摘要:

AbstractBatch equilibrium and miscible displacement studies were conducted to investigate sorption and transport of trichloroethylene (TCE) andp‐xylene in two sand aquifer materials low in organic carbon content. The utility of a bicontinuum (two‐site) sorption model to describe the extent of sorption nonequilibrium during transport in saturated columns was evaluated. Model parameters estimated from the breakthrough curves (BTC) obtained at a high pore‐water velocity (v= 24 cm/h) were used successfully to describe the BTC measured at a lower pore‐water velocity (v= 6 cm/h). The assumption of local sorption equilibrium was valid at the lower velocity, and the measured BTC could be described by an equilibrium sorption model coupled to a convective‐dispersive transport model. Values for column retardation factors estimated by fitting the two‐site model to the BTC were comparable with those estimated from equilibrium sorption isotherms. BTC measured for displacement of binary mixtures (TCE plusp‐xylene) and single‐solute (TCE orp‐xylene alone) were identical, suggesting that there is no competitive sorption between these two solutes. These column observations were consistent with sorpt

ISSN:0730-7268    

DOI:10.1002/etc.5620071001

出版商:Wiley Periodicals, Inc.    

年代:1988

数据来源: WILEY

摘要:

AbstractProcedures for the extraction of chloroguaiacols and chlorocatechols from contaminated sediment samples were examined. Using one sample, a comparison was made of the following procedures: solvent extraction with water‐miscible solvents, steam distillation, Soxhlet extraction witht‐butyl methyl ether, and several more aggressive methods employing BF3/methanol, HBr/water and KOH/methanol. The recoveries of the chlorinated compounds were highly variable. Recovery of the chloroguaiacols by the nonaggressive procedures was generally low, but it was significantly greater using methanolic alkali. The efficacy of the latter procedure was confirmed by the data obtained with three other sediment samples. Qualitatively similar differences in recoverability were also observed when a high molecular weight alkali‐stage chlorolignin was examined. Therefore it was not possible to determine whether the monomeric chlorinated compounds were bound to natural organic compounds in the sediment or to the chlorolignin, which is produced during the bleaching process. In an experiment using one sediment sample incubated under anaerobic conditions for nine months, no change occurred in the amount of extractable chloroguaiacols and there was an approximate 40% reduction in the corresponding chlorocatechols. It is therefore postulated that the binding mechanisms of the chloroguaiacols and chlorocatechols in the sediment phase are significantly different, and that an indeterminate fraction is not accessible to microbial transformation. There are, it is noted, inherent limitations to interpreting the results of experiments on binding and desorption in which xenobiotics are exposed to the sediment phase for only a short

ISSN:0730-7268    

DOI:10.1002/etc.5620071002

出版商:Wiley Periodicals, Inc.    

年代:1988

数据来源: WILEY

摘要:

AbstractA laboratory acidification experiment was conducted with a Rocky Mountain zooplankton assemblage from a subalpine lake located downwind of energy development activities and significant sources of acid precursors. The objective of the study was to assess the relative effects of lowered pH (treatment pH 4.2 and 5.2, control pH 6.8) on the survival of different crustacean zoo‐plankton species under controlled conditions for extended periods (19 to 41 d). Analysis of variance (e.g.,F= 4.55,p<0.05) indicated statistically significant differences between controls and treatments (acid treatments contained fewer individuals than did controls) for all four species, and significant differences among species. Newman‐Keuls multiple range tests (e.g.,q= 4.02,pCyclopssp. At pH 4.2,H. gibberumwas significantly more tolerant thanD. roseaandD. lintoni(q= 4.50,p<0.025), but no other significant differences were apparent. The results agree generally with those of other published experiments and field surv

ISSN:0730-7268    

DOI:10.1002/etc.5620071003

出版商:Wiley Periodicals, Inc.    

年代:1988

数据来源: WILEY

摘要:

