Showing papers in "Environmental Toxicology and Chemistry in 1995"

To normalize or not to normalize? Fat is the question

Abstract: Concentrations of lipophilic contaminants in biota are frequently corrected for variation in tissue lipid content. Usually, this correction is accomplished by dividing tissue contaminant concentration by lipid concentration to form lipid-normalized data. This ratio-based approach is satisfactory when contaminant concentration varies in direct proportion to lipid content. However, when such a relationship does not exist, erroneous conclusions may be reached. Recent research has emphasized the potential shortcomings of the use of ratio variables. We demonstrate the importance of considering these shortcomings when lipid-normalizing data. Three examples are presented, and an alternative approach based upon the use of analysis of covariance (ANCOVA) is suggested.

Acute and chronic toxicity of ammonium nitrate fertilizer to amphibians from southern ontario

Abstract: Increasing nitrate levels in surface and ground waters are of global concern. Effects of nitrates on human health are well documented, but effects on amphibians have received little attention. I exposed Bufo americanus (American toad), Pseudacris triseriata (chorus frog), Rana pipiens (leopard frog), and Rana clamitans (green frog) tadpoles to ammonium nitrate fertilizer in water. In acute tests, mortality varied among species (96-h LC50; 13.6-39.3 mg/L NO3-N) and significant weight loss occurred. In chronic tests (100 d; 0, 2.5, 5, 10 mg/L NO3-N) chorus frog and leopard frog tadpoles had significantly lower survivorship in the 10-mg/L treatments, but green frog survivorship was not affected. Number of chorus frogs metamorphosing was significantly lower in the 10-mg/L treatment, but development time was not affected. In acute exposures, reduced activity, weight loss, and physical abnormalities were observed. Toxic effects of ammonium nitrate occurred in all four species at concentrations that are commonly exceeded in agricultural areas globally. Nitrate fertilizers may play a role in the apparent global amphibian decline.

Influence of developmental stage, salts and food presence on various end points using Caenorhabditis Elegans for aquatic toxicity testing

Abstract: This study used a randomized block design to investigate the importance of several variables in using the free-living soil nematode, Caenorhabditis elegans, for aquatic toxicity testing. Concentration-response data were obtained on nematodes of various developmental stages exposed to four metals (Cd, Pb, Cu, and Hg) and a water-soluble organic toxicant, sodium pentachlorophenate (PCP), under conditions of varied solvent medium (with or without salts and with or without a bacterial food source). The end points measured were 24- and 96-h mortality LC50 value, as well as development of larval stages to adulthood and evidence of reproduction. The results suggest that nematodes of various ages respond similarity to a given toxicant for all end points measured, although adults cultured from eggs appeared more sensitive than adults cultured from dauer larvae. The most important environmental variable in determining toxicity was the medium in which the tests were conducted. The presence of potassium and sodium salts in the medium significantly (p < 0.05) reduced the toxicity of many test samples. The presence of bacteria had little effect on 24-h tests with salts, but was important in 96-h survival and development. Based on sensitivity and ease of handling, adults cultured from eggs are recommended inmore » both 24h and 96-h tests.« less

Use of joint toxic response to define the primary mode of toxic action for diverse industrial organic chemicals

Abstract: An important aspect of understanding how multiple toxicants jointly act involves defining the primary mode of toxic action for the chemicals of interest. We have explored the use of 96-h acute toxicity tests with juvenile fathead minnows and primarily binary chemical mixtures to define the primary acute mode of toxic action for diverse industrial organic chemicals. Our investigation mainly considered the two special cases of noninteractive joint action known as concentration (simple similar) and response (independent) addition. The different forms of joint toxicity with binary mixtures were graphically illustrated by isoboie diagrams. Designated as the mode of action-specific reference toxicants were 1-octanol, phenol, and 2,4-dimtrophenol. It was observed from binary isobole diagrams that a chemical with a similar primary mode of toxic action to that of a reference toxicant would display a concentration-addition type of joint action with the reference toxicant over the entire mixture ratio range. Dissimilar chemicals with very steep concentration-response curves generally showed an interaction that was less-than-concentration additive, but consistently demonstrated a joint toxicity that was greater than predicted by the response-addition model. The more-than-concentration additive and complex isoboles that are indicative of interactive toxicity were not commonly observed in our experiments.

