摘要:

AbstractChloroguaiacols are common components of bleached‐kraft pulp mill effluent known to bioaccumulate in aquatic organisms and to sorb on particulate material and sediments. Ionization properties of the chloroguaiacols must be known in order to explain their sorptive behavior in aquatic systems. To obtain this information, thermodynamic acid dissociation constants (pKa) of guaiacol (o‐methoxyphenol) and nine chloroguaiacols have been determined by spectrophotometric methods. These experimental pKavalues have been compared with literature values, values predicted by the Hammett equation, and predictions by quantum chemical calculations using MOPAC 6.0 with AM1 and MNDO Hamiltonian operators. Experimental and predicted acidities were strongly correlated, and the correlation equations obtained have been used to calculate pKavalues for those chloroguaiacols that were unavailable for experimental measurem

ISSN:0730-7268    

DOI:10.1002/etc.5620150601

出版商:Wiley Periodicals, Inc.    

年代:1996

数据来源: WILEY

摘要:

AbstractDespite reports of species‐specific differences, the rat cell line H4IIE continues to be used to assess the toxicity of many halogenated aromatic hydrocarbon (HAH) contaminants for diverse populations using an approach that relates aryl hydrocarbon (Ah) receptor‐mediated responses by HAHs to that of 2,3,7,8‐tetrachlorodibenzo‐p‐dioxin (TCDD). To assess the relevance of H4IIE for human populations, we examined levels of aryl hydrocarbon hydroxylase (AHH) and ethyoxyresorufinO‐deethylase (EROD) activities in H4IIE rat liver, HepG2 human liver, and MCF‐7 human breast cells treated with TCDD and three coplanar polychlorinated biphenyl (PCB) congeners (77, 126, 169), alone or in combination, and to fractions extracted from the muscle tissue of Lake Ontario rainbow trout(Oncorhynchus mykiss). H4IIE was generally more sensitive to all HAH treatments. Both AHH and EROD activities were induced in all cells treated with TCDD and PCB‐126, alone or combined with each other. In contrast, neither activity was induced in human cells treated with PCB‐77 or PCB‐169. For inducing concentrations of PCBs, the induction response in all cell lines treated with 5 nM TCDD‐PCB mixtures was generally nonadditive; only the response in H4IIE treated with 10−3nM TCDD–PCB mixtures was generally additive. With tissue extracts, induction was restricted to H4IIE cells treated with TCDD/PCB‐or organochloride pesticide‐containing fractions. Our initial results suggest that differences in the properties of each HAH or in levels of Ah receptor in each cell line are not likely to underlie the significant differences in the mur

ISSN:0730-7268    

DOI:10.1002/etc.5620150602

出版商:Wiley Periodicals, Inc.    

年代:1996

数据来源: WILEY

摘要:

AbstractGibbs free energies of formation for the ideal gas, liquid phase, and species in solution were estimated for 75 polychlorinated dibenzo‐p‐dioxins (PCDDs) at 298.15 K and 100,000 Pa. These values were used to calculate standard redox potentials, with H2as the electron donor. Owing to the lack of experimental thermodynamic data for the involved chemical species, the standard‐state ideal gas enthalpies of formation were evaluated by several semiempirical methods including the Modified Neglect of Diatomic Differential Overlap (MNDO), Austin Model 1 (AM1), and MNDO–Parametric Method 3 (PM3). Three different implementations of Benson's group additivity method for estimation of ideal gas enthalpies of formation were also evaluated. As a result of the evaluation, the CHETAH program based on Benson's group additive method was chosen for ideal gas enthalpy of formation calculations. Entropies, vapor pressure, and aqueous solubility were calculated by existing methods in order to complete the thermodynamic cycle. Calculated redox potentials indicate that chlorodioxins, including 2,3,7,8‐tetrachlorodioxin, can serve as electron acceptors in anaerobic environments, at least from a thermodynamic pe

ISSN:0730-7268    

DOI:10.1002/etc.5620150603

出版商:Wiley Periodicals, Inc.    

