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At least 577 records · Page 32Linked to original sources
USGS1994

Effects of water temperature and pH on toxicity of terbufos, trichlorfon, 4-nitrophenol and 2,4-dinitrophenol to the amphipod Gammarus pseudolimnaeus and rainbow trout (Oncorhynchus mykiss)

Acute toxicity tests were conducted to determine (a) the individual and interactive effects of water temperature (7, 12, 17°C), pH (6 5, 7 5, 8 5, 9 5), and time on the toxicity of terbufos, trichlorfon, 4 nitrophenol, and 2,4-dinitrophenol to rainbow trout ( Oncorhynchus mykiss ) and the amphipod Gammarus pseudohmnaeus , and (b) the individual and interactive effects of water temperature and pH on chemical bioconcentration during acute tests with rainbow trout and Gammarus exposed to terbufos, 4 nitrophenol, and 2,4 dinitrophenol The toxicity of all four chemicals was significantly affected by pH in all tests, except for Gammarus exposed to terbufos The toxicity of terbufos to rainbow trout and Gammarus was less at pH 7 5 than at higher or lower pH The toxicity of both nitrophenols decreased as pH increased, whereas the toxicity of trichlorfon increased with pH The effect of pH on trichlorfon toxicity decreased with temperature Temperature significantly affected the toxicity of all four chemicals to both species Toxicity increased with temperature in all tests, except for rainbow trout exposed to nitrophenols, toxicity decreased as temperature increased for rainbow trout Chemical bioconcentration was also significantly af fected by temperature and pH and was directly related to toxicity in most tests Significant interactive effects between toxicity modifying factors were also frequently observed Temperature and pH effects on chemical toxicity need to be consid ered in chemical hazard assessment to ensure adequate protection of aquatic organisms

Environmental Toxicology and Chemistry↗
USGS1994

Acute toxicity of 4-nitrophenol, 2,4-dinitrophenol, terbufos and trichlorfon to grass shrimp (Palaemonetes spp.) and sheepshead minnows (Cyprinodon variegatus) as affected by salinity and temperature

The toxicities of two industrial chemicals (4-nitrophenol and 2,4-dinitrophenol) and two organophosphate insecticides (terbufos and trichlorfon) to juvenile grass shrimp (Palaemonetes spp.) and sheepshead minnows (Cyprinodon vanegatus) were determined by static, 96-h toxicity tests in a factorial design with 12 combinations of salinity and temperature (15, 20, 25, 30ppt x 17, 22, 27°C). Concentrations of the toxicants, including bioconcentradon, were determined as appropriate by gas or liquid chromatography and the use of 14 C-labeled compounds. The 96-h LC50s for 4-nitrophenol ranged from 12 to 31 mg/L and for 2,4-dinitrophenol from 13 to 50 mg/L. Toxicity decreased as salinity increased for 4-nitrophenol and both test organisms. Toxicity decreased as salinity increased for 2,4-dinitrophenol and sheepshead minnows, but toxicity to grass shrimp increased as salinity increased. Toxicity decreased with increased temperature for grass shrimp exposed to 2,4-dinitrophenol and sheepshead minnows exposed to 4-nitrophenol, increased with temperature for sheepshead minnows exposed to 2,4-dinitrophenol, and no change was observed for grass shrimp exposed to 4-nitrophenol. Bioconcentration of phenols in both test organisms increased as concentration increased. The 96-h LC50s for terbufos ranged from 3.4 to 6.6 μg/L and for trichlorfon from 6.3 to 19,300 μg/L. Terbufos and trichlorfon toxicity to grass shrimp and sheepshead minnows increased with increased temperature. BCFs for terbufos were greater in sheepshead minnows than grass shrimp, but were reversed for trichlorfon.

