong p-d Orbital Hybridization Boosts Molecular O2 Activation on Ru/TiO2 for Low-Temperature Dibromomethane Oxidation.

Low-temperature catalytic oxidation is of significance to the degradation of halogenated volatile organic compounds (HVOCs) to avoid hazardous byproducts with low energy consumption. Efficient molecular oxygen (O2) activation is pivotal to it but usually limited by the insufficient electron cloud density at the metal center. Herein, Ru-B catalysts with enhanced electron density around Ru were designed to achieve efficient O2 activation, realizing dibromomethane (DBM) degradation T90 at 182 °C on RuB1/TiO2 (about 30 °C lower than pristine Ru/TiO2) with a TOFRu value of 0.055 s-1 (over 8 times that of Ru/TiO2). Compared to the limited electron transfer (0.02 e) on pristine Ru/TiO2, the Ru center gained sufficient negative charges (0.31 e) from BOx via strong p-d orbital hybridization. The Ru-B site then acted as the electron donor complexing with the 2π* antibonding orbital of O2 to realize the O2 dissociative activation. The reactive oxygen species formed thereby could initiate a fast conversion and oxidation of formate intermediates, thus eventually boosting the low-temperature catalytic activity. Furthermore, we found that the Ru-B sites for O2 activation have adaptation for pollutant removal and multiple metal availability. Our study shed light on robust O2 activation catalyst design based on electron density adjustment by boron.

Method development for in situ study of marine vanadium peroxidase based on SERS and chemometrics

AbstractVanadium peroxidases from marine algae are responsible for the production of ozone‐depleting compounds, volatile halogenated organic compounds (VHOC). Due to the impact the release of these compounds has on the global atmospheric and biogeochemical processes, there is an interest within marine sciences in developing analytical methods for studying the various aspects of the VHOC production, particularly in situ. This study aimed to provide new methods towards the development of in situ methods within marine sciences.We demonstrate the use of design of experiments together with orthogonal partial least squares (OPLS) and transposed orthogonal partial least squares (T‐OPLS) to address the qualitative spectral analysis of an enzyme‐buffer system. The measurements were performed with surface‐enhanced Raman spectroscopy (SERS) on vanadium bromoperoxisase from the red algae Corallina officinalis. The chemometric tools used aimed to provide greater insights into how factors such as time, amount of gold nanoparticles and enzyme concentration influence the spectral responses and whether there was any synergy between those factors. The results acquired in this report aim to support future method development of chemometrics within in situ applications in marine sciences.

Effect on water quality and control of chemically enhanced backwash by-products (CEBBPs) in the adsorption-ultrafiltration process

Abstract The overall purpose of this research was to investigate the typical types of chemically enhanced backwash by-products (CEBBPs) produced in the chemically enhanced backwash (CEB) process and the influence of variability of CEB factors on typical CEBBPs in the adsorption-ultrafiltration process. Moreover, health risk assessment was utilized to assess the potential adverse health effects from exposure to effluent after the optimal online CEB. The results of the study found the NaClO backwash reagent could react with organic matter to produce CEBBPs, including 9 kinds of volatile halogenated organic compounds (VHOCs) and 9 kinds of haloacetic acids (HAAs) during the CEB process. After a comprehensive consideration of the influence of a single factor on the CEBBPs formation and membrane cleaning effect, the optimal CEB parameters were 6 min of BD, 120 min of BI, 30 L/(m2·h) of BF and 50 mg/L of RC. Under the optimum CEB cleaning parameters, the effluent does not pose a non-carcinogenic risk and posed potential carcinogenic risk to local residents. The lifetime carcinogenic risk (LCR) value for HAAs (6.68E-06) is very close to the LCR value of CEBBPs (6.78E-06), indicating that the HAAs are the main substances in the effluent after CEB.

Preparation of Carbotrap/silica composite for needle trap field sampling of halogenated volatile organic compounds followed by gas chromatography/mass spectrometry determination.

