ISSN:0730-7268    

DOI:10.1002/etc.5620120201

出版商:Wiley Periodicals, Inc.    

年代:1993

数据来源: WILEY

ISSN:0730-7268    

DOI:10.1002/etc.5620120202

出版商:Wiley Periodicals, Inc.    

年代:1993

数据来源: WILEY

摘要:

AbstractMany studies relate the ecological fate of a contaminant to its chemical structure, but few combine quantitative structure‐activity relationships with environmental properties that may modulate those effects, so the modulating role of such properties remains unquantified. This study determines the effects of variations in suspended biomass, dissolved and colloidal organic carbon, and pH on the time course of 2,2′,4,4′,5,5′‐hexachlorobiphenyl uptake by laboratory cultures ofSelenastrum capricornutumPrintz. Variations in pH had no effect, but uptake increased with biomass and decreased at higher levels of organic carbon, measured as absorbance at 440 nm (Abs, per meter). Coefficients for these effects combined with existing relations based on simple first‐order molecular connectivity (χ) or capacity ratio (K′) yielded semi‐empirical equations to predict the instantaneous rate of uptake and bioconcentration factor (BCF) of organic contaminants: log rate = −3.30 + 0.32χ+ 1.1 log biomass ‐ 0.42 log Abs; log BCF = 4.11 + 0.86 logK′ ‐ 0.87 log biomass — 0.22 log Abs. These equations, entirely based on pure laboratory cultures, were assessed by comparing predicted uptake with the time courses of polychlorinated biphenyl (PCB) uptake by plankton in water from 11 Quebec lakes and proved to be more effective than predictions based on c

ISSN:0730-7268    

DOI:10.1002/etc.5620120203

出版商:Wiley Periodicals, Inc.    

年代:1993

数据来源: WILEY

摘要:

AbstractSamples of a furnace carbon black, N‐330, were collected from the production line during a period of three years. Following extraction with benzene and solvent exchange, the mutagenic response was determined with the AmesSalmonellaassay in the TA98 and TA100 strains with and without addition of S9. The samples were mainly mutagenic in the presence of S9, showing that polycyclic aromatic hydrocarbons (PAHs) were the major mutagenic impurities. The mutagenic response varied 30‐fold among the samples. Analysis of PAHs in the range from phenanthrene to coronerie also showed a wide variation between samples being correlated to the mutagenic response. The large concentration differences of impurities between batches implies that a single batch cannot be used for generalized toxicological studies. The presence of PAH and mutagenic impurities in the investigated carbon black is a significant source of these environmental pollutants compared to another source of concern, automobile exha

ISSN:0730-7268    

DOI:10.1002/etc.5620120204

出版商:Wiley Periodicals, Inc.    

年代:1993

数据来源: WILEY

摘要:

AbstractThe effect of 1, 5, 10, 15, and 20% (v/v) of wastewater from olive oil mills (“alpechin”) was investigated in cells ofAzotobacter chroococcumgrown in chemically defined media (N‐free or with NH+4) and dialyzed‐soil media. Wastewater from olive oil mills at concentrations of 1 to 20% (v/v) significantly reduced dinitrogen fixation and growth ofAzotobacter chroococcumin chemically defined N‐free medium, whereas the presence of 1 to 15% had a stimulatory effect on dinitrogen fixation and growth ofAzotobacterin dialyzed‐soil medium.Azotobacter chroococcumgrew on NH+4media (without glucose) amended with alpechin, suggesting that these wastes were utilized byAzotobacteras a ca

ISSN:0730-7268    

DOI:10.1002/etc.5620120205

出版商:Wiley Periodicals, Inc.    

年代:1993

数据来源: WILEY

摘要:

AbstractThe computer‐automated structure evaluation (CASE) methodology has been used to investigate the correlation between chemical structure and rate of biodegradation. A training set consisting of 283 diverse organic chemicals of known biodegradation activity was evaluated. Computer‐automated structure evaluation identified six major activating fragments that contained oxygen in a carbonyl or hydroxyl group, suggesting that the presence of oxygen plays a significant role in biodegradation. The training set predicts the biodegradation categories correctly 74% of the time for an independent validation set of 27 chemicals. By also using a data base of diverse chemicals whose activity was based on acclimated inocula, two prediction results were obtained for each of the 27 chemicals of an independent validation set. Analysis of the results showed that the chemicals could be grouped into five prediction categories. Two of these categories included chemicals for which both data bases predicted exactly the same activity, whereas a third category contained two chemicals for which no conclusion was made. The other two categories include chemicals of intermediate activity, that is, chemicals that can undergo slow or fast biodegradation, depending on the conditions. In addition, the identification of activating structural fragments has provided information on mechanisms for biodegradation in the environm

ISSN:0730-7268    

DOI:10.1002/etc.5620120206

出版商:Wiley Periodicals, Inc.    

