ISSN:0730-7268    

DOI:10.1002/etc.5620140301

出版商:Wiley Periodicals, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractAn in vitro bioassay procedure was used to investigate the toxic action of chlorophenols on mitochondrial respiratory parameters The toxicity of these compounds was evaluated by determining their effects on the energy coupled reverse electron transfer (RET) in submitochondrial particles (SMPs) from beef heart mitochondria The bioassay procedure is based on the spectrophotometric recording of the effects of toxicants on the rate of NAD+reduction, induced by ATP and succinate at the first site level of the respiratory chain The toxicity end point was expressed as the toxicant concentration that causes 50% inhibition of NAD+reduction rate (EC50). The EC50 values determined for the 14 tested chlorophenols ranged from 17 mg/L for 2 chlorophenol to 0 081 mg/L for pentachlorophenol, indicating a general trend of increasing toxicity with increasing chlorine substitution Among chlorophenol isomers, which have the same number of chlorine atoms, a lesser toxicity was associated with ortho‐substituted chlorophenols, whereas meta substituted chlorophenols were much more toxic The EC50 values were compared with the toxicity data for a variety of bioassays, by means of linear regression analysis High degrees of correlation obtained with toxicity tests involving different freshwater species demonstrate the ability of SMPs to reproduce the toxic effects of the tested compounds upon aquatic organisms This supports the assessment that the respiratory chain is the main target of this class of toxicants Results obtained with chlorophenols and, in previous studies, with other environmental contaminants confirm the suitability of the SMP bioassay as a prescreening or complementary short term test for monitoring aquatic toxici

ISSN:0730-7268    

DOI:10.1002/etc.5620140302

出版商:Wiley Periodicals, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractPseudomonas syringaecells were exposed to 100 μM copper alone, or to previously equilibrated copper sulfate‐ligand solutions. Ligand concentrations were determined experimentally as those that reduced the free copper concentration to 5 μM (determined with a Cu2+‐selective electrode). These values were in agreement with those calculated by computational equilibrium simulation based on published stability constants. Exposure ofP. syringaecells to copper sulfate, chloride, or nitrate resulted in similar high mortality, suggesting that copper was responsible for cell death. Acetate, succinate, proline, lysine, cysteine, and EDTA significantly reduced both the amount of copper bound to the cells and cell death, indicating that not only strong chelating agents but also weak and moderate copper ligands can effectively antagonize copper toxicity. However, cysteine and EDTA were considerably more effective than acetate, succinate, proline, and lysine, indicating that copper toxicity is not simply a function of free copper concentration but depends on the nature of the ligand. The results suggested that a significant fraction of copper bound to acetate, succinate, proline, or lysine was displaced to the bacteria or, alternatively, mixed copper‐ligand‐cell complexes could be formed. On the contrary, none of these phenomena occurred for the copper complexes with cystein

ISSN:0730-7268    

DOI:10.1002/etc.5620140303

出版商:Wiley Periodicals, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractThe comparative mineralization of eight polycyclic aromatic compounds in five soils collected from an abandoned coal tar refinery in eastern Ohio was determined. The soils showed differences only in total extractable hydrocarbon content of the soil chemical characteristics measured. The compounds studied included five polycyclic aromatic hydrocarbons (phenanthrene, anthracene, pyrene, and carcinogenic benz[a]anthracene and benzo[a]pyrene) and threeN‐heterocyclic aromatics (9H‐carbazole, and carcinogenic 7H‐dibenzo[c,g]carbazole and dibenz[a,j]acridine). Mineralization was measured by serum bottle radiorespirometry. Only phenanthrene, anthracene, pyrene, benz[a]anthracene, and carbazole were mineralized in the soils after 64 d. Two of the soils with eight to 15 times the hexane‐extractable hydrocarbon content consistently showed more rapid initial rates and higher overall extents of mineralization compared to the other three soils. Overall extents of mineralization ranged from 38 to 55% for phenanthrene, 10 to 60% for anthracene, 25 to 70% for pyrene, background to 40% for benz[a]anthracene, and 25 to 50% for carbazole after 64 d. Extents of mineralization by indigenous soil microbiota appear to be more dependent on the chemical characteristics of the soil and not soil total biomass and activity. Cultures capable of degrading phenanthrene, anthracene, and pyrene were obtained following enrichment techniques. AMycobacteriumsp. capable of degrading these three compounds was isolated and reintroduced into two of the soils, resulting in mineralization enhanced above that of the indigenous soil microbial population. These data indicate that the future success of bioremediation methods relies on the characterization of environmental parameters affecting microbial degradation as well as the isolation of microbial populations that can reduce toxicity in the envi

