摘要:

AbstractMethomyl degrades rapidly in chlorinated water and the rate increases with decreasing pH, increasing temperature and increasing chlorine concentrations. Reaction rate with free chlorine is 1,000‐fold faster than with chloramine. Methomyl forms methomyl sulfoxide andN‐chloromethomyl before degrading to acetic acid, methanesulfonic acid and dichloromethylam

ISSN:0730-7268    

DOI:10.1002/etc.5620090501

出版商:Wiley Periodicals, Inc.    

年代:1990

数据来源: WILEY

摘要:

AbstractResults from a long‐term study on leaching and transformation of the herbicide glufosinate‐ammonium (ammonium‐DL‐homoanalin‐4‐yl (methyl)phosphinate) in a layered soil column were compared with model calculations. Soil columns with layers of loamy sand and sand were treated with 3 kg/ha glufosinate‐ammonium, applied to the soil surface. The soils were irrigated and the leachate was monitored for glufosinate‐ammonium and the main metabolite 3‐methylphosphinico‐propionic acid during a period of 256 d. Calculations for glufosinate‐ammonium and the metabolite were performed with the soil column model EXSOL. Linear equilibrium sorption coefficients (Kd) and first‐order half‐lives were used for fitting effluent curves for both the herbicide and the metabolite. Sorption coefficients were compared with those values estimated from a relation to the clay content derived from batch studies. Fitted half‐lives were compared with the results from die‐away and14CO2evolution studies of both the parent and the daughter compound. The observed leaching of glufosinate‐ammonium could be well simulated usingKd(0.5 cm3/g) and half‐life (11.2 d). The half‐life fitted for the metabolite (10–30 d) was a factor 2 to 3 smaller than that measured with batch degradation experiments. This may be the result of using degradation data estimated by14CO2evolution, which only indirectly indica

ISSN:0730-7268    

DOI:10.1002/etc.5620090502

出版商:Wiley Periodicals, Inc.    

年代:1990

数据来源: WILEY

摘要:

AbstractNutrient export from intact soil‐core microcosms in leachate or by plant uptake was evaluated as a means to assess the ecosystem impacts from the environmental release of genetically modified root‐colonizing bacteria. Intact cores of two soil types, a Burbank sandy loam and a Palouse silt loam, were excavated for use as microcosms, seeded with corn and wheat, respectively, and inoculated withAzospirillum lipoferumtransposon Tn5 mutants. Microcosms were leached at 33 d and 67 d after seeding and the leachate analyzed for sulfate, phosphate, ammonium, nitrite, nitrate, dissolved organic carbon and inorganic carbon. Statistically significant differences in leachate nutrient concentrations between treatments were due to differences in soil types, rather than inoculation with the bacteria. The high variation in the concentrations of nutrients in the leachates from replicate microcosms, attributed to real field variation, suggest that the measurement of nutrient export in leachate from microcosms may not be a sensitive indicator of ecosystem impacts. One exception was dissolved organic carbon (and total carbon). A statistically significant difference (p≥ 0.05) was observed between the microcosms receiving live inoculum and those receiving heat‐killed cells for leachate organic carbon concentration. Plant uptake of N, P, S, B, Cu, Fe, Mg, Mn and Zn was not affected by inoculation but the coefficients of variation were considerably lower than for the leachate analyses. It is suggested that, although the leaching of organic carbon from microcosms may be used as a holistic indicator of ecosystem impacts from the release of genetically engineered microorganisms (GEMs), measurements of plant assimilation of nutrients and specific rates of microbial transformation of nutrients may provide more sensitive effects end

ISSN:0730-7268    

DOI:10.1002/etc.5620090503

出版商:Wiley Periodicals, Inc.    