年代:1993

数据来源: WILEY

摘要:

AbstractBlood samples from sharp‐shinned hawks (Accipiter striatus) were collected from 1985 to 1989 during the fall migration at Hawk Cliff, Ontario, and during the spring migration at Whitefish Point, Michigan, and analyzed for organochlorine contaminants. The study was designed to investigate the potential of using blood samples from birds of prey trapped by banders as a means of estimating the organochlorine exposure of migrant birds on their breeding and wintering grounds. Mean plasma levels averaged over the entire sample were highest forp,p′‐DDE (0.28 mg/kg, wet weight), followed by total polychlorinated biphenyls (PCBs) (0.08 mg/kg, wet weight). Mean levels of DDE, mirex, oxychlordane, heptachlor expoxide, dieldrin, hexachlorobenzene, and PCBs increased significantly in hatch‐year birds from their first southward migration to their return flight the following spring as second‐year birds. Thereafter, mean residue levels of the more persistent chemicals, including DDE, oxychlordane, and PCBs, did not change significantly between seasons in adult age classes. In contrast, dieldrin and heptachlor epoxide, which have a shorter half‐time in the body, increased significantly in the blood of all age classes after each winter and decreased significantly after each breeding season. The results were interpreted in terms of the clearance rates of the compounds as well as the diet of the birds on the breeding grounds. The sharp‐shinned hawk is a useful indicator species for contaminant‐monitoring programs involvin

ISSN:0730-7268    

DOI:10.1002/etc.5620120207

出版商:Wiley Periodicals, Inc.    

年代:1993

数据来源: WILEY

摘要:

AbstractThe fate of organic chemicals in the environment depends on their susceptibility to biodegradation. Hence, development of regulations concerning their manufacture and use requires information on the extent and rate of biodegradation. Recent studies have attempted to correlate the kinetics of biodegradation with the molecular structure of the compound. This has led to the development of structure‐biodegradation relationships (SBRs) using the group contribution approach. Each defined group present in the chemical structure of the compound is assigned a unique numerical contribution toward the calculation of the biodegradation kinetic constants. In this paper, a nonlinear group contribution method has been developed using neural networks; it is trained using literature data on the first‐order biodegradation kinetic rate constant for a number of priority pollutants. The trained neural network is then used to predict the biodegradation kinetic constant for a new list of compounds, and the results have been compared with the experimental values and the predictions obtained from a linear group contribution method. It has been shown that the nonlinear group contribution method using neural networks is able to provide a superior fit to the training set data and test data set and produce a lower prediction error than the previous linear met

ISSN:0730-7268    

DOI:10.1002/etc.5620120208

出版商:Wiley Periodicals, Inc.    

年代:1993

数据来源: WILEY

摘要:

AbstractWe measured lead and cadmium concentrations in eggs and in the breast feathers of fledglings of common tern (Sterna hirundo), roseate tern (S. dougallii), Forster's tern (S. forsteri), black skimmer (Rynchops niger), and herring gull (Larus argentatus) nesting in mixed‐species colonies in the New York Bight in 1989. Metal concentrations in fledgling feathers represent in part metals sequestered in the egg by females and accumulation from food brought back to chicks by parents, and thus may be a measure of local metal acquisition. There were significant interspecific differences in lead in eggs, and lead and cadmium in fledgling feathers. Herring gulls had the most lead in eggs (up to means of 6,740 ng/g, dry weight), whereas the terns had the least (mean of 318 ng/g, dry weight). Cadmium concentrations were generally low in all examined eggs (<22 ng/g, dry weight). Lead concentrations were high in fledgling feathers (up to 4,090 ng/g, dry weight) in some populations of all species. Cadmium was highest in fledgling feathers of herring gull and skimmers. Among fledgling terns, the roseate tern (a federally endangered species) had the highest concentrations. For all species except herring gull, the feathers of fledglings had higher levels of metals than did egg

ISSN:0730-7268    

DOI:10.1002/etc.5620120209

出版商:Wiley Periodicals, Inc.    

年代:1993

数据来源: WILEY

摘要:

AbstractIn this paper we describe test methods utilizing the aquatic oligochaeteLumbriculus variegatusto assess the acute and chronic toxicity and the presence of bioaccumulatable compounds in contaminated sediments.Lumbriculus variegatuswas chosen as a test species because (a) it represents an ecologically relevant component of freshwater ecosystems (i.e., oligochaetes); (b) it is suitable for long‐term testing and evaluation of chronic toxicity end points (e.g., growth, reproduction); (c) it is exposed via all important routes of concern, including ingestion of contaminated particles; and (d) it has sufficient biomass to assess bioaccumulation of contaminants. Also,Lumbriculus variegatusis easily cultured and handled. Described herein are culturing procedures and test protocols (e.g., test length, sample size, feeding, etc.) forLumbriculus variegatus, as well as two examples of the types of experimental data generated when using the oligochaete in tests with contaminated sediment

ISSN:0730-7268    

DOI:10.1002/etc.5620120210

出版商:Wiley Periodicals, Inc.    

年代:1993

数据来源: WILEY