A needle trap device (NTD) was packed with Carbotrap/silica composite sorbent and applied for field sampling of halogenated volatile organic compounds (HVOCs) followed by gas chromatography/mass spectrometry (GC/MS) separation and determination. Carbotrap B, as a highly pure surface sorbent, was prepared using sol-gel method to improve its surface properties for adsorption/desorption of the target analytes. The effects of important experimental variables on the sampling and determination of trichloroethylene (thrCE) and tetrachloroethylene (tetCE) using the proposed NTD-GC/MS strategy were evaluated and optimized. The results showed that sampling temperature and relative humidity interfered with sampling efficiency of the developed method and peak area responses of the analytes decreased with increasing temperature and relative humidity. The peak areas of the analytes increased with raising desorption temperature from 180 to 250°C, and increasing desorption time from 1 to 3min. The carryover experiments showed that the carryover effect disappeared after 3min of desorption time. The Limits of Detection (LODs) and Limits of Quantitation (LOQs) of the analytes were in the range 0.01-0.03 and 0.05-0.09, respectively. The results indicated that the developed NTD-GC/MS procedure can be used as a technology with high sensitivity for the field sampling and determination of HVOCs.

UIO-66-NH2 Packed Needle Trap for Accurate and Reliable Sampling and Analysis of the Halogenated Volatile Organic Compounds in Air

ABSTRACT This paper introduces a novel inside needle adsorption trap device based on UiO-66-NH2 adsorbent for the sampling and analysis of halogenated volatile organic compounds (HVOCs), including chloroform, carbon tetrachloride, and perchloroethylene in air. In this study, the UiO-66-NH2 adsorbent was first synthesized and then packed into spinal needles (22 Gauge). This study was conducted both in the laboratory and in the field. Scanning Electron Microscope (SEM), Fourier Transform Infrared Spectroscopy (FT-IR) and X-Ray Diffraction (XRD) were used to investigate the sorbent characteristics. In this study, Response Surface Methodology (RSM) and Central Composite Design (CCD) were utilized to optimize the effects of sampling parameters and desorption parameters on needle trap device (NTD) performance. In this regard, a constant concentration of the compounds of interest was injected into a standard chamber, and then the packed NTD was used for the sampling of HVOCs under a given condition. According to the results, the maximum peak area response was obtained at 280 ˚C of desorption temperature and 4 min of desorption time. The results showed that increased sampling humidity and temperature interfered with the NTD performance and decreased the peak area responses of the analytes. The proposed NTD had a high sensitivity for the sampling and analysis of the desired compounds. Limit of Detection (LOD) and the Limit of Quantitation (LOQ) of the NTD for the analytes were in the range 0.01-0.03 and 0.02-0.05 ng.mL-1, respectively. Moreover, the repeatability of the proposed NTD was obtained to be in the range of 2.3-9.1%. Therefore, the NTD packed with UiO-66-NH2 adsorbent can be used as a suitable and robust method for the active sampling and analysis of occupational/environmental pollutants in the air.

Emission of volatile halogenated organic compounds over various Dead Sea landscapes

