bluuebunny/crossref_metadata_2025 huggingface dataset:
Aerobic biodegradation of virginiamycin in soil
Authors: Weerasinghe Chandralal A , Towner Dwight
Published: March 2010

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 >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

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

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

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

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

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

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

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.
Trace metal exchange in solution by the fungicides Ziram and Maneb (dithiocarbamates) and subsequent uptake of lipophilic organic zinc, copper and lead complexes into phytoplankton cells
Authors: Phinney Jonathan T , Bruland Kenneth W
Published: March 2010

The fungicides Ziram and Maneb (class dithiocarbamate) are organic Zn and Mn complexes in which the trace metal is chelated to organic dithiocarbamate ligands. The resulting organic metal complex is small, neutrally charged, and lipophilic in character. Short-term uptake experiments using a coastal diatom demonstrated that these lipophilic organic Zn and Mn complexes diffuse across the lipid bilayer that constitutes the plasma membrane. In addition, Cu2+ and Pb2+ ions in seawater solution undergo exchange reactions with Zn and Mn and form lipophilic organic Cu and Pb complexes that also diffuse across the plasma membrane and into the cytosol of the cell. Intracellularly, these trace metals are thought to dissociate from the transport ligand and complex intracellular ligands. Based on these results, the presence of dithiocarbamate fungicides in surface water can inadvertantly enhance the passive uptake of a variety of toxic heavy metals from the water into microorganisms.
Photochemical Formation of volatile mercury in high Arctic lakes
Authors: Amyot Marc , Lean David , Mierle Greg
Published: March 2010

Formation rates of dissolved gaseous mercury (DGM were measured in three high (74 °N) Arctic lakes and one wetland. The rate of formation of DGM was controlled by (1) the intensity of solar radiation, particularly ultraviolet-B (280–320 nm) and ultraviolet-A (320–400 nm) wavebands and (2) the concentration of available photoreducible Hg(II) complexes. Additions of hydrogen peroxide and of fulvic acids did not enhance DGM formation rates in our experiments. This study illustrates that photoreduction of mercury occurs in a wide range of aquatic systems even in the high arctic where radiation levels are lower but continue for the entire day during the summer.
Bioaccumulation and metallothionein response in the asiatic clam (Corbicula fluminea) after experimental exposure to cadmium and inorganic mercury
Authors: Baudrimont Magalie , Metivaud Jacqueline , Maury-Brachet Régine , Ribeyre Francis , Boudou Alain
Published: March 2010

The involvement of metallothioneins (MTs) in cadmium (Cd) and inorganic mercury (Hg[II])bioaccumulation by the freshwater bivalve Corbicula fluminea was experimentally investigated after 0, 15, 30, and 45 d of exposure from the water column source. Three levels of contamination were studied for each metal: 0, 5, and 35 μg Cd/L and 0, 1.45, and 5 μg Hg/L, with two replicates per condition. Forty eight experimental units (EUs) were conducted simultaneously. The mollusks were fed twice a week by additions of phytoplanktonic algae. Quantification of MTs was done by Hg-saturation assay, using cold Hg(II). A partial purification of these proteins was conducted by gel-filtration chromatography, followed by Cd determinations in the different eluted fractions. Results at the whole organism (soft tissues) and organ or tissue group (gills, mantle, foot, visceral mass) levels show high metal concentrations, with a fourfold greater accumulation of inorganic Hg than Cd after 30 d exposure at the same concentration of 5 μg/L. Gills and visceral mass were the principal storage compartments. A significant increase in MT concentrations was revealed in these two organs after exposure to Cd: ratios between the MT concentrations in contaminated and control mollusks were 2.4 and 2.8, respectively, for 5 and 35 μg Cd/L. Cd burdens in the cytosol and in ≤18-kDa protein fractions, similar to purified mammal MTs, correspond to 30 and 14% of the total Cd accumulated in the whole organisms. No significant increase in MT biosynthesis was observed after exposure to inorganic Hg, despite the high metal concentrations in the organs.
Relative acute effects of low pH and high iron on the hatching and survival of the water mite (Arrenurus manubriator) and the aquatic insect (Chironomus riparius)
Authors: Rousch Jeffrey M , Simmons Thomas W , Kerans Billie L , Smith Bruce P
Published: March 2010