Environmental Toxicology and Chemistry↗
USGS1994

Effects of water temperature on the toxicity of 4-nitrophenol and 2,4-dinitrophenol to developing rainbow trout (Oncorhynchus mykiss)

Early-life-stage (ELS) toxicity tests were conducted to determine the effect of selected water temperatures on the toxicity of 4-nitrophenol and 2,4-dinitrophenol to rainbow trout ( Oncorhynchus mykiss ). NOECs were determined for growth and mortality at selected time intervals and water temperatures of 7, 12, and 17°C. As tests progressed, NOECs leveled to constant time-independent values that were similar for tests at each temperature. In 4-nitrophenol tests, the time-independent NOEC values at 7, 12, and 17°C, respectively, were 1.16, 1.20, and 1.16 mg/L for growth and 3.40, 3.38, and 2.20 mg/L for mortality. For 2,4-dinitrophenol, time-independent NOEC values at 7, 12, and 17°C, respectively, were 1.07, 0.50, and 0.80 mg/L for growth and 1.30, 1.89, and 1.60 mg/L for mortality. Temperature did, however, affect the rate at which time-independent NOECs were reached. More time was required to reach time-independent NOECs as temperature decreased. For example, the time-independent NOEC in 4-nitrophenol tests at 17°C was reached in 14 d, whereas it required 42 d at 7°C. The effect of temperature on toxicity must be considered in hazard assessment protocols to assess risk accurately and protect aquatic organisms adequately. Chronic toxicity tests are necessary to assess risk because acute toxicity tests cannot provide the information necessary to predict the long-term effects of factors such as temperature in natural environments.

Environmental Toxicology and Chemistry↗
USGS1994

Evaluation of peroxidase as a biochemical indicator of toxic chemical exposure in the aquatic plant Hydrilla verticillata, Royle

Laboratory bioassays were conducted to determine the utility of peroxidase (POD) activity as a biochemical indicator of contaminant exposure in the aquatic plant Hydrilla verticillata , Royle. The plants were exposed to anthracene, sulfomet-uron methyl (Oust®), Cd 2+ , Cr 6+ , Cu 2+ , Mn 2+ , and Se 4+ in concentration factors of 10. POD was extracted and measured by spectrophotometric assay. There was a significant increase in POD activity after a 5-d exposure to each of the chemicals at 1 mg/L. The optimum pH for POD activity after exposure to the chemicals was 5.5 to 6.0. The increase in POD was found to be dose dependent for each of the chemicals. The lowest concentration of chemical to induce a significant POD increase was 0.01 mg/L for anthracene, Oust, Cd, Cr, and Cu; 0.1 mg/L for Se; and 1.0 mg/L for Mn.

Environmental Toxicology and Chemistry↗
USGS1994

Hepatic cadmium, metal-binding proteins and bioaccumulation in bluegills exposed to aqueous cadmium

We examined sublethal responses of juvenile bluegills Lepomis macrochirus to aqueous cadmium in two 28-d tests (test I, 0.0-8.4 μg Cd per liter; test II, 0.0-32.3 μg Cd per liter) in an intermittent-flow diluter. The experimental design was completely randomized, with two replicates in each of eight treatments (seven Cd exposures and one water control with 25 fish per replicate). Cadmium did not affect the growth of test fish. The mean whole-body concentrations of Cd in exposed fish were 1.8- to 44-fold those in controls in the two tests. Mean concentrations of hepatic nonthionein cytosolic Cd (not bound by metal-binding proteins, MBP) in all Cd treatments greatly exceeded those in controls, and mean concentrations of hepatic MBP in all treatments except one (0.8 μg Cd per liter in test I) exceeded those in controls. Nonthionein cytosolic Cd, hepatic MBP, and whole-body Cd in bluegills were linearly related to exposure concentrations within the range 0 to 20 μg Cd per liter. Much of the total Cd-binding capacity of hepatic MBP per fish was occupied by Cd after the 28-d exposures, although additional Cd-binding capacity remained unoccupied by Cd in fish in all treatments. The mean total Cd-binding capacity of hepatic MBP per fish, which ranged from 1.7 to 14 nmol Cd in test I and from 0.8 to 24 nmol Cd in test II, increased in a concentration-response manner at exposure concentrations below 13 μg/L. Nonthionein cytosolic Cd was the most sensitive indicator of Cd exposure, based on an LOEC of 0.8 μg Cd per liter.

