摘要:

AbstractBluegill sunfish (Lepomis macrochirus) were continuously exposed to 0.1 μg/ml of uniformly radiolabeled [14C]3‐chloro‐p‐toluidine hydrochloride (CPTH) for 28 d, after which the fish were transferred to flowing untreated water for a 28‐d depuration period. At periodic intervals during the treatment and depuration periods, samples of water and fish were analyzed for [14C] residues to determine the degree of CPTH absorption. Samples of bluegill that were exposed to the radiolabeled chemical for 28 d were analyzed to determine the distribution of the radiolabel and to isolate and identify possible metabolites. The steady‐state concentrations in the bluegill tissues were reached by day 7 of exposure to the radiolabeled compound, with mean concentrations in the edible, nonedible, and whole‐body tissues determined to be 2.9, 12.0, and 7.5 μg/g of tissue, respectively. Bioconcentration factors of 33×, 150×, and 88× were calculated for the three types of tissues. About 64% of the accumulated radiolabeled CPTH and metabolites were eliminated from the fish on day 28 of depuration. The distribution of radioactivity was found to be similar in all tissue groups. One metabolite was confirmed asN‐acetyl‐3‐chloro‐p‐toluidine, with two metabolites suggested to be 4‐acetamido‐2‐chlorobenzoic acid and 4‐amino‐2‐chlorobenzoic acid. TheN‐acetylated breakdown product has been previously reported to occur in both mammals and birds; thus, the metabolism of CPTH in fish may parallel that observed in these other species. Although the effects of biomagnification cannot be fully assessed at this time, we can conclude that when bluegill sunfish are continuously exposed to sublethal levels of CPTH, bioconcentration will not occur to an appreciable extent, and that residues will be rapidly excreted upon removal of the fish from the CPTH source. Furthermore, published information pertaining to various aquatic organisms indicates that bioaccumulation will not be a problem if

ISSN:0730-7268    

DOI:10.1002/etc.5620151001

出版商:Wiley Periodicals, Inc.    

年代:1996

数据来源: WILEY

摘要:

AbstractDegradation of the pesticide 3‐chloro‐p‐toluidine hydrochloride (CPTH) occurred in a loam soil when applied at concentrations of 3.5 and 35 μg/g. The compound degraded according to pseudo‐first‐order kinetics, with a calculated rate constant of 2.74 × 10−2h−1, at a soil temperature of 22°C; this rate constant yielded a half‐life of 25 h. The loss of radiolabeled CPTH from soil was suggested to be controlled by both irreversible binding to the soil colloids and microbial transformation. Mineralization of the radiolabeled CPTH was interpreted as involving two zero‐order kinetic rates; an initial rate of carbon dioxide release was estimated to be 0.33% d−1(half‐life of 152 d), followed by a slower rate of 0.07% d−1, which resulted in a half‐life of 718 d. Approximately 13% of the radiolabeled CPTH that was applied to soil at 3.5 μg/g was mineralized to [14C] carbon dioxide during the 99‐d incubation period. A primary metabolite was identified asN‐acetyl‐3‐chloro‐p‐toluidine (ACPTH); this metabolite reached a maximum concentration at the 1‐d sampling period, and degraded with a pseudo‐first‐order rate constant of 2.67 × 10−2h−1; the half‐life for ACPTH was calculated to be 26 h. When CPTH was applied to soil at 35 μg/g, the compound was also mineralized in soil by a similar metabolic pathway to that observed at the lower concentration. However, the rate of mineralization was slower, which suggests that elevated soil concentrations of

ISSN:0730-7268    

DOI:10.1002/etc.5620151002

出版商:Wiley Periodicals, Inc.    

年代:1996

数据来源: WILEY

摘要:

AbstractThe movement of radiolabeled 3‐chloro‐p‐toluidine hydrochloride (CPTH) in a loam soil was evaluated in a column leaching study. Twenty‐five‐gram portions of the soil were treated with about 30 μg/g of uniformly labeled [14C]CPTH, and then incubated (aged) for 24 h under aerobic conditions; this soil was applied to untreated soil columns, which were then leached with dilute aqueous calcium sulfate for a total leachate volume equal to or greater than 50.8 times the cross‐sectional area, or about 450 to 600 ml. Results indicated that about 2% of the initial radiolabeled compound leached through the soil profile, with the mean apparent partition coefficient calculated to be 65 ml/g. The soil columns were separated into 6‐cm sections and extracted with dilute aqueous calcium sulfate, followed by 80% aqueous acetonitrile. About 90% of the [14C]CPTH was sorbed to the uppermost 6 cm of soil. Following extraction, the residual soil was combusted, with these results indicating that an average 77% of the parent compound and products present in the upper 6 cm were bound to the soil colloids. Approximately 1% of the applied radiolabeled compound volatilized during the soil aging and leaching processes. The mean mass balance based upon [14C] analyses was 102%. One major metabolite was detected in leachate fractions and soil extracts, which was tentatively identified asN‐acetyl‐3‐chloro‐p‐toluidine, based upon HPLC retention times. This same degradation product was previously identified and confirmed using mass spectroscopy in CPTH aerobic soil biodegradation and fish accumulation studies. The extent to which CPTH was bound to the loam soil colloids, with only minimal movement through the soil profile, suggests a low potential for mobility of this pesticide

ISSN:0730-7268    

DOI:10.1002/etc.5620151003

出版商:Wiley Periodicals, Inc.    