年代:1996

数据来源: WILEY

摘要:

AbstractThe responses of carbofuran, diazinon, and chlorpyrifos to standard acute toxicity identification evaluation (TIE) procedures were characterized. The test species wasCeriodaphnia dubia. The TIE procedures included solid‐phase extraction, recovery in methanol eluates, hydrolysis under acid and base conditions, and retention in specific methanol/water fractions. In addition, the effect of the metabolic inhibitor, piperonyl butoxide, on the toxicity of each of the pesticides was determined. Diazinon degraded quickly under acid conditions, whereas carbofuran degraded under base conditions. In both cases, concentrations were reduced to nontoxic levels within 6 h. Conversely, acidic or basic conditions were not effective in reducing the concentration of chlorpyrifos over the same time period. Solid‐phase extraction removed at least 95% of diazinon and carbofuran from solution, but was less effective with chlorpyrifos. All three pesticides eluted separately in characteristic methanol/water fractions. Piperonyl butoxide ameliorated the toxicity of diazinon and chlorpyrifos, but not carbofuran. Up to 1.5% methanol did not interfere with the protective action of piperonyl butoxide. Case studies in which these techniques were applied to ambient water samples are also descri

ISSN:0730-7268    

DOI:10.1002/etc.5620150604

出版商:Wiley Periodicals, Inc.    

年代:1996

数据来源: WILEY

摘要:

AbstractRemediation of sediments at Eagle River Flats, Alaska, a salt marsh contaminated with solid particles of white phosphorus (P4), may require severe alterations of the wetland by dredging, draining, or covering. However, some sediments may undergo decontamination naturally in areas that are seasonally subaerially exposed. The persistence of millimeter‐size P4particles was studied in laboratory and field experiments. White phosphorus particles were found to be persistent in saturated sediments. In unsaturated sediments, loss was rapid (within 24 h) at 20°C, and was retarded by low temperatur

ISSN:0730-7268    

DOI:10.1002/etc.5620150605

出版商:Wiley Periodicals, Inc.    

年代:1996

数据来源: WILEY

摘要:

AbstractThe concentrations of a number of organic and inorganic compounds in the wastewater from sprinkling of landstored softwood timber was monitored during a period of up to 18 weeks. A recycling system using a watering intensity of 160 mm/24 h, and an open system with intensities between 55 to 12 mm/24 h were studied. The compound classes investigated included dissolved organic carbon; distillable phenols; resin acids; bacterial phospholipid fatty acids (PLFA); organic and inorganic phosphorus, sulfur, and nitrogen; and a number of metal ions. In the recycling system, the peak concentrations occurred after 4 to 6 weeks, and the amounts accumulated through refilling of water largely exceeded those present in the wastewater at the end of the storage. In the open system, net loads of compounds occurred during the first weeks, which thereafter turned into uptakes for most compounds. The PLFA increased during the first weeks and clearly responded to the peak concentrations in the waters. Already from the start there were strong uptakes of nitrate, sulfate, and many minerals in the piles, suggesting that the supply of macro‐ and micronutrients necessary for microbial growth, as well as available terminal electron acceptors, may be a limiting factor for the extent of microbial degradation performed in the pil

ISSN:0730-7268    

DOI:10.1002/etc.5620150606

出版商:Wiley Periodicals, Inc.    

年代:1996

数据来源: WILEY

摘要:

AbstractThe UV photolysis and H2O2/UV advanced oxidation of two intermediate compounds of the degradation of atrazine in water, deethylatrazine and deisopropylatrazine, have been studied. The influence of hydrogen peroxide and bicarbonate ion concentrations was observed both in organic‐free water and in surface waters. Both UV photolysis and UV/H2O2oxidation techniques lead to significant rates of elimination of these compounds, although they were lower in surface waters, likely due to the presence of natural radical scavengers. However, in the presence of 0.01 M bicarbonate ion, degradation rates were similar regardless of the type of water used. A kinetic study of both techniques was also conducted. Quantum yields and rate constants of the reaction between the hydroxyl radical and both intermediates were determine

ISSN:0730-7268    

DOI:10.1002/etc.5620150607

出版商:Wiley Periodicals, Inc.    

