bluuebunny/crossref_metadata_2025 huggingface dataset:
Variables determining the impact of diazinon on aquatic insects: Taxon, developmental stage, and exposure time
Authors: Stuijfzand Suzanne C , Poort Liesbeth , Greve Gerdit D , van der Geest Harm G , Kraak Michiel H S
Published: March 2010

Several variables determine the impact of a pesticide onaquatic invertebrates. In this study, aquatic insects weresubjected to the common insecticide diazinon; we analyzed the variables taxon, developmental stage, and exposure time. Effects of diazinon on the caddis fly Hydropsyche angustipennis and the midge Chironomus riparius were determined in the laboratory during different exposure times (48 and 96 h) using mortality, activity, and growth as end points. Last instars of both species displayed a clear behavioral response at concentrations much lower than those affecting survival. Doubling the exposure time from 2 to 4 d decreased survival of midges and caddis flies by a factor 1.4 to 8.4. The 96-h 50% lethal concentrations were: 1.3 μg/L (first instar of the caddis fly), 29 μg/L (fifth instar of the caddis fly), 23 μg/L (first instar of the midge) and 167 μg/L (fourth instar of the midge). Within the spectrum of tested insects (nine species for which 48-h 50% lethal concentrations have been reported in the literature), H. angustipennis is the second most sensitive, and C. riparius the most tolerant species. However, the ranking of species strongly depends on the developmental stage; differences between species are often smaller than differences between instars of one species. The large difference in sensitivities between young and old larvae imply that the impact of a pesticide strongly depends on the season of occurrence. Runoff from pesticide applications on crops is more likely to occur in spring and summer and may have a relatively greater impact on insect communities since young larvae prevail in these seasons. In addition, recovery of typical riverine insects such as H. angustipennis from incidental exposure will be slow, considering their relatively long life cycle.
Accumulation of silver from the diet in two marine benthic predators: The snow crab (Chionoecetes opilio) and American plaice (Hippoglossoides platessoides)
Authors: Rouleau Claude , Gobeil Charles , Tjälve Hans
Published: March 2010

The kinetics and fine-scale tissue distribution of a single dose of 110mAg ingested with food were determined in snow crab and American plaice through the techniques of in vivo gamma counting and whole-body autoradiography. Metal that was retained after the first 3 d was distributed in all the soft tissues of snow crab, whereas it concentrated in gut, liver, and gallbladder of the American plaice. In snow crab, the biological half-life of retained Ag, which represented 67–100% of the ingested dose, was greater than 1000 d. In contrast, in American plaice the retained fraction represented only 4–16% of the ingested dose and the biological half-life ranged from 13 to 102 d. Modeling the trophic accumulation of Ag for snow crab and American plaice living in the St. Lawrence Estuary, assuming realistic values for food ingestion rates and Ag concentration in benthic organisms of lower trophic levels, reveals that continuous feeding on Ag-contaminated prey would result in much higher metal levels in the snow crab than in the American plaice. Measurement of Ag concentrations in snow crab and American plaice from the St. Lawrence Estuary, an environment receiving significant inputs of anthropogenic Ag, confirmed this prediction. The similarity between laboratory-based predictions and field data strongly suggests that predation is the major transfer route of Ag towards these marine benthic predators.
Dose-dependent stimulation of hepatic retinoic acid hydroxylation/oxidation and glucuronidation in brook trout,Salvelinus fontinalis, after exposure to 3,3′,4,4′-tetrachlorobiphenyl
Authors: Boyer Patrick M , Ndayibagira Aristocle , Spear Philip A
Published: March 2010

Extremely low stores of vitamin A have been reported in fish and birds inhabiting regions contaminated by coplanar polychlorinated biphenyls (PCBs) and other organochlorines, suggesting many possible effects on retinoid biochemical pathways. Metabolic imbalances associated with biologically active retinoids (e.g., retinoic acid) could be associated with teratogenesis, edema, growth inhibition, reproductive impairment, immunosuppression, and susceptibility to cancer. Sexually mature brook trout were injected intraperitoneally with the coplanar PCB 3,3′,4,4′-tetrachlorobiphenyl (TCBP) and again 4 weeks later. At 8 weeks, retinoic acid metabolism was measured in liver microsomes. To our knowledge, retinoic acid conjugation by UDP-glucuronyltransferase is described here for the first time in fish. A substantial rate of glucuronidation was detected in the microsomes from control brook trout, which tended to increase over the dose range of TCBP. Glucuronidation was significantly greater in fish receiving the 10 μg/g body weight dose level. Metabolism through the cytochrome P450 system was also dose-dependent, resulting in significantly greater production of 4-hydroxyretinoic acid at the 10 μg/g dose level. In contrast, subsequent oxidation to 4-oxo-retinoic acid was greatest at the 1 μg/g dose level and did not increase further at higher doses. Liver stores of dehydroretinyl palmitate/oleate were significantly decreased at the 5 and 10 μg/g dose levels.
Genetic indicators of herbicide stress in the pacific oyster Crassostrea gigas under experimental conditions
Authors: Moraga Dario , Tanguy Arnaud
Published: March 2010

