摘要:

AbstractThe disappearance kinetics of 4‐chlorostilbene oxide (CSO) were determined in aquifer samples and in sediment‐water systems to derive kinetic expressions that describe heterogeneous effects. Disappearance rate constants were determined in heterolytic systems and compared with those obtained in distilled water to delineate the effect of solids on the kinetics of hydrolysis. In both neutral and acid hydrolysis studies, the sorption‐desorption rates of CSO were faster than the hydrolysis rates in either the aqueous or sediment‐sorbed phases. Both dissolved and sorbed CSO hydrolyzed at either neutral or acidic pHs. Above pH 5, where neutral hydrolysis dominates, the hydrolysis rate constant of CSO in sterile sediment‐water systems was the same as in distilled water. This suggests that sorption neither retards nor promotes the neutral hydrolysis pathway. At pHs below 5, where acid hydrolysis dominates, the pseudo‐first‐order hydrolysis rate constant was lower for the sorbed fraction than the rate constant in distilled water at the same pH. This indicates that hydrolysis rate constant in the sorbed phase is slower than that in the bulk aqueous phase.Kinetics of hydrolysis were studied in raw sediment samples and samples sterilized by heat or with formalin to distinguish between abiotic and biotic hydrolysis processes. Above pH 5, the hydrolysis rate constants were larger in nonsterile systems when compared with the rate constants in the sterile systems, suggesting that both biotic and abiotic pathways contribute to the disappearance of CSO. Below pH 5, the hydrolysis rate constants were, within experimental error, the same in the sterile and nonsterile systems. In aquifer samples, the average disappearance rate constant of CSO was 0.85 (±0.11) × 10−4min−1, which is about the same as the rate constant in distilled water. These results suggest that there is no heterolytic enhancement of the neutral hydrolysis rate constant by th

ISSN:0730-7268    

DOI:10.1002/etc.5620090801

出版商:Wiley Periodicals, Inc.    

年代:1990

数据来源: WILEY

摘要:

AbstractA high‐carbon coal stack ash has been separated by particle size and then by composition, into strongly magnetic, weakly magnetic, “nonmagnetic” mineral, heavy carbon and light carbon fractions. Eleven of these fractions have been characterized by bulk iron and carbon analyses and BET surface area determinations. The photochemical transformation of pyrene, deposited from the vapor phase onto these eleven ash fractions, has been studied. Appreciable phototransformation of adsorbed pyrene was observed for only three fractions; in those fractions, the bulk percentage of carbon (0.4–0.7%) and the specific surface area (0.50–0.68 m2/g) were both very low. For all fractions having bulk carbon percentages ≥ 4% and specific surface areas ≥ 2.85 m2/g, no detectable phototransformation of adsorbed pyrene was observed. There was no discernible correlation of photochemical reactivity of adsorbed pyrene with the iron content of the ash fractions. In general, the specific surface area of the fractions increased with increased carbon content; two different forms of carbon having different surface areas

ISSN:0730-7268    

DOI:10.1002/etc.5620090802

出版商:Wiley Periodicals, Inc.    

年代:1990

数据来源: WILEY

摘要:

AbstractThe microbial mineralization of [U‐14C‐ring] linear alkylbenzene sulfonate (LAS) and [U‐14C‐ethoxylate] linear alcohol ethoxylate (LAE) was examined in 11 soils. These soils differed in their physical‐chemical properties and were obtained from geographically distinct locations. With one exception, they had no previous exposure to synthetic surfactants. Soil samples were amended with trace levels (50 ng/g soil) of each14C surfactant, and evolution of14CO2was measured over time. When appropriate, the data were fitted to a first‐order production equation, and first order rate constants and asymptotic yields of14CO2were estimated using nonlinear regression. Both surfactants were mineralized without a lag period in every soil tested. Yields ranged from 16 to 71% and 30 to 69% for LAS and LAE respectively. First‐order rate constants ranged from 0.14 to 0.63 for LAS and 0.07 to 0.62 for LAE. Mean half‐life (across all soils) was 2 d for both surfactants. Community microbial activity, measured as the rate of acetate incorporation into lipids, did not correlate with either the rate or extent of surfactant mineralization. Subjecting these soils to cycles of wetting and drying in the laboratory prior to testing in most cases resulted in more rapid and extensive mineralization. These results indicate that microbial communities in soils have an indigenous ability to degrade low concentrations of LAS and LAE. This ability appears to be ubiquitous since it is present in a wide array of soil types from various locations. In addition, laboratory experiments involving wetting and drying of soils indicated that both the rate and extent of mineralization may be affected by climat