ΣPAH: A Model to predict the toxicity of polynuclear aromatic hydrocarbon mixtures in field‐collected sediments

Abstract: The {Sigma}PAH model estimates the probability of toxicity of PAH-contaminated sediments using a combination of equilibrium partitioning, WSAR, toxic unit, additivity, and concentration-response models. The sediment concentration of organic carbon and 13 PAH (polynuclear aromatic hydrocarbon) compounds were measured. Interstitial water concentrations (PAH{sub iw}) of the 13 compounds were predicted by equilibrium partitioning. The 10-d LC50 of each compound in interstitial water (10-d LC50{sub iw}) was predicted by a QSAR regression of 10-d LC50{sub iw} (From spiked sediment tests) to K{sub ow}. Toxic unit concentrations of individual compounds (TU{sub i}) were predicted as PAH{sub iw}/10-d LC50{sub iw}. The total number of toxic units of the 13 compounds ({Sigma}TU{sub i}) was calculated assuming the additivity of toxic effects of PAHs. {Sigma}TU{sub i} was used to predict the probability of toxicity to marine and estuarine amphipods using a concentration-response model derived from spiked sediment toxicity tests. The {Sigma}PAH model was verified by comparing predicted and observed toxicity in field-collected sediment samples. There was 86.6% correspondence and no significant difference between predicted and observed toxicity at PAH-contaminated sites. Ecological-effect levels predicted by the {Sigma}PAH model correspond with several sediment-quality guidelines.

The effects of motorway runoff on freshwater ecosystems: 1. Field study

Abstract: The effects of motorway runoff on the water quality, sediment quality, and biota of small streams were investigated over a 12-month period. Downstream of motorway runoff discharges there was an increase in the sediment concentrations of total hydrocarbons, aromatic hydrocarbons, and heavy metals and an increase in the water concentrations of heavy metals and selected anions. Hydrocarbon contamination of sediments was positively correlated with potential contaminant loading (i.e., length of road drained/stream size). The greatest effect was observed at Pigeon Bridge Brook, a small stream receiving drainage from a 1,500-m stretch of the Ml motorway. The dominant PAHs in contaminated sediment at this site were phenanthrene, pyrene, and fluoranthene, whereas the dominant metals were zinc, cadmium, chromium, and lead. Differences between the station upstream and downstream of discharges in the diversity and composition of the macroinvertebrate assemblages were detected in four out of the seven streams surveyed. However, there was no evidence of an effect on either the diversity or abundance of epilithic algae. The diversity of the aquatic hyphomycete assemblage was only affected at the most impacted site. Reductions in macroinvertebrate diversity were associated with reductions in the processing of leaf litter and a change from an assemblage based on benthic algae and coarse particulate organic matter to one dependent upon fine particulate organic matter.

A mechanistic model of contaminant-induced feeding inhibition in Daphnia magna

Abstract: Particles in water ubiquitously carry a net negative charge. It was hypothesised that the interaction between suspended particles and pollutants in water results in a process of adsorption that can be related to the charge of the pollutant concerned, and that this is a potential route of pollutant uptake by aquatic animals such as particle-grazing zooplankton. Experiments with the alga Chlorella vulgaris were conducted to test the hypothesis that pollutant-induced feeding inhibition in the cladoceran Daphnia magna was dependent on this mechanism. Using compounds differing in charge, results supported the hypothesis that, while all compounds were capable of causing feeding inhibition, electropositive species such as cadmium induced effects close to the chronic no-effect concentration, whereas electronegative species such as vanadium induced effects only at or close to lethal levels. It was suggested that for those compounds capable of causing feeding inhibition at sublethal concentrations, this inhibition would be a key mechanism impairing reproduction and growth, with potential consequences for grazing animals at population and community levels in natural ecosystems.

