bluuebunny/crossref_metadata_2025_split huggingface dataset:
Mechanisms of photoinduced toxicity of photomodified anthracene to plants: Inhibition of photosynthesis in the aquatic higher plant Lemna gibba (duckweed)
Authors: Huang Xiao-Dong , McConkey Brendan J , Babu T Sudhakar , Greenberg Bruce M 
Published: March 2010

Abstract
Polycyclic aromatic hydrocarbon (PAH) toxicity is enhanced by light, especially ultraviolet (UV) radiation. To examine a potential mechanism(s) of photoinduced toxicity of PAHs to plants, the effects of anthracene and its photoproducts on photosynthesis were investigated using the aquatic higher plant Lemna gibba L. G-3 (duckweed). Photosynthetic activity was monitored both in vivo and in vitro by measuring chlorophyll a (Chl a) fluorescence, carbon fixation, and electron transport. In simulated solar radiation (a light source with a visible light: UV-A: UV-B ratio similar to sunlight), inhibition of photosynthesis was more rapid with photomodified anthracene than with intact anthracene, and intact anthracene appeared to only inhibit photosynthesis following its photomodification. The primary site of action of photomodified anthracene was found to be electron transport at or near photosystem I (PSI). This was followed by inhibition of photosystem II (PSII), probably due to excitation pressure on PSII once the downstream electron transport through PSI was blocked. Accordingly, higher chemical concentrations and/or longer exposures were required to inhibit PSII than PSI. Net photosynthesis (carbon fixation) was also inhibited, implying that the inhibition of electron transport in PSI by photomodified anthracene can lead to diminished primary productivity. A linkage between inhibition of photosynthesis and inhibition of plant growth was established in terms of the initial site of action (PSI) and primary productivity (carbon fixation), which suggested that Chl a fluorescence can be used as a bioindicator of PAH impacts on plants.
Exposure of male american plaice (Hippoglossoides platessoides) to contaminated marine sediments decreases the hatching success of their progeny
Authors: Nagler James J , Cyr Daniel G 
Published: March 2010

Abstract
There is increasing concern over the effect environmental contaminants may be having on male vertebrate reproduction, particularly persistent organics. This study sought to determine the effects of marine sediments, contaminated with organic compounds, on the reproductive performance of male American plaice (Hippoglossoides platessoides). Maturing fish were exposed to contaminated sediments, in the laboratory, for a 5-month period leading up to spawning. Sediments were obtained from three known environmentally contaminated sites, in which site 1 was the most toxic, followed by site 2, with site 3 relatively uncontaminated (i.e., control). Semen collected from all males with motile sperm were used to fertilize eggs from a single nonsediment-exposed female. Eggs fertilized with sperm from males exposed to sediments from site 1 produced 48% fewer larvae (p &lt; 0.05), compared to the control group (i.e., site 3). Similarly, males exposed to site 2 produced 35% fewer larvae, relative to the control. There were no differences between groups with respect to sperm number, seminal sodium and potassium concentrations, and gonadosomatic index. The levels of liver cytochrome P450 1A1 (CYP1A1) mRNA, used as a biomarker for exposure to organics, were threefold higher in fish exposed to site 1 sediments, and twofold higher in fish exposed to site 2 sediments, relative to the site 3-exposed controls, at the end of the experiment. A significant negative correlation (r = −0.65, n = 16, p &lt; 0.007) exists between male CYP1A1 levels and hatch success, with increasing CYP1A1 levels corresponding to decreased numbers of hatched larvae. These data indicate that long-term exposure of male American plaice to marine sediments contaminated with organics can result in a reduction in the number of eggs hatched, which correlates with increased levels of hepatic CYP1A1.
Polychlorinated biphenyls in a terrestrial predator, the pine marten (Martes martes L.)
Authors: Bremle Gudrun , Larsson Per , Helldin Jan Olof 
Published: March 2010