This study examined use of the oyster Crassostrea gigas as a bioindicator of experimental pollution caused by two concentrations of five pesticides (atrazine, isoproturon, alachlore, metolachlore, and diuron) used in agricultural and urban activities. The effect of these pesticides on the genetic structure of the marine bivalve was studied as part of an environmental biomonitoring project. This research was performed on two natural estuarine populations sampled along the French Atlantic coast as part of an ongoing monitoring program to survey the ecosystem of Brittany using two approaches: identifying the genetic markers based on the alleles and genotypes associated with pollution effects, and searching for a correlation between these markers and the sensitivity or tolerance of individuals under stress conditions. Results indicate a differential survival of individuals subjected to the various pollutants examined. The sensitivity of alleles and genotypes to environmental stress can be assessed based on the significant differences in allele and genotype frequencies observed between resistant and sensitive individuals when subjected to the pesticides. This genetic study included examination of five enzyme systems (Ak, Pgi, Cap, Pgm, and Mdh) involved in physiologic processes. A total of six alleles and five genotypes at three loci (Ak, Pgi, and Pgm) were identified as being markers of resistance or sensitivity. It is hypothesized that these markers could be used as potential genetic markers in estuarine ecosystem monitoring.
Evaluating multimedia chemical persistence: Classification and regression tree analysis
Authors: Bennett Deborah H , McKone Thomas E. , Kastenberg William E
Published: March 2010

For the thousands of chemicals continuously released into the environment, it is desirable to make prospective assessments of those likely to be persistent. Widely distributed persistent chemicals are impossible to remove from the environment and remediation by natural processes may take decades, which is problematic if adverse health or ecological effects are discovered after prolonged release into the environment. A tiered approach using a classification scheme and a multimedia model for determining persistence is presented. Using specific criteria for persistence, a classification tree is developed to classify a chemical as “persistent” or “nonpersistent” based on the chemical properties. In this approach, the classification is derived from the results of a standardized unit world multimedia model. Thus, the classifications are more robust for multimedia pollutants than classifications using a single medium half-life. The method can be readily implemented and provides insight without requiring extensive and often unavailable data. This method can be used to classify chemicals when only a few properties are known and can be used to direct further data collection. Case studies are presented to demonstrate the advantages of the approach.
Effect of metal complexation on the degradation of dithiocarbamate fungicides
Authors: Weissmahr Kenneth W , Sedlak David L
Published: March 2010

When dithiocarbamate fungicides are released to the environment, it is assumed that they degrade within days to weeks via acid-catalyzed hydrolysis. However, the formation of complexes between dithiocarbamates and trace elements can slow transformation reactions. Experiments performed with a component of the fungicide Ziram, dimethydithiocarbamate (DMDC), indicate that complexation by cadmium, copper, or zinc inhibit acid-catalyzed hydrolysis. Evaluation of the stability constant for the complexes between the metal and DMDC indicate that copper is the only metal that is most likely to inhibit the transformation reactions under conditions encountered in the environment. Measurement of the transformation of DMDC and ethylenebis(dithiocarbamate) (EBDC) in the presence of trace amounts of Cu(II) yielded half lives greater than 2 weeks, irrespective of pH. Experiments performed in surface water samples indicate that, when DMDC is discharged to natural waters in an uncomplexed form, it may not be stabilized by the Cu(II) present in the water, possibly because natural organic matter outcompetes DMDC for Cu(II). When DMDC is complexed by Cu(II) before it is released to natural waters, the compound is more persistent because acid-catalyzed hydrolysis is inhibited.
A novel laboratory system for determining fate of volatile organic compounds in planted systems
Authors: Orchard Brady J , Doucette William J , Chard Julie K , Bugbee Bruce
Published: March 2010

Contradictory observations regarding the uptake and translocation of volatile organic compounds (VOCs) by plants have been reported, most notably for trichloroethylene (TCE). Experimental artifacts resulting from the use of semistatic or low-flow laboratory systems may account for part of the discrepancy. Innovative plant growth chambers are required to rigorously quantify the movement of VOCs through higher plants while maintaining a natural plant environment. The plant must be sealed in a chamber that allows rapid exchange of air to remove the water vapor lost in transpiration, to resupply the CO2 consumed in photosynthesis, and to resupply the O2 consumed in root-zone respiration. Inadequate airflow through the foliar region results in high humidity, which dramatically reduces transpiration and may reduce contaminant flux. Oxygen depletion in static root zones induces root stress, which can increase root membrane permeability. The root zone must be separated from the shoots to differentiate between plant uptake and foliar deposition. Here we describe the design, construction, and testing of a dual-vacuum, continuous high-flow chamber system for accurately determining the fate of VOCs in plants. The system provides a natural plant environment, complete root/shoot separation, the ability to quantify phytovolatilization and mineralization in both root and shoot compartments, continuous root-zone aeration, and high mass recovery.
Short-term effects of linear alkylbenzene sulfonate on freshwater plankton studied under field conditions
Authors: Jørgensen Erik , Christoffersen Kirsten
Published: March 2010