Abstract. Volatile halogenated organic compounds (VHOCs), such as methyl halides (CH3X; X is Br, Cl and I) and very short-lived halogenated substances (VSLSs; bromoform – CHBr3, dibromomethane – CH2Br2, bromodichloromethane – CHBrCl2, trichloroethylene – C2HCl3, chloroform – CHCl3 – and dibromochloromethane – CHBr2Cl) are well known for their significant influence on ozone concentrations and oxidation capacity of the troposphere and stratosphere and for their key role in aerosol formation. Insufficient characterization of the sources and the emission rate of VHOCs limits our ability to understand and assess their impact in both the troposphere and stratosphere. Over the last two decades, several natural terrestrial sources for VHOCs, including soil and vegetation, have been identified, but our knowledge of emission rates from these sources and their responses to changes in ambient conditions remains limited. Here we report measurements of the mixing ratios and fluxes of several chlorinated and brominated VHOCs from different landscapes and natural and agricultural vegetated sites at the Dead Sea during different seasons. Fluxes were generally positive (emission into the atmosphere), corresponding to elevated mixing ratios, but were highly variable. Fluxes (and mixing ratios) for the investigated VHOCs ranged as follows: CHBr3 from −79 to 187 nmol m−2 d−1 (1.9 to 22.6 pptv), CH2Br2 from −55 to 71 nmol m−2 d−1 (0.7 to 19 pptv), CHBr2Cl from −408 to 768 nmol m−2 d−1 (0.4 to 11 pptv), CHBrCl2 from −29 to 45 nmol m−2 d−1 (0.5 to 9.6 pptv), CHCl3 from −577 to 883 nmol m−2 d−1 (15 to 57 pptv), C2HCl3 from −74 to 884 nmol m−2 d−1 (0.4 to 11 pptv), methyl chloride (CH3Cl) from -5300 to 10,800 nmol m−2 d−1 (530 to 730 pptv), methyl bromide (CH3Br) from −111 to 118 nmol m−2 d−1 (7.5 to 14 pptv) and methyl iodide (CH3I) from −25 to 17 nmol m−2 d−1 (0.4 to 2.8 pptv). Taking into account statistical uncertainties, the coastal sites (particularly those where soil is mixed with salt deposits) were identified as sources of all VHOCs, but this was not statistically significant for CHCl3. Further away from the coastal area, the bare soil sites were sources for CHBrCl2, CHBr2Cl, CHCl3, and probably also for CH2Br2 and CH3I, and the agricultural sites were sources for CHBr3, CHBr2Cl and CHBrCl2. In contrast to previous reports, we also observed emissions of brominated trihalomethanes, with net molar fluxes ordered as follows: CHBr2Cl > CHCl3 > CHBr3 > CHBrCl2 and lowest positive flux incidence for CHCl3 among all trihalomethanes; this finding can be explained by the soil's enrichment with Br. Correlation analysis, in agreement with recent studies, indicated common controls for the emission of CHBr2Cl and CHBrCl2 and likely also for CHBr3. There were no indications for correlation of the brominated trihalomethanes with CHCl3. Also in line with previous reports, we observed elevated emissions of CHCl3 and C2HCl3 from mixtures of soil and different salt-deposited structures; the flux correlations between these compounds and methyl halides (particularly CH3I) suggested that at least CH3I is also emitted via similar mechanisms or is subjected to similar controls. Overall, our results indicate elevated emission of VHOCs from bare soil under semiarid conditions. Along with other recent studies, our findings point to the strong emission potential of a suite of VHOCs from saline soils and salt lakes and call for additional studies of emission rates and mechanisms of VHOCs from saline soils and salt lakes.

Spatiotemporal distributions of halocarbons in the marine boundary air and surface seawater of the Changjiang estuary and its adjacent East China Sea

Spatiotemporal distributions of volatile halogenated organic compounds (VHOCs) were investigated in the marine boundary air and surface seawater of the Changjiang (Yangtze River) estuary and its adjacent East China Sea in two cruises from March 11, 2015 to March 21, 2015 and from July 9, 2015 to July 20, 2015. Results revealed that the concentrations of released chlorofluorocarbons (CFCs) such as CFC-12, CFC-11, and CFC-114 in China decreased, suggesting that limitations set by the Chinese government on CFCs production and consumption have taken effect. Atmospheric concentrations of CFCs were affected by local industrial sources of emission and transport of terrestrial pollutants from coastal areas to varying degrees. Seasonal variations in atmospheric VHOCs were probably due to seasonal differences in prevalent monsoon and biogenic production. In the study periods, the investigated area was an essential source of atmospheric CH3Br and CH3I but was a net sink of CFC-12, CFC-11, and CH3Cl.

