bluuebunny/crossref_metadata_2025_split huggingface dataset:
Measuring variability in phytotoxicity testing using crop and wild plant species
Authors: Boutin Céline , White Andrea L. , Carpenter David 
Published: March 2010

Abstract
A series of experiments was conducted to assess the level of variability in phytotoxicity testing and to investigate factors that may explain some of the observed uncertainties and inconsistencies. The work was conducted in greenhouse or growth chamber environments with plants growing individually in pots and harvested 28 d after spraying with two herbicides, glyphosate and atrazine, as formulated products. Between six and 10 doses were used on five or six replicates, necessitating over 4,500 individually growing plants. In the first set of experiments, several ecotypes (originating from different areas of the world) of eight wild plant species were tested. Significant differences in sensitivity to atrazine and glyphosate were found among ecotypes of most species tested. In the second suite of experiments, the reproducibility of results during different seasons (when growing conditions vary) was investigated using three crops and four wild plant species. Results showed that seasonal variability elicited a pronounced discrepancy in response between plants tested at different times of the year. It was found that no consistent effects could be attributed to the biotic or abiotic factors investigated. Several ecotypes of the same species differed in their seed size, percentage germination, or germination requirements, as well as in growth patterns, but these differences could not explain differences in herbicide sensitivity. Likewise, differences in phytotoxicity could not be attributed to factors such as temperature, light intensity, and sunlight duration. The present study supports the inclusion of an uncertainty factor in risk assessments to account for the intrinsic variability in plant sensitivity to herbicides. Environ. Toxicol. Chem. 2010;29:327–337. © 2009 SETAC
Polybrominated diphenyl ethers, toxaphenes, and other halogenated organic pollutants in great blue heron eggs
Authors: Champoux Louise , Moisey John , Muir Derek C.G. 
Published: March 2010

Abstract
The great blue heron (Ardea herodias) has been used as a bioindicator of the state of the St. Lawrence River (Québec, Canada) since 1996. At 5-year intervals, selected breeding colonies along the River and its estuary are visited to estimate reproductive success and determine levels of contamination. Brominated flame retardants are found in many ecosystems and are increasing in concentration in the Great Lakes, which is the source of much of the water for the St. Lawrence River. In 2001 and 2002, in addition to polychlorinated biphenyls (PCBs) and chlorinated pesticides, the levels of polybrominated diphenyl ethers (PBDEs), polychlorinated bornanes (toxaphene) congeners and non-ortho-substituted PCBs were measured for the first time in pools of great blue heron eggs. The PBDE levels in great blue heron eggs (70–1,377 ng/g wet wt) were comparable to those measured in herring gull (Larus argentatus) eggs from the Great Lakes. Toxaphene was detected in great blue heron eggs at levels comparable to those of other major chlorinated pesticides. Major toxaphene congeners were octachlorobornane P44 and the nonachlorobornane P50. Environ. Toxicol. Chem. 2010;29:243–249. © 2009 SETAC
The effects of continuous and pulsed exposures of suspended clay on the survival, growth, and reproduction ofDaphnia magna
Authors: Robinson Sarah E. , Capper Neil A. , Klaine Stephen J. 
Published: March 2010