The toxic effects of linear alkylbenzene sulfonate (LAS) on several planktonic freshwater organisms were studied over a 5-d period using small in situ enclosures. The experimental setup, an unreplicated regression design, made it possible to calculate no effect concentrations (NEC), an environmental risk assessment. The NEC varied several orders of magnitude between the different groups of organisms, with ciliates and heterotrophic nanoflagellates being the most sensitive groups (NEC as low as 0.02 mg LAS/L). The high sensitivity of the protozoans makes their exclusion from most ecotoxicological studies questionable, and this must be reconsidered in the future. Most other planktonic organisms were only affected at concentrations higher than normally found in aquatic habitats. Exceptions to this general trend were the photosynthetic activity of the phytoplankton and cryptophyte abundance, which both were nearly as sensitive parameters as the protozoan abundance. The toxicity of LAS was generally higher in the present investigation, compared with the vast majority of laboratory-derived results, indicating a limited relevance of the latter and the need for field experiments in order to determine impacts of xenobiotics in the aquatic environments.
Tolerance and genetic relatedness of three meiobenthic copepod populations exposed to sediment-associated contaminant mixtures: Role of environmental history
Authors: Kovatch Charles E , Schizas Nikolaos V , Chandler G. Thomas , Coull Bruce C , Quattro Joseph M
Published: March 2010

Meiobenthic copepod populations (Microarthridion littorale) were collected from three South Carolina, USA, estuaries having different pollution stress histories (i.e., pristine sediments, high polycyclic aromatic hydrocarbon [PAH] sediments, high metals/moderate PAH sediments) and then assayed for survival and reproductive output in 14-d exposures to pristine and heavily PAH/metals-contaminated sediments. Whole-sediment reproduction bioassays were used to determine whether copepods exposed to a highly contaminated sediment mixture exhibited differential survival and reproductive outputs as a function of previous environmental histories and whether genetic relatedness among populations measured as DNA sequences of the mitochondrial gene, cytochrome apoenzyme b, were linked to copepod contaminant tolerance. Overall, adult survival and reproductive success in contaminated sediments were significantly reduced relative to controls for all three populations irrespective of environmental histories. Differential resistance to sediment-contaminant mixtures by the two copepod populations inhabiting the contaminated sites was not found, despite their previous exposures to mixed contaminants at ΣPAH and ΣMetal concentrations of 7,287 to 2,467 ng/g dry wt and 461 to 3,497 μg/g, respectively. Significant genetic differentiation, however, was found between copepod populations from the control and the two contaminated sites. Generally, cross-population survival and reproductive outputs were not significantly different and could not be linked to genetic differentiation at the population level.
Assessment of the photoenhanced toxicity of a weathered oil to the tidewater silverside
Authors: Little Edward E , Cleveland Laverne , Calfee Robin , Barron Mace G
Published: March 2010

Studies were conducted to determine the interactive toxicity of a water-accommodated fraction (WAF) of a weathered middle distillate petroleum and solar radiation to an estuarine organism, the tidewater silverside (Menidia beryllina). Juvenile silversides were monitored for survival and growth during a 7-d static renewal exposure to dilutions of WAFs of an environmentally weathered oil collected in the vicinity of an abandoned oil field in California. Ultraviolet (UV) treatments were based on incident sunlight intensity and spectra measured at this site. Exposure to UV alone was not lethal to the fish, and WAF in the absence of UV was toxic at the highest total petroleum hydrocarbon (TPH) concentration (3.03 mg/L) after 96 h of exposure. Water-accommodated fractions toxicity increased significantly with increasing UV irradiance and duration of exposure. The 7-d LC50 concentrations for the control, low, medium, and high irradiance were 2.84, 1.27, 0.93, and 0.51 mg/L TPH, respectively. Significant mortality occurred among fish previously exposed to WAF in the absence of irradiance, whereas WAF toxicity was unaffected by UV exposure prior to the toxicity test. Thus, the mode of action is a photosensitization of the accumulated petroleum residue rather than a photoactivation of WAF. Chemical analysis indicates that the WAF contains limited amounts of polycyclic aromatic hydrocarbons (PAHs) known to be photoenhanced, suggesting that other constituents may be responsible for the observed photoenhanced toxicity.
Alterations in prey capture and induction of metallothioneins in grass shrimp fed cadmium-contaminated prey
Authors: Wallace William G , Brouwer Thea M. Hoexum , Brouwer Marius , Lopez Glenn R
Published: March 2010

The aquatic oligochaete Limnodrilus hoffmeisteri from a Cd-contaminated cove on the Hudson River, Foundry Cove, New York, USA, has evolved Cd resistance. Past studies have focused on how the mode of detoxification of Cd by these Cd-resistant worms influences Cd trophic transfer to the grass shrimp Palaemonetes pugio. In the present study, we investigate reductions in prey capture in grass shrimp fed Cd-contaminated prey. We also investigate the induction of metal-binding proteins, metallo-thioneins, in these Cd-exposed shrimp. Grass shrimp were fed field-exposed Cd-contaminated Foundry Cove oligochaetes (for 1 week) or laboratory-exposed Cd-contaminated Artemia salina (for 1 or 2 weeks). Following these exposures, the ability of Cd-dosed and control shrimp to capture live A. salina was compared. Results show that shrimp fed laboratory-exposed Cd-contaminated A. salina for 2 weeks exhibit significant reductions in their ability to successfully capture prey (live A. salina). Reductions in prey capture were also apparent, though not as dramatic in shrimp fed for 1 week on field-exposed Cd-contaminated Foundry Cove oligochaetes. Shrimp were further investigated for their subcellular distribution of Cd to examine if alterations in prey capture could be linked to saturation of Cd-metallothionein. Cd-dosed shrimp produced a low molecular weight (∼10,000 daltons) Cd-binding metallothionein protein in a dose- and time-dependent manner. Most importantly, successful prey capture decreased with increased Cd body burdens and increased Cd concentration bound to high molecular weight proteins (i.e., enzymes).
Development of a toxicity identification evaluation procedure for characterizing metal toxicity in marine sediments
Authors: Burgess Robert M , Cantwell Mark G , Pelletier Marguerite C , Ho Kay T , Serbst Jonathan R , Cook Howard F , Kuhn Anne
Published: March 2010

