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Mengder Fang - One of the best experts on this subject based on the ideXlab platform.
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pollution topography of chlorobenzenes and Hexachlorobutadiene in sediments along the kaohsiung coast taiwan a comparison of two consecutive years survey with statistical interpretation
Chemosphere, 2005Co-Authors: Chonlin Lee, Hueijing Song, Mengder FangAbstract:Abstract Forty sediments were analyzed for chlorobenzenes (CBs) and Hexachlorobutadiene (HCBD) to investigate their pollution topography along the Kaohsiung coast, Taiwan. Maximum CB concentrations found, varied from 15.4 ng/g dw for 1,2,3-TCB to 56.8 ng/g dw for 1,2,4-TCB, while higher HCBD concentrations were detected among north-bound stations (around the exit of the Tsoying outfall pipe) and its concentration decreases from north to south. Compared to a previous survey executed a year before, there is no statistically significant difference in CB and HCBD congeners between these two surveys (p = 0.68–0.87, two-tailed paired t-test). The spatial distribution of toxic index reveals that biological effects might occur near Tsoying and Dalinpu outfall pipe outlets which dispose of petro-chemical wastewater. Evidence found in this study also shows distinct CB patterns from the two nearby sources, the Dalinpu outfall pipe outlet and the Kaoping estuary. Principal component analysis shows that four principal components conducting CBs and HCBD distribution were extracted. Both the first two components (accounted for 58.8% of the total variance), comprised all of the CBs except HCB (DCBs to PeCB), were found not capable of differentiating any distinct pollution source. On the other hand, HCBD and HCB were extracted as third and fourth components, respectively, pointing out their distinct sources in this area.
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concentrations of chlorobenzenes Hexachlorobutadiene and heavy metals in surficial sediments of kaohsiung coast taiwan
Chemosphere, 2000Co-Authors: Chonlin Lee, Hueijing Song, Mengder FangAbstract:This work analyzes surface sediment samples collected from 40 stations along the Kaohsiung coast in southern Taiwan for chlorobenzenes (CBs), Hexachlorobutadiene (HCBD) and heavy metals (Cu, Zn, Pb, Cd, Ni, Fe, Mn and Cr). The highest CBs concentrations are recorded in station T7-15 (about 10 km west off the outlet of Da-lin-pu ocean outfall pipe), with total di-, tri-, tetra-, penta- and hexa-chlorobenzenes concentrations of 290.5, 117.1, 64.5, 15.7 and 22.3 ng/g, respectively. The major pollution source of HCBD is most likely located in the Tso-yin ocean outfall field; while the Dah-lin-pu ocean outfall field and Kao-ping Chi estuary, located in the southern portion of Kaohsiung coast, are the major contributors of hexachlorobenzene. The concentration of CBs congeners correlate fairly well with each other, as do metals. However, concentrations of organics (CBs and HCBD) did not correlate with metals. This finding implies that the pollution characteristics of organics and heavy metals in this highly utilized coastal zone markedly differ from each other.
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sources and distribution of chlorobenzenes and Hexachlorobutadiene in surficial sediments along the coast of southwestern taiwan
Chemosphere, 1997Co-Authors: Chonlin Lee, Mengder FangAbstract:Abstract The spatial distribution of chlorobenzenes in surficial sediments of the estuaries of major rivers along the coast of southwestern Taiwan was determined. Analytical results from sediment sampling stations indicate that the three outfall fields near Taiwan's largest industrial city, Kaohsiung, exhibit the highest concentrations of chlorobenzenes. More specifically, sediments from Tso-yin outfall field, which receives the wastewater from a very large petrochemical complex, had concentrations of 1,3,5-trichlorobenzene, pentachlorobenzene, hexachlorobenzene and Hexachlorobutadiene 2–3 times higher than those from Chon-chou and Da-lin-pu outfall fields. Chlorobenzene congeners in sediments from the three outfall fields correlate closely and most of their correlation coefficients are even higher than those reported for Ise Bay, Japan. Results from undeveloped areas, estuaries of the Da-du, Tso-shui, and Chi-shui Chi, will be of value after the impact of planned industrial expansion development begins.