Environmental Toxicology and Chemistry↗
USGS1994

Community‐level field method for testing the toxicity of contaminated sediments in estuaries

The objective of this study was to demonstrate a method for testing the toxicity of contaminated sediments under field conditions. An artificial sediment that matches field sediment in grain‐size distribution and organic matter content was mixed from 11 components and used as the test substrate. Clean sediments and sediments spiked with zinc (∼8,000 mg/kg) were exposed in the field on a holding rack anchored on the bottom of Mobile Bay, Alabama. The abundance and diversity (species richness) of benthic invertebrate recruits were used as indicators of sediment quality. The number of recruits was significantly reduced by the presence of zinc in one‐week exposures.

Environmental Toxicology and Chemistry↗
USGS1994

Anaerobic biodegradation of halogenated and nonhalogenated N-, s-, and o-heterocyclic compounds in aquifer slurries

The fate of several halogenated and nonhalogenated heterocyclic compounds in anoxic aquifer slurries was investigated Substrate depletion and methane formation were monitored in serum bottle incubations by HPLC and GC, respectively Pyridine, pyrimidine, thiophene, and furan were not mineralized following an 11-month incubation, but the corresponding carboxylated or oxygenated compounds were That is, >74% of the theoretically expected amount of methane was recovered from nicotinic acid, uracil, or 2-furoic acid Chlorinated derivatives, like 2 chloro- or 6-chloronicotinic acid, as well as 4 chloro- and 5-chlorouracil resisted mineralization However, 5-bromouracil was reductively dehalogenated to stoichiometric amounts of uracil, whereas 2-chloropyrimidine was metabolized to a more polar unidentified compound that resisted further anaerobic biodegradation Microorganisms acclimated to 5-bromouracil were unable to transform 4 chloro or 5 chlorouracil These findings illustrate how the structure of heterocyclic contaminants influences their susceptibility to anaerobic decay

Environmental Toxicology and Chemistry↗
USGS1994

Avian nesting success and diversity in conventionally and organically managed apple orchards

This study examines the effects of operational use of pesticides on avian species inhabiting apple orchards in Pennsylvania Mourning dove ( Zenaida macroura ) and American robin ( Turdus migratorius ) nests were monitored in three organic and three conventional apple orchards during 1990 and 1991 In 1991 we surveyed the avian communities of these orchards by using line transects Organophosphorus (OP) (e g, azinphos methyl, phosphamidon, parathion, dimethoate), carbamate (CA) (e g, methomyl, formetanate, oxamyl), and organochlorine (endosulfan) pesticides, known to be highly toxic to birds, were sprayed individually or in mixtures as part of routine pest management as many as 19 times during peaks in breeding activity Spray card tests revealed that OP pesticides were deposited on 86% of the nests in conventional orchards Daily survival rates (DSRs) for nests of both species were higher in the organic orchards than in the conventional orchards for 1991 and for years combined ( p < 0 05) Species diversity was greater in the organic orchards ( H = 2 43) than in the conventional orchards ( H = 1 79) Repeated applications of pesticides within the conventional orchards reduced the reproductive success of doves and robins and may have lowered avian species diversity compared with organic orchards

Pennsylvania↗
USGS1994

Relation among cytochrome P450, AH-active PCB congeners and dioxin equivalents in pipping black-crowned night-heron embryos