A multiagency effort is underway to develop whole sediment toxicity identification evaluation (TIE) methods. Whole sediment TIE methods will be critical tools for characterizing toxicity at hazardous waste sites (e.g., Superfund sites) and in the conduct of environmental risk assessments. The research approach is based on the predominance of three classes of toxicants in sediments: ammonia, nonpolar organic chemicals, and metals. Here we describe a procedure for characterizing acute toxicity caused by metals in whole marine sediments. The procedure involves adding a chelating resin to sediments, resulting in the sequestration of bioavailable metal while not stressing testing organisms. Within the testing chambers, the presence of resin resulted in statistically significant reductions in the overlying and interstitial water concentrations of five metals (cadmium, copper, nickel, lead, and zinc) generally by factors of 40 and 200. Toxicity to both the amphipod Ampelisca abdita and mysid Americamysis bahia (formerly Mysidopsis bahia) of sediments spiked with the five metals was decreased by approximately a factor of four when resin was present. While very effective at reducing the concentrations and toxicity of metals, the resin has only minor ameliorative effects on the toxicity of ammonia and a representative nonpolar toxicant (Endosulfan). Resin and accumulated metal were easily isolated from the testing system following exposures allowing for the initiation of phase II TIE (identification) procedures. This procedure using the addition of a chelating resin provides an approach for determining the importance of metals to the toxicity of marine sediments. Work is continuing to validate the method with environmentally contaminated sediments.
Critical body residues in the marine amphipodAmpelisca abdita: Sediment exposures with nonionic organic contaminants
Authors: Fay Amanda A , Brownawell Bruce J , Elskus Adria A , McElroy Anne E
Published: March 2010

Body residues associated with acute toxicity were determined in the marine amphipod Ampelisca abdita exposed to spiked sediments. Nonylphenol and 2,2′,4,4′-tetrachlorobiphenyl critical body residues (CBRs, body residue of contaminant at 50% mortality) were 1.1 μmol/g wet tissue and 0.57 μmol/g wet tissue, respectively, values near the low end of the CBR range expected for compounds acting via narcosis. The polycyclic aromatic hydrocarbons tested, benzo[a]pyrene (BaP) and benz[a]anthracene (BaA), were not acutely toxic at exposure concentrations of up to 43 and 1,280 μg/g dry sediment for BaA and BaP respectively, and body burdens up to 1.2 μmol/g wet tissue (for BaP). Neither polycyclic aromatic hydrocarbon (PAH) was significantly metabolized by A. abdita. The microextraction technique employed here allowed residue analysis of samples containing as few as three amphipods (0.33 mg dry wt). The CBR approach avoids confounding factors such as variations in bioavailability and uptake kinetics and could be employed to assess the relative contribution of specific contaminants or contaminant classes in mixtures to effects observed in toxicity tests with Ampelisca and other organisms.
Predicting the probability of detecting organochlorine pesticides and polychlorinated biphenyls in stream systems on the basis of land use in the Pacific Northwest, USA
Authors: Black Robert W , Haggland Alan L , Voss Frank D
Published: March 2010

We analyzed streambed sediment and fish tissue (Cottus sp.) at 30 sites in the Puget Sound and Willamette basins in Washington and Oregon, USA, respectively, for organochlorine pesticides and polychlorinated biphenyls (PCBs). The study was designed to determine the concentrations of organochlorine pesticides and PCBs in fish tissue and sediment by land use within these basins and to develop an empirical relation between land use and the probability of detecting these compounds in fish tissue or sediment. We identified 14 organochlorines in fish tissue and sediment; three compounds were unique to either fish tissue or sediment samples. The highest number of organochlorines detected in both fish tissue and streambed sediment was at those sites located in watersheds dominated by urban land uses. Using logistic regression, we found a significant relation between percentage agriculture and urban land use and organochlorines in fish tissue. The results of this study indicate that organochlorine pesticides and PCBs are still found in fish tissues and bed sediments in these two basins. In addition, we produced statistically significant models capable of predicting the probability of detecting specific organochlorines in fish on the basis of land use. Although the presented models are specific to the two study basins, the modeling approach could be applied to other basins as well.
Design criteria and derivation of indicators for ecological position, direction, and risk
Authors: Landis Wayne G. , McLaughlin John F
Published: March 2010