W Dekant - One of the best experts on this subject based on the ideXlab platform.
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binding of Hexachlorobutadiene to α2u globulin and its role in nephrotoxicity in rats
Toxicology and Applied Pharmacology, 1997Co-Authors: Axel Pahler, Gerhard Birner, Maria Michaela Ott, W DekantAbstract:Abstract Hexachlorobutadiene (HCBD) is nephrotoxic in rats causing damage to the proximal tubules. Renal toxicity is presumed to be due to bioactivation by glutathione S-conjugate formation and further processing by the enzymes of the mercapturic acid pathway to reactive intermediates. Recent studies revealed major sex-dependent differences in the pattern of urinary metabolites and gave evidence for the excretion of unmetabolized HCBD in the urine of male, but not female, rats. The objective of this study was to investigate the basis for the excretion of unchanged HCBD in the urine. We administered [ 14 C]-HCBD (200 mg/kg bw, po) to male and female Sprague–Dawley (SD) and NCI Black–Reiter rats (NBR), an α 2u -globulin-deficient strain. No major differences in the disposition and in the rates of excretion of [ 14 C]-derived radioactivity were observed between animals of both strains. Previously observed sex-specific differences in the formation of urinary metabolites in Wistar rats were now confirmed in SD rats and were also found in NBR rats. In contrast to male SD rats, however, NBR rats did not excrete unmetabolized HCBD with urine. [ 14 C]-HCBD (10% of total urinary metabolites) was only present in the urine of male SD rats. Anion-exchange HPLC showed radioactivity associated with the α 2u -globulin fraction in urine and renal cytosol of male SD rats; the radioactive compound was identified as HCBD bound to the protein. The results indicate that the male-specific urinary excretion of HCBD is associated with its binding to α 2u -globulin. Light microscopic examination revealed the formation of hyaline droplets indicative of the accumulation of α 2u -globulin in the kidney of male SD rats after staining with Lee's methylene blue basic fuchsin. H&E staining additionally confirmed the finding of more pronounced necrotic changes in renal tubules of male SD rats than in females as previously described for Wistar rats. Binding of HCBD to α 2u -globulin may contribute to the pronounced nephrotoxicity in male rats.
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biotransformation of the Hexachlorobutadiene metabolites 1 glutathion s yl pentachlorobutadiene and 1 cystein s yl pentachlorobutadiene in the isolated perfused rat liver
Xenobiotica, 1992Co-Authors: Michael Koob, W DekantAbstract:1. The first step in the bioactivation of the nephrotoxin Hexachlorobutadiene is the biosynthesis of 1-(glutathion-S-yl)-1,2,3,4,4-pentachloro-1,3-butadiene (GPCB). GPCB formed in the liver is secreted into bile, may be reabsorbed in the gut, intact or after hydrolysis to 1-(cystein-S-yl)-1,2,3,4,4-pentachloro-1,3-butadiene (CPCB), and undergo enterohepatic circulation or translocation to the kidney. Hepatic uptake and metabolism of GPCB and CPCB may thus influence the disposition of these S-conjugates. We therefore studied the metabolism and uptake of CPCB and GPCB in the isolated perfused rat liver.2. Dose-dependent uptake of GPCB and CPCB from the perfusion medium by isolated perfused liver was demonstrated; CPCB is cleared from the perfusion medium to a much higher extent than GPCB.3. GPCB and CPCB are intensively biotransformed to biliary metabolites. These metabolites were identified by thermospray mass spectrometry as products of the conjugation reaction of GPCB and CPCB with glutathione and subseq...
Chonlin Lee - One of the best experts on this subject based on the ideXlab platform.
