ISSN:0730-7268    

DOI:10.1002/etc.5620120101

出版商:Wiley Periodicals, Inc.    

年代:1993

数据来源: WILEY

ISSN:0730-7268    

DOI:10.1002/etc.5620120102

出版商:Wiley Periodicals, Inc.    

年代:1993

数据来源: WILEY

摘要:

AbstractSewage sludge containing typical indigenous concentrations of polynuclear aromatic hydrocarbons (PAHs) was applied to several different soils in glass microcosms. Biologically active and sterilized soils were monitored for PAH content over a period of approximately 205 d. Agricultural soils with and without previous exposure to sewage sludge were tested, together with a forest soil and a soil from a major roadside. Loss of PAHs from a soil spiked with a PAH standard solution was also investigated. Results indicate the PAH compounds with less than four benzene rings are susceptible to abiotic loss processes. However, losses by these mechanisms were insignificant for compounds with four or more benzene rings. Half‐lives for the sludge‐applied PAHs were derived and indicated a strong dependence of persistence on chemical structure. Half‐lives for phenanthrene and benzo[gle]perylene were between 83 and 193 d and 282 and 535 d, respectively. Mean half‐lives correlate directly with logKowand inversely with log water solubility. Behavior of PAHs was different in each soil, probably due to different soil characteristics and history of PAH exposure. The soil spiked with PAHs provided the lowest half‐life values for most PAH compounds, suggesting a higher susceptibility of spiked PAHs to both abiotic and biological de

ISSN:0730-7268    

DOI:10.1002/etc.5620120103

出版商:Wiley Periodicals, Inc.    

年代:1993

数据来源: WILEY

摘要:

AbstractThis paper presents information on pesticide concentrations in Lake Erie tributaries draining agricultural watersheds, information distilled from data sets spanning nearly a decade and including up to 750 samples per tributary. Pesticide concentrations are strongly skewed and approximately lognormal. Average concentrations in tributaries are correlated with the amount applied in the basin, but with important secondary effects from chemical properties and modes of application of the pesticides. During runoff of storm events following application, concentrations rise rapidly, peak about the time of peak discharge, and decline slowly thereafter. These patterns do not match those for nutrients, major ions, or sediment, indicating a different pathway from the fields for pesticides. On an annual basis, elevated monthly average concentrations are usually observed from May to August, and low concentrations are present during the rest of the year. Monthly average concentrations of atrazine and alachlor generally exceed maximum contaminant levels (MCLs) in at least one month following application, but those of other herbicides do not. Annual averages are below MCLs for all compounds. No long‐term trends are apparent. Comparisons of patterns in large and small tributaries show that small tributaries have higher maximum concentrations, more frequent concentrations below detection limit, and fewer intermediate concentrations. Smaller tributaries have more strongly skewed distributions and much greater temporal variability in concentrations than do larger river

ISSN:0730-7268    

DOI:10.1002/etc.5620120104

出版商:Wiley Periodicals, Inc.    

年代:1993

数据来源: WILEY

摘要:

AbstractBatch equilibrium studies were conducted with 1,2‐ethanediamine (EDA) andN‐(2‐aminoethyl)‐1,2‐ethanediamine (DETA) to examine the physico‐chemical factors that influence the sorption of the amines to soil. Sorption isotherms were generated using a variety of surface and subsurface soils. The results from this investigation demonstrated that, despite their miscibility in water, both EDA and DETA sorbed strongly to soil. The rate of sorption for both amines was fairly rapid, and equilibrium was achieved within several hours. Sorption isotherms could be best described by the Freundlich equation, and a series of Freundlich constants,Kd's, were developed for each soil and amine. Sorption of the ethyleneamines correlated closely with the cation exchange capacity (CEC) and organic content of the soil. Soils with increased CEC and organic content exhibited higher affinities for the amines. This dependence of sorption on CEC and organic content was most likely due to the strong electrostatic interaction between the positively charged amine and the negatively charged soil surface. For all soils DETA sorbed more strongly than EDA, although the sorption constants varied over an order of magnitude for both compounds. In order to decrease the variation observed in theKdvalues, the sorption constants were normalized to the organic carbon content of the soil and uniqueKocvalues were developed for each amine. The averageKocvalues for EDA and DETA were 4,766 and 19,111, r

ISSN:0730-7268    

DOI:10.1002/etc.5620120105

出版商:Wiley Periodicals, Inc.    

年代:1993

数据来源: WILEY

摘要:

AbstractFlow cytometry is often used to detect DNA aneuploidy and mosaicism associated with malignancy or genetic damage. Yet DNA aneuploidy and mosaicism detected by flow cytometry may be more apparent than real. In contrast to the DNA mass observed for blood, we consistently found markedly different values and higher variability for DNA mass among other tissues collected from the same animal. Prepared mixtures of blood and other cells generated multiple fluorescence peaks identical to those that might be expected for aneuploid mosaicism. Moreover, analysis of tissues such as feather pulp, which contains a combination of cell types, yielded multiple fluorescence peaks that were not observed when blood alone was analyzed. Thus care should be exercised in classifying DNA values from different tissues as normal or abnormal, because the appearance of supernumerary fluorescence peaks might not always indicate the presence of abnormal cell populations.

ISSN:0730-7268    

DOI:10.1002/etc.5620120106

出版商:Wiley Periodicals, Inc.    