The baseline specifications for indicators for ecological risk assessment and management are presented. These indicators may be related to the assessment space as determined by cultural values and laws. This assessment space is a multivariate expression of the assessment endpoints. The three types of indicators include current position, the probability of leaving the assessment space, and the probability of reentering the assessment space. The formulation of indicators must recognize that ecological systems are dynamically complex and composed of both deterministic and stochastic components. As has been demonstrated in laboratory ecological systems and field experiments, the best impact indicators change over time, eliminating the possibility of a single variable being an accurate measure of position and change. We set six specific requirements for developing a useful set of indicators, as follows. The indicators must be placed in the context of the assessment space. Because projections cause the loss of information, a variety of methods with different assumptions about the nature of the system should be used. The best attributes to measure alteration of the system change over time; to use just one set may result in missing the dynamic complexity of the system and subsequent impacts. Ecological systems are both deterministic and stochastic, and representation of each is important. The stochastic component can have a tremendous impact, changing the overall dynamics. Spatial context is critical in making accurate predictions and must be known.
Assessing ecological risk in watersheds: A case study of problem formulation in the Big Darby Creek watershed, Ohio, USA
Authors: Cormier Susan M , Smith Marc , Norton Sue , Neiheisel Tim
Published: March 2010

The Big Darby Creek watershed, a highly valued ecosystem in central Ohio, USA, threatened by intensive agriculture and suburban encroachment, served as an example of how case specifics can be applied to refine and direct the planning and problem formulation stage of the U.S. Environmental Protection Agency's ecological risk assessment framework. Big Darby Creek was selected as one of five national pilot risk assessments designed to provide specific examples of how to perform an ecological risk assessment and, at the same time, to refine and improve the assessment process. The case study demonstrates how characteristics of the watershed were used to give direction to the components of establishing goals, identifying and characterizing the resource and threats to it, selecting appropriate assessment endpoints, and developing conceptual models. The hypotheses generated in the conceptual model describe expected relationships and interactions between the ecosystem at risk, identified potential stressors, and ecological effects and set the groundwork for the analysis phase that follows problem formulation.
A weight-of-evidence approach for Northern river risk assessment: Integrating the effects of multiple stressors
Authors: Lowell Richard B , Culp Joseph M , Dubé Monique G
Published: March 2010

Northern river ecosystems are subject to a variety of stressors having multifaceted (and sometimes opposing) effects, making interpretation at a regional scale difficult. We have addressed this problem by using a weight-of-evidence approach that combines analysis of field data (to determine patterns) with experimental hypothesis testing (to determine mechanisms). Two of the more important sources of aquatic impacts in western Canada are pulp mill and municipal effluents. Their regional impacts on benthic biota were evaluated for two major river systems, the Thompson and Athabasca rivers, using an integrative approach. In the more southerly Thompson River, several lines of evidence (including field and laboratory experiments, field sampling over a 20-year period, and isotopic analysis) led to the conclusion that, although some toxic effects were apparent, these effects were usually masked by the (sometimes excessive) nutrient enhancement effects of these effluents, sometimes via novel pathways. Furthermore, analysis of the data revealed a fairly delicate balance in effluent treatment involving trade-offs between the negative effects of toxic contaminant loading versus a switch to a more eutrophic community. In the more northerly Athabasca River, effluent effects can be modified by the added impact of another stressor: widespread winter freeze-up, which prevents reaeration of oxygen-depleted waters, coupled with low dissolved oxygen levels in the substratum where benthic invertebrates are found, resulting in a net shift in effluent effect from one of nutrient enhancement to a more inhibitory effect. Advantages to applying formalized causal criteria, as outlined in this weight-of-evidence approach, include helping to tie together diverse assemblages of data on the effects of multiple stressors and identifying important informational gaps, thus making ecological risk assessments more rigorous and robust.
Degradation and impact of phthalate plasticizers on soil microbial communities
Authors: Cartwright Colin D , Thompson Ian P , Burns Richard G
Published: March 2010

To assess the impact of phthalateson soil microorganismsand to supplement the environmental risk assessment for these xenobiotics, soil was treated with diethyl phthalate (DEP) or di (2-ethyl hexyl) phthalate (DEHP) at 0.1 to 100 mg/g. Bioavailability and membrane disruption were proposed as the characteristics responsible for the observed fate and toxicity of both compounds. Diethyl phthalate was biodegraded rapidly in soil with a half-life (t50 deg) of 0.75 d at 20°C, and was not expected to persist in the environment. The DEHP, although biodegradable in aqueous solution (t50deg < 15 d at 20°C), was recalcitrant in soil, because of poor bioavailability (only 10% degraded by 70 d at 20°C) and was predicted to account for the majority of phthalate contamination in the environment. Addition of DEP or DEHP to soil at a concentration similar to that detected in nonindustrial environments (0.1 mg/g) had no impact on the structural diversity (bacterial numbers, fatty acid methyl ester analysis) or functional diversity (BIOLOG) of the microbial community. At concentrations representative of a phthalate spill, DEP (>1 mg/g) reduced numbers of both total culturable bacteria (by 47%) and pseudomonads (by 62%) within 1 d. This was due to disruption of membrane fluidity by the lipophilic phthalate, a mechanism not previously attributed to phthalates. However, DEHP had no effect on the microbial community or membrane fluidity, even at 100 mg/g, and was predicted to have no impact on microbial communities in the environment.
Toxicity of tri-n-butyltin to sea urchin eggs and larvae: Relation to bioaccumulation at the nanomolar level
Authors: Girard Jean-Pierre , Szpunar Joanna , Pedrotti Maria-Luiza , Pesando Danielle
Published: March 2010

