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At least 451 records · Page 25Linked to original sources
USGS1993

Biomarkers of contaminant exposure in common terns and black-crowned night herons in the Great Lakes

Morphological and biochemical indexes of contaminant exposure were examined in hatching common terns ( Sterna hirundo ) and black-crowned night herons ( Nycticorax nycticorax ) from industrialized and nonindustrialized locations in the Great Lakes. In 1984, naturally incubated, pipping common tern and black-crowned night heron embryos collected from industrialized locations exhibited smaller femur-length-to-body-weight ratios, elevated hepatic microsomal aryl hydrocarbon hydroxylase (AHH) activities, and lower hepatic DNA concentrations ( P < 0.05). In addition, a high incidence of subcutaneous edema was noted in pipping herons ( P < 0.01). In 1985, reduced hatching success was observed for laboratory-incubated common tern eggs collected from the industrialized sites, compared to nonindustrialized sites ( P < 0.01). Day-old hatchlings exhibited reduced femur-length-to-body-weight ratio, developmental anomalies, and elevated hepatic AHH activity ( P < 0.05). For hatching common terns studied in 1984 and 1985, femur-length-to-body-weight ratio was inversely related to AHH activity ( r = −0.67, P < 0.05) and inversely related to log-transformed PCB concentrations ( r = −0.70, P ≤ 0.05) of unincubated eggs from the same colony. The activity of AHH in hatching terns was also directly related ( r = 0.71, P ≤ 0.05) to log-transformed PCB concentrations in unincubated eggs. Other examined contaminants, including DDE, other organochlorine pesticides, and mercury, were not directly related to these effects.

Environmental Toxicology and Chemistry↗
USGS1993

Sensitivity of early-life stage golden trout to low pH and elevated aluminum

Early-life-stage golden trout ( Oncorhynchus aguabonita aguabonita ) were exposed to acid and Al to examine the response and determine the sensitivity of a western, alpine salmonid to conditions simulating an episodic pH depression. Freshly fertilized eggs, alevins, and swim-up larvae were exposed for 7 d to one of 12 combinations of pH and Al, and surviving fish were held to 40 d post-hatch to determine the effect of exposure on subsequent survival and recovery. Golden trout are sensitive to conditions simulating episodic acidification events typically observed in the field. Significant mortality occurred when the pH of test waters was below 5.0 in the absence of Al or when pH was 5.5 in the presence of 100 μg/L total Al. Behavioral impairments were sensitive indicators of low pH and Al stress. Impaired locomotory and feeding behavior occurred at pH 5.5 without Al and at Al concentrations > 50 μg/L. In contrast, growth, RNA-to-DNA ratio, and whole-body ion concentration were relatively less sensitive indicators of sublethal acid and Al stress.

Environmental Toxicology and Chemistry↗
USGS1993

Acute toxicity of the herbicide bromoxynil to Daphnia magna

The acute toxicities of technical-grade bromoxynil octanoate (BO) and two commercial formulations, Buctril® and Bronate®, to < 24-h-old neonate Daphnia magna (Straus) were determined in soft, hard, and oligosaline water. In addition, effects of life stage, feeding, aging the herbicide, and exposure duration on BO toxicity to daphnids were investigated. Regardless of formulation, life stage, and water quality, BO was found to be extremely to highly toxic to daphnids in standard tests; 48-h EC50 values ranged from 41 to 161 m̈g/L. Bromoxynil octanoate was the most toxic to neonates in soft water and the least toxic in hard water. The acute toxicities of the three bromoxynil herbicides to a given age group of daphnids were similar within the same water type. Overall, neonates and 7-d-old adults were more sensitive than 14- or 15-d-old adults to each herbicide. Feeding daphnids during the toxicity test significantly decreased BO toxicity compared to not feeding them. Aging BO (as Buctril) in hard water decreased its toxicity, and the rate of deactivation was rapid, with an estimated half-life of biological activity of 13 h. Daphnids immobilized by exposures to toxic BO concentrations for ≤ 6 h recovered their mobility, whereas exposures of 18 and 24 h to BO produced toxic effects in daphnids similar to those exposed for 48 h. These results indicated that standard continuous exposure tests may not adequately predict the acute toxicity of BO to freshwater animals in the field.