年代:1990

数据来源: WILEY

摘要:

AbstractLakes Bay, an estuarine embayment located near Atlantic City, New Jersey, currently supports commercial shellfishing; however, the surrounding basin is a prime location for development. Synpotic surveys were conducted during the summer of 1986 to determine background conditions and the response to stormwater runoff inputs of three metals; copper, lead and cadmium. Background (dry weather) conditions of all three metals were found to be not significantly different than those reported for world natural waters. Significant amounts of lead and copper were found to be input to the system through a major storm water sewer that discharges to a lagoon. Sediment analysis showed that considerable sedimentation occurs in this lagoon, thus localizing the effect of this input to the system. A local stormwater retention basin was not found to be a significant source of metals. Cadmium levels were not found to be significantly different between dry and wet weather conditions. The high salinity of the system required extensive sample extraction procedures prior to analysis by atomic absorption spectrophotometry to minimize matrix interferences.

ISSN:0730-7268    

DOI:10.1002/etc.5620090504

出版商:Wiley Periodicals, Inc.    

年代:1990

数据来源: WILEY

摘要:

AbstractThe photochemical degradation of tetraphenylborate (TPB) and diphenylboric acid (DPBA) was studied in stream water and humic acid solutions. The rates of indirect photolysis of TPB and DPBA were similar and directly proportional to the concentration of stream water dissolved organic matter (DOM) and humic acid for values<10 mg/L. Direct photolysis of both organoborates was nondetectable during a 2‐h irradiation period. Indirect photolysis rates varied only slightly from pH 6.0 to 9.0, but increased markedly below pH 6.0. Removal of dissolved oxygen increased reaction rates by a factor of two, indicating that the reaction mechanism does not involve singlet oxygen oxygenatio

ISSN:0730-7268    

DOI:10.1002/etc.5620090505

出版商:Wiley Periodicals, Inc.    

年代:1990

数据来源: WILEY

摘要:

AbstractThe effects of dissolved humic materials (DHM) on the photo‐induced toxicity of anthracene to fathead minnows(Pimephales promelas)and daphnia(Daphnia magna)were studied in a laboratory system under simulated sunlight. In the fathead minnow toxicity tests, four concentrations of anthracene (0, 6.6, 13.1 and 19.1 μ g/L) and five concentrations of DHM (0, 0.5, 1.0, 3.0 and 6.0 mg C/L) were achieved. In the daphnia toxicity tests, four concentrations of anthracene (0, 5.58, 10.49 and 21.03 μ g/L) and four concentrations of DHM (0, 0.8, 2.7 and 6.9 mg C/L) were achieved. DHM significantly reduced acute photo‐induced toxicity in both organisms. Median lethal times (LT50) were directly related to DHM concentration and inversely related to water anthracene concentration across the tested ranges of each variable. The presence of DHM also reduced anthracene bioaccumulation, and LT50 values for both fish and daphnia were inversely related to body anthracene concentration. Findings presented in this study demonstrate that the photo‐induced toxicity of anthracene is primarily a fugacity‐dependent phenomenon, that selective attenuation of the active wavelengths of solar ultraviolet radiation by DHM also results in a decreased level of acute toxicity and that a common mode of acute photo‐induced toxicity between fish and dap

ISSN:0730-7268    

DOI:10.1002/etc.5620090506

出版商:Wiley Periodicals, Inc.    

年代:1990

数据来源: WILEY

摘要:

AbstractSimple assumptions for individual toxic response, exchange of toxicant with environmental concentrations and body composition are used in a model to evaluate the effect of lipid variation on toxic response in a subpopulation of similarly sized individuals. This model represents the internal distribution of a chemical such that more hydrophobic chemicals preferentially move into body lipid. Thus, for exposures of equal chemical activity, both increasing body fat and greater hydrophobicities increase the exposure duration that can be withstood without effect. In simulated 96 h bioassays the effect of increased tolerance to higher hydrophobicities was apparent for chemicals whoseKOWexceeded 104. These simulations are compared to published observations. Simulations are also compared to other published data for longer‐term bioassays. The effect of interspecies gill morphology on toxic response is also explored. It is concluded that variation in lipid can account for much variation in tolerance in a subpopulation of similarly sized individuals; that gill morphology is another variable influencing toxic response; and that, in general, for similarly exposed organisms, the fattest survives the longes

ISSN:0730-7268    

DOI:10.1002/etc.5620090507

出版商:Wiley Periodicals, Inc.    