Environmental assessments on schools located on or near former industrial facilities: Feedback on attenuation factors for the prediction of indoor air quality

One of the goals of the French national campaign called “Etablissements Sensibles (Sensitive Establishments)” is to evaluate indoor air degradation in schools because of vapor intrusion of volatile compounds from soil gases towards the indoor air, related to the presence of former industrial sites on or near the establishment. During this campaign, as recommended by the United States of Environmental Protection Agency (US EPA), indoor air quality was evaluated from soil gas concentrations using generic attenuation factors, and extra investigations into soil gases and indoor air were performed when the estimated values exceeded target indoor air concentrations. This study exploits matched data on subsurface soil gases and indoor air that came from the “Sensitive Establishments” campaign. It aims to consolidate and refine the use of attenuation factors as a function of environmental variables acquired routinely during environmental assessments. We have been able to select the measured environmental variables that have the most influence on vapor intrusion using Principal Components Analysis and hypotheses tests. Since the collected data are mainly related to weak sources (only 15% schools required risk management measures related to vapor intrusion), halogenated volatile organic compounds (HVOC) were selected as tracer compounds for vapor intrusion for this study. This choice enables the exclusion or minimization of background sources contributions.From the results we have calculated the descriptive statistics of the attenuation factors distribution for the subslab-to-indoor air pathway and refined the attenuation factors for this pathway through an easily obtained parameter, building age. Qualitative comparison of attenuation factors according to the building age shows that attenuation factors observed for building less than 50 years are lower than attenuation factors for buildings 50 years old and above. These results show the utility of creating databases for consolidating and refining attenuation factors and therefore improving their use.

Identification and determination of disinfection byproducts in chlorine-containing household cleansing products

Seven halogenated volatile organic compounds (HVOCs) and two haloacetic acids were detected and quantified in 15 household products, including sodium hypochlorite, by gas chromatography-mass spectrometry (GC-MS). Chloroform was detected in a range of 0.2–30.2 mg kg−1 in all products, and carbon tetrachloride was observed in 13 samples in a range of 0.05–352 mg kg−1. Dichloroacetic acid and trichloroacetic acid were also detected up to 94 and 146 mg kg−1 in household products. The estimated human exposures of chloroform, carbon tetrachloride, dichloroacetic acid and trichloroacetic acid were calculated to 0.041, 0.240, 0.913 and 2.39 mg/kg/day by the exposure algorithm from the Japan National Institute of Technology and Evaluation, respectively. According to the calculated result, the total estimated human exposure of chloroform were determined to exceed the tolerable concentration of inhalation exposure presented by the World Health Organization. The DBPs should be controlled to the lowest concentrations in the chlorine-containing household cleansing products.

Spatio-temporal distributions of chlorofluorocarbons and methyl iodide in the Changjiang (Yangtze River) estuary and its adjacent marine area

Temporal and spatial distribution patterns of volatile halogenated organic compounds (VHOCs), such as dichlorodifluoromethane (CFC-12), trichlorofluoromethane (CFC-11), trichlorotrifluoroethane (CFC-113), and methyl iodide (CH3I), in the Changjiang (Yangtze River) estuary and its adjacent marine area were measured during two cruises from 21 February to 10 March 2014 and from 10 to 21 July 2014. VHOC concentrations showed seasonal variation with higher values during winter. VHOC distributions evidently decreased along the freshwater plume from the river mouth to the open sea and from inshore to offshore regions. VHOC distributions were obviously influenced by the Changjiang runoff, anthropogenic inputs, and biological release of phytoplankton. The study area was a net sink for CFC-12 and CFC-11, but a net source for atmospheric CH3I during the study periods.