Modeling silver binding to gills of rainbow trout (Oncorhynchus mykiss)

Abstract: Rainbow trout (Oncorhynchus mykiss, 1–3 g) were exposed to ∼0.1 μM silver (Ag) (∼11 μg.L−1 Ag) for 2 to 3 h in synthetic soft water (Ca, Na ∼ 300 μM, pH 6.5–7.5) to which was added Ca, Na, H+, dissolved organic carbon (DOC), CI, or thiosulfate (S2O3). Gills were extracted and gill Ag concentrations were measured using graphite-furnace atomic absorption spectrophotometry. The concentrations of cations (Ca, Na, H+) and complexing agents (DOC, CI, S2O3) needed to keep Ag off the gills were used to calculate conditional equilibrium binding constants (K) at the gills. Log K for Ag-gill binding was 10.0, with approximately 1.3 nmol Ag binding sites per fish. All experimentally determined log K values were entered into an aquatic chemistry equilibrium model, MINEQL+, to predict Ag binding at trout gills. For a series of natural waters, model-predicted gill Ag concentrations correlated well with observed gill Ag concentrations, with one exception, very hard city of Waterloo tapwater. This exception may indicate a kinetic constraint on the thermodynamic basis of the model.

A comparison of standard acute toxicity tests with rapid‐screening toxicity tests

Abstract: This study compared the relative sensitivity of five inexpensive, rapid toxicity tests to the sensitivity of five standard aquatic acute toxicity tests through literature review and testing. The rapid toxicity tests utilized organisms that require little culturing or handling prior to testing: a freshwater rotifer (Branchionus calyciflorus); brine shrimp (Artemia salina); lettuce (Lactuca sativa); and two microbial tests (Photobacterium phosphoreum--Microtox{reg_sign} test, and a mixture of bacterial species--the Polytox{reg_sign} test). Standard acute toxicity test species included water fleas (Daphnia magna and Ceriodaphnia dubia), green algae (Selenastrum capricornutum), fathead minnows (Pimephales promelas), and mysid shrimp (Mysidopsis bahia). Sensitivity comparisons between rapid and standard acute toxicity tests were based on LC50/EC50 data from 11 test chemicals. Individually, the lettuce and rotifer tests ranked most similar in sensitivity to the standard tests, while Microtox fell just outside the range of sensitivities represented by the group of standard acute toxicity tests. The brine shrimp and Polytox tests were one or more orders of magnitude different from the standard acute toxicity tests for most compounds. The lettuce, rotifer, and Microtox tests could be used as a battery for preliminary toxicity screening of chemicals. Further evaluation of complex real-world environmental samples is recommended.

Endocrine and metabolic dysfunction in yellow perch, Perca flavescens, exposed to organic contaminants and heavy metals in the St. Lawrence River

Abstract: The endocrine and biochemical responses to the acute stress of capture and handling were investigated in sexually mature and in immature male and female yellow perch, Perca flavescens, from a site contaminated by organic contaminants (PAHs and PCBs) and heavy metals (Hg, Cd, As, and Zn) and from a reference site in the St. Lawrence River. Following a standardized capture and handling stress, fish from the contaminated site did not exhibit the expected physiological stress response observed in fish from the reference site. Blood cortisol and thyroxine levels were lower, and liver glycogen stores were greater in mature males and females, as well as in the immature fish from the contaminated site, compared to the reference site. Fish from the contaminated site also had smaller gonads and lower condition factor. The impaired ability to elevate blood cortisol in response to an acute stress may be used as a biomarker of toxic stress in health assessment of feral fish from polluted environments.

Concentrations, transport and biological effects of dormant spray pesticides in the San Francisco Estuary, California

Abstract: The transport and biological effects of dormant spray pesticides were examined in the San Francisco Estuary, California, by measuring dissolved-pesticide concentrations and estimating toxicity using bioassays at a series of sites in January and February 1993 Distinct pulses of pesticides, including diazinon, methidathion, and chlorpyrifos, were detected in the San Joaquin River in January and February and in the Sacramento River in February following rainfall The higher pesticide loads in the Sacramento River compared with those in the San Joaquin River can be attributed to the greater amount of rainfall in the Sacramento Valley The use patterns and water solubility of the pesticides can account for the observed temporal and spatial distributions in the two rivers The pesticide pulses detected at Sacramento were followed through the northern embayment of San Francisco Estuary In contrast, the pesticide distribution in the Sacramento-San Joaquin Delta changed from distinct pulses to steady increases in concentration over time Seven-day bioassays indicated that Sacramento River water at Rio Vista was acutely toxic to Ceriodaphnia dubia (water flea) for 3 consecutive d and San Joaquin River water at Vernalis for 12 consecutive d These water samples all had the highest diazinon concentrations Examination of 96-h LC50 values (lethal concentration that kills 50% of test organisms in 96 H) indicates that measured diazinon concentrations could account for most but not all the observed toxicity Other pesticides present could contribute to the toxicity