AbstractSuspended sediments are a natural component of aquatic ecosystems, but anthropogenic activity such as land development can result in significant increases, especially after rain events. Continuous exposures of suspended clay and silt have been shown to affect growth and reproduction of Cladocera, leading to a decrease in population growth rate. The mechanism of clay toxicity in these filter-feeding organisms is clogging of the gut tract, resulting in decreased food uptake and assimilation. When placed in clean water, daphnids can purge clay from their gut and recover. In many surface waters, aquatic organisms experience episodic exposures of high concentrations of suspended solids driven by rain events. However, little is known about the consequences of pulsed exposures on individuals and populations. The objective of the present study was to characterize the effects of continuous and pulsed exposures of natural and defined clays on survival, growth, and reproduction of Daphnia magna. Two defined clays, montmorillonite and kaolinite, as well as clay isolated from the Piedmont region of South Carolina, USA, were used. Continuous exposures of clays elicited a dose dependent decrease in survival. Toxicity varied depending on clay source with montmorillonite &gt; natural clay &gt; kaolinite. Pulsed exposures caused a decrease in survival in a 24 h exposure of 734 mg/L kaolinite. Exposure to 73.9 mg/L also caused an increase in the time to gravidity, although there was not a corresponding decrease in neonate production over 21 d. No significant effects resulted from 12 h exposures even at 730 mg/L, almost 10 times the 24-h reproductive effects concentration. This suggests that exposure duration impacted toxicity more than exposure concentration in these pulsed exposures. Environ. Toxicol. Chem. 2010;29:168–175. © 2009 SETAC
Sulfate reduction, molecular diversity, and copper amendment effects in bacterial communities enriched from sediments exposed to copper mining residues
Authors: Pavissich Juan P. , Silva Macarena , González Bernardo 
Published: March 2010

Abstract
Sulfate-reducing bacterial communities from coastal sediments with a long-term exposure to copper (Cu)-mining residues were studied in lactate enrichments. The toxicity of excess copper may affect sulfate-reducing bacterial communities. Sulfate reduction was monitored by sulfate and organic acid measurements. Molecular diversity was analyzed by 16S rRNA, dissimilatory sulfate reduction dsrAB, and Cu translocating phospho-type adenosine triphosphatases (P-ATPases) cop-like gene sequence profiling. The influence of Cu amendment was tested in these enrichments. Results showed fast sulfate reduction mostly coupled to incomplete organic carbon oxidation and partial sulfate reduction inhibition due to copper amendment. The 16S rRNA clonal libraries analysis indicated that δ- and γ-Proteobacteria and Cytophaga–Flexibacter–Bacteroides dominated the enrichments. The dsrAB libraries revealed the presence of Desulfobacteraceae and Desulfovibrionaceae families-related sequences. Copper produced significant shifts (i.e., a decrease in the relative abundance of sulfate-reducing microorganisms) in the enriched bacterial community structure as determined by terminal-restriction fragment length polymorphism (T-RFLP) profiling and multivariate analyses. Clonal libraries of cop-like sequences showed low richness in the enriched microbial communities, and a strong effect of copper on its relative abundance. Novel Cu-PIB-ATPase sequences encoding Cu resistance were detected. The present study indicates that Cu does not significantly affect sulfate reduction and genetic diversity of taxonomic and dissimilatory sulfate-reduction molecular markers. However, the diversity of Cu resistance genetic determinants was strongly modified by this toxic metal. Environ. Toxicol. Chem. 2010;29:256–264. © 2009 SETAC
The influence of diet on the assimilation efficiency of 47 polychlorinated biphenyl congeners in Japanese koi (Cyprinus carpio)
Authors: Liu Jian , Haffner G. Douglas , Drouillard Ken G. 
Published: March 2010

Abstract
The influence of diet on polychlorinated biphenyl (PCB) assimilation was investigated by measuring dietary assimilation efficiencies (AEs) for 47 PCB congeners in juvenile koi (Cyprinus carpio) fed five experimental diets. Two of the diets were naturally contaminated and were obtained by collecting mayflies from Lake Erie (ON, Canada) and emerald shiners from the Detroit River (MI, USA). The remaining diets consisted of commercial fish pellets (lipid contents from 6.7 to 24%) that were contaminated by spiking with a PCB mixture. Experimental fish were held individually to quantify the amount of food consumed per fish and, following a 48-h fasting period to facilitate food digestion and assimilation; AEs were determined by mass balance. Fish fed the benthic invertebrate food exhibited the highest PCB AEs (70–101%) and were significantly elevated compared to the other diet treatments (AEs ranging from 23 to 87%). The PCB AEs for fish fed emerald shiners did not differ from those fed pellet formulations. Variation among PCB AEs was not related to diet lipid content. For all diet treatments, PCB AEs were significantly related to chemical hydrophobicity. The relationship between chemical AE and n-octanol/water partition coefficient (KOW) was best explained by a linear model compared to a two-phase resistance model. Overall, PCB AEs were observed to be dependent on both diet type and chemical hydrophobicity, with both factors contributing nearly equally to the variation measured in this toxicokinetic parameter. Environ. Toxicol. Chem. 2010;29:401–409. © 2009 SETAC
Exchange of polycyclic aromatic hydrocarbons among the atmosphere, water, and sediment in coastal embayments of southern California, USA
Authors: Sabin Lisa D. , Maruya Keith A. , Lao Wenjian , Diehl Dario , Tsukada David , Stolzenbach Keith D. , Schiff Kenneth C. 
Published: March 2010