Distributions and sources of volatile chlorocarbons and bromocarbons in the Yellow Sea and East China Sea

Six volatile halogenated organic compounds (VHOC), namely, chloroform, carbon tetrachloride, trichloroethylene, bromodichloromethane, dibromochloromethane, and bromoform, were studied in the Yellow Sea and East China Sea from April to May, 2009. The spatial variability of these VHOC was influenced by various factors, including anthropogenic inputs, biogenic production and complicated hydrographic features such as Changjiang Diluted Water, Yellow Sea Cold Water Mass, and Kuroshio Current. Diurnal study results showed that factors such as solar irradiation, biological activity, and tide affected the abundance of these VHOC. Correlation analyses revealed that bromodichloromethane was positively correlated with chlorophyll a in surface seawater. Principal component analysis suggested that chlorinated compounds like carbon tetrachloride originated from anthropogenic sources whereas brominated compounds such as bromodichloromethane originated from biogenic sources. Sources of other chlorinated and brominated compounds may not be governed by biological processes in the marine environment.

Dynamics of halocarbons in coastal surface waters during short term mesocosm experiments

Environmental context Halocarbons are trace gases important in atmospheric ozone chemistry whose biogenic production – among other factors – depends on light-induced stress of marine algae. Several studies have confirmed this effect in laboratory experiments but knowledge in natural systems remains sparse. In mesocosm experiments, which are a link between field and laboratory studies, we observed that the influence of natural levels of ultraviolet radiation on halocarbon dynamics in the marine surface waters was either insignificant or concealed by the complex interactions in the natural systems. Abstract The aim of the present study was to evaluate the influence of different light quality, especially ultraviolet radiation (UVR), on the dynamics of volatile halogenated organic compounds (VHOCs) at the sea surface. Short term experiments were conducted with floating gas-tight mesocosms of different optical qualities. Six halocarbons (CH3I, CHCl3, CH2Br2, CH2ClI, CHBr3 and CH2I2), known to be produced by phytoplankton, together with a variety of biological and environmental variables were measured in the coastal southern Baltic Sea and in the Raunefjord (North Sea). These experiments showed that ambient levels of UVR have no significant influence on VHOC dynamics in the natural systems. We attribute it to the low radiation doses that phytoplankton cells receive in a normal turbulent surface mixed layer. The VHOC concentrations were influenced by their production and removal processes, but they were not correlated with biological or environmental parameters investigated. Diatoms were most likely the dominant biogenic source of VHOCs in the Baltic Sea experiment, whereas in the Raunefjord experiment macroalgae probably contributed strongly to the production of VHOCs. The variable stable carbon isotope signatures (δ13C values) of bromoform (CHBr3) also indicate that different autotrophic organisms were responsible for CHBr3 production in the two coastal environments. In the Raunefjord, despite strong daily variations in CHBr3 concentration, the carbon isotopic ratio was fairly stable with a mean value of –26‰. During the declining spring phytoplankton bloom in the Baltic Sea, the δ13C values of CHBr3 were enriched in 13C and showed noticeable diurnal changes (–12‰ ±4). These results show that isotope signature analysis is a useful tool to study both the origin and dynamics of VHOCs in natural systems.

Ecotoxicological effects of ballast water effluent teated by an electrolytic method on marine environment

Ballast water effluent treated by an electrolytic method contains reactive chlorine species and disinfection by-products (DBPs). In this study, we conducted whole effluent toxicity (WET) testing and ecological risk assessment (ERA) to investigate its ecotoxicological effects on marine environment. WET testing was carried out for three marine pelagic organisms, i.e., diatom Skeletonema costatum, rotifer Brachionus plicatilis and fish Paralichthys olivaceus. The biological toxicity test revealed that S. costatum was the only organism that showed apparent toxicity to the effluent; it showed no observed effect concentration (NOEC), lowest observable effect concentration (LOEC) and effect concentration of 50% (EC50) values of 12.5%, 25.0% and 83.3%, respectively, at brackish water condition. In contrast, it showed insignificant toxicity at seawater condition. B. plicatilis and P. olivaceus also showed no toxicities to the effluent at the both salinity conditions. Meanwhile, chemical analysis revealed that the ballast water effluent contained total residual oxidants (TROs) below 0.03 μg/L and a total of 20 DBPs including bromate, volatile halogenated organic compounds (VOCs), halogenated acetonitriles (HANs), halogenated acetic acids (HAAs) and chloropicrin. Based on ERA, the 20 DBPs were not considered to have persistency, bioaccumulation and toxicity (PBT) properties. Except monobromoacetic acid, the ratio of predicted environmental concentration (PEC) to predicted no effect concentration (PNEC) of the other 19 DBPs did not exceed 1. Thus, our results of WET testing and ERA indicated that the ballast water effluent treated by electrolysis and subsequently neutralization was considered to have no adverse impacts on marine environment.