Abstract
A terrestrial predator population, the pine marten ( Martes martes, L.), inhabiting an area in mid-Sweden was investigated for polychlorinated biphenyls, p,p′-DDE, lindane, and hexachlorobenzene. The condition of the animals, as shown by intestine fat amounts or fat content of muscle tissue, showed negative relationships with concentration of persistent pollutants. The relationship resulted in a higher concentration of pollutants as intestinal fat amounts or muscle fat content decreased and lower levels of pollutants as these indexes of condition improved. The results indicate that terrestrial predators show changes in pollutant concentration due to condition, caused by food availability and starvation. No differences in pollutant concentration were recorded between males and females and no relationship was found for levels of pollutants and age or reproduction (females). The latter results are in contrast to those found for aquatic predatory mammals.
The selective dietary accumulation of planar polychlorinated biphenyls in the otter (Lutra lutra)
Authors: Leonards Pim E G , Zierikzee Yolanda , Brinkman Udo A Th , Cofino Wim P , van Straalen Nico M , van Hattum Bert 
Published: March 2010

AbstractThe decline of the populations of otters in Western Europe is assumed to be related to the accumulation of polychlorinated biphenyls (PCBs) in this species. A study was conducted to investigate the trophic transfer of non-ortho, mono-ortho-, and di-ortho-substituted PCBs in the food web of the otter (Lutra lutra) in the Oude Venen lake system in the Netherlands, with relatively low PCB contamination. This area was one of the last strongholds of otters in the Netherlands and the species is considered to be virtually extinct since 1988. A marked increase in concentration of chlorinated biphenyls (CBs) was observed with successive trophic levels of the aquatic food web. Mean concentrations of the sum of 28 CB congeners (ΣCB) increased from 142 ng CB/g (organic carbon basis) in sediment and particulate matter to 588 ng CB/g (lipid weight basis) in invertebrates, to 2,450 ng CB/g (lipid weight) in fish, and 70,940 ng CB/g (lipid weight) in otter. A diet-specific biomagnification factor (BMF) of 14 was calculated from fish to otter based on ΣCB; however, on the basis of toxic equivalent concentrations (ΣTEQ), a BMF of 41 was found. This higher BMF on TEQ basis was mainly due to the enrichment of non-ortho-substituted CB 126 in otter, compared to fish. In fish CB 126 contributed 30 to 50% to ΣTEQ, while this congener contributed 60 to 80% in otters. A shift in the CB patterns was found from relatively high concentrations of lowly chlorinated CBs in the abiotic compartments to the higher chlorinated CBs (five to seven chlorine atoms) at the highest trophic level. The relatively low concentrations of CB 77 and CBs with vicinal H-atoms at the meta-para position in otter compared to fish indicates that otters can metabolize these CBs and have P4501A-like and P4502B-like enzyme systems. It appears that even in an ecosystem with relatively low CB contamination, concentrations of CBs can be relatively high in aquatic top predators. The non-ortho-substituted CBs seem to be the most important toxic threat for otters, firstly because of the relatively high BMFs of CB 126 and CB 169 and secondly because of the formation of metabolites of CB 77.
Structure–biodegradability study and computer-automated prediction of aerobic biodegradation of chemicals
Authors: Klopman Gilles , Tu Meihua 
Published: March 2010

AbstractIt is shown that a combination of two programs, MultiCASE and META, can help assess the biodegradability of industrial organic materials in the ecosystem. MultiCASE is an artificial intelligence computer program that had been trained to identify molecular substructures believed to cause or inhibit biodegradation and META is an expert system trained to predict the aerobic biodegradation products of organic molecules. These two programs can be used to help evaluate the fate of disposed chemicals by estimating their biodegradability and the nature of their biodegradation products under conditions that may model the environment.
Aerobic biodegradation of virginiamycin in soil
Authors: Weerasinghe Chandralal A , Towner Dwight 
Published: March 2010