ISSN:0730-7268    

DOI:10.1002/etc.5620090803

出版商:Wiley Periodicals, Inc.    

年代:1990

数据来源: WILEY

摘要:

AbstractThree groups of rainbow trout (Salmo gairdneri) having average body weights of 2.9, 61 and 440 g were exposed at 12°C by the water to di‐2‐ethylhexyl phthalate (DEHP). The kinetics of uptake and bioconcentration were characterized in each group using a compartmental model. Most of the model parameters, when expressed per unit body weight, were similar in the three sizes of fish. The two major exceptions were the uptake rate parameter, a measure of the capacity of the gill to extract DEHP from water and the apparent size (volume of distribution) of the large DEHP storage compartment, which is a measure of the capacity of the fish to accumulate DEHP. The values of these parameters declined as body weight increased; they followed the allometric equation with body weight exponents of 0.44 and 0.77, respectively. The body weight‐associated changes in the pharmacokinetic parameters caused the bioconcentration factor to decline as body weight increased, from 51.5

ISSN:0730-7268    

DOI:10.1002/etc.5620090804

出版商:Wiley Periodicals, Inc.    

年代:1990

数据来源: WILEY

摘要:

AbstractThe relationship between copper speciation and acute toxicity to the Australian freshwater shrimp,Paratya australiensiswas determined using a combination of copper ion selective electrode measurements, complexing resins and computer calculations to measure the speciation in test solutions. A number of problems were encountered with the use of the copper ion selective electrode in waters containing added complexing agents.In solutions containing nitrilotriacetic acid or glycine, uncomplexed copper(II) ions were found to be the most acutely toxic form of copper to the shrimp. However, at least one other species, the singly charged complex (Cu‐Glycine)+, also appears to be mildly toxic. The results of this study demonstrate the importance of considering metal speciation when assessing the impact of heavy metals on aquatic organism

ISSN:0730-7268    

DOI:10.1002/etc.5620090805

出版商:Wiley Periodicals, Inc.    

年代:1990

数据来源: WILEY

摘要:

AbstractThe acute toxicity of copper to the Australian freshwater shrimp,Paratya australiensis, was shown to decrease in solutions of increasing alkalinity brought about by the addition of NaHCO3. This effect could not be explained merely in terms of changes in copper speciation in the solutions. Estimates of the free copper(II) ion concentration of the LC50 values were made using both copper ion selective electrodes measurements and chemical equilibrium computer calculations. Whereas there were discrepancies between the estimates obtained using these two methods, both indicated an apparent increase in tolerance ofP. australiensisto the free copper(II) ion in more alkaline waters. An additional set of experiments, in which NaCl was added to test waters in place of NaHCO3, demonstrated that the increased tolerance ofP. australiensisto copper in higher alkalinity waters was caused by a combination of physiological effects associated with increased ionic strength of the test waters and, to a lesser extent, changes in metal speciation in test waters. Further study of the reason for the discrepancy between estimates of copper(II) concentrations derived from ion selective electrode measurements and computer calculations is required.

ISSN:0730-7268    

DOI:10.1002/etc.5620090806

出版商:Wiley Periodicals, Inc.    