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pollution topography of chlorobenzenes and Hexachlorobutadiene in sediments along the kaohsiung coast taiwan a comparison of two consecutive years survey with statistical interpretation
Chemosphere, 2005Co-Authors: Chonlin Lee, Hueijing Song, Mengder FangAbstract:Abstract Forty sediments were analyzed for chlorobenzenes (CBs) and Hexachlorobutadiene (HCBD) to investigate their pollution topography along the Kaohsiung coast, Taiwan. Maximum CB concentrations found, varied from 15.4 ng/g dw for 1,2,3-TCB to 56.8 ng/g dw for 1,2,4-TCB, while higher HCBD concentrations were detected among north-bound stations (around the exit of the Tsoying outfall pipe) and its concentration decreases from north to south. Compared to a previous survey executed a year before, there is no statistically significant difference in CB and HCBD congeners between these two surveys (p = 0.68–0.87, two-tailed paired t-test). The spatial distribution of toxic index reveals that biological effects might occur near Tsoying and Dalinpu outfall pipe outlets which dispose of petro-chemical wastewater. Evidence found in this study also shows distinct CB patterns from the two nearby sources, the Dalinpu outfall pipe outlet and the Kaoping estuary. Principal component analysis shows that four principal components conducting CBs and HCBD distribution were extracted. Both the first two components (accounted for 58.8% of the total variance), comprised all of the CBs except HCB (DCBs to PeCB), were found not capable of differentiating any distinct pollution source. On the other hand, HCBD and HCB were extracted as third and fourth components, respectively, pointing out their distinct sources in this area.
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concentrations of chlorobenzenes Hexachlorobutadiene and heavy metals in surficial sediments of kaohsiung coast taiwan
Chemosphere, 2000Co-Authors: Chonlin Lee, Hueijing Song, Mengder FangAbstract:This work analyzes surface sediment samples collected from 40 stations along the Kaohsiung coast in southern Taiwan for chlorobenzenes (CBs), Hexachlorobutadiene (HCBD) and heavy metals (Cu, Zn, Pb, Cd, Ni, Fe, Mn and Cr). The highest CBs concentrations are recorded in station T7-15 (about 10 km west off the outlet of Da-lin-pu ocean outfall pipe), with total di-, tri-, tetra-, penta- and hexa-chlorobenzenes concentrations of 290.5, 117.1, 64.5, 15.7 and 22.3 ng/g, respectively. The major pollution source of HCBD is most likely located in the Tso-yin ocean outfall field; while the Dah-lin-pu ocean outfall field and Kao-ping Chi estuary, located in the southern portion of Kaohsiung coast, are the major contributors of hexachlorobenzene. The concentration of CBs congeners correlate fairly well with each other, as do metals. However, concentrations of organics (CBs and HCBD) did not correlate with metals. This finding implies that the pollution characteristics of organics and heavy metals in this highly utilized coastal zone markedly differ from each other.
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sources and distribution of chlorobenzenes and Hexachlorobutadiene in surficial sediments along the coast of southwestern taiwan
Chemosphere, 1997Co-Authors: Chonlin Lee, Mengder FangAbstract:Abstract The spatial distribution of chlorobenzenes in surficial sediments of the estuaries of major rivers along the coast of southwestern Taiwan was determined. Analytical results from sediment sampling stations indicate that the three outfall fields near Taiwan's largest industrial city, Kaohsiung, exhibit the highest concentrations of chlorobenzenes. More specifically, sediments from Tso-yin outfall field, which receives the wastewater from a very large petrochemical complex, had concentrations of 1,3,5-trichlorobenzene, pentachlorobenzene, hexachlorobenzene and Hexachlorobutadiene 2–3 times higher than those from Chon-chou and Da-lin-pu outfall fields. Chlorobenzene congeners in sediments from the three outfall fields correlate closely and most of their correlation coefficients are even higher than those reported for Ise Bay, Japan. Results from undeveloped areas, estuaries of the Da-du, Tso-shui, and Chi-shui Chi, will be of value after the impact of planned industrial expansion development begins.
Marc Babut - One of the best experts on this subject based on the ideXlab platform.
