摘要:

AbstractThe toxicity of 16 pesticides to the energy‐producing process of photosynthesis was determined from inhibition or depression of the assimilation rate of [14C]bicarbonate by natural plankton samples collected from Jack's Lake, a mesotrophic lake on the edge of the Canadian Shield 200 km northeast of Toronto, Ontario. Measurements were made at increasing concentrations of pesticide while samples were exposed to optimal light. At the same time, in the same 300‐ml bottle, measurements of maximal uptake rates for phosphate and ammonium were made using radiotracer and stable isotope methods. In this way the more commonly used screening technique of photosynthetic inhibition could be compared to the energy‐demanding processes of phosphate and ammonium uptake. Phosphate assimilation was inhibited at much higher herbicide concentrations than carbon fixation, whereas ammonium assimilation was inhibited at intermediate concentrations. Herbicides that specifically inhibit photosynthesis were most toxic to carbon uptake, while those herbicides affecting other cellular metabolic processes had a greater influence on phosphate and ammonium assimilation. No relationship was found among pesticide toxicity and molecular weight, solubility, or l

ISSN:0730-7268    

DOI:10.1002/etc.5620140111

出版商:Wiley Periodicals, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractIn 1991, eggs of the common tern (Sterna hirundo) were collected at eight different locations and incubated artificially. The residual yolk sacs of the hatchlings from the highly polluted colonies, located in the main sedimentation area of the Rhine and Meuse rivers, contained on average 16 ng TEQ (toxicity equivalency) per gram lipid, which was fivefold higher than the concentrations in the reference colony. The hepatic EROD activity was induced fourfold compared to the reference colony (p<0.005). At the individual level, a significant relationship was found between log TEQ and both log EROD and log PROD (r= 0.568,p<0.05 andr= 0.661,p<0.02, respectively). Average TEQ concentration in chicks that hatched after 23 d of incubation were twice the concentration of those that hatched after 21 d (p<0.05). No concentration‐related effects on morphology and physiology were found. The non‐ortho‐ and mono‐ortho‐PCBs were predominant regarding the total TEQ, while the PCDDs and PCDFs contributed less than 10%. The PCB patterns were highly similar among the individual birds and among different locations. In contrast, PCDD and PCDF patterns were not similar at all locations, and two distinct patterns could be recognized and related to sediments that were deposited during different tim

ISSN:0730-7268    

DOI:10.1002/etc.5620140112

出版商:Wiley Periodicals, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractAdaptation to selected metals is known to modify life‐cycle characteristics of some invertebrates and can modify the response to other metals. The reverse process, i.e., adaptation to nonpolluted conditions in a metal‐tolerant strain, was studied here for a cadmium‐tolerant population of the midgeChironomus ripariusto detect whether this “backward” adaptation followed the same lines. It appeared that cadmium‐tolerant populations, reared in the absence of cadmium, continued to suffer from high mortality rates and lowered larval growth rates and reproductive success. Also, some cadmium‐tolerant populations accumulated more zinc than did nontolerant populations. Successive experiments in which both cadmium‐tolerant and nontolerant populations were exposed to zinc indicated that the reduced growth rate and reproduction were a direct consequence of zinc shortage in tolerant midges reared in the absence of cadmium. Mortality among cadmium‐tolerant midges was, however, not lowered by zinc exposure and, judged by their high mortality rates, these midges were even more sensitive to zinc than were nontolerant chironomids. It was concluded that cadmium‐tolerant chironomid populations recovering from prolonged exposure are affected by an increased need for zinc as well as by an increased mortality rate as a direct consequence of the earlier

ISSN:0730-7268    

DOI:10.1002/etc.5620140113

出版商:Wiley Periodicals, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractField and laboratory experiments were conducted to monitor seasonal cytochrome P4501A monooxygenase (MO) activity (measured as ethoxyresorufinOdeethylase (EROD) activity) in gizzard shad (Dorosoma cepedianum) Basal EROD activity declined in midsummer but returned to postspawning spring levels by late summer Seasonal variation in basal EROD activity corresponded with changes in liver somatic index, condition factor, and percent body lipid, indicating that seasonal variation in basal field EROD activity may result from changing physiological condition Benzo[a]pyrene induction experiments demonstrated that, although thelevelof EROD activity changed seasonally, the magnitude of induction relative to corn oil injected controls remained the same Kinetic studies indicated monthly changes in apparentVmaxbut no change in apparentKmTaken together, these results suggest that seasonal changes in EROD activity reflect changes in hepatic P4501A protein concentration This study has demonstrated that it can be inappropriate to interpret EROD activity from a suspect site without first understanding how seasonal field conditions influence P4501A activity