Pipping black-crowned night-heron (Nycticorax nycticorax) embryos were collected from a relatively uncontaminated site (next to Chincoteague National Wildlife Refuge, VA) and three polluted sites (Cat Island, Green Bay, Lake Michigan, WI; Bair Island, San Francisco Bay, CA; West Marin Island, San Francisco Bay, CA). Hepatic cytochrome P-450-associated monooxygenases and cytochrome P-450 proteins, induced up to 85-fold relative to the reference site, were associated with concentrations of total polychlorinated biphenyls (PCBs) and 11 PCB congeners that are presumed to express toxicity through the arylhydrocarbon (Ah) receptor. Multiple regression revealed that up to 86% of the variation of cytochrome P450 measurements was accounted for by variation in the concentration of these PCB congeners. Toxic equivalents (TEQs) of sample extracts, predicted mathematically (summed product of PCB congener concentrations and toxic equivalency factors), and dioxin equivalents (TCDD-EQs), derived by bioassay (ethoxyresorufin-O-dealkylase activity of treated H4IIE rat hepatoma cells), were greatest in Cat Island samples. Cytochrome P450-associated monooxygenases and cytochrome P450 proteins were related to TEQs and TCDD-EQs; adjusted r-2 often exceeded 0.5 for the relation among mathematically predicted TEQs and cytochrome P450 measurements. These data extend previous observations in heron embryos of an association between P450 and total PCB burdens to include Ah-active PCB congeners, and presumably other compounds, which interact similarly with the Ah receptor. Benzyloxyresorufin O-dealkylase, ethoxyresorufin O-dealkylase, and cytochrome P450 1A appear to be the most reliable measures of exposure to Ah-active PCB congeners in black-crowned night-heron embryos. These findings provide further evidence that cytochrome P450-associated parameters have considerable value as a biomarker for assessing environmental contamination of wetlands.

Environmental Toxicology and Chemistry↗
USGS1994

Chemical characterization of sediments and pore water from the upper Clark Fork River and Milltown Reservoir, Montana

The upper Clark Fork River basin in western Montana is widely contaminated by metals from past mining, milling, and smelting activities As part of a comprehensive ecological risk assessment for the upper Clark Fork River, we measured physical and chemical characteristics of surficial sediment samples that were collected from depositional zones for subsequent toxicity evaluations Sampling stations included five locations along the upper 200 km of the river, six locations in or near Milltown Reservoir (about 205 km from the river origin), and two tributary reference sites Concentrations of As, Cd, Cu, Mn, Pb, and Zn decreased from the upper stations to the downstream stations in the Clark Fork River but then increased in all Milltown Reservoir stations to levels similar to uppermost river stations Large percentages (50 to 90%) of the total Cd, Cu, Pb, and Zn were extractable by dilute (3 n) HCl for all samples Copper and zinc accounted for greater than 95% of extractable metals on a molar basis Acid-volatile sulfide (AVS) concentrations were typically moderate (0 6 to 23 μmol/g) in grab sediment samples and appeared to regulate dissolved (filterable) concentrations of Cd, Cu, and Zn in sediment pore waters Acid volatile sulfide is important in controlling metal solubility in the depositional areas of the Clark Fork River and should be monitored in any future studies Spatial variability within a sampling station was high for Cu, Zn, and AVS, therefore, the potential for toxicity to sediment dwelling organisms may be highly localized.

Environmental Toxicology and Chemistry↗
USGS1994

Toxicity of metal-contaminated sediments from the upper Clark Fork River, Montana, to aquatic invertebrates and fish in laboratory exposures

Sediments of the upper Clark Fork River, from the Butte and Anaconda area to Milltown Reservoir (230 km downstream), are contaminated with As, Cd, Cu, Pb, Mn, and Zn primarily from mining activities. The toxicity of pore water from these sediments was determined using Daphnia magna (48-h exposure), rainbow trout (96-h exposure), and Microtox®. However, pore-water data from these exposures were questionable because of changes in the toxicity of pore-water samples after 5 to 7 d of storage. Whole-sediment tests were conducted with Hyalella azteca (28-d exposure), Chironomus riparius (14-d exposure), rainbow trout ( Oncorhynchus mykiss ) 21- to 28-d exposure and Daphnia magna (2- to 22-d exposure). Sediment samples from Milltown Reservoir and the Clark Fork River were not generally lethal to test organisms. However, both reduced growth and delayed sexual maturation of amphipods were associated with exposure to elevated concentrations of metals in sediments from the reservoir and river. Relative sensitivity (most sensitive to least sensitive) of organisms in whole-sediment toxicity tests was: Hyalella azteca > Chironomus riparius > rainbow trout > Daphnia magna . Relative sensitivity (most sensitive to least sensitive) of the three end points evaluated with Hyalella azteca was: length > sexual maturation > survival. The lack of lethal effects on organisms may be related to temporal differences in sediment, acid-volatile sulfide, or organic carbon.