ISSN:0730-7268    

DOI:10.1002/etc.5620140304

出版商:Wiley Periodicals, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractThe rate of leaching of pesticides from fence posts made with recycled high‐density polyethylene plastics from pesticide containers was determined. Posts were 7.5 cm in diameter and contained 100, 50, or 25% pesticide‐container plastics, with pesticide‐free sources of low‐density polyethylene used as the diluent. As posts are manufactured in a number of diameters, results are reported as μg/m2. The 7.5‐cm posts had a surface area of about 0.5 m2. Trifluralin was the only pesticide detected in the leachates. Total amounts of trifluralin leached from these three products, using well water, were 17, 234, and 90 μg/m2of the surface area of the posts, respectively. Total amounts leached using simulated acid rain were 85, 196, and 84 μg/m2respectively. Weathering of posts for 1 year resulted in significantly lower concentrations of trifluralin in the leachate using simulated acid rain, total amounts of trifluralin leached were 4, 6, and 6 μg/m2for the 100, 50, and 25% contents, respectively. The amount of trifluralin released in all instances was judged to be insufficient to cause injury to sensitive plants and did not exceed Canadian guidelines for the protection of drinking water for humans or livestock. Trifluralin levels in the leachate did exceed Canadian guidelines for the protection of aquatic life in some cases, suggesting caution in the use of the products in aquatic

ISSN:0730-7268    

DOI:10.1002/etc.5620140305

出版商:Wiley Periodicals, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractA study was made of the efficiency of liquid‐liquid extraction of eight chlorinated hydrocarbons of varying lipophilicity from filtered (1 μm) organic free water, soil humic acid solution, lacustrine dissolved organic matter solution, and a natural water The efficiency of hexane extraction of the spiked chemicals without pH adjustment (i e the conventional technique) was reduced with increasing concentration of dissolved organic matter (DOM) and increasing chemical lipophilicity At the same time, increasing amounts of the more lipophilic chemicals were found in subsequent extracts of the water at pH 12, and after chromic acid oxidation of the DOM The results indicated that conventional liquid‐liquid extraction underestimates the concentrations of “dissolved” highly lipophilic chemicals in fresh water, the extent of the underestimation depending upon the nature of the DOM Sixteen day exposure experiments with filtered natural waters containing roughly 5 mg/L DOM indicated that 6 to 8% of the most lipophilic chemical tested, mirex, was not recovered by standard hexane extraction without pH adjustment, with 5 mg/L of a soil derived humic acid, 49% of mirex was not recovered by standard hexane extraction without pH adjustment For highly lipophilic chemicals that are not destroyed by chromic acid oxidation, it is recommended that total concentrations in filtered or centrifuged fresh waters be determined by the chromic acid oxidation/extraction

ISSN:0730-7268    

DOI:10.1002/etc.5620140306

出版商:Wiley Periodicals, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractA computer program has been developed that can predict the most probable metabolites formed from aerobic biodegradation of chemicals. Predictions are based on an expert evaluation of the parent chemical's molecular structure. The program was designed to recognize molecular fragments within complete chemical structures that are sites of microbial attack. The system is based on a dictionary of transformation rules, consisting of a compilation of molecular transformation operators relevant to microbial attack. The user inputs chemical structures, and the output is a visual or printed display of the potential metabolites resulting from the appropriate metabolic pathways. New chemicals can be evaluated, since the program recognizes structural fragments rather than complete molecular structures.