AbstractThe present study investigated cross-media transport between both the sediment and the water column and between the water column and the atmosphere, to understand the role of each compartment as a source or a sink of polycyclic aromatic hydrocarbons (PAH) in southern California, USA, coastal waters. Concentrations of PAH were measured in the atmosphere, water column, and sediment at four water-quality-impaired sites in southern California: Ballona Creek Estuary, Los Angeles Harbor, Upper Newport Bay, and San Diego Bay. These concentrations were used to calculate site-specific sediment–water and atmosphere–water exchange fluxes. The net sediment–water exchange of total PAH (t-PAH) was positive, indicating that sediments were a source to the overlying water column. Furthermore, the net atmosphere–water exchange (gas exchange + dry particle deposition) of t-PAH was typically positive also, indicating the water column was a net source of PAH to the surrounding atmosphere through gas exchange. However, in all cases, the magnitude of the diffusive flux of PAH out of the sediments and into the water column far exceeded input or output of PAH through air/water exchange processes. These results demonstrate the potential importance of contaminated sediments as a source of PAH to the water column in coastal waters of southern California. Environ. Toxicol. Chem. 2010;29:265–274. © 2009 SETAC
The biodegradation of hydroquinone
Authors: Harbison Kenneth G. , Belly Robert T. 
Published: March 2010

AbstractHydroquinone is readily degraded by an acclimated activated sludge unit when present at concentrations of 100 mg/L in synthetic photographic or synthetic domestic wastes. A number of pure cultures of yeasts, fungi, and bacteria were isolated from soil and sludges which can utilize hydroquinone as a sole carbon source.1,4-Benzoquinone, 2-hydroxy-1,4-benzoquinone, and β-ketoadipic acid were detected as minor components during the biodegradation of hydroquinone by pure cultures, but they did not persist. The total organic carbon during biodegradation was accounted for within experimental error by hydroxylated aromatic compounds. At pH 7 or below, biodegradation by pure cultures or sludges leaves only ca. 2.1% of the total organic carbon in solution after 3–5 days. This value is comparable to values observed for easily assimilated substrates under similar conditions.At higher pH and in the absence of sulfite, some humic acids may be formed by chemical oxidation if the inoculum is low; these materials resist biodegradation.
Review: Behavior of organic chemicals at soil, air, water interfaces as related to predicting the transport and volatilization of organic pollutants
Authors: Spencer William F. , Farmer Walter J. , Jury William A. 
Published: March 2010

