Showing papers in "Environmental Toxicology and Chemistry in 1983"
TL;DR: In this article, ground water from a shallow aquifer contaminated by coal-tar wastes was analyzed using GC-MS and probe distillation high-resolution mass spectrometry, finding organic bases in the aqueous phase included primary aromatic amines and azaarenes.
Abstract: Ground water from a shallow aquifer contaminated by coal-tar wastes was analysed using GC-MS and probe distillation high-resolution mass spectrometry. Organic bases found in the aqueous phase included primary aromatic amines and azaarenes. The oily-tar phase contained numerous azaarenes varying from 6 to 12 rings in size.
112 citations
TL;DR: Rainbow trout, fathead minnows and Daphnia magna were exposed to silver for 96 h in replicated flow-through tests in replicated static acute tests as mentioned in this paper.
Abstract: Rainbow (Salmo gairdneri) and steelhead (Salmogairdneri) trout and fathead minnows (Pimephales promelas) were exposed to silver for 96 h in replicated flow-through tests. Rainbow trout, fathead minnows and Daphnia magna were exposed to silver in replicated static acute tests. Steelhead trout embryo-larval stages were tested in a flow-through system for 60 d, and D. magna were exposed through complete life cycles in replicated static-renewal tests. All silver concentrations were measured values. No differences were seen between flow-through and static LC50 values. Rainbow trout 96-h flow-through LC50 values were 8.6 and 9.7 μg/L silver; static values were 10.9 and 8.5 μg/L. The 96-h LC50 for steelhead trout in the flow-through test was 9.2 μg/L. Fathead minnow 96-h flow-through LC50 values were 5.6 and 7.4 μg/L silver; static values were 9.4 and 9.7 μg/L. The absence of food in static tests with D. magna caused silver to be about 10 times more toxic; the 48-h static mean EC50 value for D. magna without food was 0.9 μg/L, compared to 12.5 μg/L in the test with food. The early-life-stage test with steelhead trout, from newly fertilized eggs to post-swimup juveniles, showed complete mortality at 1.3 μg/L and significant reduction in fish survival at 0.5 μg/L silver. Mean weight and length at end of test were greatly reduced at 1.1 μg/L, and were significantly different from controls at 0.1 μg/L. The mean 21-d EC50 value for the D. magna test with food was 3.5 μg/L. The 21-d lowest significant (α = 0.05) effect on survival occurred at 4.1 μg/L. The mean silver concentration at which there was a significant decrease in total Daphnia young/female/day after 21 d, compared to the control was 10.5 μg/L silver.
99 citations
TL;DR: The first comprehensive evaluation of the environmental safety of three similar cationic surfactants to aquatic life is reported in this article, where the authors conducted toxicity tests in a high-quality laboratory water and in river waters that were used to model realistic receiving streams.
Abstract: The first comprehensive evaluation of the environmental safety of three similar cationic surfactants to aquatic life is reported. Toxicity tests were conducted that exposed freshwater and marine species, representing three trophic levels, to the dialkyl dimethyl ammonium compounds. The studies were conducted in a high-quality laboratory water and in river waters that were used to model realistic receiving streams. Most current laboratory test methods for the assessment of chemical effects on aquatic life do not consider the physical and chemical properties of the test material in surface waters. This safety assessment shows that these considerations are important in developing realistic conclusions about the ecological safety of cationic surfactants. In tests using river water, acute and chronic toxicities and bioconcentration were considerably less than those in corresponding tests conducted in filtered laboratory waters. This reduction in toxicity and/or uptake was attributable to the aqueous insolubility of the surfactants, strong adsorption to natural solids and tendency to form chemical complexes with anionic substances. The mean ratio of the concentration of anionic to cationic surfactants in municipal sewage treatment plant effluent is 4:1. Safety margins were calculated for daphnids and fathead minnows using the ratio of the no observed effect concentration, determined from chronic toxicity tests, to mean measured surface water concentrations. Safety margins for fish and daphnids were 7 and 11, respectively, for a river having a low wastewater effluent dilution factor of 10. For a river with a higher dilution factor of 150, the values were 115 (fish) and 190 (daphnids). Projected safety margins for marine invertebrates and fish were several orders of magnitude greater than those for freshwater species. Based on available information and expected usage levels, the projected environmental impact of these surfactants on aquatic life is minimal.
