ISSN:0730-7268    

DOI:10.1002/etc.5620140601

出版商:Wiley Periodicals, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractExperimental results show thatChlorella pyrenoidosahas an ability to accumulate and biodegrade phthalate esters. Bioconcentration factors of dimethyl phthalate (DMP), diethyl phthalate (DEP), and dibutyl phthalate (DBF) reached their maxima of 162 at 24 h, 205 at 12 h, and 4,077 at 12 h. The average biodegradation rates of DMP, DEP, and DBF per day were found to be 13.4 mg/L, 7.3 mg/L, and 2.1 mg/L, respectively. Based on the experimental data, a second‐order kinetic equation was formulated as ‐ dC/dt=KNr, with a factorrindicating the rate of algal growth. Calculation of this equation fits well with the observed data, and the standard deviations between calculated and observed values were 1.72 mg/L, 1.80 mg/L, and 0.26 mg/L for DMP, DEP, and DBF, respectiv

ISSN:0730-7268    

DOI:10.1002/etc.5620140602

出版商:Wiley Periodicals, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractAnaerobic microorganisms enriched from Rhine River sediments are able to remove chlorine substituents from poly‐chlorinated dibenzo‐p‐dioxines (PCDDs). A model PCDD, 1,2,3,4‐tetrachlorodibenzo‐p‐dioxin (1,2,3,4–TeCDD) was reduc‐tively dechlorinated to both 1,2,3–and l,2,4–trichlorodibenzo‐/>‐dioxins (1,2,3–and 1,2,4–TrCDD). These compounds were further dechlorinated to 1,3–and 2,3–dichlorodibenzo‐p‐dioxins and traces of 2–monochlorodibenzo‐p‐dioxin. This is the first report in the literature of the anaerobic microbial dechlorination of PCDDs. The same enrichment culture was previously found to deSchlorinate chlorinated benzenes (CBs) and polychlorinated biphenyls (PCBs). An anaerobic culture able to remove aryl chlorines from three classes of compounds has not been reported before. The rate at which the culture dechlorinates 1,2,3,4–TeCDD (t1/2= 15.5 d) was between those observed for CBs and PCBs. This study shows that reductive dechlorination may have an effect on PCDDs in sediments, as has been demonstrated for CBs and PCBs. The formation of metabolites with a conserved 2,3‐substitution pattern from 1,2,3,4–TeCDD indicates that dechlorination of highly chlorinated dibenzo‐p‐dioxins may result in metabolites that a

ISSN:0730-7268    

DOI:10.1002/etc.5620140603

出版商:Wiley Periodicals, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractThe estrogenic properties of many environmental contaminants, such as DDE and PCBs, have been associated with reproductive failure in a variety of vertebrate species. While estrogens have been measured in many invertebrate species, the function of this hormone in invertebrates is controversial. The objective of the present study was to identify possible physiological and biochemical target sites for the estrogenic effects of some xenobiotics on the freshwater crustaceanDaphnia magnausing the model environmental estrogen diethylstilbestrol (DES). Chronic exposure of daphnids to 0.50 mg/L DBS reduced molting frequency among first‐generation juveniles and decreased fecundity of second‐generation daphnids. Adult first‐generation daphnids chronically exposed to DES, as well as adult daphnids acutely exposed to DES for only 48 h, were examined for steroid hormone metabolic capabilities using testosterone as the model steroid. The rate of elimination of two major hydroxylated metabolites of testosterone was significantly reduced, and elimination of glucose conjugates of testosterone was significantly elevated from exposure to 0.50 mg/L DES. These results demonstrate that multigeneration exposure of daphnids to DES results in reduced fecundity and altered steroid metabolic capabilities. Thus, some arthropods, like vertebrates, are sensitive to the effects of endocrine‐disrupting ch

ISSN:0730-7268    

DOI:10.1002/etc.5620140604

出版商:Wiley Periodicals, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractA laboratory study was conducted to determine whether commercial surfactants enhance the bioremediation of PAH‐contaminated sediments. Phenanthrene was chosen as a representative PAH; an inoculum of PAH‐degrading microorganisms, enriched from an aquatic sediment, was used in sediment‐water slurry microcosm biodegradation experiments. Of seven nonionic surfactants tested, only one (Triton X‐100) did not inhibit phenanthrene mineralization at concentrations above the critical micelle concentration (CMC). Temporal studies on Triton X‐100 revealed that while it initially inhibited mineralization in sediment‐free microcosms, after 1 week Triton X‐100 slightly improved phenanthrene biotransformation and mineralization in microcosms with and without sediment. For all treatments, phenanthrene disappearance was complete after 9 d, and mineralization reached 50 to 65% after 12 d. Sorption to the sediment appears to have reduced the free aqueous surfactant concentration, thereby reducing surfactant toxicity to the microorganisms. These results suggest that many surfactants are toxic to PAH‐degrading microorganisms, and while surfactant addition may not always have adverse effects on biodegradation, the use of surfactants might not be desirable to achieve complete cont

ISSN:0730-7268    

DOI:10.1002/etc.5620140605

出版商:Wiley Periodicals, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractEarthworms of the speciesEudrilus eugeniaewere exposed to dieldrin, using the contact filter paper method, to study the sublethal effects of the pesticide, which is still widely used in many parts of Africa, on the ultrastructure of spermatozoa. The concentrations ranged from 0.154 to 1.54 μg/cm2and exposures lasted 48 h. The spermathecae were dissected out and prepared for electron microscopy. Dieldrin was extracted from the worms by steam distillation and analysed by ECD‐gas chro‐matography. A description of the sperm ultrastructure is presented. This study showed that dieldrin at relatively low concentrations caused structural damage, especially to the nucleus of the sperm. It is argued that this finding could contribute toward the development of a model for predicting environmental quality, based on sperm morphology, sperm motility, and sperm density. The sublethal effects of dieldrin on sperm morphology could provide a subanimal test for ecotoxicity since its effects will most probably be manifested at the population l