Montana↗
USGS1994

Use of benthic invertebrate community structure and the sediment quality triad to evaluate metal-contaminated sediment in the upper Clark Fork River, Montana

The upper Clark Fork River, above Flathead River, is contaminated with large amounts of As, Cd, Cu, Pb, Mn, and Zn ores from past mining activities. The contaminated area extends from the Butte and Anaconda area to at least 230 km downstream to Milltown Reservoir. Both the upper Clark Fork River and Milltown Reservoir have been designated as U.S. Environmental Protection Agency Superfund sites because of metal-contaminated bottom sediments. We evaluated the impacts of past mining activities on the Clark Fork River ecosystem using benthic invertebrate community assessment, residue chemistry, and toxicity testing. Oligochaeta and Chironomidae generally accounted for over 90% of the benthic invertebrate community in the soft sediment depositional areas. Taxa of Oligochaeta and Chironomidae were predominantly pollution tolerant. Higher numbers of Chironomidae genera were present at stations with higher concentrations of metals in sediment identified as toxic by the amphipod Hyalella azteca in 28-d exposures. Frequency of mouthpart deformities in genera of Chironomidae was low and did not correspond to concentrations of metals in sediment. Total abundance of organisms/m 2 did not correspond to concentrations of metals in the sediment samples. Chemical analyses, laboratory toxicity tests, and benthic community evaluations all provide evidence of metal-induced degradation to aquatic communities in both the reservoir and the river. Using a weight-of-evidence approach-the Sediment Quality Triad - provided good concurrence among measures of benthic community structure, sediment chemistry, and laboratory toxicity.

Montana↗
USGS1994

Bioaccumulation of metals by Hyalella azteca exposed to contaminated sediments from the upper Clark Fork River, Montana

Macroinvertebrates contaminated with metals in the Clark Fork River of Montana have been demonstrated to be a potentially toxic component in the diet of trout Because sediment was the suspected source of metals to these invertebrates, bioaccumulation of As, Cd, Cu, Pb, and Zn from sediment was evaluated by exposing the amphipod Hyalella azteca for 28 d in the laboratory to samples of sediment collected from depositional areas of the Clark Fork River Benthic invertebrates collected from riffles adjacent to the depositional areas were also analyzed for metals The pattern of metal accumulation between laboratory-exposed and field-collected animals was similar, however, the concentrations of metals in laboratory exposed amphipods were often 50 to 75% less than were the concentrations of metals in the field collected invertebrates These findings indicate that sediment is a significant source of metals to invertebrates in the Clark Fork River Additional studies should be conducted to determine threshold concentrations for effects of dietary metals on fish Long-term monitoring of the river should include sampling benthic invertebrates for metal accumulation.

Environmental Toxicology and Chemistry↗
USGS1994

Physiological changes and tissue metal accumulation in rainbow trout exposed to foodborne and waterborne metals

Sublethal physiological effects and metal residue accumulation in tissues were measured in adult and juvenile rainbow trout fed a metal-contaminated diet and/or exposed to waterborne metals for 21 d. The consumption of metal-contaminated invertebrates from the Clark Fork River, Montana, significantly affected scale loss and metal accumulation in gut tissue of adult trout. Survival, scale loss, and metal accumulation in gill and kidney tissue were affected by exposure to a waterborne mixture of Cd, Cu, and Pb at twice the acceptable levels and Zn at the maximum acceptable level established by the U.S. Environmental Protection Agency for protection of aquatic wildlife. A combination of dietary and waterborne metals also caused lipid peroxidation in the kidney of adult fish and decreased whole-body potassium of juvenile trout. In general, metal accumulation in tissues was higher in gill and kidney with waterborne exposures and was higher in stomach and pyloric caeca with dietary exposure. And metal concentrations in juvenile whole-body tissues accumulated significantly with a combination of waterborne and dietary metals. Although some physiological changes were noted (scale loss, lipid peroxidation of kidney), an exposure time longer than 21 d is probably needed to observe more extensive physiological changes. Regardless, results from this study suggest that a full assessment of metal exposure to fish populations in natural systems must include evaluation of dietary as well as waterborne metal contamination.