71 citations
TL;DR: A new method for risk assessment is described and applies it to assessing the risk of chronic toxicity of mercury to largemouth bass by extrapolation between taxa and between toxicity test types by regression analysis.
Abstract: This article describes a new method for risk assessment and applies it to assessing the risk of chronic toxicity of mercury to largemouth bass. The method consists of extrapolation between taxa and between toxicity test types by regression analysis. The variance terms in the regression analyses are combined with the point estimate of the geometric mean of the maximum allowable toxic concentration (GMATC) to derive a probability distribution of the GMATC. This distribution is then compared to the ambient contaminant concentration to derive the probability or risk of chronic toxicity. This general approach to risk analysis is applicable to any organism or toxicant.
54 citations
TL;DR: In this paper, Chironomus tentans larvae were exposed to three different sediments containing 50 to 500 μg/kg (wet weight) of each chemical, or were held in screened containers in water above the treated sediment for 24 or 96-h.
Abstract: Uptake and elimination of 14C-labeled terbutryn, fluridone, triphenyl phosphate (TPP), trans-permethrin, methoxychlor and 2,4,5,2′,4′,5′-hexachlorobiphenyl (HCBP) by Chironomus tentans larvae were studied in sediment-water systems. Animals were exposed to three different sediments containing 50 to 500 μg/kg (wet weight) of each chemical, or were held in screened containers in water above the treated sediment for 24 or 96-h. Elimination of radioactivity was determined over a 48-h interval. Results were analyzed by use of a one-compartment kinetic model. Larvae exposed in sand or in water above sand had significantly higher concentrations of each chemical than those exposed in or above river (silty) or pond (silty clay) sediments. Uptake of terbutryn and fluridone, two hydrophilic compounds, was similar (24-h exposure) to that of methoxychlor and greater than that for TPP, trans-permethrin or HCBP, due to much greater partitioning of the former compounds into water above each sediment. TPP, trans-permethrin, methoxychlor and HCBP concentrations were significantly higher in larvae from sediment than in animals held in water above sediment. Uptake rate constants from water for each chemical were much greater than those for sediment, but due to the relatively large sediment-to-water ratio (1:5) and the high proportion of chemical in sediment, relative contributions of sediment and water uptake to body burden were similar. Assimilation of each compound by larvae from ingested sediments appeared to be negligible except for TPP and HCBP. Estimates of assimilation of TPP and HCBP in sand-water systems were much greater than those for sediments with higher organic matter content.
51 citations
40 citations
TL;DR: Intrinsic rates of population increase (r), calculated from life-tables, decreased with increasing mercury concentration, which corresponds well with the upper limit of the maximum acceptable toxicant concentration, the usual endpoint of life-cycle toxicity tests.
Abstract: The epibenthic mysid Mysidopsis bahia was chronically exposed throughout its entire life cycle to inorganic mercury. The experimental design permitted the precise measurements of survival rates; individual and population growth rates; and sublethal reproductive responses, including time to sexual maturation and first brood release, egg development time, brood size and frequency of reproduction. Mercury was acutely toxic (96-h LC50) to juveniles at 3.5 μg L−1, chronically toxic (35-d LC50) at 1.8 μg L−1 and differentially toxic to males and females (α = 0.05). Male and female mortality rates were 35 and 18%, respectively, from sexual maturation (day 14) through termination of the assay (day 35). Reproductive effects included delays in sexual maturation and brood release at 1.6 μg L−1, a doubling of brood development time at 2.5 μg L−1 and subsequent abortion and significant decreases in the total broods released (and therefore juveniles produced) at 1.6 μg L−1. Intrinsic rates of population increase (r), calculated from life-tables, decreased with increasing mercury concentration. The critical value (r = 0) for mercury occurs at 1.6 μg L−1, which corresponds well with the upper limit of the maximum acceptable toxicant concentration, the usual endpoint of life-cycle toxicity tests. The toxicity test system is a sensitive, precise model for studying lethal, sublethal and potential population consequences of pollution.