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environmental quality standards for water framework directive priority substances challenges and opportunities
Integrated Environmental Assessment and Management, 2007Co-Authors: Mark Crane, Marc BabutAbstract:The recently published Daughter Directive on priority substances is the culmination of several years of effort by the European Commission to develop consistent, Europe-wide environmental quality standards (EQS) that are scientifically based and protective of Europe's surface waters. This commentary describes progress to date in deriving EQS under the Water Framework Directive and identifies some remaining challenges and opportunities. In the Daughter Directive, annual average EQS are set for surface waters for all 33 priority substances. No sediment standards are included, and biota EQS are proposed for methyl-mercury, hexachlorobenzene and Hexachlorobutadiene. Important remaining questions include whether the standard chemical risk assessment methodology is appropriate for deriving water column EQS and whether it would be appropriate to derive EQS for sediment or biota or to adopt alternative strategies. Moreover, some cross-cutting issues about the cessation of discharges of naturally occurring or ubiquitous substances and the advantages and disadvantages of member states setting their own EQS are briefly addressed.
Biao Zhou - One of the best experts on this subject based on the ideXlab platform.
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a strategy for the synthesis of 1 2 dichlorotetrafluorocyclobutene from Hexachlorobutadiene and its reaction pathway
Industrial & Engineering Chemistry Research, 2017Co-Authors: Xiaomeng Zhou, Pingli Zhang, Biao ZhouAbstract:In this paper, a novel strategy for the preparation of 1,2-dichlorotetrafluorocyclobutene (DTB) was proposed via a catalytic gas-phase process of fluorination using Hexachlorobutadiene (HCBD) and anhydrous HF. In order to search for suitable catalysts and reveal the reaction pathway for this synthetic route, a series of studies were carried out. First, CrOx/ZnO catalysts with different promoters (Ni, Cu, In, Al) were prepared by a precipitate method and the optimum reaction conditions were investigated. The highest activity was achieved on the Cr–Ni–Zn catalyst, whose yield of DTB reached 90% by a multiple cycle reaction. Second, the effects of different promoters on the properties of catalysts were studied by Brunauer–Emmett–Teller (BET) surface area analysis, scanning electron microscopy (SEM), X-ray diffraction (XRD), temperature-programmed desorption in ammonia (NH3-TPD), and X-ray photoelectron spectroscopy (XPS). It was found that the Cr–Ni–Zn catalyst showed the excellent catalytic performances wit...
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A Strategy for the Synthesis of 1,2-Dichlorotetrafluorocyclobutene from Hexachlorobutadiene and Its Reaction Pathway
2017Co-Authors: Xiaomeng Zhou, Pingli Zhang, Biao ZhouAbstract:In this paper, a novel strategy for the preparation of 1,2-dichlorotetrafluorocyclobutene (DTB) was proposed via a catalytic gas-phase process of fluorination using Hexachlorobutadiene (HCBD) and anhydrous HF. In order to search for suitable catalysts and reveal the reaction pathway for this synthetic route, a series of studies were carried out. First, CrOx/ZnO catalysts with different promoters (Ni, Cu, In, Al) were prepared by a precipitate method and the optimum reaction conditions were investigated. The highest activity was achieved on the Cr–Ni–Zn catalyst, whose yield of DTB reached 90% by a multiple cycle reaction. Second, the effects of different promoters on the properties of catalysts were studied by Brunauer–Emmett–Teller (BET) surface area analysis, scanning electron microscopy (SEM), X-ray diffraction (XRD), temperature-programmed desorption in ammonia (NH3-TPD), and X-ray photoelectron spectroscopy (XPS). It was found that the Cr–Ni–Zn catalyst showed the excellent catalytic performances with more CrOxFy species, higher oxygen concentration, and widely distributed acid strength on its surface. Third, combining experimental results with theoretical calculations, a reaction pathway has been proposed. This study offers an economic synthetic route for DTB from HCBD, which is a valuable and promising method for industrial production