年代:1990

数据来源: WILEY

摘要:

AbstractA method to determine the mortality effects of a hydrophobic chemical on a population is proposed. The ecotoxicological protocol is based on individual organism response and is derived from the static theory of “survival of the fattest.” This study, focusing upon effects of mortality and the effects of toxicant stress on population succession, examines the static assessment survival of the fattest in a dynamic population model. A premise in this approach is that risk assessment should not be based solely upon chemical properties of the toxicant and that the biology of the exposed organisms is an important factor in the determination of effe

ISSN:0730-7268    

DOI:10.1002/etc.5620090508

出版商:Wiley Periodicals, Inc.    

年代:1990

数据来源: WILEY

摘要:

AbstractSolubility values for eight phthalate esters investigated ranged from 0.020 to 121 mg/L. Acute toxicity tests were conducted with fathead minnows (Pimephales promelas) and all eight phthalate esters. Acute and chronic tests were conducted with rainbow trout (Oncorhynchus mykiss) and Japanese medaka (Oryzias latipes) using di‐2‐ethylhexylphthalate. In addition, the chronic toxicity of the three di‐n‐butylphthalates and a mixture of these three phthalates was examined using daphnids (Daphnia magna). Fathead minnow 96‐h LC50 values for di‐n‐butyl‐ortho‐phthalate, di‐n‐butyl‐tere‐phthalate, di‐n‐butyl‐iso‐phthalate and α, w‐butylene di[o‐(4‐hydroxybutoxycarbonyl)‐benzoate] were 1.1, 0.61, 0.90 and 121 mg/L, respectively. Di‐n‐octyl‐ortho‐phthalate, di‐n‐octyl‐iso‐phthalate and di‐n‐octyl‐tere‐phthalate were not acutely toxic to fathead minnows at concentrations that exceeded the water solubility estimates for each phthalate. Di‐2‐ethylhexyl‐phthalate was not acutely toxic to any tested species at the highest tested concentrations. No significant adverse effects were observed on hatchability, survival or growth of rainbow trout exposed to a mean di‐2‐ethylhexylphthalate concentration of 0.502 mg/L (the highest concentration tested) in a 90‐d embryo‐larval test. However, exposure to a mean di‐2‐ethylhexylphthalate concentration of 0.554 mg/L significantly reduced the growth of Japanese medaka during a 168‐d larval test. Significant adverse effects on reproduction occurred in 21‐d chronic tests withD. magnaat concentrations of 1.91, 0.20 and 0.64 mg/L for di‐n‐butyl‐ortho‐phthalate, di‐n‐butyl‐iso‐phthalate and di‐n‐butyl‐tere‐phthalate, respectively. A daphnid mi

ISSN:0730-7268    

DOI:10.1002/etc.5620090509

出版商:Wiley Periodicals, Inc.    

年代:1990

数据来源: WILEY

摘要:

AbstractThe influence of competition, exploitation and level of energy input on toxicant fate and effect in simple aquatic laboratory ecosystems was studied. Twenty‐four systems composed of populations of guppies (Poecilia reticulata), snails (family Planorbidae) and various taxa of algae were maintained in 40‐liter flow‐through glass aquaria. Guppies and snails were competitors for a common food resource. Ecosystems were established in which guppies and snails were sympatric and allopatric. The systems were exposed to three levels of guppy exploitation and received two levels of energy input. System dynamic and near steady‐state behavior were documented through monthly measurements of population biomasses. Biomasses of interacting populations were displayed on phase planes. Shifts in system structure followed chronic exposure to a sublethal concentration of dieldrin. System responses to the toxicant ranged from increased population biomass to population extinction and were influenced by level of exploitation, energy input rate and species competition. Toxicant concentrations were determined in adult female fish. Both toxicant effect and fate were influenced by system organization and environment. Quite different conclusions concerning toxicant performance in these systems could have been drawn if observation had been restricted to only one set of organizational and environmental con

ISSN:0730-7268    

DOI:10.1002/etc.5620090510

出版商:Wiley Periodicals, Inc.    

年代:1990

数据来源: WILEY