年代:1996

数据来源: WILEY

摘要:

AbstractThe uptake processes of134Cs in two earthworm species were investigated as well as the effect of temperature on these processes. The results show that equilibrium concentrations in the two species differ by 1.5‐to fivefold. Equilibrium concentrations range from 367 to 963 Bq g−1inLumbricus rubellusand from 920 to 1,893 Bq g−1inEisenia foetida; biological half‐lives range from 56 to 119 h and 52 to 64 h, respectively. Assimilation was two to four times higher inE. foetidaand elimination rate one to two times higher inE. foetidathan inL. rubellus. Further, the results show that temperature may affect the134Cs concentration in these earthworms by a factor of 1.4 to 2.1 between 10 and 20°C, depending on the species. The maximum difference found within one species was a factor of 2.6. Our results show no clear effect of temperature on the assimilation, but a small negative effect on elimination, resulting in an increasing biological half‐life and concentration factor with higher te

ISSN:0730-7268    

DOI:10.1002/etc.5620150608

出版商:Wiley Periodicals, Inc.    

年代:1996

数据来源: WILEY

摘要:

AbstractAt least two search methods for bird carcasses have been suggested to estimate bird mortality from the use of a pesticide, one outlined by the U.S. Environmental Protection Agency (EPA) and one we propose. The proposed estimator provides a nonparametric, model‐free procedure for estimation of nontarget bird kills. Data were collected during a field study to compare the methods. These data were used to provide parameters for a computer simulation comparing characteristics of the mortality estimates produced by the two methods. The proposed method demonstrates marked advantages with respect to bias and mean squared error when compared to several interpretations of the EPA method in various search and mortality scenarios. In addition, the proposed method often provides estimates in instances where the EPA method cannot. The proposed estimator allows the estimation of search efficiency and survival probability simultaneousl

ISSN:0730-7268    

DOI:10.1002/etc.5620150609

出版商:Wiley Periodicals, Inc.    

年代:1996

数据来源: WILEY

摘要:

AbstractZebra mussels,Dreissena polymorpha, were collected monthly from a copper‐contaminated reservoir over a period of nearly 3 years. Copper concentrations in the organisms showed marked fluctuations reflecting changes in the water contamination. Bioconcentration patterns were influenced by the specific capacity of this sentinel organism to biologically integrate the continuously evolving water pollution; the sampling pattern, which inevitably introduced a certain subjectivity into monitoring results; and weight changes in the animals within the yearly cycle. Consequently, the successive monthly indications obtained with the zebra mussels provided a current biological assessment of a complex dynamic contamination situation. In a second experiment, caged mussels from three different populations were transferred for 3 months into the reservoir and sampled on six occasions. Mortality rates, attachment capacity, and a condition index revealed no substantial fitness disturbances in the transplanted organisms. Differences in dry weight throughout the experiment were attributable to the initial characteristics of each population. The influence of body mass on monitoring results was eliminated by replacing copper concentrations (μg/g dry weight) with copper burdens (μg/specimen). In terms of copper burdens, the three transplanted populations exhibited very similar metal patterns. Moderate quantitative differences between introduced and indigenous populations were interpreted as the result of physiological adaptation of the indigenous mussels to their contaminated environment. This study showed that the transfer technique withD. polymorphais a useful tool for active biomonitoring progr

ISSN:0730-7268    

DOI:10.1002/etc.5620150610

出版商:Wiley Periodicals, Inc.    

年代:1996

数据来源: WILEY