ISSN:0730-7268    

DOI:10.1002/etc.5620140606

出版商:Wiley Periodicals, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractRats were exposed in utero and through mother's milk either to the coplanar PCB congener 3,3′,4,4′,5–CB (IUPAC no. 126) or to the mono‐ortho‐substituted PCB congener 2,3′,4,4′,5–CB (IUPAC no. 118). The different groups of mothers were exposed to 1 and 5 mg/kg body weight of PCB 118, and 2 μg/kg b.w. of PCB 126 every second day from day 10 to day 20 of gestation. The exposure did not affect the body weight of the dams or the size, weight, sex ratio, or physical development of the offspring. Operant behavioral testing revealed that the PCB‐exposed offspring showed both poorer visual discrimination and higher activity level than did the controls. The coplanar PCB 126 congener was the most potent treatment. These results show that both PCB 118 and PCB 126 produced significant neurotoxic effects in the offspring of exposed females in absence of clinical maternotoxic and

ISSN:0730-7268    

DOI:10.1002/etc.5620140607

出版商:Wiley Periodicals, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractThe effects of an acute exposure to either 14–monochlorodehydroabietic acid (MCDHAA) or 12,14–dichlorodehydro‐abietic acid (DCDHAA) were examined in juvenile rainbow trout,Oncorhynchus mykiss.The experimentally determined 96–h LC50 values (and their 95% confidence limits) were 1.03 (0.72, 1.48) and 0.91 (0.70, 1.21) mg/L, for MCDHAA and DCDHAA, respectively. To measure effects on several biochemical parameters, swimming performance, and disease resistance, juvenile trout were exposed for 24 h to sublethal concentrations of one or the other resin acid in an intermittent‐flow respirometer. Hematocrit, plasma lactate, and liver protein were significantly affected by exposure to the highest dose (80% of the 96‐h LC50 value) of either of the resin acids. Plasma cortisol levels were 14‐and 3‐fold higher than were controls. Resistance to infection byAeromonas salmonicidawas significantly reduced; the cumulative percent mortalities due to furunculosis in fish exposed to MCDHAA or DCDHAA reached 20 and 26%, respectively. Swimming performance, measured as critical swimming speed (mean values 6.32 ± 0.20 and 5.93 ± 0.15 body lengths per second for MCDHAA and DCDHAA, respectively), was not significantly affected by re

ISSN:0730-7268    

DOI:10.1002/etc.5620140608

出版商:Wiley Periodicals, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractTwelve freshwater phytoplankton species were used to investigate the factors affecting the toxicity of the organo‐phosphorus insecticide fenitrothion (O,O‐dimethyl‐O‐nitro‐m‐tolyl phosphorothioate) to algae. The unicellular chlorophytesAnkistrodesmus falcatus, Chlamydomonas segnis, Chlamydomonas reinhardtii, Chlorella pyrenoidosa, Chlorella vulgaris, Cosmariumsp.,Pediastrumsp.,Scenedesmus obliquus, Selenastrum capricornutum, and Staurastrumsp.; the bacillariophyteNaviculasp.; and the cyanophyteAnabaenasp. were exposed to three concentrations (0.1, 1.0, and 10.0 mg/L) of fenitrothion. Differential growth effects were observed among the species exposed to fenitrothion over short (96 h) and long‐term (14 d) durations. Fenitrothion concentrations eliciting a 50% growth reduction over 96 h (EC50) ranged from 0.8 to 24.4 mg/L. Selected properties of the test algae (cell size, lipid content, and bioconcentration capacity) were measured and examined for their relationship to fenitrothion sensitivity. Strong correlations were obtained between fenitrothion sensitivity and cell surface area/volume (S/V) ratios, cell lipid content, and fenitrothion bioconcentration capacity of the cells, suggesting that these attributes may be useful predictors of differential sensitivity to lipophilic xenobiotics in unicellular phytoplankton. A positive relationship observed between cell S/V ratio and the bioconcentration of fenitrothion further implicates algal cell size as a significant factor in alga/pesticide interaction and subsequent vulnerability to lipophili

ISSN:0730-7268    

DOI:10.1002/etc.5620140609

出版商:Wiley Periodicals, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractDirect insecticide deposition on adults of the chrysomelid beetleGastrophysa polygoniL. was measured by use of fluorescent spray tracer. The beetles captured 1 .3‐to 2.5–fold the spray volume of an equivalent area of weed leaf surface. This disproportionate rate of exposure declined down through the crop canopy toward the ground. Spray deposition was measured for insects placed on both the upper and the lower surfaces ofPolygonum convolvulusL. leaves within winter wheat crop canopies. The upper‐to‐lower‐surface deposition ratio was 2.3 irrespective of the position of the leaf in the crop canopy. The mortality of adultG. polygoniexposed to pesticides on their host plant was estimated, based on measurements of spray deposition on insects in different positions, the laboratory dose‐response relationship for dimethoate, and the distribution pattern of adults on the host plant measured in the laboratory. At full recommended field rate (280 g ha−1) an expected 40.7% of the adult population would die as a result of direct exposure to dimethoate. The mortalities on specific positions on the plant ranged between zero and 76.7%. To reduce predicted mortality to a level of 10%, it would be necessary to reduce field rate to 50% according to these calculations. Those individuals surviving the dimethoate treatment had a reduced fertility, whereas the egg viability w

ISSN:0730-7268    

DOI:10.1002/etc.5620140610

出版商:Wiley Periodicals, Inc.    

年代:1995

数据来源: WILEY