Environmental Toxicology and Chemistry↗
USGS1993

Re-exposure of mallards to selenium after chronic exposure

Adult male mallards ( Anas platyrhynchos ) were fed a control diet or a diet containing 15 ppm selenium as seleno-D,L-methionine for 21 weeks. After this initial exposure, the mallards were fed untreated food for 12 weeks, then were re-exposed to selenium at 100 ppm for five weeks. During re-exposure to 100 ppm selenium, the birds that had previously been exposed to 15 ppm selenium and those that had not previously been exposed did not differ in percentage of mortality (14.7 and 14.3%), weight loss in survivors (39.3 and 41.2%), selenium concentrations in the livers of survivors (35 and 53 ppm, wet weight), or selenium concentrations in the livers of birds that died (35 and 40 ppm, respectively). When the data from the birds that had previously been exposed to 15 ppm selenium were combined with the data from the birds that had not previously been exposed, selenium concentrations in the livers of birds that had died on the 100-ppm selenium treatment (38 ppm) did not differ from the concentrations in the livers of birds that had survived (43 ppm).

Environmental Toxicology and Chemistry↗
USGS1993

Biomonitoring environmental contamination with pipping black-crowned night heron embryos: Induction of cytochrome P450

Cytochrome P450-associated monooxygenase activities and cytochrome P450 proteins were measured in pipping black-crowned night heron ( Nycticorax nycticorax ) embryos collected from a reference site (next to the 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). In a laboratory study, artificially incubated night heron embryos from the reference site were treated with 3-methylcholanthrene (200 μg administered into the air cell 2 d before pipping) or phenobarbital (2 mg daily for 2 d before pipping). Compared to controls (untreated + vehicle-treated embryos), 3-methylcholanthrene induced a greater than fivefold increase in activities of several monooxygenases (arylhydrocarbon hydroxylase, AHH; benzyloxyresorufin- O -dealkylase, BROD; ethoxyresorufin- O -dealkylase, EROD; pentoxyresorufin- O -dealkylase, PROD) and a greater than 100-fold increase in the concentration of immunodetected cytochrome P450 1A (CYP1A). Phenobarbital treatment resulted in only a slight increase in BROD activity but induced proteins recognized by antibodies to cytochrome P450 2B (CYP2B) by 2,000-fold. In a field study, activities of AHH, BROD, EROD, and ethoxycoumarin- O -dealkylase (ECOD) were up to 85-fold higher in pipping black-crowned night herons collected from Cat Island compared to other sites. Hepatic CYP1A and CYP2B cross-reactive proteins were detected in significantly more individuals from Cat Island than from the reference site. Greatest burdens of total PCBs and p,p ′-DDE were detected in embryos from Cat Island. Cytochrome P450-associated monooxygenase activities and cytochrome P450 proteins (AHH, BROD, EROD, ECOD, CYP1A, CYP2B) were significantly associated with total PCB burdens ( r = 0.50-0.72). These data indicate that cytochrome P450 may be a useful biomarker of exposure to some PCB mixtures in black-crowned night heron embryos.

Environmental Toxicology and Chemistry↗
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&deg;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 &mu;g/L and for trichlorfon from 6.3 to 19,300 &mu;g/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

Salinity and temperature effects on chronic toxicity of 2,4-dinitrophenol and 4-nitrophenol to sheepshead minnows ( Cyprinodon variegatus )

Toxicity tests (28-d early-life-stage) were conducted to determine the effects of nine combinations of salinity (15, 20, 25 ppt) and temperature (22, 27, 32°C) on the toxicity of 2,4-dinitrophenol (2,4-DNP) and 4-nitrophenol (4-NP) to sheepshead minnows ( Cyprinodon variegatus ). The highest tested concentration having no observed effect (NOEC) on mortality and growth was derived weekly. The NOECs at test termination indicated that the survival and growth of fish exposed to 2,4-dinitrophenol were not significantly affected by salinity, temperature, or the salinity temperature interaction. However, 28-d NOECs of fish surviving from 4-nitrophenol exposures were significantly affected by temperature, but the highest value exceeded the lowest by only a factor of two. The overall data suggest that variations of salinity and temperature do not change the NOEC; only the exposure time required to attain the same NOEC is altered.

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↗