ISSN:0730-7268    

DOI:10.1002/etc.5620140307

出版商:Wiley Periodicals, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractAccumulation of the polychlorinated terphenyl formulation Aroclor 5432 in aquatic species has previously been reported Polychlorinated terphenyls (PCTs) are structurally similar to polychlorinated biphenyls (PCBs), and were used in related applications However, their biological effects have not been thoroughly studied Effects of PCT mixtures on levels of hepatic cytochrome P4501A (P4501A) and associated ethoxyresorufinO‐deethylase (EROD) activity in the mummichog (Fundulus heterochtus), a common estuarine fish, were assessed here Fish were injected intraperitoneally with PCT formulations Aroclor 5432, Aroclor 5460, or the PCB formulation Aroclor 1254, at doses of 0 32 to 100 mg/kg body weight Elevated levels of P4501A and EROD activity were detected in fish injected with Aroclor 5432 and Aroclor 1254 doses of 32 and 100 mg/kg Induction resulting from Aroclor 5432 was greater than that caused by equivalent doses of Aroclor 1254 Treatment with Aroclor 5460 did not result in significant induction Because commercial PCT mixtures contain small amounts of PCBs, the PCB components may have contributed to the induction observed for Aroclor 5432 This work represents the first report of hepatic cytochrome P4501A induction caused by Aroclor 5432 in teleosts and, similar to work in mammalian systems, suggests that the effects of this mixture may be at least partially mediated through Ah receptor bindi

ISSN:0730-7268    

DOI:10.1002/etc.5620140308

出版商:Wiley Periodicals, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractClean and spiked sediment formulations of various silt sand and clay sand ratios were tested for toxicity using a bioassay that utilizes bioluminescent bacteria Measured toxicities of clean and copper sulfate–spiked sediments were negatively but nonlinearly related with percent silt and percent clay, but no significant relationship existed between measured toxicity and sediment composition for methyl parathion–spiked formulations Results suggest that solid phase sediment bioassays using bioluminescent bacteria may be useful for testing the toxicities of single contaminants in formulated artificial sediments of known particle size composition, and for repeated samples collected from the same site However, extreme caution must be taken when testing sediments of varying composition or which may be differentially contaminated or contain a suite of contamin

ISSN:0730-7268    

DOI:10.1002/etc.5620140309

出版商:Wiley Periodicals, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractCyclically parthenogenetic zooplankters like rotifers are important tools for assessing toxicity in aquatic environments Sexual reproduction is an essential component of rotifer life cycles, but current toxicity tests utilize only asexual reproduction We compared the effects of four toxicants on asexual and sexual reproduction of the rotiferBrachionus calyciflorusToxicants had a differential effect on sexual and asexual reproduction, with sexual reproduction consistently the most sensitive Concentrations of 0 2 μg/ml PCP (sodium pentachlorophenate) had no effect on the asexual reproductive rate, but significantly reduced sexual reproduction Likewise, chlorpyrifos concentrations of 0 3 μg/ml had no significant effect on asexual reproduction, but sexual reproduction was significantly reduced There was no difference in NOECs, LOECs, and chronic values for asexual and sexual reproduction for cadmium and naphthol tests However, comparison of toxicant effect levels revealed that sexual reproduction was more strongly reduced at each toxicant concentration The four toxicants tested inhibited sexual reproduction 2 to 68 times more than asexual reproduction at the lowest observed effect concentrations Toxicants inhibited sexual reproduction in its initial step sexual female production Because sexual reproduction is more sensitive, toxicity tests based exclusively on asexual reproduction may not be protective of rotifer life cycl

ISSN:0730-7268    

DOI:10.1002/etc.5620140310

出版商:Wiley Periodicals, Inc.    

年代:1995

数据来源: WILEY