Toxicity and bioaccumulation of sediment-associated contaminants using freshwater invertebrates: A review of methods and applications

Abstract: This paper reviews recent developments in methods for evaluating the toxicity and bioaccumulation of contaminants associated with freshwater sediments and summarizes example case studies demonstrating the application of these methods. Over the past decade, research has emphasized development of more specific testing procedures for conducting 10-d toxicity tests with the amphipod Hyalella azteca and the midge Chironomus tentans. Toxicity endpoints measured in these tests are survival for H. azteca and survival and growth for C. tentans. Guidance has also been developed for conducting 28-d bioaccumulation tests with the oligochaete Lumbriculus variegatus, including determination of bioaccumulation kinetics for different compound classes. These methods have been applied to a variety of sediments to address issues ranging from site assessments to bioavailability of organic and inorganic contaminants using field-collected and laboratory-spiked samples. Survival and growth of controls routinely meet or exceed test acceptability criteria. Results of laboratory bioaccumulation studies with L. variegatus have been confirmed with comparisons to residues (PCBs, PAHs, DDT) present from synoptically collected field populations of oligochaetes. Additional method development is currently underway to develop chronic toxicity tests and to provide additional data-confirming responses observed in laboratory sediment tests with natural benthic populations.

A proposal for the definition of resource equivalency factors for use in product life-cycle assessment

Abstract: Environmental life-cycle assessment (LCA) of products has been the focus of growing attention in the last few years. The methodological framework has been developed rapidly, and a provisional “Code of Practice” has been drawn up by an international group of experts. One of the elements of LCA is impact assessment, which includes a characterization step in which the contributions of resource extraction and polluting emissions to impact categories such as resource depletion, global warming, and acidification are quantified and aggregated as far as possible. This can be achieved by multiplying extractions and emissions by a so-called equivalency factor and aggregating the results in one or more effect score(s) per impact category. In this report a proposal is developed for equivalency factors indicating the relative depletion of a resource per unit extracted. It is proposed to measure depletion by physical data on reserves and production and regeneration rates, and to distinguish between abiotic and biotic resources. Equations are developed to calculate equivalency factors for these two categories of resources, resulting in so-called abiotic depletion potentials (ADP) and biotic depletion potentials (BDP). The application of these ADPs and BDPs in LCA is illustrated.

The effects of motorway runoff on freshwater ecosystems. 2: Identifying major toxicants

Abstract: Previous studies have provided prima facie evidence that runoff from the MI motorway, UK, affects both the qual- ity of the receiving water and the biota living there, in sites short distances from point sources-i.e., possible worst-case situa- tions. Because discharges contain a wide variety of contaminants, both the identification of toxicants and the establishment of causal relationships between observed changes in waterhediment quality and biology are often difficult. In this particular case, the problem was addressed by conducting a series of toxicity tests using the benthic amphipod Gummnruspulex. The abundance of this species was greatly reduced downstream of the point where motorway runoff entered the stream. Stream water contami- nated with motorway runoff was not toxic to G. pulex. However, exposure to contaminated sediments resulted in a slight re- duction in survival over 14 d, and sediment manipulation experiments identified hydrocarbons, copper, and zinc as potential toxicants. Spiking experiments confirmed the importance of hydrocarbons, and fractionation studies indicated that most of the observed toxicity was due to the fraction containing polycyclic aromatic hydrocarbons. Animals exposed to contaminated sedi- ments and water spiked with sediment extract accumulated aromatic hydrocarbons in direct proportion to exposure concentrations.

