摘要:

AbstractThe kinetics of disappearance of methyl parathion (0,0‐dimethyl‐0‐p‐nitrophenyl phosphorothioate) were studied in anaerobic sediment samples in the laboratory as a function of methyl parathion concentration, pH and Eh. The disappearance of methyl parathion is described by first‐order kinetics and amino methyl parathion (0,0‐dimethyl‐0‐p‐aminophenyl phosphorothioate) was identified as a reduction product. In the strongly reducing sediments, the half‐lives were on the order of a few minutes. In water isolated from the sediment, no reaction could be detected over the period of a week. Also, there is no apparent correlation between the first‐order disappearance rate constants and the pH of the sediment samples. In heat‐sterilized sediments, the disappearance rate constants are retarded about two orders of magnitude relative to nonsterile sediments. In chemically treated sediments, first‐order disappearance rate constants are comparable to those

ISSN:0730-7268    

DOI:10.1002/etc.5620051201

出版商:Wiley Periodicals, Inc.    

年代:1986

数据来源: WILEY

摘要:

AbstractThe ability of the Pesticide Root Zone Model (PRZM) to simulate the movement of aldicarb or aldoxycarb residues was evaluated using the soil properties and amounts of rainfall and irrigation measured in 34 unsaturated zone field study plots. Maximum leaching depth values obtained from the PRZM simulations agreed relatively well with those observed in the field experiments. Where irrigation water was applied in spatially nonuniform patterns to a field (as in furrow or flood irrigation), simulations show that the placement of the pesticide in relation to irrigation water must also be considered. The comparisons presented in this paper show that PRZM (if supplied with the proper degradation rates and appropriate soil, weather and agricultural parameters) can be used to assess movement of pesticides in agricultural environments. When used in conjunction with multiple year rainfall records, this model can be used to develop probability distributions of pesticide movement in the unsaturated zone. PRZM can also be linked to a ground water solute transport model to provide predictions of pesticide concentrations and transport in ground water. These techniques are useful in performing risk assessments and in developing potential management practices when needed.

ISSN:0730-7268    

DOI:10.1002/etc.5620051202

出版商:Wiley Periodicals, Inc.    

年代:1986

数据来源: WILEY

摘要:

AbstractBenomyl and carbendazim exhibited high acute toxicity to channel catfish,Ictalurus punctatus(Rafinesque), but were much less toxic to rainbow trout,Salmo gairdneri(Richardson), and bluegills,Lepomis macrochirus(Rafinesque). Changes in water temperature, pH, and water hardness altered the acute toxicity to fish of both compounds; however, the alterations were less marked in channel catfish than in rainbow trout. Carbendazim injected intraperitoneally was not readily metabolized and was the major radioactive product excreted by the three fish species. The rapid depuration of radiocarbon into the containment water and the storage of residues in the gall bladder of each species indicated that both branchial and biliary excretion were major pathways for the elimination of carbendazim by fish. In the carbendazim residue dynamic studies, rainbow trout had the highest uptake rate constant and bioconcentration factor of the three species. Much less carbendazim was accumulated by channel catfish than by the other two species, but this residue level (0.44 μg/g) appeared to be lethal after 48 h of exposure. The elimination rate constant and biological half‐life of carbendazim were similar for rainbow trout and bluegills; however, the elimination rate constant was larger and the biological half‐life shorter in channel catfish than in the other two species. It was concluded that benomyl and carbendazim were selectively toxic to channel catfish compared with rainbow trout and bluegill, but because of the instability of benomyl and the fast elimination of carbendazim, the possibility of these compounds excessively bioconcentrating in fish was re

ISSN:0730-7268    

DOI:10.1002/etc.5620051203

出版商:Wiley Periodicals, Inc.    