ISSN:0730-7268    

DOI:10.1002/etc.5620140114

出版商:Wiley Periodicals, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractThis study investigated the influence of acid‐volatile sulfide (AVS) and interstitial water (IW) metal concentrations on bioavailability and toxicity of Cd and Ni to an infaunal sediment‐ingesting marine worm,Neanthes arenaceodentata.Ten‐d exposures were conducted with sediments, contaminated primarily with Cd and Ni, from Foundry Cove (Hudson River, NY), and with uncontaminated sediments spiked with Cd or Ni. Molar ratios of simultaneously extracted metal (SEM)/AVS ranged from<0.02 to 44 for Cd‐spiked, 0.02 to 241 for Ni‐spiked, and<0.06 to 125 for Foundry Cove sediments. In all experiments, significant mortality was not observed when SEM/AVS ratios were<1.0 and interstitial water toxic units (IWTU) were1.0, sediments were either lethal or worms did not burrow. Mortality of worms in Foundry Cove sediments was ≤20%, and worms burrowed in all these sediments. However, IW contained<1.0 TU (Ni + Cd) in all Foundry Cove sediments except one (IWTU = 1.69). Metal concentrations in worms generally increased with increases in sediment metal concentration, SEM/AVS molar ratio, and IW metal concentration. The presence of metal in worms from sediments with SEM/AVS ratios<1.0 may be evidence of release of Cd or Ni from oxidized metal sulfide (a result of burrowing), uptake of metal from ingested sediment, or adsorption to body surfaces. These results support the hypothesis that when the concentration of AVS in sediments exceeds that of divalent metals (Cd, Cu, Hg, Ni, Pb, Zn) sediments will not be acutely toxic. However, a greater number of sediments was correctly predicted to be nontoxic when interstitial water metal concentration of<

ISSN:0730-7268    

DOI:10.1002/etc.5620140115

出版商:Wiley Periodicals, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractA study was conducted over the course of a year to determine the induction of hepatic cytochrome P4501A (CYP1A) in three species of benthic fish collected from a contaminated site compared to fish sampled from a less‐contaminated site Juvenile fish were used to minimize effects of reproductive status and migration CYP1A was determined by two catalytic assays [aryl hydrocarbon hydroxylase (AHH) and ethoxyresorufinOdeethylase (EROD)] and by an immunoassay (ELISA) utilizing polyclonal antibodies raised against purified CYP1A from cod AHH activities were measured by a standard method (AHHstd) and by two variations of the standard method All three primary CYP1A measures (AHHstd, EROD, and ELISA) showed consistent between site differences, indicating that induction of CYP1A can be a reliable biomarker of contaminant exposure in fish if appropriate biological variables are controlled for in field studies Multiple ANOVA demonstrated that the AHHstdand ELISA data showed less variability due to species or temporal differences, and less unexplained variability, compared to the data from the EROD assay or either variation of the AHH assay For all measures, variability associated with site differences far outweighed species or temporal variability Immunoassay, while less sensitive than the AHHstdassay, is nonetheless recommended to be used in conjunction with catalytic assays because of the potential for samples to lose catalytic activity if not handled properly The current results suggest that the lower noncontaminant related variability of AHHstdmakes this CYP1A measure potentially more useful for monitoring programs in which analysis of trends is a primary go