38 citations
TL;DR: In this paper, the effects of water hardness on toxicity of sodium fluoride to rainbow trout (Salmo gairdneri) were evaluated using static bioassays, and the results showed that the toxicity increased from 51 to 193 mg/L [F] as water hardness levels rose from 17 to 385 mg/l CaCO3.
Abstract: Static bioassays were conducted to determine effects of water hardness on toxicity of sodium fluoride to rainbow trout (Salmo gairdneri). Ninety-six hour LC50 values increased from 51 to 193 mg/L [F] as water hardness levels rose from 17 to 385 mg/L CaCO3. Tests of chronic toxicity at different water hardness levels are needed before fluoride standards for aquatic life, such as fish, can be set.
34 citations
TL;DR: Tests that combine these two organisms are recommended, since Daphnia, although an open-water species, responds not only to dissolved materials in the water but also to particulates released from the sediments by the physical activity of Hexagenia.
Abstract: The toxicity of 12 freshwater sediments to the water flea, Daphnia magna Straus, and the mayfly nymph, Hexagenia, were tested in recycling laboratory microcosms. The organisms were tested both together and singly. Significant differences in Daphnia mortality between test and control sediments occurred in only two cases in which Daphnia was tested alone, and in five cases in which it was tested with Hexagenia. Significant Hexagenia mortality occurred in only two cases. The results imply that (a) Hexagenia is a less sensitive indicator of freshwater sediment toxicity than is Daphnia and (b) the presence of Hexagenia usually intensifies the Daphnia response. Tests that combine these two organisms are recommended, since Daphnia, although an open-water species, responds not only to dissolved materials in the water but also to particulates released from the sediments by the physical activity of Hexagenia. These types of tests could be used, on a standardized, routine basis, as indicators of potential problems.
32 citations
TL;DR: Sheepshead minnows (Cyprinodon variegatus) were exposed to the synthethic pyrethroid insecticides AC 222,705, permethrin or fenvalerate for 28 d in early life stage toxicity tests, with survival and size of fish being the most sensitive measures of effect.
Abstract: Sheepshead minnows (Cyprinodon variegatus) were exposed to the synthethic pyrethroid insecticides AC 222,705, permethrin or fenvalerate for 28 d in early life stage toxicity tests. AC 222,705 was 370 times more toxic than permethrin and 30 times more toxic than fenvalerate, with survival and size of fish being the most sensitive measures of effect. AC 222,705 significantly reduced survival of hatched fish at 0.61 μg/L and their average weight at 0.06 μg/L; no effects were detected at 0.03 μg/L. Two of the AC 222,705 concentrations that diminished weights, 0.06 and 0.12 μg/L, were below our limit of chemical detection (0.15 μg/L). Permethrin reduced survival of hatched fish at 22 μg/L; no effects were detected at 10 μg/L. Fenvalerate significantly reduced survival of hatched fish at 3.9 μg/L and both weight and length at 2.2 μg/L; no effects were detected at 0.56 μg/L. The 96-h LC50 divided by the no-effect concentration was 0.8 for permethrin, 9 for fenvalerate and 37 for AC 222,705. The mean bioconcentration factors determined from concentrations measured in whole fish divided by average concentrations measured in exposure water were 480 for permethrin and 570 for fenvalerate; AC 222,705 was not detected in fish that survived the exposure.
32 citations
TL;DR: In this paper, Nocardiopsis spp. and Bacillus megaterium were used to metabolize 2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD).
Abstract: 2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) was metabolized by pure cultures of Nocardiopsis spp. and Bacillus megaterium. The degree of metabolism was strongly dependent on the solvent used, with ethyl acetate giving the best results. TCDD metabolism by B. megaterium increased when the concentration of soybean extract was reduced from 1.6% to 0.8%. Two TCDD-degrading bacteria were isolated from farm soil that consistently showed a low level of TCDD-degrading activity.
TL;DR: In this article, colonized Hester-Dendy substrates were deployed for 96 hours in an urban river reach, storm drain channel and a control site to assess the toxicity of urban runoff.