年代:1996

数据来源: WILEY

摘要:

AbstractThe thin organic film (surface microlayer) found on natural waters can concentrate hydrophobic pollutants. Enrichment factors (EFs), the ratio of pollutant concentration in microlayer to that in subsurface water, previously have been measured in relatively thick (˜50–150 μm) aqueous sections of surface. A modified sampling method, using glass plates silanized with dichlorodimethylsilane, allowed the collection of samples with virtually no dilution by subsurface water. Surface microlayers from a flooded rice field, collected onto silanized plates and analyzed by GC‐MS, showed 26 fatty acids and esters of 8 to 24 C atoms, saturated and unsaturated, and methyl esters of nonanoic, hexacosanoic, and octacosanoic acids as well as cholesterol. Microlayers were collected with both silanized and unsilanized glass plates after application of carbofuran (3.27 kg/ha) and a mixture of carbofuran (3.12 kg/ha) and thiobencarb (3.04 kg/ha) to 9.8‐m2field plots. Log EF was 0.14 to 1.43 for carbofuran and 0.04 to 2.30 for thiobencarb in samples collected with unsilanized plates; log EF from silanized plates was 3.88 to 7.55 and 4.04 to 5.74 for carbofuran and thiobencarb, respectively. Log EFs in samples collected from a commercial rice field with silanized plates were 3.88 and 4.18 for carbofuran and 4.77 and 5.15 for thiobencarb, greater than predicted from theirKow. Thiobencarb irradiated (285–340 nm) in isolated microlayers was photodegraded more rapidly than by itself. The only identified photoproduct was 4‐chlorobenzyl mercaptan. These observations have significance for pesticide fate, analysis, and ec

ISSN:0730-7268    

DOI:10.1002/etc.5620151004

出版商:Wiley Periodicals, Inc.    

年代:1996

数据来源: WILEY

摘要:

AbstractA study was conducted to evaluate the effect of viscosity of nonaqueous‐phase liquids (NAPLs) on biodegradation of phenanthrene in soil slurries and to find means to enhance the process in viscous NAPLs. When present in kerosene, diesel fuel, fuel oil, and mixtures of the NAPLs, phenanthrene was biodegraded rapidly. Gasoline alone or in mixtures with other solvents prolonged the acclimation phase and reduced the rate of mineralization of the hydrocarbon. The rate and extent of biodegradation decreased with increasing viscosity of nontoxic NAPLs. The slow mineralization of phenanthrene initially in 150 Bright stock or crude oils was enhanced by vigorous agitation of soil slurries, addition of a nonionic surfactant and delayed inoculation, or increasing the temperature. The data suggest means for enhanced bioremediation of toxicants present in viscous NAPL

ISSN:0730-7268    

DOI:10.1002/etc.5620151005

出版商:Wiley Periodicals, Inc.    

年代:1996

数据来源: WILEY

摘要:

AbstractMetals are common toxicants found in effluents and other environmental samples. Within Toxicity Identification Evaluation methods proposed by the U.S. Environmental Protection Agency and others, addition of ethylenediaminetetraacetic acid (EDTA) is used as an indicator of metal toxicity. Previous experiments showed that addition of sodium thiosulfate, originally included to detect toxicity due to oxidants, was also effective at reducing toxicity from some common metals. In the present study, we characterized the effectiveness of both EDTA and thiosulfate in removing the toxicity of 16 different metal ions toCeriodaphnia dubia. Ethylenediaminetetraacetic acid addition removed toxicity associated with all cationic metals tested except for Cr3+, Fe2+, Al3+, and Ag+. Thiosulfate addition was less effective than EDTA for Zn2+, Mn2+, Pb2+, and Ni2+, but reduced toxicity of both Ag+and selenite (Se[VI]), which EDTA did not. Results of this research can be used to categorize metal toxicity in unknown samples based on the response to additions of EDTA and thiosulfate.

ISSN:0730-7268    

DOI:10.1002/etc.5620151006

出版商:Wiley Periodicals, Inc.    