Nnomolar concentrations of tri- n-butyltin (TBT) from 5 × 10−10 M to 5 × 10−9 M, were assayed on sea urchin (Paracentrotus lividus) egg cleavage and on larval development. Preincubation enhanced TBT toxicity to first cleavage DNA and protein syntheses but not to intracellular calcium sequestration. Exposure to nanomolar TBT affected the larval development up to the ninth day by reducing arm length and increasing the diameter of the rudiment. Chromatographic analysis of TBT in eggs shows a dose-dependent biomagnification with a half-time of 5 min, which is much shorter than the length of preincubation necessary to provoke cytotoxicity at the same concentration (5 × 10−9 or 5 × 10−10 M). Our data suggest that nanomolar concentrations of TBT similar to those encountered in polluted waters could directly affect sea urchin egg development after fertilization and the larval cycle, these effects being independent of bioaccumulation.
Assessing the potential toxicity of resuspended sediment
Authors: Bonnet Corinne , Babut Marc , Férard Jean-François , Martel Louis , Garric Jeanne
Published: March 2010

Two moderately contaminated freshwater sediments (Sorel Harbour, St. Lawrence River, Canada) were subjected to a suspension event. The objective was to assess the environmental impact of the disposal of dredged material in water, in particular, the short-term effects of dumping on the water column and the long-term effects of dredged sediment deposits. In a series of microcosms, the sediments were left to stand for 25 d under flow-through conditions (reference conditions). In a second series of microcosms, sediments were vigorously suspended for 15 min before being left to settle and were submitted to the same treatment as reference sediments during the following 25 d. Physicochemical and biological parameters (Daphnia magna and Hydra attenuata survival) were measured in overlying water throughout the experiment. Sediment toxicity was assessed with Chironomus tentans and Hyalella azteca exposed to sediments collected at both the beginning and end of the 25-d period. Pore-water toxicity was evaluated with D. magna. During the suspension process, in the Sorel Harbour mixed sediment overlying water, we observed effects on H. attenuata survival and ammonia and metals (chromium, copper, and zinc) releases. Meanwhile, in reference (nonmixed) and mixed sediments as well as in associated pore waters, there were no significant chemical modifications nor biological effects after the 25-d experiments. The developed approach, which attempts to simulate a dumping process, aims at allowing the assessment of the short- and long-term hazards resulting from a resuspension process in overlying water and in resettled sediments using both chemical and biological measurements.
Metabolism of fluoranthene in different plant cell cultures and intact plants
Authors: Kolb Marit , Harms Hans
Published: March 2010

The metabolism of fluoranthene was investigated in 11 cell cultures of different plant species using a [14C]-labeled standard. Most species metabolized less than 5% of fluoranthene to soluble metabolites and formed less than 5% nonextractable residues during the standardized 48-h test procedure. Higher metabolic rates were observed in lettuce (Lactuca sativa, 6%), wheat (Tricitum aestivum, 9%), and tomato (Lycopersicon esculentum, 15%). A special high metabolic rate of nearly 50% was determined for the rose species Paul's Scarlet. Chromatographic analysis of metabolites extracted from aseptically grown tomato plants proved that the metabolites detected in the cell cultures were also formed in the intact plants. Metabolites produced in tomato and rose cells from [14C]-fluoranthene were conjugated with glucose, glucuronic acid, and other cell components. After acid hydrolyses, the main metabolite of both species was 1-hydroxyfluoranthene as identified by gas chromatography–mass spectrometry and high-performance liquid chromatography with diode array detection. The second metabolite formed by both species was 8-hydroxy-fluoranthene. A third metabolite in tomatoes was 3-hydroxyfluoranthene.
Monitoring wading bird exposure to agricultural chemicals using serum cholinesterase activity
Authors: Parsons Katharine C , Matz Angela C , Hooper Michael J , Pokras Mark A
Published: March 2010

Oganophosphorus (OP) and carbamate (CB) insecticidesare widely used and havea variety of lethal and sublethal effects on nontarget wildlife, primarily through cholinesterase (ChE) inhibition. To assess possible exposure to anti-ChE compounds in wading birds, we monitored breeding colonies in northeast U.S. estuaries (Boston Harbor, MA; New York Harbor, NY; Nantucket Sound, MA; Delaware Bay, DE; and Rehoboth Bay, DE) from 1991 to 1996. We documented serum ChE activities in black-crowned night-heron (Nycticorax nyticorax), cattle egret (Bubulcus ibis), snowy egret (Egretta thula), little blue heron (E. caerulea), and glossy ibis (Plegadis falcinellus), and we investigated factors known to affect ChE, including age, nutritional and immune status, location of the colony (estuary), and exposure to ChE-inhibiting compounds. Exposure to anti-ChE compounds in all species was supported by at least one of the following: positive pyridine-2-aldoxime methochloride (2-PAM; OP) and/or spontaneous (CB) ChE reactivations, negative or nonsignificant age correlations in most species, or regional land-use patterns. We observed negative or nonsignificant relationships between ChE and age in most species. Only glossy ibis showed the age-related patterns of ChE activity observed in other altricial species. Of the remaining potential explanatory factors, location (estuary) but not nutritional or immune status was the only one having a significant relationship with ChE activity (p < 0.024). Significant differences among colonies were consistent with surrounding land uses, specifically active agriculture. We conclude that extensive monitoring of serum ChE in wildlife can identify locations of exposure and provide reference data for wildlife pesticide-risk assessment.
Genotype and toxicity relationships amongHyalella azteca: II. Acute exposure to fluoranthene-contaminated sediment
Authors: Duan Yihao , Guttman Sheldon I , Oris James T , Huang Xiaodong , Burton G Allen
Published: March 2010