Abstract: Colonized Hester-Dendy substrates were deployed for 96 h in an urban river reach, storm drain channel and a control site to assess the toxicity of urban runoff. The mean macroinver-tebrate diversity during rain events was reduced from 1.7 at the control station to 1.0 at both urban stations. Snowmelt exerted the same effect on river substrate diversity, but only reduced channel values from 2.0 to 1.4. During periods of no runoff, however, mean channel and control diversities remained the same (1.5), while river values dropped to 0.8. Similarly, substrate population densities during rain were, respectively, two and seven times more limiting for the storm drain channel and river reach stations. The same trend was evident in heavy metals uptake, indicating that dry weather toxicity in urban river reaches originates from the sediments. Runoff, then, serves to reduce toxicity during input, but increases it over the long run.
TL;DR: Pairs of adult black ducks (Anas rubripes) were fed a diet containing 0, 4 or 40 ppm cadmium as well as Cadmium chloride for avoidance of a fright stimulus as mentioned in this paper.
Abstract: Pairs of adult black ducks (Anas rubripes) were fed a diet containing 0, 4 or 40 ppm cadmium as cadmium chloride One-week-old ducklings that had been fed the same dietary concentrations of cadmium as had their parents were tested for avoidance of a fright stimulus Ducklings fed 4 ppm cadmium ran significantly farther from the stimulus than did controls or ducklings fed 40 ppm cadmium Such an alteration in behavior could have harmful effects on wild birds
TL;DR: Two fish and seven invertebrate freshwater species were exposed to diflubenzuron (Dimilin®) in acute and chronic laboratory tests and no effects on newly hatched and juvenile fathead minnows or juvenile guppies were seen at or below 36 μg/L, the highest concentration tested.
Abstract: Two fish and seven invertebrate freshwater species were exposed to diflubenzuron (Dimilin®) in acute and chronic laboratory tests. No effects on newly hatched and juvenile fathead minnows or juvenile guppies were seen at or below 36 μg/L, the highest concentration tested. An early-life-stage test (30-d) with fathead minnows showed no effect at or below 36 μg/L. No effects on survival, growth or reproduction were observed with two snail species, Juga plicifera and Physa spp., at or below 36 μg/L. Adult emergence of the caddis fly Clistoronia magnifica was inhibited at 0.1 μg/L. Daphnia magna were killed at 2.0 μg/L. Hyalella azteca mortality was significant at 2.0 μg/L. Molting and survival of the midge Tanytarsus dissimilis were affected at 4.9 μg/L. Molting and survival of the midge Cricotopus spp. were affected at 4.9 μg/L, and adult emergence did not occur at 1.6 μg/L.
TL;DR: In this article, the authors examined the differences in patterns of response in a pelagic ecosystem due to seasonal exposure and differential sensitivities of populations and trophic levels to chemical stress with a simulation model.
Abstract: Differences in patterns of response in a pelagic ecosystem due to seasonal exposure and differential sensitivities of populations and trophic levels to chemical stress were examined with a simulation model. Simulations of constant 7-d exposures initiated at different times of year demonstrated that stresses imposed during the spring reduced average producer and consumer biomass. Stresses imposed later in the year reduced grazer biomass and permitted increased phytoplankton production. Simulated exposures to phenol, naphthalene and four heavy metals (Cd, Hg, As, Pb) predicted different effects when toxic sensitivities of populations and trophic levels were ignored. Risks of increased blue-green algae production or decreased game fish production were estimated from repeated simulations that extrapolated uncertainties associated with individual toxic effects parameters. Estimates of risk that included population-specific toxicities were two or three times greater than risks estimated from trophic level toxicities alone.
TL;DR: In this article, the authors conducted long-term hydrolysis studies on aldicarb and sulfoxide for 186 to 228 d and found that the reaction rate constants for the three compounds are relatively constant below pH 7 and increase rapidly as the pH increases beyond 7.
Abstract: Hydrolysis studies were conducted on aldicarb, aldicarb sulfoxide and aldicarb sulfone for 186 to 228 d. These long-term studies show that, for a given temperature, the reaction rate constants for the three compounds are relatively constant below pH 7 and increase rapidly as the pH increases beyond 7. These rate constants generally result in shorter half-lives (under two years in most environments) than previously assumed, and would result in aldicarb residues being less persistent in groundwater than previously expected.