年代:1990

数据来源: WILEY

摘要:

AbstractThe influence of dissolved organic matter on the toxicity of copper to the Australian freshwater shrimp,Paratya australiensis, was measured using water collected from three sites in Victoria, Australia. A two‐ligand model was used to describe copper complexation in these test waters. The binding characteristics of the ligands (i.e., total ligand concentrations and conditional stability constants) were determined using a method combining ion selective electrode and anodic stripping voltammetry.Ion selective electrode measurements and the two‐ligand model were each used to estimate the concentration of copper(II) (the major toxic species) at the LC50 values. Both methods overestimated by a factor of approximately 1.5 to 3 the expected copper(II) concentration at the LC50 values, based on earlier experiments in Melbourne tap water. The agreement seems remarkably good given the many assumptions used in making the comparison and the difficulties encountered with the use of ion selective electrodes in natural wat

ISSN:0730-7268    

DOI:10.1002/etc.5620090807

出版商:Wiley Periodicals, Inc.    

年代:1990

数据来源: WILEY

摘要:

AbstractInstream toxicity was predicted with whole effluent toxicity tests. These results were then compared to the observed instream response of the aquatic community. Forty‐three comparisons were conducted in freshwater flowing systems usingCeriodaphnia dubiachronic toxicity test procedures and standardized qualitative sampling of benthic macroinvertebrates. In 88% of the comparisons there was agreement between both measures. These data suggest that the use of effluent toxicity testing results as a regulatory tool is effective and appropriate. Comparisons used whole effluent toxicity limitations similar to those being written in North Carolina's NPDES permits for discharge to surface water

ISSN:0730-7268    

DOI:10.1002/etc.5620090808

出版商:Wiley Periodicals, Inc.    

年代:1990

数据来源: WILEY

摘要:

AbstractThe effects of season on the toxicity of the prototypic organophosphorus insecticide parathion was evaluated using adult European starlings(Sturnus vulgaris)housed in outdoor pens. Groups of birds received oral doses of parathion in the fall, winter, spring and summer. Median lethal dosage, and brain and plasma cholinesterase inhibition, were found to be quite similar among seasons. Parathion may have been more toxic during hot weather (winter vs. summer LD50 estimate: 160 vs. 118 mg/kg;p<0.1). In view of previous reports in which ambient temperature extremes and harsh weather have enhanced organophosphorus insecticide toxicity to birds, it is concluded that circannual toxicity studies should include measures of sensitivity (acute oral exposure) and vulnerability (dietary exposure) to better predict responses of free‐ranging bird

ISSN:0730-7268    

DOI:10.1002/etc.5620090809

出版商:Wiley Periodicals, Inc.    

年代:1990

数据来源: WILEY

摘要:

AbstractQuantitative assessments of sediment quality frequently are based on data derived from sediments collected by grab sampling. Often only one sediment or one composited sediment is collected at a sample site, thereby preventing any determination of spatial variance. The significance of spatial variance and collection method on cladoceran toxicity and indigenous microbial activities was determined at a creosote contaminated site in the Little Scioto River in Marion County, Ohio. Replicate sediments were collected on two occasions from a horizontal sample grid (110 m2and 1.4 m2) using an Ekman dredge and hand core. Sediment particle size fractions did not vary significantly between replicate grab samples. Survival ofDaphnia magnaandCeriodaphnia dubiain 48‐h solid phase exposures varied, however, from 0 to 100% horizontally and vertically at the test site. Percent survival and β‐glucosidase activity decreased in sediment sections below a 4 to 5 cm depth. Dredged sediments produced less toxicity to the daphnids than did core collected samples. The coefficient of variance was high (>40%) for both survival and hydrolase activities (alkaline phosphatase, β‐galactosidase and β‐glucosidase) between horizontal sediment replicates collected by either dredge or core. Subsample variance, however, was small (<20%). These results highlight the important role that sediment heterogeneity and collection method have on sediment quality a

ISSN:0730-7268    

DOI:10.1002/etc.5620090810

出版商:Wiley Periodicals, Inc.    

年代:1990

数据来源: WILEY