We investigated the relative effects of low pH and high iron on a water mite, Arrenurus manubriator and an aquatic insect, Chironomus riparius. Eggs and active stages were exposed in static renewal toxicity tests to pH 6, 5, 4, 3, and 2, made by adding sulfuric acid to reconstituted soft water, or to iron levels of 200, 400, 600, 800, and 1,000 mg/L, made by adding ferrous sulfate to soft water at pH 4. Experiments were conducted at 22°C with a 16:8-h photoperiod, and treatments were replicated three times with at least nine individuals per treatment. Data were analyzed with a logistic response function and one-way ANOVA for pH and iron tests, respectively. Egg hatching was reduced at pH 2 for midges and at pH 3 for mites. Iron had no effect on hatching for either species. Survival of midge larvae was partially reduced at pH 4, and survival of mite deutonymphs, larvae, female and male adults was reduced at pH 3. Survival of midge larvae, and mite deutonymphs and male adults was reduced at 400, 200, and 1,000 mg Fe/L, respectively. Mite female adults and larvae were unaffected by iron. Higher metabolic requirements of unfed immature stages, the gelatinous covering of mite and insect eggs, the longer incubation period of mite eggs, and the greater osmoregulatory potential of adult mites may have contributed to the differences observed.
Structural-based differences in ecotoxicity of benzoquinoline isomers to the zebra mussel (Dreissena polymorpha)
Authors: Kraak Michiel H S , Wijnands Paul , Govers Harrie A J , Admiraal Wim , de Voogt Pim
Published: March 2010

Effects of four benzoquinoline isomers on the filtration rate of the zebra mussel ( Dreissena polymorpha) were analyzed, to study the effect of minor differences in chemical structure on adverse biological effects. Filtration rates were measured after 48 h of exposure to different concentrations of acridine, phenanthridine, benzo[f]quinoline, and benzo[h]quinoline in the water. The 50% effective concentration (EC50) values for filtration rate of the four isomers differed significantly. Effects increased in the order benzo[f], -[h], -[b], and -[c]quinoline, and the difference between the most toxic isomer and the least toxic isomer amounted to a factor of 30. Attempts were made to relate these differences in toxicity to the structure of the isomers. Size- or topology-related molecular descriptors provided insufficient resolution to distinguish between the benzoquinoline isomers, and none of the electronic descriptors separately provided a significant correlation with the observed effects. In an alternative approach, molecular shape, accessibility, and minimum agent–macromolecule distance were used to represent repulsive and attractive forces between the benzoquinoline isomers and biological membranes. This approach could tentatively explain the observed effects and is supported by a high correlation between the EC50 data and the reversed-phase C18-HPLC behavior of the benzoquinolines (k0), which is likely to be governed by similar processes.
Inhibitors of the multixenobiotic resistance mechanism in natural waters: In vivo demonstration of their effects
Authors: Smital Tvrtko , Kurelec Branko
Published: March 2010