TL;DR: In this article, the potential for ground water contamination by trace organics during the operation of a rapid infiltration system at Fort Polk, Louisiana, was investigated by using reverse ion search using capillary gas chromatography/mass spectrometry.
Abstract: A previous study at Rice University demonstrated that trace organic compounds in primary and secondary effluents treated in rapid infiltration systems are detected in associated ground water. A direct cause and effect relationship was not established, however, since background data on trace organics in the ground water were not available. Field studies on a rapid infiltration site currently under construction at Fort Polk, Louisiana, have indicated that characteristic trace organics are mostly absent from ground water underlying the site. Therefore, a laboratory study was undertaken to investigate the potential for ground water contamination by trace organics during operation of this system. Four columns were packed with topsoil obtained from one of the basins at the site. Unchlorinated secondary effluent was also obtained from the site and used as feed solution for the columns. Soil columns were operated for a period of 4 months on a 2d flooding/12-d drying cycle to parallel design operation of the rapid infiltration system. Feed solution and column effluents were monitored for 22 trace organics by reverse ion search using capillary gas chromatography/mass spectrometry. Each of nine target trace organics found consistently in the feed solution, with the exception of p-dichlorobenzene, was detected in the column effluents during the first inundation cycle; all target trace organics were detected in the column effluents during subsequent cycles. The concentrations of tetrachloroethylene, p-dichlorobenzene, acetophenone, 2-(methylthio)benzothiazole and bis(2-ethylhexyl)phthalate in the feed solution were generally reduced by passage through the soil column, whereas diethyl phthalate, benzophenone, N-butylbenzenesulfonamide and dibutyl phthalate concentrations were unaffected or enhanced. Addition of mercuric chloride during the seventh and eighth inundation cycles had variable effects for the different compounds. These preliminary results indicate that ground water contamination at the Fort Polk rapid infiltration site can occur once the system begins operation, although concentrations of specific trace organics may be significantly reduced.
TL;DR: In this paper, simple properties of chemicals, such as octanol-water partition coefficient (Kow), Henry's Law constant (Hc), and biodegradability half-life (t1/2), are used as a means of evaluating ecotoxicologic testing requirements prior to direct screening using various organisms.
Abstract: Simple properties of chemicals—the octanol-water partition coefficient (Kow), Henry's Law constant (Hc) and biodegradability half-life (t1/2) — provide a means of evaluating ecotoxicologic testing requirements prior to direct screening using various organisms. Based on potential for exposure, arrays of properties portending ecotoxicologic concern are suggested for bioaccumulation and chronic effects, multispecies-multimedia involvement, inhalation toxicology and abiotic atmospheric effects.
TL;DR: The U.S. National Mussel Watch Program initially used split-sample analyses for interlaboratory quality control purposes as discussed by the authors, which indicated the possibility of analytical discrepancies as well as problems in the split sample technique itself.
Abstract: The U.S. National Mussel Watch Program initially used split-sample analyses for interlaboratory quality control purposes. These indicated the possibility of interlaboratory analytical discrepancies as well as problems in the split-sample technique itself. For the third year of the program, two mussel homogenates were produced to serve as intercomparison samples — one for metals and organics, the other for radionuclides. The results obtained using these homogenates are encouraging in that generally good agreement is seen among analyses done by several labs in diverse pollutant classes. We conclude from this experience that a quality-control program relying on the analysis of large homogeneous samples of the matrix being dealt with is an essential part of any extensive, multilaboratory analytical program.
TL;DR: Rarefaction indices of diversity indicated that the distribution of individuals within species was about the same for laboratory and field assemblages of animals, and the Shannon-Weaver index of diversity, Simpson's index of dominance and the Bray-Curtis dissimilarity index differences were greater with each increase in creosote concentration.