Abstract
Aerobic biodegradation of virginiamycin was examined in six different soil types over a 64-d incubation period. The following test conditions were examined in parallel for each soil type: (1) [14C]virginiamycin at 0.5 mg carbon/50 g soil amended with 9.5 mg carbon as unlabeled glucose/50 g soil; and (2) [14C]glucose at 10 mg carbon/50 g soil was used as the reference chemical. The amounts of 14CO2 and [14C]volatile products released upon biodegradation of [14C]virginiamycin and [14C]glucose were collected over the duration of the study. Three of the six soils were extracted at the end of the study, and the extracts were analyzed by HPLC to examine the fate of the parent drug. A mass balance of the applied activity was also determined for each soil type. Virginiamycin was found to biodegrade in each soil type tested, and the calculated mineralization half-lives ranged from 87 to 173 days for three of the six soils tested with first-order rate constants of 0.004 to 0.008 day−1. Despite slow mineralization, extensive breakdown of virginiamycin into a series of minor components aerobically with no single degradation product present at &gt;10% of the initial virginiamycin concentration was observed in the remaining three soils. The mass balance of the applied activity of [14C]virginiamycin was in the range 86 to 101% and that of applied [14C]glucose was 91 to 100%. Based on the results, virginiamycin upon entry into the environment is expected to undergo extensive biotransformation in the presence of soil microorganisms.
The relationship between land use and organochlorine compounds in streambed sediment and fish in the Central Columbia Plateau, Washington and Idaho, USA
Authors: Munn Mark D , Gruber Steve J 
Published: March 2010

Abstract
We analyzeds streambed sediment and fish in the Central Columbia Plateau in eastern Washington and Idaho for or ganochlorine pesticides and polychlorinated biphenyls (ΣPCB). Our objective was to assess the effects of land use on the occurrence and distribution of these compounds; land uses in the study area included forest, dryland and irrigated farming, and urban. We detected 16 organochlorine compounds in streambed sediment and fish tissue; fish usually had more compounds and a greater frequency of detection. The most frequently detected compound was ΣDDT (sum of six isomers), which was found in 52% of bed sediment samples and 94% of whole fish composite samples. The other commonly detected compounds were dimethyl tetrachloroterephthalate (DCPA), dieldrin, hexachlorobenzene, and Σchlordane (sum of cis- and trans-chlordane, cis- and trans-nonachlor oxychlordane, heptachlor, and heptachlor epoxide). Forest was the only land use with no detections of organochlorine compounds in either fish or bed sediment. Hexachlorobenzene was the only organochlorine pesticide detected at concentrations that differed significantly among land uses: concentrations were higher in the dryland farming areas than in the irrigated farming or urban areas. In agricultural areas irrigated by surface water, ΣDDT concentrations in both streambed sediment and fish tissue were related to the percentage of land irrigated by water delivered via furrows (gravity irrigation), although ΣDDT was not detectable in bed sediments until gravity irrigation exceeded 30%. Because of the relation between gravity irrigation and soil erosion, our study supports the importance of controlling soil erosion in order to reduce the overall loading of organochlorine compounds to surface waters.
Efficacy of candidate chemicals for preventing attachment of zebra mussels (Dreissena polymorpha)
Authors: Cope W Gregory , Bartsch Michelle R , Marking Leif L 
Published: March 2010

Abstract
Forty-seven chemicals having potential for preventing the attachment of zebra mussels Dreissena polymorpha were identified and tested. For each chemical, 15 zebra mussels (5–8-mm shell length) in each of two replicates and six treatments were exposed for 48 h followed by a 48-h postexposure period in untreated water. Eleven of the chemicals inhibited the reattachment of zebra mussels after the 48-h exposure; eight had EC50 values ranging from 0.4 to 5.4 mg/L, and three had EC50 values ranging from 19.4 to 29.0 mg/L. Based on an analysis of chemical cost, solubility in water, anticipated treatment concentrations, and potential hazards to humans or the environment, three of the most promising chemicals, all antioxidants, (butylated hydroxyanisole [BHA], tert-butylhydroquinone, and tannic acid) were tested on nontarget fish (bluegill, Lepomis macrochirus; channel catfish, Ictalurus punctatus; and rainbow trout, Oncorhynchus mykiss). These chemicals were not selectively toxic to zebra mussels; only the tests with bluegill and BHA and with channel catfish and tannic acid had 48-h LC50 values greater than the concentrations effective for preventing the reattachment of zebra mussels. Although the attachment of zebra mussels can be prevented with selected antioxidants, an alternative formulation should be investigated to minimize effects on nontarget organisms, such as fish.
Serum B esterases as a nondestructive biomarker in the lizard Gallotia galloti experimentally treated with parathion
Authors: Sanchez Juan Carlos , Fossi Maria Cristina , Focardi Silvano 
Published: March 2010

