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At least 181 records · Page 10Linked to original sources
PubMed1987

Chemical changes of organic compounds in chlorinated water. XIV. Characterization and determination of halogenated organics formed during chlorination of water from the Tama River.

Water samples collected from the Tama River were treated with chlorine under the conditions utilized for water renovation, in order to characterize and determine the halogenated organics formed in this reaction. It was found that the concentrations and compositions of organic halogens in chlorinated river water are strongly dependent on the sampling points. Chlorinated river-water showed total trihalomethane (THM) levels ranging from 26 to 96 micrograms/l. Higher concentrations of THMs and a high ratio of brominated THMs to total THMs were found on chlorination of water samples taken from the midstream of the Tama River, as compared with those observed from the upstream. The range of non-purgeable (NPOX) and n-hexane-extractable organic halogen (EOX) levels in the chlorinated river-water was from 146 to 417 microgram/l and from 15 to 105 micrograms/l, respectively. Gas chromatographic analyses of n-hexane extracts demonstrated that chlorine treatment of river-water not only produces, in addition to THMs, new lower-molecular-weight and chromatographiable organic halogen compounds (COX), but also decomposes the original halogenated organics present. The amounts of THMs, COX, EOX and NPOX in chlorine-treated river-water were found to be dependent on the pH of the solutions.

Chlorine↗
PubMed1980

Gas chromatography mass spectrometry computer analysis of volatile halogenated hydrocarbons in man and his environment--A multimedia environmental study.

As part of a study to make a comparative analysis of selected halogenated compounds in man and the environmental media, a quantitative gas chromatography mass spectrometric analysis of the levels of the halogenated compounds found in the breath, blood and urine of an exposed population (Old Love Canal area, Niagara, New York) and their immediate environment (air and water) was undertaken. In addition, levels of halogenated hydrocarbons in air samples taken in the general Buffalo, Niagara Falls area were determined.

Air Pollutants↗
PubMed2001

A GC/ECNI-MS method for the identification of lipophilic anthropogenic and natural brominated compounds in marine samples.

GC/ECNI-MS in both the full scan and selected ion monitoring modes was applied to study the patterns of brominated compounds in the blubber of marine mammals from a variety of locations. The adipose tissue of one polar bear was also studied. Occurrence of three major residues originating from the use of brominated flame-retardants (PBDE 47, 99, and 100) and several potential naturally occurring brominated compounds was studied in the samples. A series of three major natural brominated compounds (BC-1, BC-2, BC-3) recently identified in dolphins from Australia was included in this study. Two further brominated compounds, BC-10 and BC-11, were studied for the first time. ECNI-MS full scan spectra were obtained for BC-3 and BC-10. A natural mixed halogenated compound (MHC-1) and an unknown brominated compound (UBC-1) were investigated as well. Evidence for the natural production of these secondary metabolites and their bioaccumulation in higher organisms as well as analytical protocols for their detection in the environment are presented. Some of these naturally occurring compounds may be misinterpreted as anthropogenic brominated compounds. In ECNI-MS, brominated compounds are usually identified by the detection of the fragment ions m/z 79 ([79Br]-) and m/z 81 ([81Br]-). In this work, it is shown that monitoring of additional ion traces corresponding to [Br2]- (160 type), [HBr2]- (161 type), [BrCl]- (116 type), and [HBrCl]- (117 type) fragment ions allows distinguishing between different classes of brominated compounds. This technique was used to demonstrate that UBC-1 is neither a PBDE nor a PBB congener, whereas a second mixed halogenated compound (MHC-2) was identified as a result of the ECNI-MS response at m/z 114/116. Studies on blubber extracts of marine mammals from four continents resulted in the detection of significant differences in the global distribution of brominated compounds. Our results suggest that naturally occurring organobromines are more abundant than anthropogenic brominated compounds in several regions of the world.

Adipose Tissue↗
PubMed1980

Effects of halogenated organic compounds on photosynthesis in estuarine phytoplankton.

Chlorine oxidants (chlorine gas, sodium hypochlorite, and calcium hypochlorite) are used as biocides to control fouling in seawater cooled power generating plants and to kill pathogens in sewage effluents entering estuarine waters. Organisms killed include algae, fungi, bacteria, barnacles, oysters, and clams. Use of these chemicals in saline waters results in the formation of halogenated by-products (JOHANNESSON 1958, DUURSAM & PARSI 1976, DOVE 1973). BEAN et al, (1978), in a study of chlorinated seawater, identified eighteen organic compounds generated by chlorination. Due to rapid substitution of bromine for chlorine, brominated rather than chlorinated by-products are formed (FARKAS et al. 1949, GALAL-GORCHEV & MORRIS 1965, MACALADY et al. )977, SUGAM & HELZ 1977). The effects of these chlorinated by-products on estuarine phytoplankton are not known. Experiments in this study examined singly the effects of fifteen commercially available compounds on photosynthesis by estuarine phytoplankton.