Abstract: Macrobenthic animal communities that colonized uncontaminated and creosote-contaminated sand (177, 844 and 4,420 μg/g, nominal) during 8 weeks were compared to assess effects of marine-grade creosote on community structure. Aquaria were colonized in the laboratory by planktonic larvae entrained in continuously supplied unfiltered seawater and in the field by animals that occurred naturally. Individuals and species in aquaria that contained 844 and 4,420 μg creosote/g sand were significantly fewer (α = 0.05) than those in the control. Abundance of animals in field-colonized communities contaminated with 177 μg/g creosote, but not in laboratory-colonized communities, also was less than that in the control. The lowest creosote concentration at either site that affected numbers of individuals or species was 844 μg/g for mollusks and 177 μg/g for echinoderms, annelids and arthropods. The Shannon-Weaver index of diversity, Simpson's index of dominance and the Bray-Curtis dissimilarity index differences were greater with each increase in creosote concentration. Rarefaction indices of diversity indicated that the distribution of individuals within species was about the same for laboratory and field assemblages of animals. Initial measured concentrations of creosote in sand (midrange concentration) decreased by 30% in the laboratory and by 42% in the field at the end of the 8-week test.
TL;DR: In this article, the authors conducted static and flow-through tests with fathead minnows, rainbow trout and Daphnia magna to determine their relative sensitivities to measured concentrations of the insecticide endosulfan and to compare responses of fish in replicated static and Flow-through exposure procedures.
Abstract: Flow-through and static tests were conducted with fathead minnows, rainbow trout and Daphnia magna to determine their relative sensitivities to measured concentrations of the insecticide endosulfan and to compare responses of fish in replicated static and flow-through exposure procedures. Fathead minnow 96-h static LC50 values were 1.3, 0.8 and 1.3 μg/L endosulfan. The 96-h LC50 values for fatheads in flow-through tests were 1.7 and 1.0 μg/L. Rainbow trout 96-h static LC50 values were 1.7 and 1.6 μg/L. The 96-h LC50 values for rainbows in flow-through tests were 0.3 and 0.4 μg/L. Acute 48-h static EC50 values for D. magna were 343 and 271 μg/L endosulfan. These results suggest that differences in species sensitivity can be as great as three orders of magnitude.
TL;DR: Analysis of the chronic toxicity data was based on days to first brood, number of young per brood and total number ofYoung produced per adult, and analyses indicate that with one exception, no statistically significant effects were observed at < 2.0 mg/L Se, giving rise to a maximum acceptable toxicant concentration (MATC).
Abstract: The acute and chronic toxicity to Daphnia magna Straus of selenium introduced as sodium selenate was examined, as was the acute toxicity of selenium introduced as sodium selenite. Acute toxicity was determined by standard, static 48-h tests. Chronic toxicity was determined by a 32-d static renewal test. Nominal, initially measured and finally measured total and dissolved selenium concentrations were determined during the chronic test. Analysis of the chronic toxicity data was based on days to first brood, number of young per brood and total number of young produced per adult. These analyses indicate that with one exception, no statistically significant effects (p ≤ 0.05) were observed at < 2.0 mg/L Se, giving rise to a maximum acceptable toxicant concentration (MATC) of 1.73 mg/L Se. Dry-weight analyses of adults at the termination of the chronic test and for fifth-brood young indicate an MATC of 1.2 mg/L Se. The 48-h EC50 for selenate was 5.3 ± 0.6 mg/L Se. The 48-h EC50 for selenite was 1.1 ± 0.2 mg/L Se. However, a 7-d EC50 determined during chronic selenate exposure was 1.9 (1.78–2.01) mg/L Se. This lethal threshold concentration is not significantly different from the chronic MATC.
TL;DR: In this article, a method was developed for the qualitative and quantitative characterization of waterborne organosilicon substances, which are present as low-molecular-weight silanols (such as silicone hydrolysis products), and higher-molesilicon-weight materials (e.g., silicones), which can be caused to undergo hydrolyisation to yield such low molecular weight silanol-functional materials.