ISSN:0730-7268    

DOI:10.1002/etc.5620140116

出版商:Wiley Periodicals, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractEmbryos of the mummichog (Fundulus heteroclitus) were exposed to 2, 5, or 10 m̈g/L methylmercury (meHg) throughout development; these are concentrations below those which cause teratological effects in this species. After hatching, larvae were maintained in clean seawater and tested for prey‐capture ability, usingArtemia salinanauplii. Larvae that had been exposed to 10 m̈g/L methylmercury (and in two out of three trials, 5 m̈g/L) initially exhibited slower prey‐capture ability than did the other groups. This is an indication of a subtle functional impairment due to the toxicant (“behavioral teratology”). However, the effect was transitory, and by about 1 week after hatching the prey capture of these larvae equalled that of the controls and the other treated groups. Growth of these larvae was also comparable to that of controls. The exposure may have caused retardation of neurological development, which was subsequently compensated for, and therefore no long‐lasting effects were produced. In the field, however, embryos exposed to toxicants would probably continue to be exposed as larvae, and might not have the opportunity to recover from the deleterious effects, but rather might have th

ISSN:0730-7268    

DOI:10.1002/etc.5620140117

出版商:Wiley Periodicals, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractSeasonal variations in the mixed‐function oxygenase (MFO) system components (cytochrome P450, “418” peak, and NADPH‐cytochrome c[P450] reductase) and antioxidant enzymes (catalase, superoxide dismutase [SOD], glutathione peroxidase [GPX], and DT‐diaphorase) of the musselMytilus galloprovincialishave been evaluated. Its relation with contaminant body burden (PAHs, PCBs, DDTs, and lindane) as well as environmental parameters (water temperature, salinity, oxygen concentrations, and suspended matter) was determined. As a general trend, low MFO and antioxidant enzyme activities were detected in February‐March, a peak in late April, and a gradual decrease with a minimum in June. This pattern was similar to tissue concentrations of PAHs, PCBs, DDTs, and lindane normalized to lipid weight. Cytochrome P450 content, however, exhibited a steady decrease from February to June. The observed seasonal variations are presumably related to the metabolic status of the animal, itself dependent on such factors as gonadal ripening, food availability, and the hydrological cycle, which regulates productivity

ISSN:0730-7268    

DOI:10.1002/etc.5620140118

出版商:Wiley Periodicals, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractWe evaluated the ability of three mathematical models to predict toxicity to common shiners and rainbow trout during intermittent (pulsed) exposures to monochloramine, based on data from continuous‐exposure toxicity tests. If a power term for the exposure‐water concentration was included in the models, a concentration × time (Cxt) model and the Mancini uptake‐depuration model predicted pulse LC50s to within ±50% of the observed pulse LC50s, for the first four pulses in toxicity tests with 2‐h pulse/22‐h recovery cycles. Beyond the fourth pulse cycle, though, the pulse LC50s predicted using the Cxt model appeared to diverge considerably from the trend of the experimental pulse LC50s, partly because this model does not predict an incipient lethal level (CILL) for either continuous or intermittent exposures. The Mancini model predicted theCILLmoderately well in the common shiner intermittent‐exposure test but not in the rainbow trout intermittent‐exposure test. The Breck three‐dimensional damage‐repair model did not predict pulse LC50 orCILLvalues as well as did the other two models, probably because not enough partial‐mortality data were available to parameterize the model adequately. Although the underlying processes appear to be more complex than what these simple models assume, the models may still be adequate for use in regulating a few pulse dischar

ISSN:0730-7268    

DOI:10.1002/etc.5620140119

出版商:Wiley Periodicals, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractSets of independently derived environmental quality objectives (EQOs) for air, water, and soil may not be coherent in that maintaining the concentration at EQO level in one compartment may lead to exceeding EQO levels in other compartments. A methodology to evaluate this coherence is suggested. Starting from a steady concentration in the compartment of focus (the primary compartment), steady‐state concentrations in the adjacent (secondary) compartments are estimated using a multimedia fate model. If air is the primary compartment, steady‐state concentrations in water and soil close to the equilibrium concentrations can be expected, and coherence of EQOs can be evaluated easily by means of an extended equilibrium partitioning procedure. If water or soil is the primary compartment, the steady‐state concentration in air is usually well below the equilibrium concentration. Subequilibrium steady‐state concentrations are sensitive to assumed model parameters. The procedure is illustrated with the results of a coherence analysis for seven chemicals for The Neth

ISSN:0730-7268    

DOI:10.1002/etc.5620140120

出版商:Wiley Periodicals, Inc.    

年代:1995

数据来源: WILEY