Abstract
Lizards (Gallotia galloti) were given either single or consecutive acute oral treatments of the organophosphorus (OP) insecticide parathion in two different experiments. Brain, serum, and liver microsomal esterase activities and liver microsomal monooxygenase activities were measured 6 and 24 h after the single acute treatment at each of four different doses (Experiment 1) or periodically up to 72 d after a number of consecutive acute treatments at two different doses (Experiment 2). Inhibition of serum butyrylcholinesterase (BChE) and carboxylesterase activities was observed in all treatment groups after 24 h and in the groups treated with 2.5, 5, and 7.5 mg/kg of parathion 6 h after treatment. Brain acetylcholinesterase (AChE) was inhibited at all doses after 6 h but only at the highest dose after 24 h. Highly significant nonlinear correlations, based on a piecewise linear regression model, were obtained between brain AChE activity and serum esterase activities at two sampling times after the single acute treatment. Liver microsomal carboxylesterase was found to be induced at the lower doses 6 and 24 h after treatment. Liver microsomal monooxygenase activity was higher 6 h after treatment than at 24 h, but the difference was not statistically significant. In Experiment 2, serum esterase activities recovered exponentially over a period of weeks. An increase in the recovery time to normal esterase activity was observed after each consecutive acute treatment. Brain AChE activity was inhibited at the end of consecutive administrations of parathion at the higher dose, and liver microsomal monooxygenase activity was inhibited at both doses. Symptoms of poisoning were observed in lizards treated with the higher dose of parathion, but no mortality was recorded. Two main conclusions can be drawn: (1) serum esterase activities recovered extremely slowly after acute treatment with parathion and even more slowly after consecutive acute treatments, and (2) there was a nonlinear correlation between the nondestructive biomarkers, serum “B” esterases, and the destructive biomarker, brain AChE, 6 and 24 h after exposure. These results suggest that G. galloti should be an ideal bioindicator organism to assess OP exposure in the Canary Islands instead of the birds commonly used for this purpose.
The interactive effects of essential ions and salinity on the survival of Mysidopsis bahia in 96-H acute toxicity tests of effluents discharged to marine and estuarine receiving waters
Authors: Douglas W Scott , Horne Michael T 
Published: March 2010

Abstract
The importance of salinity in whole effluent toxicity tests using marine organisms has been acknowledged in most testing protocols. However, little if any attention has been given to the specific effects of alteration of the ionic composition of seawater solutions to the test organism. The presence of persistent toxicity in effluents with no apparent toxic agents prompted examination of the potential influence of essential ions on the survival of the opossum shrimp, Mysidopsis bahia, a common effluent toxicity indicator organism. Through stepwise additions of ionic salts to deionized water, the minimum complement of salts to maintain survival of M. bahia during 96-h exposures was determined to be Ca, Mg, K, Br, Na, and Cl. The toxicity curves for Ca, Mg, K, and Br were then determined across test salinity ranging from 10 to 35 parts per thousand. These curves for Ca, Mg, and K revealed that there are significant negative effects on survival when the essential ions are present in either low or high concentrations relative to the levels in natural seawater. Although there were no statistically detectable effects of Br on organism survival over the concentration range tested (5–480 mg/L), Br toxicity at concentrations less than 5 mg/L and greater than 700 mg/L have been shown in other studies. In addition, the tolerance ranges for K, Ca, and Mg were shown to shift significantly with changes in salinity, with lower salinity causing an apparent decrease in tolerance to an excess of essential ions. Tests with toxic effluents from five industrial and municipal sources revealed that adjustment of the ionic balance prior to testing reduced or eliminated toxicity in four of the five whole effluents tested. Suggestions for integrating this information into biomonitoring programs and toxicity identification evaluations are presented.
Toxicity identification evaluations of produced-water effluents
Authors: Sauer Ted C , Costa Helder J , Brown John S , Ward Timothy J 
Published: March 2010