Abstract: A novel method has been developed for the qualitative and quantitative characterization of (a) waterborne organosilicon substances, which are present as low-molecular-weight silanols (such as silicone hydrolysis products), and (b) higher-molecular-weight materials (e.g., silicones), which can be caused to undergo hydrolysis to yield such low-molecular-weight silanol-functional materials. This method is capable of good to excellent accuracy and precision in the parts per million range and, with suitable precautions, has the potential for extension to determinations in the low parts per billion range. Although particularly valuable for the analysis of water-soluble species, this method can also be adapted to yield useful information concerning water-insoluble organosilicon materials present in aqueous systems, such as colloidal suspensions, surface films, or sedimentary slurries. Because of its inherent sensitivity and selectivity, this method constitutes a valuable tool for measuring and characterizing the silicone content of industrial and municipal waste waters, surface and ground waters, foods and biological tissues, etc. The determination of water-soluble organosilanol species is accomplished by the acid-catalyzed trimethylsilylation of the silanol functionality with hexamethyldisiloxane (HMDS) followed by gas-liquid chromatographic assay of the resulting HMDS extract. Water-insoluble components are determined by subjecting the sample to acidic predigestion before the addition of the HMDS-derivatizing and extracting reagent. The possibility of dimethyl- or monomethyl-silicon artifacts arising from inadvertent trace cleavage of methyl groups from the HMDS can be determined and/or precluded by the use of hexaethyldisiloxane or perdeutero-HMDS when appropriate.
TL;DR: In this paper, the potential induction of phytoalexin production by stress following exposure to ozone, sulfur dioxide and several herbicides was evaluated in bean (Phaseolus vulgaris L.) cultivars and lines varying in sensitivity to ozone injury.
Abstract: The potential induction of phytoalexin production by stress following exposure to ozone, sulfur dioxide and several herbicides was evaluated in bean (Phaseolus vulgaris L.) cultivars and lines varying in sensitivity to ozone injury. The isoflavonoids, coumestrol and several other coumestans were extracted from leaf tissue after various periods of exposure to ozone, sulfur dioxide or application of various herbicides. Elicitation of isoflavonoid production varied with lines and cultivars, but generally increased with increased plant injury caused by ozone, sulfur dioxide or herbicide.
TL;DR: No significant differences in LC50 values were found between the sexes except in starved animals at 26°C, when males were more sensitive than females, which may be due to differences in nutritional stress among the sexes.
Abstract: Acute toxicity tests were performed on adult males and females of a freshwater calanoid copepod, Diaptomus clavipes Schacht, using the azaarene acridine as the test compound. Tests were performed at three temperatures (16, 21 and 26°C) and over a range of nutritional states (fed, starved and stock). Observations on mortality were made at 24-h intervals for 96 h.
Analysis of the data was based on comparisons (using different treatment combinations) of the parameters in a logistic survival function used to describe the mortality data. Median lethal concentrations (using 96-h LC50 values) were estimated from the logistic survival function as well as from the probit function, for comparative purposes. The LC50 values ranged from 1.64 to 6.70 mg/L, depending on temperature, nutritional state of the animals and sex. The LC50 values were highest for animals (fed before testing) at 16°C. As food availability decreased and temperature increased, toxicity of acridine increased up to fourfold. No significant differences in LC50 values were found between the sexes except in starved animals at 26°C, when males were more sensitive than females. This difference in toxicity between the sexes at 26°C may be due to differences in nutritional stress between the sexes (at this temperature), since control mortality at this temperature was also higher in males than in females.
TL;DR: Morphological changes in hepatocytes of mature brown trout and juvenile rainbow trout and accompanying chronic exposures to copper and zinc were examined by transmission electron microscopy, indicative of a reduction in ability to maintain intracellular water and cation balance and possible intranuclear metal sequestering.