Evaluation of soil toxicity at joliet army ammunition plant

Abstract: Environmental toxicity testing and chemical analyses of soil were performed as part of an ecological risk assessment at the Joliet Army Ammunition Plant (JAAP), Johet, Illinois Soils were collected from an area where munitions were loaded, assembled, and packed (area L7, group 1), and from an area where waste explosives were burned on unprotected soil (area L2) Control samples were collected from an adjacent field Soil toxicity was determined using early seedling growth and vigor tests, earthworm survival and growth tests, and Microtox® assays Relative toxicity of soils was determined within each area based on statistical significance (p = 0 05) of plant and earthworm growth and survival, and the effective concentration at which luminescence of the bacterium Photobacterium phosphoreum was reduced by 50% (EC50) in the Microtox assay Samples were designated as having high, moderate, or no significant toxicity Soil that had significant toxicity according to at least one test, and representative samples showing no toxicity, were analyzed for munitions via HPLC Chemical residues found in soils were 2,4,6 trinitrotoluene (TNT), 1,3,5 trinitrobenzene (TNB), 2,4 dinitrotoluene (2,4-DNT), 2,6 dinitrotoluene, 2 amino-4,6-DNT, 4-ammo-2,6 DNT, 1,3,5 trinitro 1,3,5 triazine (RDX), and octahydro-1,3,5,7 tetramtro-l,3,5,7-tetrazocme (HMX) All soils with no significant toxicity were void of these chemicals However, some soils void of munitions still showed toxicity that may have been caused by elevated levels of heavy metals Linear regressions of toxicity test results vs chemical concentrations showed that TNT and TNB accounted for most of the soil toxicity Lowest observable-effect concentrations (LOEC) of TNT were de termined from these data This study presents a simple, relatively inexpensive methodology for assessing toxicity of soils containing TNT, RDX, and other contaminants related to munitions production

A field evaluation of cytochrome P4501A as a biomarker of contaminant exposure in three species of flatfish

Abstract: A 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 ethoxyresorufin O-deethylase (EROD)] and by an immunoassay (ELISA) utilizing polyclonal antibodies raised against purified CYP1A from cod. AHH activities were measured by a standard method (AHH[sub std]) and by two variations of the standard method. All three primary CYP1A measures (AHH[sub std], 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 AHH[sub std] and 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 AHH[sub std] assay, is nonetheless recommendedmore » 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 AHH[sub std] makes this CYP1A measure potentially more useful for monitoring programs in which analysis of trends is a primary goal.« less

A summary of the acute toxicity of 14 phthalate esters to representative aquatic organisms

Abstract: Acute aquatic toxicity studies were performed with 14 commercial phthalate esters and representative freshwater and marine species. The 14 esters were dimethyl phthalate; diethyl phthalate; di-n-butyl phthalate; butyl benzyl phthalate; dihexyl phthalate; butyl 2-ethylhexyl phthalate; di-(n-hexyl, n-octyl, n-decyl) phthalate; di-(2-ethylhexyl) phthalate; diisooctyl phthalate; diisononyl phthalate; di-(heptyl, nonyl, undecyl) phthalate; diisodecyl phthalate; diundecyl phthalate; and ditridecyl phthalate. Phthalate esters with alkyl chain lengths of four carbon atoms or fewer were determined to be acutely toxic at concentrations ranging from 0.21 to 377 mg/L depending on the ester and the solubility of the test chemical in water. There was a general trend for the lower-molecular-weight phthalate esters (C1 to C4 alkyl chain lengths: dimethyl phthalate; diethyl phthalate; di-n-butyl phthalate; and butyl benzyl phthalate) to become more toxic with decreasing water solubility for all species tested. There were only minor differences in species sensitivity to each of the phthalate esters. Phthalate esters with alkyl chain lengths of six carbon atoms or more were not acutely toxic at concentrations approaching their respective aqueous solubilities. Insufficient mortality occurred to calculate either LC50 or EC50 values or acute no-observed-effect concentrations for these higher-molecular-weight phthalate esters. The lack of toxicity observed for the higher-molecular-weight phthalate esters resulted from their limited water solubility (≤1.1 mg/L).

Behavioral responses of Daphnia pulex exposed to carbaryl and Chaoborus kairomone

Abstract: An analysis of digitized three-dimensional video records of free-swimming Daphnia pulex identified six measurements of swimming behavior that can be used to quantify individual behavioral responses to pesticides or natural chemical signals. Protocols are given for measuring the parameters that showed statistically significant changes in pesticide treatments. The most efficient experimental design would involve observing as many animals as possible, with one observation per animal. Parameters most likely to be useful in future studies are velocity, turning angle, upward and downward angles during hops, variance in vertical position, and hopping frequency. The parameters varied in usefulness, defined as the ratio of within-treatment to among-treatment variance (F ratios). Velocity was the most useful (i.e., had the highest F ratio); hopping frequency was the least useful. Daphnia exhibited three kinds of swimming behavior, as defined by eight parameters: (a) “spinning” (extreme and continuous escape response) to acutely toxic levels of Carbaryl (40 ppb); (b) “irritation” (an increase in escape-like behavior) to low levels of Carbaryl (1 ppb); and (c) “null” behavioral responses to Chaoborus-conditioned water, in which there was no detectable change in any measurement of swimming behavior. In predation trials, bluegill sunfish preferentially selected individuals showing “spinning” behavior. Results from this and other studies of Daphnia swimming behavior suggest a conservative-swimming hypothesis for understanding constraints on Daphnia swimming behavior.