年代:1996

数据来源: WILEY

摘要:

AbstractOn July 14, 1991, 72,000 L of the pesticide Metam (active ingredient, methyl isothiocyanate) was accidentally released into the Upper Sacramento River. We hypothesized that the spill affected streamside microbial communities and that the effects were persistent. To address this hypothesis, we sampled river soils a year later from sites above and below the spill as well as from an agricultural area and determined soil carbon dioxide efflux (as a measure of soil respiration) in response to methyl isothiocyanate in controlled‐environment microcosms, resulting in estimates of the EC50 and soil degradation rates of methyl isothiocyanate. The soil respiration EC50s for the river soils ranged from 13.2 to 51.4 μg/g methyl isothiocyanate, whereas that of the agricultural soil was 72.2 μg/g. Thus, the soils from the Upper Sacramento River were more sensitive to the toxicologic effects of methyl isothiocyanate than was the agricultural soil. Soils from below the spill site also showed higher (factor two or more) EC50s than soils from reference locations above the spill site. The half‐life of methyl isothiocyanate in soils ranged from 2.7 to 6.9 days and was longer by a factor of two in the river soils. These degradation rates are controlled by both biotic (microbial) and abiotic processes. The presence of a microbial community accelerated the degradation rate by a factor of two. The pattern of EC50 data demonstrates that changes in the microbial community in the river soils were persistent a full year after the spill and that the stress elicited responses that were indicative of physiologic accommodation or selection for resistance at the population, species, and/or community

ISSN:0730-7268    

DOI:10.1002/etc.5620151007

出版商:Wiley Periodicals, Inc.    

年代:1996

数据来源: WILEY

摘要:

AbstractAcute toxicity of 10 chlorophenols and 10 nitrophenols with identical substitution patterns is analyzed with the pollen tube growth (PTG) test. Concentration values of 50% growth inhibition (IC50) between 0.1 and 300 mg/L indicate that the absolute sensitivity of this alternative biotest is comparable to conventional aquatic test systems. Analysis of quantitative structure–activity relationships using lipophilicity (logKow), acidity (pKa), and quantum chemical parameters to model intrinsic acidity, solvation interactions, and nucleophilicity reveals substantial differences between the intraseries trends of log IC50. With chlorophenols, a narcotic‐type relationship is derived, which, however, shows marked differences in slope and intercept when compared to reference regression equations for polar narcosis. Regression analysis of nitrophenol toxicity suggests interpretation in terms of two modes of action: oxidative uncoupling activity is associated with a pKawindow from 3.8 to 8.5, and more acidic congeners withdiortho‐ substitution show a transition from uncoupling to a narcotic mode of action with decreasing pKaand logKow. Model calculations for phenol nucleophilicity suggest that differences in the phenol readiness for glucuronic acid conjugation as a major phase‐II detoxication pathway have no direct influence on acute PTG toxicity of the co

ISSN:0730-7268    

DOI:10.1002/etc.5620151008

出版商:Wiley Periodicals, Inc.    

年代:1996

数据来源: WILEY

摘要:

AbstractA field‐monitoring program has been carried out to assess the environmental effects associated with drill cutting discharges at a drilling location in the North Sea, after drilling with ester‐based muds. The study included a baseline survey just before drilling started and three postdrilling surveys, 1, 4, and 11 months after termination of drilling. During these surveys, ester concentrations and macrofauna densities were determined at distances between 75 and 3,000 m from the well. For the first and second postdrilling surveys, ester concentrations ranged between 2 and 4,700 mg·kg−1dry sediment. During the third survey, esters were detected up to 200 m, with concentrations between 1 and 250 mg·kg−1dry sediment. Between 500 and 3,000 m, ester concentrations were below detection level. The half‐life was estimated as 133 d. This value reflects the composite effects of biodegradation and sediment relocation. During the second postdrilling survey, a reduced abundance as well as a reduced species richness of the macrofauna was observed up to 200 m from the well. Also, the presence ofCapitella capitatawas an obvious sign of disturbed sediment conditions in this area. A few species showed abundance gradients over the whole sampling transect and occurred in reduced abundance up to 500 or 1,000 m compared to the 3,000‐m reference station. The third postdrilling survey clearly revealed effects at 75 to 200 m from the well. At distances ≥500 m, persistent effects could no longer be demonstrated. Although the results of the present study show that effects had not completely disappeared after 1 year, there are signs of recovery of the macrobenthos, because a reasonable number of species had recolonized the area in the vicinity of the well site, particularly at 200 m, in fair

ISSN:0730-7268    

DOI:10.1002/etc.5620151009

出版商:Wiley Periodicals, Inc.    

年代:1996

数据来源: WILEY

摘要:

AbstractRecent controversy over the potential role of methyl bromide (MeBr) in damaging the ozone layer has spurred interest in qualitatively increasing our understanding of the transformation and movement of this fumigant. In contrast to the extensive uses of this common agricultural fumigant, a paucity of data exits on the environmental fate of MeBr. Our research indicates that MeBr is rapidly volatilized from fumigated soil (within the first 24 h) and volatility significantly increases with temperature (35°C>25°C>15°C) and moisture (−3 kPa>−33 kPa>−300 kPa). Degradation of MeBr, measured by production of bromide ion (Br−), was also positively related to temperature and moisture. Undisturbed soil column studies indicated that MeBr rapidly volatilized (>50% of the MeBr flux occurred in 48 h) and did not leach into subsurface soil. Residual MeBr was degraded in the soil column, as evident by the high concentrations of Br−in the leachate water. These studies provide valuable information for assessing the fate of MeBr in soil, which should lead to more informed decisions for regula

ISSN:0730-7268    

DOI:10.1002/etc.5620151010

出版商:Wiley Periodicals, Inc.    

年代:1996

数据来源: WILEY