Abstract: Morphological changes in hepatocytes of mature brown trout (Salmo trutta Linnaeus) and juvenile rainbow trout (Salmo gairdneri Richardson), accompanying chronic exposures to copper and zinc, were examined by transmission electron microscopy. At a concentration of copper not inhibitory to the final stages of gonadal development or spawning of brown trout, structural alterations included contraction of mitochondria and a tendency for nuclei to be slightly enlarged. Concentrations of copper or zinc lethal to a small fraction (10% and 4%, respectively) of a population of juvenile rainbow trout exposed for 42 d during larval and early juvenile development caused hepatocyte changes in survivors indicative of a reduction in ability to maintain intracellular water and cation balance and possible intranuclear metal sequestering. Specific structural alterations included increased vesiculation of rough endoplasmic reticulum, an increase in the abundance of electron-dense particles in the nucleus, increases in the numbers of multilaminar and globular inclusions, pooling of glycogen, increased autophagocytic activity and an increase in the number of necrotic cells. At advanced stages of toxicosis (concentrations of copper or zinc lethal to approximately 50% of the juveniles exposed for 42 d during development), loss in integrity of mitochondrial membranes, rupturing of plasma and nuclear membranes, separation of granular and fibrillar nuclear components, fragmentation of endoplasmic reticulum, and extensive autophagic vacuolization were significant features of hepatocytes of surviving juvenile rainbow trout.
TL;DR: This work has shown that when growth of Selenastrum capricornutum is optimized, both systems are equally sensitive and quantitatively related to toxicant concentration.
Abstract: Dynamic (flow-through) algal bioassays generally have been found to be more sensitive to toxicants than have static (batch) bioassays, and have led to lower estimates of maximum allowable toxicant concentrations. When growth of Selenastrum capricornutum is optimized, both systems are equally sensitive and quantitatively related to toxicant concentration.
TL;DR: It is hoped that the gray bats remaining in this area of Missouri survive the residues of dieldrin and heptachlor still in their food chains and prove to be unaffected by the new organophosphates.
Abstract: Dead gray bats (Myotis grisescens) containing lethal concentrations of dieldrin were found beneath a maternity roost in Bat Cave Nos. 2 and 3, Franklin County, Missouri, in 1976, 1977 and 1978. Whereas residues of dieldrin, DDE [1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene] and PCB polychlorinated biphenyls in bats appeared not to change significantly over the 3 years, residues of heptachlor-related chemicals increased in 1977 to potentially dangerous concentrations and remained elevated in 1978. Lethal brain levels of dieldrin in adult bats (geometric mean = 12.1 μg/g), compared with juvenile bats (geometric mean = 6.5 μg/g), indicated that juveniles are nearly twice as sensitive. The estimated population of gray bats (as maximum number of nonflying young) at Bat Cave Nos. 2 and 3 in 1976 and 1978 was 1,800 bats, but in 1979 no bats were present. Dieldrin, perhaps in conjunction with heptachlor, may have caused the decline and disappearance of this colony. However, dieldrin was banned in 1974 and Missouri's authorization to use heptachlor on corn expired in 1981. Furthermore, three organophosphate insecticides (chlorpyrifos, dyfonate and mocap) are to be substituted. We hope that the gray bats remaining in this area of Missouri survive the residues of dieldrin and heptachlor still in their food chains and prove to be unaffected by the new organophosphates.
TL;DR: In this paper, statistical regressions that relate rates of transport processes to chemical characteristics of polycyclic aromatic hydrocarbons were used to estimate parameters in a model that predicts the fate of a simulated anthracene spill onto the surface (25 m2) of a 12.5 m3 pond ecosystem.
Abstract: Statistical regressions that relate rates of transport processes to chemical characteristics of polycyclic aromatic hydrocarbons were used to estimate parameters in a model that predicts the fate of a simulated anthracene spill onto the surface (25 m2) of a 12.5 m3 pond ecosystem. During 60 d following a simulated spill of 2.0 g/m2 anthracene, predicted concentration in sediments peaked at 550 μg/m2. Predicted bioaccumulation was maximal in rooted macrophytes (0.35 μg/g dry weight), followed by benthic invertebrates (0.23 μg/g dry weight) and zooplankton (0.04 μg/g dry weight). Precision of predicted concentrations depends upon precise estimation of model parameters that define maximum water solubility and that regulate photolytic degradation, volatilization, sorption and bioaccumulation of anthracene. In 200 simulations, values of 29 model parameters were chosen at random from distributions with standard deviations that ranged between 0.5 and 53% of their means. Results demonstrate greater precision in predictions of the relative distribution of anthracene among water, sediments and total biota than precision of predicted concentrations of individual pond components.