Concentrations Of Tetrachloroethene Research Articles

First polish national congress on technology

The paper presents the results of the analysis of water and bottom sediment samples from different locations along the Odra river, collected during eight campaigns in the years 1997–2000. All the basic organic pollutants were determined. Pollution of water with PCBs was negligible while with PAHs was not critical. Concentrations of volatile organochlorine compounds in water were the highest in Brzeg Dolny and its surroundings. Concentrations of tetrachloroethene were exceptionally high in the Szczecin Lagoon. The Odra sediments were non-polluted or only slightly polluted with PCBs, pesticides and different classes of volatile organic pollutants. However, PAHs were present in rather large concentrations, especially in the upper course of the Odra river. The data obtained contributed to the evaluation of pollutants discharges to the Baltic sea via Szczecin Lagoon as well as to the characterization of pollution sources (point sources and area sources) in the Odra catchment area.

Photochlorination of tetrachloroethene in carbon tetrachloride solutions

Validation of the mechanism of tetrachloroethene photochlorination at low C2Cl4 concentrations was investigated. The reaction was examined in carbon tetrachloride solution. For initial tetrachloroethene concentrations below 2 mol I−1, the solvent participates in a free-radical chain photochlorination. The presence of CCl4 disturbs the course of this particular chain reaction and influences the duration of the induction period.

Comparison of Stainless Steel vs. PTFE Miniwells for Monitoring Halogenated Organic Solute Transport

AbstractField tests of organic solute transport behavior have often been monitored using small‐diameter wells (miniwells). To determine if experimental results could be significantly biased by sorption to, desorption from, or diffusion through sampling lines, dissolved concentrations of tetrachloroethene and carbon tetrachloride were measured in ground water samples collected simultaneously from the same spatial location during a forced‐gradient test in the Borden aquifer using polytetrafluoroethene (PTFE) and stainless steel miniwells (1/8‐inch O.D.).A semiautomated organic analytical system was used on‐site to obtain real‐time results, which avoided sample holding problems and permitted optimizing sampling times. The breakthrough curves (plots of concentration vs. time) for both organic compounds indicate that under the conditions of this experiment (low organic solute concentrations, short exposure time of sampling lines to the plume, adequate flushing of sampling lines) there is no significant difference between concentration histories (breakthrough curves) collected using a polytetrafluoroethene sampling line and those collected using a stainless steel sampling line. This suggests that organic solute tailing seen in this and also in a similar transport experiment previously conducted at the site is the result of transport processes in the aquifer rather than an artifact introduced by the PTFE miniwells.

Concentrations of tetrachloroethene in blood and trichloroacetic acid in urine in workers and neighbours of dry-cleaning shops.

Tetrachloroethene concentrations in blood and trichloroacetic acid concentrations in urine were determined--primarily over the course of a week--for 29 persons living in the vicinity of dry-cleaning shops. The mean levels of tetrachloroethene increased during the week. In some neighbours concentrations were exceeding the German biological threshold limit value for tetrachloroethene (1000 micrograms/l blood), persisting over the whole week in one case. The concentrations of tetrachloroethene in blood depended on the floor and the construction type of the building where these people were living, but not of the type of system used in the dry-cleaning shops. 5 of 12 dry-cleaners were found to have tetrachloroethene levels exceeding the German biological threshold limit value, some of them by a considerable amount.

Reductive dechlorination of high concentrations of tetrachloroethene to ethene by an anaerobic enrichment culture in the absence of methanogenesis

Tetrachloroethene, also known as perchloroethylene (PCE), is a common groundwater contaminant throughout the United States. The incomplete reductive dechlorination of PCE--resulting in accumulations of trichloroethene, dichloroethene isomers, and/or vinyl chloride--has been observed by many investigators in a wide variety of methanogenic environments. Previous mixed-culture studies have demonstrated that complete dechlorination to ethene is possible, although the final dechlorination step from vinyl chloride to ethene is rate limiting, with significant levels of vinyl chloride typically persisting. In this study, anaerobic methanol-PCE enrichment cultures which proved capable of dechlorinating high concentrations PCE to ethene were developed. Added concentrations of PCE as high as 550 microM (91-mg/liter nominal concentration; approximately 55-mg/liter actual aqueous concentration) were routinely dechlorinated to 80% ethene and 20% vinyl chloride within 2 days at 35 degrees C. The methanol level used was approximately twice that needed for complete dechlorination of PCE to ethene. The observed transformations occurred in the absence of methanogenesis, which was apparently inhibited by the high concentrations of PCE. When incubation was allowed to proceed for as long as 4 days, virtually complete conversion of PCE to ethene resulted, with less than 1% persisting as vinyl chloride. An electron balance demonstrated that methanol consumption was completely accounted for by dechlorination (31%) and acetate production (69%). The high volumetric rates of PCE dechlorination (up to 275 mumol/liter/day) and the relatively large fraction (ca. one-third) of the supplied electron donor used for dechlorination suggest that reductive dechlorination could be exploited for bioremediation of PCE-contaminated sites.