年代:1986

数据来源: WILEY

摘要:

AbstractPesticide spray formulations include a variety of adjuvants as wetting agents, surfactants or emulsifiers. DOWANOL TPM (tripropylene glycol methyl ether) is one such adjuvant in current common use in spray formulations of the insecticide fenitrothion. Unlike some other adjuvants which we have tested, DOWANOL appears to have no significant toxicity for duckweed,Lemna minorL., an environmentally important aquatic plant, which has been previously shown to be sensitive to some formulations. Four parameters were monitored, namely, biomass, photosynthetic function, adenosine triphosphate level and changes in the electrical potential of the bathing media. Reported concentrations of DOWANOL in forest pools after spraying are of the order of 1 μg ml−1. We have tested concentrations up to 956 μg ml−1. The highest concentration produced significant functional impairment in the plants, which, however, recovered within 2 d in freshwater. Lower concentrations had no measurable effects. The threshold concentration for DOWANOL toxicity toLemnais thus about three orders of magnitude higher than observed field concentrations, and we conclude that it therefore can be judged to be a relatively environmentally safe adj

ISSN:0730-7268    

DOI:10.1002/etc.5620051204

出版商:Wiley Periodicals, Inc.    

年代:1986

数据来源: WILEY

摘要:

AbstractDaphnia magnaare commonly trapped at the surface of test waters inD. magnatoxicity tests. These “floaters” complicate interpretation of test results. A screen device was designed to physically prevent theDaphniafrom touching the water surface. The effectiveness of the device was evaluated using several complex efflue

ISSN:0730-7268    

DOI:10.1002/etc.5620051205

出版商:Wiley Periodicals, Inc.    

年代:1986

数据来源: WILEY

摘要:

AbstractThe extent and routes of metabolism affect the bioconcentration and toxicity of xenobiotics in crayfish. To investigate thein vivoxenobiotic metabolism of threep‐nitrophenol derivatives, rice field crayfish were exposed to 0.1 to 0.01 mg L−114C‐substrate solutions for 15 h. At apparent steady‐state uptake, the crayfish were transferred to a recycling flow‐through metabolism chamber for 24 h where the depurated products were collected and concentrated on a column of Amberlite XAD‐4 resin. The tissue absorption and distribution of14C‐compounds at the apparent steady‐state and post depuration periods were measured by complete tissue combustion and recovery of evolved14CO2. The structure and concentration of metabolites in resin and soft tissue extracts were determined by cochromatography with authentic standards in HPLC and TLC systems. The crayfish rapidly absorbed the radiolabeled chemicals from solution and depurated metabolites of oxidation and conjugation reactions. The most prominent metabolites were the β‐D‐glucosides of the free phenols, with lesser amounts of the corresponding sulfate esters. Observed oxidations includedO‐demethylation, aromatic sidechain oxidation and phosphorothioate deesterification. Body burdens of the originalp‐nitrophenol derivatives were markedly reduced by the presence of these m

ISSN:0730-7268    

DOI:10.1002/etc.5620051206

出版商:Wiley Periodicals, Inc.    

年代:1986

数据来源: WILEY

摘要:

AbstractAquatic toxicity testing is conducted largely by means of a single experimental protocol‐the concentration‐response toxicity test. This procedure has a number of well‐known limitations resulting from the fact that the relationship between the waterborne toxicant concentration and the actual body toxicant concentration which is producing the observed biological response is unknown. Hence quantifying the influence of chemical potency, physical, chemical and biological factors and elapsed time on the outcome of toxicity tests is difficult. Interpretation, and even more significantly, predictability may be severely restricted. Using, and further quantifying, the links between octanol‐water partition coefficients, bioconcentration and acute and chronic toxicity quantitative structure‐activity relationships (QSARs) for narcotic organic chemicals has allowed the following conclusions to be made:(1)Establishing internal toxicant concentrations related to acute and chronic effects, as estimated in this paper, will allow the toxicological significance of body burdens of certain organic chemicals, both singly and in certain mixtures, to be determined.(2)Chemical potency, as determined in the exposed organism, appears to be essentially constant for each of the biological responses and organic chemical groups examined.(3)The acute and chronic QSARs discussed herein are all parallel, each having a slope of unity.(4)It appears, as a first approximation, that a one‐compartment, first‐order kinetics model could provide a quantitative means of studying aquatic toxicity test results, both retrospectively and prospectively.(5)Bioconcentration and toxicity kinetics appear to be similar, but the internal toxicant concentration endpoint is different, fixed for toxicity and variable for bio

ISSN:0730-7268    

DOI:10.1002/etc.5620051207

出版商:Wiley Periodicals, Inc.    

年代:1986

数据来源: WILEY