AbstractIn situand mobile on‐site striped bass prolarval and yearling survival studies were conducted in the Choptank River and in the Chesapeake and Delaware (C&D) Canal area of the Upper Chesapeake Bay. Extensive chemical analyses of both organic and inorganic contaminants in the habitat water were performed and water quality parameters were monitored during these experiments. Surviving yearling striped bass were subjected to histological examination.Prolarval survival data from both thein situand mobile on‐site studies were similar for each spawning area. Prolarval survival ranged from 30 to 45% after 96 h of exposure to Choptank River water in four separate experiments (twoin situ, two on‐site); control survival was greater than 74%. Based on a comparison of laboratory toxicity data and reported field concentrations in the Choptank River for various water quality and contaminant conditions, the following combination of conditions was potentially stressful to striped bass prolarvae: low hardness (36 to 48 mg/L CaCO3), monomeric aluminum (0.150 mg/L), cadmium (0.003 mg/L) and copper (0.040 mg/L). Yearling survival in bothin situand on‐site tests ranged from 93 to 100% in both the control and Choptank River water after 9dof exposure. Survival of striped bass prolarvae in C&D Canal water ranged from 52.5 to 70% after 96 h of exposure in four separate experiments. Control survival of prolarvae was not significantly different. Survival of yearling striped bass in on‐site andin situtests was 95% or greater in C&D Canal water and control water. Acute contaminant effects were not verified in the C&D C

ISSN:0730-7268    

DOI:10.1002/etc.5620071004

出版商:Wiley Periodicals, Inc.    

年代:1988

数据来源: WILEY

摘要:

AbstractConcentrations of highly carboxylated porphyrins (HCPs) in the livers of adult herring gulls (Larus argentatus) from colonies throughout the Great Lakes were found to be markedly elevated in comparison with those in gulls from coastal areas and in seven other species of birds consuming diets uncontaminated with polyhalogenated aromatic hydrocarbons (PHAHs). The highes levels were found in gulls from lower Green Bay (Lake Michigan), Saginaw Bay (Lake Huron) ant Lake Ontario. We suggest that the high levels of HCPs reflect PHAH‐induced derangement of heme biosynthesis. Determination of HCPs offers promise as a specific and sensitive biological marker of PHAH‐induced toxicity and as a measure of the toxicological significance of the chemical burden in gulls, terminal members of Great Lakes food cha

ISSN:0730-7268    

DOI:10.1002/etc.5620071005

出版商:Wiley Periodicals, Inc.    

年代:1988

数据来源: WILEY

摘要:

AbstractYoung Japanese quail (Coturnix japonica) were administered NaF for 16 d either in their diet or by esophageal intubation. Based on the total fluoride ion (Σmg F−) intake over the 16‐d experimental period, fluoride administered by intubation was at least six times more toxic than that fed in the diet. Dietary concentrations of 1,000 ppm F−(Σmg F−for 16 d = approx. 144) produced no mortality, whereas intubated doses produced 73% or greater mortality in all groups administered 54 mg F−/kg/d or more (Σmg F−for 16 d ≥ approx. 23 mg). Graphic comparison of the regression of log F−ppm in femurs/mg F−intake showed that fluoride levels in the femurs of quail administered fluoride by intubation were higher than in those administered

ISSN:0730-7268    

DOI:10.1002/etc.5620071006

出版商:Wiley Periodicals, Inc.    

年代:1988

数据来源: WILEY

摘要:

AbstractThe growth inhibition (96‐h EC50) of two species of green algae,Selenastrum capricornutumandChlorella vulgaris, caused by phenol and 12 chlorophenols (from mono‐Cl to penta‐Cl) was determined according to the Organization for Economic Cooperation and Development guidelines for testing chemicals. The responses of the algae to the chemicals were measured by cell counting, and 96‐h EC50 values were correlated with six physicochemical parameters of chlorophenols. The parameters employed in the quantitative structure‐activity relationship (QSAR) analyses weren‐octanol/water partition coefficient (logPow), dissociation constant (pKa), Hammett Σσ constant, index of valence molecular connectivity (1χv), perimeter of the efficient cross section of molecule (ΣD) and melting point (F). In the S.capricornutumassay, the toxicity increased as the number of substituted chlorine atoms increased. In theC. vulgarisassay, although toxicity increased from phenol to dichlorophenol, the toxicities of di‐, tri‐, tetra‐ and pentachlorophenol were almost the same. QSAR study shows that logPowgives the best correlation, even in theC. vulgarisassay, by the use of the square of logPow. Therefore, the growth inhibition of these algae caused by chlorophenols is mostly influenced by lipophilicity, as is stated frequently in toxicity studies

ISSN:0730-7268    

DOI:10.1002/etc.5620071007

出版商:Wiley Periodicals, Inc.    

年代:1988

数据来源: WILEY

摘要:

AbstractThe time required for continuous chlorination to produce 100% mortality in adultCorbicula flumineawas determined. The total residual chlorine concentrations maintained were lower than any previously tested: 0.05, 0.10 and 0.20 mg/L.

ISSN:0730-7268    

DOI:10.1002/etc.5620071008

出版商:Wiley Periodicals, Inc.    

年代:1988

数据来源: WILEY