This study examined the genotypic responses of Hyalella azteca to the toxicity of sediment contaminated by the polycyclic aromatic hydrocarbon (PAH) fluoranthene. We monitored the time to death for 696 H. azteca exposed to ultraviolet light and sediment spiked with fluoranthene. The survival distribution functions within the genotypes at each of three variable allozyme loci (acid phosphatase [ACP*], glucose-6-phosphate isomerase [GPI*], and phosphoglucomutase [PGM*]) were compared using a log-rank test. Results showed significant differences among SDFs at all three loci. No association of heterozygosity with time to death was observed. The homozygote ACP*-CC was associated with decreased survivorship compared with ACP*-AA, ACP*-BB, and ACP*-AB. However, GPI*-AA was associated with increased survivorship compared with GPI*-BB, GPI*-CC, and GPI*-BC. Significant differences in resistance also were observed for PGM*-BB versus either PGM*-AC or PGM*-BC. These results indicate that differential resistance to PAH phototoxicity was genetically related, producing significant alteration in the frequencies of several genotypes in the population.
Characterizing aquatic ecological risks from pesticides using a diquat dibromide case study III. Ecological process models
Authors: Bartell Steven M , Campbell Kym Rouse , Lovelock Cynthia M , Nair Shyam K , Shaw Jennifer L
Published: March 2010

The purpose of this study was to add to the set of risk characterization approaches developed in an earlier study beyond simple comparisons of exposure and effects (e.g., quotients, overlapping frequency distributions) through use of ecological models. These models were used to evaluate the ecological risks from diquat dibromide for individual Daphnia using an individual-oriented model, a population of bluegill sunfish (Lepomis macrochirus) using a demographic model, and ecological communities within a generic lake in Central Florida, USA, using the Comprehensive Aquatic Systems Model. The ecological models presented in this study more realistically address the potential risks posed by pesticides to individual organisms, populations, communities, and ecosystems than risk assessment methods based on simple comparisons of exposure and effects. The ecological impacts calculated by these models support the inference of minimal risks being posed by diquat dibromide to aquatic systems as concluded from previous empirical comparisons of exposure and toxicity data.
Different sensitivity to organophosphates of acetylcholinesterase and butyrylcholinesterase from three-spined stickleback (Gasterosteus aculeatus): Application in biomonitoring
Authors: Sturm Armin , Wogram Jörn , Segner Helmut , Liess Mathias
Published: March 2010

Different cholinesterases from brain and body muscle of the fish three-spined stickleback (Gasterosteus aculeatus) were investigated concerning their potential use in the biomonitoring of organophosphate insecticides (OPs). Stickleback brain contained acetylcholinesterase (AChE) but no butyrylcholinesterase (BChE). Body muscle contained both AChE and BChE. In vitro, body muscle BChE was three orders of magnitude more sensitive than brain or body muscle AChE to the OPs paraoxon and dichlorvos. In 1998, cholinesterase activities were recorded in stickleback from eight streams differing in pesticide contamination. Automated on-site samplers that selectively collect water during runoff events were used to obtain water samples for pesticide analysis. The OP parathion was found in stream water sampled during runoff events in five cases. The variation of brain and body muscle AChE activity between streams was not related to water contamination by pesticides. Body muscle BChE was strongly decreased (>85%) in stickleback collected at all streams with previous parathion contamination events. A significant decrease in BChE (78%) occurred also, however, at one stream where other pesticides but no OPs were found. Because stickleback AChE and BChE differed strongly in their in vitro sensitivity and their response in the field, these enzymes should be considered separately in studies with fish.
Relative importance of calcium and magnesium in hardness-based modification of copper toxicity
Authors: Welsh Paul G , Lipton Joshua , Chapman Gary A , Podrabsky Tracy L
Published: March 2010

We cause of the relationship between water hardness and the toxicity of many metals, total hardness is used as a model parameter to calculate ambient water quality criteria for copper and other metals. However, the relative contribution of the Ca and Mg components of total hardness as modifiers of metals toxicity is not considered in the water quality criteria. Acute Cu toxicity was measured in rainbow trout (Oncorhynchus mykiss) and chinook salmon (O. tshawytscha) swim-up fry in laboratory waters that were formulated to have similar total hardness and alkalinity but different Ca and Mg concentrations. Experiments were performed at nominal total hardness values of 40 and 90 mg/L (as CaCO3). In four paired toxicity tests, acute Cu toxicity was significantly lower, i.e., 96-h LC50s were higher, in laboratory waters containing proportionately more Ca (Ca:Mg molar ratios of 1.5–5.2) than in waters containing less Ca (Ca:Mg molar ratios of 0.2–0.8). The relative increase in the 96-h Cu LC50 at higher Ca concentrations, but similar total hardness concentrations, was between 28 and 86% when the low Ca treatment was similar to American Society for Testing and Materials laboratory water (Ca:Mg molar ratio = 0.7). Failure to account for differences in Ca when matching or adjusting for total hardness thus exerts an important influence on the prediction of metal toxicity. These differences must be addressed in water-effect ratio testing in which paired tests with laboratory and site waters are conducted.
Assimilation of cadmium, chromium, and zinc by the green musselPerna viridisand the clamRuditapes philippinarum
Authors: Chong Kit , Wang Wen-Xiong
Published: March 2010