Hydrocarbons, Halogenated↗
PubMed2006

Chemical characterization of odorous gases at a landfill site by gas chromatography-mass spectrometry.

The composition of odorous gases emitted from a municipal landfill in the city of Izmir, Turkey was investigated using gas chromatography-mass spectrometry, and these data were examined in relation with the odor concentrations. Several volatile organic compounds (VOCs) were identified and quantified at five sampling sites in May and September 2005. Detected VOCs were monoaromatics (0.09-47.42 microg m(-3)), halogenated compounds (0.001-62.91microg m(-3)), aldehydes (0.01-38.55 microg m(-3)), esters (0.01-7.54 microg m(-3)), ketones (0.03-67.60 microg m(-3)), sulfur/nitrogen containing compounds (0.03-5.05 microg m(-3)), and volatile fatty acids (VFAs) (0.05-43.71 microg m(-3)). High levels of aldehydes (propanal up to 38.55 microg m(-3)) and VFAs (formic acid up to 43.71 microg m(-3)) were measured in May. However, VOC concentrations were relatively low in September. The monoaromatics and halogenated compounds were the abundant VOCs in landfill air for the both sampling periods. The benzene-to-toluene (B:T) ratio at the landfill site was significantly lower than urban areas indicating the presence of higher amounts of toluene in landfills compared to traffic exhaust rich urban areas. A statistically significant linear relationship was found between odor concentrations determined by olfactometry and total VOC concentrations. The relationships of odor concentrations with the different groups of chemicals were also examined using a step-wise multiple regression analysis. It was found that the concentrations of aldehydes, ketones, and esters are the best estimators, explaining 96% of the variability in odor concentrations (r2 = 0.96, n = 10, P < 0.01).

Air Pollutants↗
PubMed1996

Chloracne in the 1990s.

BACKGROUND: Chloracne is a disease associated with toxicity of halogenated compounds used in some industrial processes. A patient affected by chloracne led us to study a total of nine cases from a single factory. METHODS: We studied the clinical features of nine patients exposed chronically to chlorobenzenes. On all of them blood samples were drawn and biopsies of affected skin and liver were taken. Their work environment was visited and studied. RESULTS: All nine patients were men and had polymorphic skin lesions, characterized mainly by comedones and cysts. They had chronic conjunctivitis and seven had cysts in the Meibomian glands. All of them had polyneuropathy and liver damage and seven had hypertriglyceridemia. Compounds known to cause chloracne were found in exceedingly high concentrations in the water used in the workplace. CONCLUSIONS: Every patient exposed to halogenated compounds with the cutaneous manifestations of chloracne should be carefully investigated for systemic complications (such as ophthalmic, neuropathic, hepatic, and lipoprotein abnormalities).

Acne Vulgaris↗
PubMed2005

Molecular analysis of Desulfitobacterium frappieri pcp-1 involved in reductive dehalogenation of pentachlorophenol.

Desulfitobacterium are Gram positive, spore-forming, strictly anaerobic bacteria, that belong to the Firmicutes, Clostridia, Clostridiales, and Peptococcaceae. Most known members of the genus Desulfitobacterium have the ability to dechlorinate several halogenated compounds by a mechanism of reductive dehalogenation and use them as electron acceptors to generate energy (halorespiration). Desulfitobacteria are therefore perfect candidates to be used in bioremediation treatments of environment polluted with halogenated compounds. Understanding the physiology and the molecular mechanisms of these bacteria will help to develop better bioremediation systems. This report summarizes works that have been done in our laboratories with D. frappieri PCP-1 on reductive dehalogenases, genes encoding these dehalogenases and their expression, and the development of lab-scale PCP-degrading reactors using this bacterium.

Biodegradation, Environmental↗
PubMed2001

Biochemical characterization of broad-specificity enzymes using multivariate experimental design and a colorimetric microplate assay: characterization of the haloalkane dehalogenase mutants.

The pH indicator dye-based colorimetric method and multivariate experimental design were used for the systematic biochemical characterization of the broad-specificity enzymes haloalkane dehalogenases. Halogenated compounds for characterization of the enzymes were selected using Principal Component Analysis. The substrates were characterised by 24 physico-chemical and structural descriptors. Thirty-four substrates were selected for testing out of 194 halogenated compounds. Relative activities determined using the optimised colorimetric microplate assay were validated against the catalytic constants determined by gas chromatography. The applicability of the assay was tested with F151L, F154L and F169L mutants of the haloalkane dehalogenase from Sphingomonas paucimobilis UT26.

Colorimetry↗