Alteration of the homing‐flight in the honey bee Apis mellifera L. Exposed to sublethal dose of deltamethrin

Abstract: Foraging activity of bees is currently disturbed by treatments with pyrethroid agrochemicals. To discover eventual troubles of spatial orientation of the foragers, we exposed bees to sublethal doses of deltamethrin sufficiently low to avoid motor incoordination or muscular troubles. In an insect-proof tunnel, bees were trained to forage at a feeder 8 m from their nucleus. When temperature and global radiance conditions were optimal, some foragers were caught, exposed to a deltamethrin dose 27 times lower than its LD50, and released after 20 min of recovering. Among the contaminated bees, 54% took flight toward the sun and 81% did not come back to their nest within 30 s (which is 3 times longer than the mean time of control bees). Because pyrethroids are known to disturb learning and memory, we cannot conclude if this disorientation is due either to a trouble of information storage (wrong spatial perception or phototropism increase), or to a trouble of information retrieval (bad comparison of actual and memorized patterns). Routine chemical analysis of exposed bees does not detect residues of deltamethrin 3 h after bee sublethal exposure, although bees evidenced alteration in the flight.

Steady-state model of biota sediment accumulation factor for metals in two marine bivalves

Abstract: A model of the biota sediment accumulation factor (BSAF) is developed to relate the ratio of metal concentrations in two marine bivalves (Crassostrea virginica and Mytilus edulis) to sediment metal concentration. A generalized metal BSAF can be approximated by a simple relationship that is a function of sediment to water column partitioning, the bioconcentration factor (BCF), the depuration rate, the metal assimilation efficiency from food, the bivalve feeding rate, and the growth rate. Analyses of “Mussel Watch” data indicate that the median BSAF across stations varies by about three orders of magnitude from Zn, Cd, and Cu at the highest levels of BSAF = 1 to 10, while Cr has the lowest BSAF at 0.01. Total Hg is about 1.0 and Ni and Pb are approximately 0.1. Calibration of the model indicates that the food route of metal accumulation is significant for all metals but especially for Zn, Cd, Cu, and Hg where virtually all of the observed BSAF is calculated to be due to ingestion of metal from food in the overlying water. These results indicate a potential significance of the metal-binding protein metallothionein, which results in relatively high binding of metal and resulting low depuration rates.

Physiological and biochemical perturbations in Daphnia magna following exposure to the model environmental estrogen diethylstilbestrol

Abstract: The estrogenic properties of many environmental contaminants, such as DDE and PCBs, have been associated with reproductive failure in a variety of vertebrate species. While estrogens have been measured in many invertebrate species, the function of this hormone in invertebrates is controversial. The objective of the present study was to identify possible physiological and biochemical target sites for the estrogenic effects of some xenobiotics on the freshwater crustacean Daphnia magna using the model environmental estrogen diethylstilbestrol (DES). Chronic exposure of daphnids to 0.50 mg/L DES reduced molting frequency among first-generation juveniles and decreased fecundity of second-generation daphnids. Adult first-generation daphnids chronically exposed to DES, as well as adult daphnids acutely exposed to DES for only 48 h, were examined for steroid hormone metabolic capabilities using testosterone as the model steroid. The rate of elimination of two major hydroxylated metabolites of testosterone was significantly reduced, and elimination of glucose conjugates of testosterone was significantly elevated from exposure to 0.50 mg/L DES. These results demonstrate that multigeneration exposure of daphnids to DES results in reduced fecundity and altered steroid metabolic capabilities. Thus, some arthropods, like vertebrates, are sensitive to the effects of endocrine-disrupting chemicals.