The green mussel Perna viridis and the clam Ruditapes philippinarum have been frequently used as biomonitors of coastal contamination in subtropical and tropical waters, yet the physiological processes controlling metal uptake in these bivalves are unknown. Assimilation efficiency (AE) is an important physiological parameter quantifying metal bioavailability from ingested food. We determined the AEs of Cd, Cr, and Zn in these bivalves feeding on five species of phytoplankton and one natural seston. The influences of the cytoplasmic distribution of metals in the algal cells and the digestive physiology of bivalves on metal AEs were also examined. Among the three metals, Zn was generally assimilated at the highest efficiency, i.e., 21 to 36% in the mussels and 29 to 59% in the clams. Cr was the least assimilated metal, with AEs being 10 to 16% in the mussels and 11 to 24% in the clams. The AEs of Cd and Zn in the clams were 1.8 to 4.7 and 1.1 to 1.9 times higher, respectively, than the AEs in the mussels. Assimilation efficiencies of Cr were, however, comparable between the mussels and the clams. A positive significant relationship between the metal AE and the percent of metals in the algal cytoplasm was found only for Cd in the clams, suggesting that Cd fractionation in the algal cells influenced its assimilation. No significant relationship, however, was found for other metals in both bivalves. A significant relationship between Cr assimilation efficiency and gut passage time (GPT) was documented in the mussels, indicating a higher assimilation when Cr was retained longer in the gut. There was also significant correlation of metal AEs among the three metals, which were probably subjected to the same digestive pathway in the bivalves. Our study demonstrated that both the green mussels and the clams were able to accumulate metals from ingested food source, and food quality appeared to have different effects on metal assimilation in different bivalve species.
Influence of iron(III) and humic acid on the photodegradation of pentachlorophenol
Authors: Fukushima Masami , Tatsumi Kenji , Morimoto Kengo
Published: March 2010

In an aqueous solution at pH 3.0 or 5.0 that contained Fe(III) only or both Fe(III) and humic acid (HA), 20 to 40% of the pentachlorophenol (PCP) present was degraded by light irradiation (λ > 370 nm, 8 h). The release of Cl− was also observed. Gas chromatography/mass spectrometry (GC/MS) studies showed that 2-hydroxy nonachlorodiphenyl ether (2HNCP) and octa-chlorodibenzo-p-dioxine (OCDD) are produced in the presence of Fe(III) only. These were formed by the dimerization of the reaction intermediates from PCP via radical coupling. In contrast, no 2HNCP and OCDD could be detected when both Fe(III) and HA were present. These results can be attributed to the reaction intermediates from PCP covalently binding with HA, which prevents dimerization between PCP-derived reaction intermediates.
An optimized microtiterplate assay to detect acetylcholinesterase activity in individual Chironomus riparius Meigen
Authors: Fisher Thomas C , Crane Mark , Callaghan Amanda
Published: March 2010

A sensitive microtiter plate assay to detect acetylcholinesterase activity in fourth-instar Chironomus riparius (Meigen) larvae was developed and optimized to allow the measurement of pesticide inhibition in individuals. Optimal conditions, including enzyme concentration, pH, and substrate concentration, allow the sensitive measurement of changes in activity following exposure to the organophosphate insecticide chlorpyrifos. Significant reductions in activity were observed at pesticide doses of 0.05, 0.1, 1.0, and 5 mg/L following a 48-h exposure.
Evidence of oxidative stress in bluegill sunfish (Lepomis macrochirus) liver microsomes simultaneously exposed to solar ultraviolet radiation and anthracene
Authors: Choi Jonghoon , Oris James T
Published: March 2010

Many polycyclic aromatic hydrocarbons (PAHs) are acutely toxic to fish and other aquatic organisms in the presence of environmentally realistic intensities of solar ultraviolet radiation (SUVR). However, the biochemical mechanism of this toxicity is not well established. In this study, increased levels of both reactive oxygen species production and lipid peroxidation were hypothesized as a toxic mechanism. To test this hypothesis, the production of superoxide anion and of a lipid peroxidation product (malondialdehyde) was measured in bluegill sunfish (Lepomis machrochirus) liver microsomes. These microsomes were exposed to a representative phototoxic PAH (anthracene [ANT]) and to SUVR and normal laboratory fluorescent light (FLU) in four different combinations: FLU + no ANT, FLU + ANT, SUVR + no ANT, and SUVR + ANT. The highest mean levels of both superoxide anion and malondialdehyde production were observed in the SUVR + ANT group, and these levels were significantly different (p < 0.05) from those in all other treatment groups. We conclude that the photoinduced toxicity of ANT, and possibly of other phototoxic PAHs, manifests at least in part through lipid peroxidation after increased production of reactive oxygen species.