Spatio-temporal variations of sea surface halocarbon concentrations and fluxes from southern Yellow Sea

Temporal and spatial distributions of five volatile halogenated organic compounds (VHOC), including chloroform (CHCl3), trichloroethylene (C2HCl3), bromodichloromethane (CHBrCl2), chlorodibromomethane (CHBr2Cl), and bromoform (CHBr3), were determined in the southern Yellow Sea (SYS) during four cruises from July 2008 to May 2009. The five VHOC distributed in the study area were affected by river inputs, anthropogenic activities, circulation system, and biological processes. In this study, CHCl3, CHBrCl2, CHBr2Cl, and CHBr3 concentrations showed significant differences between summer 2008 and spring 2009. The sea-to-air fluxes calculated using the equation of Liss and Merlivat (In: Buat-Menard P (ed) The role of air-sea exchange in geochemical cycling, 1986) indicated that the SYS was a source of CHCl3 and C2HCl3 to the atmosphere during the investigation period.

Distributions and sea-to-air fluxes of volatile halocarbons in the East China Sea in early winter

The concentrations of six volatile halogenated organic compounds (VHOC)–chloroform (CHCl3), trichloroethylene (C2HCl3), tetrachloroethylene (C2Cl4), carbon tetrachloride (CCl4), methylchloroform (CH3CCl3), and bromoform (CHBr3) in the East China Sea (ECS) in November and December 2010 were measured by a purge and trap system coupled to a gas chromatograph with an electron capture detection (ECD). Mean (range) concentrations of CHCl3, C2HCl3, C2Cl4, CH3CCl3, CCl4 and CHBr3 in the surface water were 16.90 (0.40–62.92), 16.27 (2.78–83.33), 2.40 (0.39–9.33), 32.29 (19.72–57.68), 1.70 (0.39–8.73) and 17.11 (4.33–34.46) pM, respectively. With the exception of C2HCl3, the concentrations of other five kinds of VHOC generally exhibited a decreasing trend with distance from the coast, with the low values found in the open sea. The anthropogenic sources contributed to the elevated levels of CCl4 and CH3CCl3, whereas a combination of the anthropogenic and biogenic sources might be responsible for the elevated levels of CHCl3, C2HCl3, C2Cl4 and CHBr3. In the depth profiles, vertical distributions of the six VHOC in the water column were complicated, with the maxima occurring at 0–100m depths. The mean sea-to-air fluxes of CHCl3, C2HCl3, C2Cl4 and CHBr3 were estimated to be 21.08, 29.94, 2.05 and 35.50nmolm−2d−1, respectively, indicating that the ECS was a source for the four VHOC in the atmosphere.

Headspace GC–MS Analysis of Halogenated Volatile Organic Compounds in Aqueous Samples: An Experiment for General Chemistry Laboratory

Analysis of halogenated volatile organic compounds (HVOCs) by GC–MS demonstrates the use of instrumentation in the environmental analysis of pollutant molecules and enhances student understanding of stable isotopes in nature. In this experiment, students separated and identified several HVOCs that have been implicated as industrial groundwater contaminants and deduced the isotopic content by analyzing the molecular ion region of the mass spectra. The HVOCs were analyzed by direct sampling of the headspace vapor over a dilute aqueous solution, which is designed to simulate a contaminated groundwater sample. The rapid headspace sampling and analysis allowed completion of the experiment by many lab classes per week. The impact of the lab was assessed using online surveys before and after the lab that queried student perceptions of their understanding, skills, and attitudes toward science and chemistry. The surveys showed noticeable gains in understanding and skills; however, few changes in attitudes were seen among students, the majority of whom already seemed committed to science and engineering careers and majors.

