bluuebunny/crossref_metadata_2025_split huggingface dataset:
Genetic indicators of herbicide stress in the pacific oyster Crassostrea gigas under experimental conditions
Authors: Moraga Dario , Tanguy Arnaud 
Published: March 2010

Abstract
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

Abstract
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

Abstract
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

AbstractContradictory 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

Abstract
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

Abstract
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

AbstractStudies 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

Abstract
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

AbstractA 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

AbstractBody 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

Abstract
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

Abstract
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

Abstract
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

Abstract
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.