Abstract
The transfer of organic pollutants into the atmosphere is discussed from the standpoint of mechanisms involved, factors influencing rates of volatilization, and progress in developing models for predicting transfer rates. The volatilization rate of soil-incorporated chemicals is controlled by vapor pressure of the chemical in soil and by its rate of movement to the soil surface by diffusion or by a combination of diffusion and convection in evaporating water. Vapor pressures of organic chemicals are greatly decreased by their interaction with soil mainly due to adsorption. The magnitude of the adsorption effect depends upon the nature of the chemical, its concentration, the soil water content and soil properties, such as organic matter and clay content. Vaporization of chemicals in soil or from disposal sites covered with soil can be estimated from considerations of the physical and chemical factors controlling concentrations at the soil surface and most models developed to estimate volatilization rates are based upon equations describing the rate of movement of the chemical to the soil surface by diffusion and/or convection. Considerable progress has been made in developing laboratory based models for predicting volatilization from soil. Since volatilization of soil-incorporated chemicals is controlled mainly by factors within the soil, predictions from laboratory based mathematical models should be sufficiently accurate for many purposes.
Modeling effects of pesticides on populations of soil/litter invertebrates in an orchard ecosystem
Authors: Goodman Erik D. 
Published: March 2010

Abstract
In order to efficiently determine safe levels for introduction of toxic chemicals into the environment, regulators need to understand: (1) the environmental chemistry of the chemical, (2) the time-course of its distribution in the environment, (3) the exposure of key organisms to the chemical, and (4) the effects of the chemical on the exposed biota. It is not practical to determine all of these in field studies for each new chemical; thus, some generalizations must be made based on more limited laboratory determinations. To map from these determinations to a prediction of fate and effects in the field, regulators must implicitly or explicity employ some sort of model.
This paper presents one component of a modeling effort directed toward this goal. This model attempts to represent the effects of azinphosmethyl, an example chemical, on an example population of soil/litter invertebrates, based on extensive studies in a field situation and in the laboratory. Exposure of soil/litter-resident invertebrates is based on the time-course of toxicant distribution and the activity patterns of the organisms as represented by other models developed in the author's laboratory. Examples of these predicted toxicant distributions and comparable field-determined values are presented here.
A model is proposed here to represent temporally distributed mortality of an invertebrate population caused by repeated toxicant dosing. Detailed toxicological studies on the isopod Trachelipus rathkei have allowed the best model parameterization, but models for spiders, earthworms, and springtails have also been developed. Model outputs based on laboratory data are compared with field observations of isopod populations. Results indicate some areas in which further model development is required.
Fate of 2,3,7,8-tetrachlorodibenzo-P-dioxin (TCDD) in an outdoor pond and in model aquatic ecosystems
Authors: Tsushimoto Gen , Matsumura Fumio , Sago Ryuichi 
Published: March 2010

Abstract
Environmental fate of TCDD was studied in an aquatic ecosystem, using an outdoor pond which had been dosed initially with 53.7 ppt of14C-TCDD. The levels of radiocarbon reached an equilibrium in pondweeds after one month, in fish after two months and in the sediment after six months. Using the identical components from the outdoor pond, roughly comparable data were obtained in the laboratory for short-term distribution of radiocarbon. The largest source of variance and discrepancy between the outdoor and the laboratory data was pondweeds. This material produced the largest shift in biomass due to rapid growth and subsequent massive death, causing a drastic change in distribution of radiocarbon in the second year in the outdoor ecosystem. The amounts of the total TCDD remaining in the pond after 12 and 25 months were 49.7 and 29.4%, respectively. The bulk of metabolites was detected in water and pondweeds.
Comparison of laboratory and field results for prediction of the environmental behavior of phosphate esters
Authors: Muir D. C. G. , Grift N. P. , Lockhart W. L. 
Published: March 2010

Abstract
Two phosphate ester flame retardants, triphenyl phosphate (TPP) and 2-ethylhexyldi-phenyl phosphate (EHDPP) (both 14C-labelled) were added to two small artificial ponds (3 m3 volume) to give water concentrations of 60 μg/L for each compound. Both phosphate esters had half-lives of about 15 h in the water column and showed rapid sorption to bottom sediment. At 24 h posttreatment an estimated 28% of EHDPP and 9% of TPP added could not be accounted for by measurements of radioactivity in water, sediment and biota. Calculations of volatilization rates from water of the two compounds suggested that losses of EHDPP may have been due in part to volatilization. Bioconcentration of TPP by fathead minnows (Pimephales promelas) was similar to that predicted from laboratory studies on the uptake and clearance of TPP by rainbow trout (Salmo gairdneri). Prediction of the bioconcentration of EHDPP by duckweed (Lemna minor) from laboratory studies underestimated the rapid uptake of this compound observed in the ponds.
A screening procedure for assessing the transport and degradation of solid waste constituents in subsurface and surface waters
Authors: Falco J. W. , Mulkey L. A. , Swank R. R. , Lipcsei R. E. , Brown S. M. 
Published: March 2010