Comparative fate of [14C]trichloroethylene in the root zone of plants from a former solvent disposal site

Abstract: A comparison of the environmental fate of [{sup 14}]trichloroethylene ([{sup 14}C]TCE) in vegetated and nonvegetated soils from a contaminated field site indicated increased mineralization ({sup 14}CO{sub 2} production) in soils containing vegetation. Mineralization in soils containing Lespedeza cuneata (Dumont), Pinus taeda (L.), Solidago sp. (all collected from a former chlorinated solvent disposal site), and Glycine max, germinated from commercially available seeds, accounted for > 26% of the total recovered radioactivity compared with approximately 15% for nonvegetated soil and < 9% for control (sterile) soil. Uptake of {sup 14}C into plant tissues ranged from 1 to 21% total for leaves (or needles), stems, and roots and appeared to be related to plant species and water use during the experiment. The higher mineralization rates for [{sup 14}C]TCE in the vegetated soils compared with nonvegetated soils indicates that the rhizosphere provides a favorable environment for microbial degradation of organic compounds. Therefore, vegetation may play an important role in enhancing biological remediation of contaminated surface soils in situ.

Phytotoxicity and accumulation of mercury in tobacco subjected to different exposure routes

Abstract: Experiments were conducted to study the absorption, phytotoxicity, and internal distribution of mercury (Hg) in tobacco plants (Nicotiana miersii) exposed to elemental mercury vapor (Hg[sup 0]) through the shoot or to ionic mercury (Hg[sup 2+]) through the root. Tobacco plants grown hydroponically were exposed to varying Hg[sup 0] treatment concentrations in a specially designed chamber system, examined for visible symptoms of toxicity, and analyzed for Hg content by cold vapor atomic absorption, 1 and 10 d following treatment. In a separate experiment, the roots of hydroponic tobacco plants were exposed to Hg[sup 2+] in the form of a mercury chloride solution and analyzed for growth changes and Hg content. Accumulation, toxicity response, and Hg distribution differed between the two exposure routes, even when internal Hg concentrations in the treated plants were similar. Plants exposed to Hg[sup 0] accumulated Hg in the shoots with no movement to roots. Visible signs of Hg[sup 0] stress were apparent at 1.0 mg/m[sup 3] exposure levels and greater. Root-exposed plants showed accumulation of Hg in the roots with movement to the shoots by day 10. Inhibition of root and shoot growth occurred at treatment levels of 1.0 [mu]g/ml and greater with very limited tissue damagemore » at higher treatment levels.« less

Evaluation of lipid-containing semipermeable membrane devices for monitoring organochlorine contaminants in the Upper Mississippi river

Abstract: Organochlorine contaminants sequestered in lipid-containing semipermeable membrane devices (SPMDs) were compared to those found in tangential-flow ultrafilter permeates as part of a pilot study at 10 sites in the Upper Mississippi River system. Caged and feral fish from three primary sites were also analyzed for comparison. Concentrated organochlorine (OC) compounds were readily extracted from the SPMDs by dialysis into hexane, and samples were analyzed by gas chromatography-negative chemical ionization-mass spectrometry. Fish and water samples were processed by conventional methods. Reasonable agreement was found between analyte SPMD-derived water concentrations and measured values of ultrafilter permeates; however, concentrations of the same analytes in caged fish did not appear to be proportional to water concentrations derived from SPMDs and ultrafilter permeates. The greatest number of OC compounds was detected in SPMDs; fewer were detected in caged fish and feral fish.

Seasonal variation in the mixed-function oxygenase system and antioxidant enzymes of the mussel Mytilus galloprovincialis

Abstract: Seasonal 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 mussel Mytilus galloprovincialis have 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 in the area.

Taxonomic level sufficient for assessing pollution impacts on the southern california bight macrobenthos—revisited

Abstract: Taxonomic sufficiency is the pragmatic concept of identifying organisms only to the taxonomic level necessary and sufficient to meet a study`s objectives. Sufficient taxonomy was determined for detecting differences in macrobenthic taxa richness, a dominance index, and three diversity indices between a reference and two pollution-impacted stations in the Southern California Bight using a wide variety of sampling protocols. A higher taxonomic level was deemed sufficient for a given measure and sampling protocol if the statistical power of t tests performed on data grouped to it was essentially the same as that when tests were performed on data grouped to all lower taxa. The sufficient taxon for the optimum sampling protocol was phylum except when assessing biological stimulation based on differences in mean log{sub 10} (number of taxa) where it was species. Generic dominance and diversity indices were sufficient independent of the sample units tested (0.02, 0.06, and 0.1 m{sup 2}) and sample size (n{ge}2). The authors recommend family-level identification of specimens collected using the optimum sampling protocol when assessing macrobenthic community impacts in the study area because familial analyses are very likely to be sufficient. Confounding effects of sampling variables need to be accounted for when determining the truemore » cost efficiency of and the underlying reason(s) for the sufficiency of higher taxonomy.« less

Uptake, bioavailability and elimination of hydrophobic compounds in earthworms (Eisenia andrei) in field-contaminated soil.