Xenobiotics in water that can inhibit the multixenobiotic resistance (MXR) defense mechanism in water organisms, the chemosensitizers, may cause severe ecotoxicological effects. We determined their concentrations in polluted and unpolluted river waters and seawaters using different methods. Here we present the method that enables direct determination of MXR-inhibitory potential in natural waters. This method measures the modulating potential of river water or seawater on the rate of rhodamine B (RB) accumulation in gills of a freshwater clam (Dreissena polymorpha) or a marine mussel (Mytilus galloprovincialis), respectively. The sensitivity of the method with RB even enabled the determination of MXR inhibitors by measuring their potential to modulate the rate of efflux of RB from gills of mussels. The concentrations of MXR inhibitors found by these methods (expressed in μM of verapamil-equivalents) were higher in natural waters from polluted rivers or in natural seawaters from polluted marine sites than in natural waters from unpolluted rivers or in natural seawaters from unpolluted sites. Polluted waters enhanced accumulation or decreased efflux rate of RB, a good substrate of P-glycoprotein, demonstrating that the complex mixture of chemicals present in polluted waters contains MXR-inhibiting potential. In addition, the efflux version of the method with RB has the clear advantage of not requiring that organisms be killed and so allows repeated use of the same individuals. In addition, it is the simplest and the most reliable method for measuring the activity of MXR in these organisms.
Use of perifusion to assess in vitro the functional integrity of interrenal tissue in teleost fish from polluted sites
Authors: Brodeur Julie C , Girard Caroline , Hontela Alice
Published: March 2010

A perifusion procedure adapted to field studies with fish was developed to assess in vitro the functional integrity of the cortisol-secreting interrenal tissue, which is distributed within the head kidney. The capacity of the interrenal tissue to respond to adrenocorticotropic hormone (ACTH) was assessed by stimulating isolated fish head kidney tissues with 10−7 M of ACTH139 during 10 min in perifusion, and monitoring the resulting increase in cortisol secretion. The interrenal tissue of yellow perch (Perca flavescens) from a site contaminated by a mixture of heavy metals and organic contaminants secreted significantly less cortisol in response to the standardized pulse of ACTH than did the interrenal tissue offish from a reference site (54.7 ± 8.9 vs 81.8 ± 17.7 ng cortisol/g head kidney, respectively). These results indicate that the disruption of the cortisol stress response observed in fish from polluted sites is caused, at least in part, by a dysfunction of the interrenal tissue. The perifusion procedure can be used to examine the effects of chronic exposures to pollutants on the functional integrity of the cortisol-secreting interrenal tissue in teleost fish.
A comparison of equilibrium partitioning and critical body residue approaches for predicting toxicity of sediment-associated fluoranthene to freshwater amphipods
Authors: Driscoll Susan Kane , Landrum Peter F
Published: March 2010

Equilibrium partitioning (EqP) theory, which has been used to develop sediment quality criteria, predicts that the effects of organic compounds in sediments can be assessed by comparison of organic carbon-normalized sediment concentrations and estimated pore-water concentrations to effects determined in water-only exposures. A complementary approach, the critical body residue (CBR) theory, examines actual body burdens in relation to toxic effects. Critical body residue theory predicts that the narcotic effects of nonpolar compounds should be essentially constant for similar organisms, and narcosis should be observed at body burdens of 2 to 8 μmol/g tissue. This study compares these two approaches for predicting toxicity of the polycyclic aromatic hydrocarbon (PAH) fluoranthene. The freshwater amphipods Hyalella azteca and Diporeia spp. were exposed for up to 30 d to sediment spiked with radiolabeled fluoranthene at concentrations of 0.1 (trace) to 3,940 nmol/g dry weight (=346 μmol/g organic carbon). Mean survival of Diporeia was generally high (>70%) and not significantly different from that of control animals. This result agrees with EqP predictions, because little mortality was observed for Diporeia in 10-d water-only exposures to fluoranthene in previous studies. After 10-d exposures, mortality of H. azteca was not significantly different from that of controls, even though measured interstitial water concentrations exceeded the previously determined 10-d water-only median lethal concentration (LC50). Equilibrium partitioning overpredicted fluoranthene sediment toxicity in this species. More mortality was observed for H. azteca at later time points, and a 16-d LC50 of 3,550 nmol/g dry weight sediment (291 μmol/g organic carbon) was determined. A body burden of 1.10 μmol fluoranthene-equivalents/g wet weight in H. azteca was associated with 50% mortality after 16-d exposures. Body burdens as high as 5.9 μmol/g wet weight resulted in little mortality in Diporeia. Diporeia, which has limited ability to metabolize fluoranthene and a higher lipid content, appears to be less sensitive than H. azteca, which does metabolize fluoranthene. These results demonstrate that the CBR approach is a useful complement to the EqP approach for the prediction and assessment of toxicity associated with contaminated sediments.
Chronic toxicity evaluation of wastewater treatment plant effluents with bioluminescent bacteria: A comparison with invertebrates and fish
Authors: Sweet Leonard I , Travers David F , Meier Peter G
Published: March 2010