Montana↗
USGS1995

Transfer and accumulation of organochlorines from black-crowned night-heron eggs to chicks

Eggs and sibling 1-, 3-, and 5-d-old chicks from seven black-crowned night-heron ( Nycticorax nycticorax ) broods were collected from Green Bay, Wisconsin, and analyzed for organochlorines. The concentration (μg/g) of nine organochlorines either decreased ( n = 7) or remained the same ( n = 2) as the chicks grew older. In contrast, the total mass (μg) of these nine organochlorines increased ( n = 7) or remained the same ( n = 2) as the chicks grew older. Accumulation rates of mass (μg/d) between egg and 5-d-old chicks for each of the nine organochlorines were positive and varied from 0.2 μg/d ( p,p ′-DDT) to 42 μg/d (PCBs). These results suggest that the loss of contaminant mass from eggs to chicks reported in some earlier studies was because the entire carcass was not analyzed (i.e., not including skin, gastrointestinal tract, etc.). These results also support the use of contaminant accumulation rates as an indicator of local contamination.

Environmental Toxicology and Chemistry↗
USGS1995

Development of toxic equivalency factors for PCB congeners and the assessment of TCDD and PCB mixtures in rainbow trout

This study was undertaken to evaluate the relationship between mammalian and piscine 2,3,7,8-tetrachlorodibenzo- p -dioxin (TCDD) toxic equivalency factors (TEFs) for PCBs, based on induction of CYP1A enzyme activity, catalytic protein, and mRNA. Rainbow trout administered a single i.p. injection of TCDD had an average (±SD) ED50 of 0.91 ± 0.14 μg TCDD/kg for induction of ethoxyresorufin O -deethylase (EROD) activity. Ortho-substituted PCB congeners 2,3,3′,4,4′-pentachlorobiphenyl (PCB 105), 2,3′,4,4′,5-pentachlorobiphenyl (PCB 118), 2,3,3′4,4′5-hexachlorobiphenyl (PCB !56), and 2,2′3,4,4′,5-hexachlorobiphenyl (PCB 138) did not induce CYP1A activity in rainbow trout. Only three non-ortho-substituted PCBs, i.e., 3,3′4,4′-tetrachlorobiphenyl (PCB 77), 3,3′,4,4′,5-pentachlorobiphenyl (PCB 126), and 3,3′4,4′5,5′-hexachlorobiphenyl (PCB 169) induced CYP1A enzyme activity, protein, and mRNA. The ED50s for induction of EROD activity were calculated as 134, 5.82, and 93.7 μg/kg for PCB 77, PCB 126, and PCB 169, respectively. The TCDD-TEFs based on EROD activity were 0.0006, 0.0014, and 0.0003 for PCB 77, PCB 126, and PCB 169, respectively. Binary mixtures of TCDD and three PCBs were also evaluated. Based on EROD activity and CYP1A protein, mixtures of TCDD and PCB 77 were slightly greater than additive. Mixtures of TCDD-PCB 156 and TCDD-PCB 126 were slightly less than additive. Results from these studies indicate that mammal-derived TEFs will underestimate the potency of planar chlorinated hydrocarbon mixtures to induce the CYP1A catalytic activity in rainbow trout. Also, while interactions among PCB congeners and TCDD were somewhat equivocal, they did not greatly differ from predicted additive responses.

Environmental Toxicology and Chemistry↗