Tetrachloroethene air pollution originating from coin-operated dry cleaning establishments

In 15 coin-operated dry cleaning establishments (CODC), in one building where a CODC had been run and in a private car transporting a dry-cleaned down jacket tetrachloroethene (TCE) indoor concentrations were investigated by air sampling with activated carbon tubes, elution of the carbon with toluene, and subsequent gas chromatographic analysis of the eluate. TCE concentrations in the car transporting the garment were up to 24.8 mg/m3. Within CODC air concentrations between 3.1 and 331 mg/m3 were measured. In the building where a CODC had once been run the TCE concentrations were slowly decreasing after removal of dry cleaning machines. In the basement below the CODC the TCE air concentration was 155 mg/m3 immediately after removal of the machines and 4.5 mg/m3 7.5 months later. TCE migrated from the basement via the staircase to the flats of the second floor where TCE air concentrations were about 1% of the concentrations in the basement. TCE-contaminated building material is shown to be a reservoir causing increased TCE air concentrations for a long time, which is serious considering the carcinogenic and reproductive risks from TCE exposure.

Food contamination by emissions from dry cleaning compounds

Tetrachloroethene (perchloroethylene) from dry-cleaning units may contaminate adjacent flats in the same building. Increased concentrations of tetrachloroethene have been found in foodstuffs in homes situated above dry cleaning units and in foodstuffs from groceries located neat drycleaning units. The concentrations were extremely high in foods rich in fat.

Contamination of foodstuff by gases from tetrachloroethene emissions from a dry cleaners

Tetrachloroethene (perchloroethylene) and other volatile organic compounds may contaminate the surroundings of dry-cleaning units. Increased concentrations of tetrachloroethene were found in food, human hair, textiles and dust from a vacuum cleaner in a home situated above a dry-cleaning unit. The concentrations were found to be extremely high in food rich in fat. The analytical procedure for the above-mentioned samples is described.

Biological monitoring of occupational exposure to tetrachloroethene.

MONSTER A, REGOUIN-PEETERS W, VAN SCHIJNDEL A, VAN DER TUIN J. Biological monitoring of occupational exposure to tetrachloroethene. Scand j work environ health 9 (1983) 273-281. In the breathing zone of 32 workers concentrations of tetrachloroethene were measured during five consecutive workdays. The feasibility of biological monitoring was tested by the measurement of the concentrations of tetrachloroethene in blood and exhaled air and the urinary excretion of trichloroacetic acid and trichloroethanol. The best parameter to estimate the time-weighted average exposure to tetrachloroethene over the whole workweek appears to be the concentration of both tetrachloroethene and trichloroacetic acid in blood 15-30 min after the end of the workday at the end of the workweek. Among the noninvasive methods the best parameter is the tetrachloroethene concentration in exhaled air 15-30 min after work at the end of the workweek, followed by the measurement of trichloroacetic acid in urine at the end of the workweek. In exposure to 2,050 iimol of tetrachloroethene/m3 (340 mg/m3, 50 ppm) the estimated values for the biological parameters are 13.2 ?xmol of tetrachloroethene/1 of blood, 33 iimol of trichloroacetic acid/1 of blood, 920 ^imol of tetrachloroethene/m3 of exhaled air and 6.1 iimol of trichloroacetic acid/mmol of creatinine in urine, respectively. With 95 % confidence it may be stated that an individual with a value for a biological parameter not exceeding 8.3 iimol of tetrachloroethene/1 of blood, 20 (irnol of trichloroacetic acid/1 of blood, 515 iimol of tetrachloroethene/m3 of exhaled air and 3.0 iimol of trichloroacetic acid/mmol of creatinine, respectively, had an exposure not exceeding 2,050 ^imol of tetrachloroethene/m3. The measurement of trichloroethanol in urine may be used for the estimation of the time-weighted average exposure over the previous 2 d. The concentration of tetrachloroethene in exhaled air 1530 min after exposure had little value for the estimation of the time-weighted average exposure over the last 4 h. On Monday morning the concentration of tetrachloroethene in exhaled air is still about 15 % of the time-weighted average exposure concentration during the whole preceding workweek. The half-time of trichloroacetic acid in urine and blood during the weekend is about 65-90 h.