Abstract
Toxicity identification evaluations (TIEs) were performed on 14 produced-water (PW) samples of various salinities from inland and offshore oil- and gas-production facilities operated by different companies in Wyoming, Texas, California, and Louisiana (USA) to evaluate the efficacy of TIE procedures in determining potential toxicants in PW effluents. The research involved acute (24- and 48-h) freshwater and marine toxicity tests on whole PW and PW fractions generated by standard U.S. Environmental Protection Agency and PW-specific fractionation schemes. Factors influencing PW TIEs were investigated, such as the effect of salinity in selecting fractionation manipulations, the effect of toxicity test replication (i.e., reproducibility) in distinguishing changes in toxicities between whole PW and its fractions, and the suitability of different test species in PW TIEs. The results obtained and lessons learned from conducting these PW TIEs are presented in this article. Components, or fractions, contributing to toxicity differed for each PW with no specific fraction being consistently toxic. For most PW samples, toxicity attributed to any one fraction represented only part of the toxicity of the whole sample. However, no more than two fraction types were identified as potential toxicants in any sample. Potential toxicants identified during this study, besides salinity, included acidic and basic organic compound class fractions, particulates removed by filtration at pH 11, ammonia, hydrocarbons, hydrogen sulfide, material removed by pH change, and volatile compounds.
Comparison of availability of copper(II) complexes with organic ligands to bacterial cells and to chitin
Authors: Vasconcelos M Teresa S D , Azenha Manuel A O , Cabral Joao P S 
Published: March 2010

Abstract
Bacterial cells or chitin were exposed to solutions with 100 μM total but only 5 μM free copper, due to the presence of a proper concentration of proline, lysine, cysteine, or ethylenediamine tetraacetate (EDTA). The influence of the nature and concentration of the particles and soluble ligands, on the sorption and on the desorption of the copper, at pH 6.50 and 25.0°C, was investigated. The metal sorbed by the particles and that left in the solution were measured by atomic absorption spectrometry, after different periods of contact between particles and solution. The interpretation of the results was based on the copper(II) speciation calculated through equilibrium approaches applied to homogenous or heterogeneous systems. A significant fraction of copper bound to the organic ligands was displaced to the bacteria or chitin, and the extent of chemical reaction depended on the nature of both the soluble (or leaving) ligands and sites on the particle surface (or entering ligands), as expected by the equilibrium theory. But with chitin, the uptake of copper in the presence of cysteine or EDTA was higher than expected, which may be due to the adsorption of the soluble copper complexes on the particle surface. In consequence of a competition between soluble and particulate ligands (cells or chitin), the free copper(II) concentration decreased in the solution, even in the presence of very strong chelators. The results indicate that copper availability is not a simple function of the initial free copper concentration in the solution. Desorption of the previously fixed copper, originated by free soluble ligands indicated that the sorption of copper was “quasireversible” for both particles, though a larger dismissal of the equilibrium position occurred for the cells, probably due to their biological activity. Both the bacteria and chitin were able to fix metal initially bound to an organic ligand continuously for periods longer than 30 min, the kinetics of uptake varying with the nature of both the leaving and entering ligands. Therefore, long time-scale techniques, namely batch processes, warrant studies of metal availability in natural systems.
Factors affecting sequestration and bioavailability of phenanthrene in soils
Authors: White Jason C , Kelsey Jason W , Hatzinger Paul B , Alexander Martin 
Published: March 2010

Abstract
A study was conducted to determine factors affecting the sequestration and changes in bioavailability as phenanthrene persists in soils. Phenanthrene became sequestered in seven soils differing appreciably in organic matter and clay content as measured by earthworm uptake, bacterial mineralization, or extractability. Phenanthrene also became sequestered as it aged in soil aggregates of various sizes as measured by decline in availability to a bacterium, a mild extractant, or both. Wetting and drying a soil during aging reduced the amount of phenanthrene recovered by a mild extractant and the rate and extent of bacterial mineralization of the hydrocarbon. After biodegradation of phenanthrene added to the soil, more of the compound remained if it had been aged than if it had not been aged. Wetting and drying the soil during aging further increased the amount of phenanthrene remaining after biodegradation. The rate and extent of bacterial mineralization of phenanthrene were less in leached than in unleached soil. Aging/sequestration is thus markedly affected by soil properties and environmental factors.