Abstract
An evaluation procedure was developed to rapidly screen chemicals for their potential to contaminate both subsurface and surface waters after disposal and subsequent release from landfills and lagoons. The procedure estimates movement and degradation of chemicals based on the physical and chemical properties of the compound and a defined range of environmental conditions that the compound potentially experiences in groundwater and in rivers, ponds, and reservoirs.
After high and low estimates are established, qualitative descriptors are assigned to describe the transport and persistence of the compound in subsurface and surface waters.
This procedure has been used to evaluate 193 compounds that were projected to be constituents of solid wastes from 75 manufacturing operations. The results of a sensitivity analysis indicate that where individual environmental process descriptions are defined, changes in rates of degradation of an order of magnitude are required to cause a significant number of changes in qualitative descriptors that define the transport and persistence of the compounds assessed.
The results of this application indicate that the procedure provides a means of qualitatively screening organic chemicals when specified process rate data are available. The evaluation of the small number of metals included in this assessment are speculative. Further research is required to adequately screen metals.
The fate of atrazine and a hexachlorobiphenyl isomer in naturally-derived model stream ecosystems
Authors: Lynch Thomas R. , Johnson Howard E. , Adams William J. 
Published: March 2010

Abstract
Current emphasis in hazard assessment is being placed on the development of quick and inexpensive methods to identify chemicals with potentially harmful properties. The present study was designed to test the validity of simple microcosms that have been proposed to predict chemical behavior in aquatic systems.
Six laboratory streams were used to study the fate and effects of atrazine and 2, 4, 5, 2′, 4′, 5′, - hexachlorobiphenyl (HCBP) in a naturally derived aquatic community during one annual period. Two streams were treated with the HCBP (0.100 μg/L), two received atrazine (25 μg/L) and two streams served as solvent controls. The chemicals were administered for 30 days during the fall, winter, spring, and summer; a 60 day depuration phase followed each treatment.
The substrates and benthic organisms accumulated HCBP rapidly and concentrations increased with duration of exposure. Uptake of HCBP by the biota was biphasic; the most rapid rate of accumulation occurred during the initial three hours of exposure. Maximum HCBP concentrations in the biota occurred on day 30. Bioaccumulation factors at this time ranged from 300,000 for amphipods to 1200 for clams. Fish, crayfish and other macroinvertebrates had intermediate values. There was no evidence that residue concentrations were increased by trophic transfer.
Atrazine was not accumulated in the laboratory stream communities. Atrazine bioaccumulation factors in the biota ranged from 3.5 in annelids to 480 in mayfly nymphs. Residue concentrations declined to pretreatment levels within a few days of depuration.
These results are significant in that (1) they are consistent with predictions derived from physical-chemical data and (2) the compounds behaved similarly to closely related compounds in simpler model systems. Based on our results, simpler model ecosystems and/or models based on physicalchemical data are probably adequate for predicting the fate of toxicants in aquatic systems.
Ecological toxicology: Experimental analysis of toxic substances in ecosystems
Authors: Hendrix Paul F. 
Published: March 2010

Abstract
Premanufacture testing of new chemicals is considered as an applied problem in biogeochemistry, consisting of experimentation at several complimentary levels of resolution. A descending sequential testing protocol is proposed which begins with combined fate and effects experiments in ecosystems (e.g., laboratory microcosms) followed by studies of processes and species which are hypothesized to be important at finer levels of resolution.