Surface water quality assessment by the use of combination of multivariate statistical classification and expert information

The present study deals with the assessment of surface water quality from an industrial–urban region located in northern Poland near to the city of Gdansk. Concentrations of thirteen chemicals including total polycyclic aromatic hydrocarbons (PAHs), halogenated volatile organic compounds (HVOCs) and major ions in the samples collected at five sampling points during six campaigns were used as variables throughout the study. The originality in the monitoring data treatment and interpretation was the combination of a traditional classification approach (self-organizing maps of Kohonen) with PAH diagnostic ratios expertise to achieve a reliable pollution source identification. Thus, sampling points affected by pollution from traffic (petroleum combustion products), from crude oil processing (petroleum release related compounds), and from phosphogypsum disposal site were properly discriminated. Additionally, it is shown that this original assessment approach can be useful in finding specific pollution source tracers.

Simultaneous Determination of Volatile Halogenated Organic Compounds in Brackish Water and Seawater by Purge and Trap-Gas Chromatography/Mass Spectrometry

Simultaneous determination method for 12 volatile halogenated organic compounds (VHOCs) in brackish water and seawater has been developed, based on purge and trap-gas chromatography/mass spectrometry. The limits of detection for VHOCs were <0.04 pmol L−1 for bromomethane, iodoethane and tribromomethane, <0.13 pmol L−1 for bromochloromethane, chloroiodomethane, chlorodibromomethane and bromoiodomethane, <0.21 pmol L−1 for chloromethane, dibromomethane, bromodichloromethane, and diiodomethane and 0.67 pmol L−1 for iodomethane. Good linearities of the calibration curves for 12 VHOCs were obtained in the concentration range up to100 pmol L−1. The correlation coefficients were >0.997 for bromochloromethane, chlorodibromomethane, bromodichloromethane, bromoiodomethane and tribromomethane, >0.981 for chloromethane, iodomethane, iodoethane, chloroiodomethane and diiodomethane, 0.967 for dibromomethane and 0.923 for bromomethane. Using this developed method, the concentrations of VHOCs in brackish water, coastal seawater and open ocean seawater were measured. The coefficients of variation were approximately <20% in all samples. Thus, this simultaneous highly sensitive analysis method was valuable for determination of trace levels of VHOCs concentrations in natural water.

Effects of salt and light stress on the release of volatile halogenated organic compounds bySolieria chordalis: a laboratory incubation study

AbstractThe red algaSolieria chordaliswas used as a model to investigate the effects of salt and light stress on the release of volatile halogenated organic compounds (VHOCs). We used a purge and trap technique coupled with a gas chromatograph equipped with an electron capture detector.S. chordaliswas exposed to hyposaline (22 psu), hypersaline (50 psu) and normal salinity (34 psu) media in combination with light stress (48 h in the dark followed by 24 h under continuous light). The releases of 9 VHOCs (i.e., CH3I, CH3CH2I, CH2ClI, CH2Br2, CHBrCl2, CHBr2Cl, CH2BrI, CHBr3, CH2I2) were measured after 0, 24, 48 and 72 h on algal sub-samples. In algae unstressed by salt, VHOC production rate decreased under dark conditions but increased with light exposure. However, long periods of light also resulted in higher production of di-halogenated compounds (as compared to tri-halogenated or mono-halogenated compounds). The results from salt-stressed samples indicate that hypoosmotic conditions strongly enhanced whole VHOC production rate, whereas hyper-osmotic conditions slightly reduced their production. An exception was mono-halogen production, which was higher under hyper-osmotic condition (especially during dark periods). Furthermore, long exposure to light and hyper-osmotic conditions led to a decrease in the production of di-halogenated compounds (this did not occur in thalli unstressed by salt). As halogen productions derive from different metabolic pathways, including an enzymatic mechanism, it is possible that the activity of these enzymes may be affected by exposure to various salinity conditions.