Abstract: Uptake, accumulation, and elimination of hydrophobic organic chemicals in earthworms (Eisenia andrei) exposed to field-contaminated Volgermeerpolder soil was studied Earthworms were able to take up chlorobenzenes and polychlorobiphenyls (PCBs), but body burdens did not exceed concentrations measured in the soil For the chlorobenzenes, steady state concentrations in the worms and biota to-soil accumulation factor (BSAF) values were much smaller than expected based on earlier experiments, suggesting a decreased bioavailability in the Volgermeerpolder soil Comparison of the PCB accumulation pattern in worms to the pattern in soil showed that biotransformation of the studied PCBs is of minor importance in this species Elimination of all chemicals studied was monophasic, with the exception of hexachlorobenzene, which showed a biphasic elimination The elimination half life for the initial fast phase of this compound is comparable to the elimination measured in previous studies Elimination rate constants decreased with increasing log Kow

Effect of surfactant addition on phenanthrene biodegradation in sediments

Abstract: A laboratory study was conducted to determine whether commercial surfactants enhance the bioremediation of PAH-contaminated sediments. Phenanthrene was chosen as a representative PAH; an inoculum of PAH-degrading microorganisms, enriched from an aquatic sediment, was used in sediment-water slurry microcosm biodegradation experiments. Of seven non-ionic surfactants tested, only one (Triton X-100) did not inhibit phenanthrene mineralization at concentrations above the critical micelle concentration (CMC). Temporal studies on Triton X-100 revealed that while it initially inhibited mineralization in sediment-free microcosms, after 1 week Triton X-100 slightly improved phenanthrene biotransformation and mineralization in microcosms with and without sediment. For all treatments, phenanthrene disappearance was complete after 9 d, and mineralization reached 50 to 65% after 12 d. Sorption to the sediment appears to have reduced the free aqueous surfactant concentration, thereby reducing surfactant toxicity to the microorganisms. These results suggest that many surfactants are toxic to PAH-degrading microorganisms, and while surfactant addition may not always have adverse effects on biodegradation, the use of surfactants might not be desirable to achieve complete contamination removal.

Organotins in freshwater harbors and rivers: Temporal distribution, annual trends and fate

Abstract: The occurrence of butyltin and phenyltin compounds in water, mussels, and sediment of freshwater boat harbors of Lake Lucerne, Switzerland, and six Swiss river systems was determined between 1991 and 1993 following the sales ban of organotin-containing antifouling paints. In harbor waters, average levels of tributyltin (TBT) were between 40 and 50 ng/L in 1993, which was one order of magnitude lower than in 1988. Residues of up to 9.2 μg/g TBT and 0.7 μg/g triphenyltin (TPT) occurred in zebra mussels (Dreissena polymorpha) and were related to the water concentrations. In a sediment core, high levels of TBT and TPT occurred in the upper 7 cm and 5.5 cm, respectively, with significant decreases below. Estimated sedimentation rates and the fact that transformation products did not increase with depth indicate that TBT and TPT are persistent in these sediments. In all rivers, di- and/or monobutyltin of up to 46 ng/L occurred consistently, and occasionally TBT and TPT of up to 26 and 11 ng/L, respectively. This study indicates that even though regulations were effective in reducing TBT and TPT levels in boat harbor water, contamination of surface fresh waters including rivers by organotin compounds is still widespread and has ecotoxicological consequences. Moreover, harbor sediments represent long-term reservoirs of these compounds.

The role of acid‐volatile sulfide and interstitial water metal concentrations in determining bioavailability of cadmium and nickel from contaminated sediments to the marine polychaete Neanthes arenaceodentata

Abstract: This 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 1.0, 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 <1.0 TU was used.