年代:1993

数据来源: WILEY

摘要:

AbstractThe aqueous photolysis of triclopyr was examined in both pH 7‐buffered water and natural river water under artificial lights and midsummer sunlight (40°N latitude). The pseudo‐first‐order half‐lives in pH 7‐buffered water and natural river water averaged 0.5 and 1.3 d, respectively, at 25°C. Diffuse mercury lamps and midsummer sunlight produced similar rates of triclopyr decay and photoproduct distribution for a given solution. The photolysis of untreated river water produced a significantly different distribution of photoproducts compared to sterile, pH 7‐buffered water. The photolysis of triclopyr in river water generated oxamic acid as the major photoproduct and a number of other low‐molecular‐weight carboxylic acids as minor products. Photolysis in sterile, pH 7‐buffered water produced 5‐chloro‐3,6‐dihydroxy‐2‐pyridinyloxyacetic acid as the major photoproduct, with minor amounts of oxamic acid and oth

ISSN:0730-7268    

DOI:10.1002/etc.5620120107

出版商:Wiley Periodicals, Inc.    

年代:1993

数据来源: WILEY

摘要:

AbstractAquatic organisms accumulated selenium (Se) from inorganic and organic Se species via aqueous and food‐chain exposure routes. We measured aqueous and food‐chain Se bioaccumulation from selenate, selenite, and seleno‐L‐methionine in a laboratory food chain of algae (Chlamydomonas reinhardtii), daphnids (Daphnia magna), and fish (bluegill,Lepomis macrochirus). Selenium concentrations were monitored radiometrically with75Se‐labeled compounds. All three organisms concentrated Se more strongly from aqueous selenomethionine than from either inorganic Se species. Bioconcentration factors (BCFs) estimated from 1 μg Se/L Se‐methionine exposures were approximately 16,000 for algae, 200,000 for daphnids, and 5,000 for bluegills. Algae and daphnids concentrated Se more strongly from selenite (BCFs = 220–3,600) than selenate (BCFs = 65–500) whereas bluegills concenrated Se about equally from both inorganic species (estimated BCFs = 13 to 106). Bioaccumulation of foodborne Se by daphnids and bluegills was similar in food chains dosed with different Se species. Daphnids and bluegills did not accumulate Se concentrations greater than those in their diet, except at very low dietary Se concentrations. Food‐chain concentration factors (CFs) for daphnids decreased from near 1.0 to 0.5 with increases in algal Se concentrations, whereas CFs estimated from bluegill exposures averaged 0.5 over a range of foodborne Se concentrations. In exposures based on selenite, bluegills accumulated greater Se concentrations from food than from water. Aqueous and food‐chain Se uptakes were approximately additive, and depuration rates were similar in aqueous, food‐chain, and combined exposures. Our results suggest that bluegills in Secontaminated habitats accumulate inorganic Se species primarily via food‐chain uptake, although organoselenium compounds such as Se‐methionine may contribute significantly to Se bioaccumulation by bluegills via both aqu

ISSN:0730-7268    

DOI:10.1002/etc.5620120108

出版商:Wiley Periodicals, Inc.    

年代:1993

数据来源: WILEY

摘要:

AbstractOn each of four dates between May and September 1988, ivermectin was mixed into 60 × 1 kg pats of cattle dung, such that each contained 2, 1, 0.5, or 0 mg ivermectin per kilogram. The pats were then placed on pasture in a stratified, random, block plot and exposed for 15, 30, 45, 60, or 90 d. Twelve pats and a soil sample from below each were lifted at the end of these exposure periods and invertebrates extracted from both dung and soil. This study concentrated on the differences between experimental pats with regard to the numbers and types of Diptera and Coleoptera present. A total of 65 taxa were identified, and the data sets obtained for the dung and the soil were analyzed separately, using two multivariate techniques—TWINSPAN and DECORANA. The major factors determining the fauna of the dung pats and of the soil below them were found to be length of exposure on pasture, exposure date, and ivermectin presence/absence. The presence of ivermectin in the dung markedly changed the fauna in and below treated pats, particularly affecting cyclorrhaphan fly larvae. It is suggested that the incorporated multivariate methods have great potential for use in environmental contamination studies, as they analyze complex data sets objectively and allow the identification of faunal characteristics of treated and untreated sit

ISSN:0730-7268    

DOI:10.1002/etc.5620120109

出版商:Wiley Periodicals, Inc.    

年代:1993

数据来源: WILEY

摘要:

AbstractAn analysis of sample size requirements for theCeriodaphnia dubiareproduction toxicity test is presented. Sample size requirements for detecting nominally specified biological effect sizes in the presence of different variance models are examined over a range of false positive error rates (α) and false negative error rates (β). Mean total young produced per female from control organisms in 53 separate toxicity tests yields a mean (22.52) and variance (68.25) that are used in sample size determinations. Results from these calculations demonstrate that in tests using the currently accepted sample size of 10 organisms per concentration, hypothesis‐testing techniques are capable of detecting a range of 31 to 100% reproductive inhibition relative to controls. This wide range of minimum detectable inhibition values indicates that the ability to detect biologically significant levels of reproductive inhibition in this test is constrained by the statistical properties (i.e., power) associated with the currently accepted test protocol. It is suggested that the design of theCeriodaphniatoxicity test be based not only on a minimum level of control reproductive output (as currently recommended), but also on the ability to detect a specified level of reproductive inhibit

ISSN:0730-7268    

DOI:10.1002/etc.5620120110

出版商:Wiley Periodicals, Inc.    

年代:1993

数据来源: WILEY