The use of bioluminescent bacteria in chronic toxicity testing is a potentially useful yet unexplored tool in whole effluent biomonitoring. The purpose of this study was to determine the chronic toxicity of 14 different wastewater treatment plant effluents to Chronic Microtox® bacteria (Vibrio fischeri), a cladoceran (Ceriodaphnia dubia), and a minnow (Pimephales promelas). The invertebrate and fish have been utilized extensively for the evaluation of effluents and in establishing water quality criteria. The results of this study suggest that the 22-h Microtox Chronic Toxicity Test may correlate well with the most sensitive chronic no-observed-effect concentration value of the three-brood C. dubia test.
Bioconcentration of [14C]butyl benzyl phthalate in bluegill sunfish (Lepomis macrochirus)
Authors: Carr Katherine H , Coyle Gerald T , Kimerle Richard A
Published: March 2010

A short-term study was conducted to measure the bioconcentration factors for intact butyl benzyl phthalate (BBP) in whole fish, fillet (edible tissues), and viscera (non-edible) tissues of bluegill sunfish (Lepomis macrochirus). A group of 24 fish was exposed for 3.27 d to [14C] BBP in a dynamic system. Intact BBP was quantified by chromatographic analyses for each tissue fraction. Significant metabolism of BBP was observed in the fish, with intact BBP representing less than 3% of the total radioactivity in each type of tissue. Measured bioconcentration factors (BCFs) for intact BBP (normalized to 6% lipid) were 9.4 (whole fish), 8.7 (viscera), and 1.7 (fillet). These BCFs were considerably lower than previously published BCF values, which were based on total radioactive residues in whole fish.
A novel approach for dissolving chemicals with low aqueous solubility: Generator disk in the headspace
Authors: Ramos Eñaut Urrestarazu , Vaes Wouter H J , Verhaar Henk J M , Hermens Joop L M
Published: March 2010

In this communication a novel approach of preparing solutions of chemicals in water with a low solubility is presented. The method consists of loading a C18 coated Empore® disk with the chemical of interest, followed by desorption of the chemical into the water through the vapor phase.
Physiological profiling of indigenous aquatic microbial communities to determine toxic effects of metals
Authors: Lehman R Michael , Colwell Frederick S , Garland Jay L
Published: March 2010

Conventional bioassays for environmental assessment frequently rely on nonindigenous single species. We employed an assay in which whole environmental samples were distinguished by the ability of the native heterotrophic microbial communities to oxidize 95 different sole carbon sources generating a community-level physiological profile (CLPP). The average metabolic response (AMR) to the 95 variables defining the CLPP was used in laboratory bioassay studies with copper to construct dose–response curves over several different periods of exposure: 1 h (acute), 1 d, 2 d, and 4 d. The acute dose–response of Snake River bacterioplankton communities measured by AMR was compared to the dose–response of Photobacterium phosphoreum (used in the Microtox test) and a proprietary mixed consortia (used in the Polytox test). In laboratory bioassay studies, CLPP AMR exhibited acute dose–response behavior over a greater range in copper concentrations and with less variability (per dose) than Microtox and Polytox. The acute sensitivity of CLPP AMR to copper was roughly equal to Microtox and much greater than Polytox. After a longer exposure (1 d) to copper, Snake River communities became more sensitive to copper but no additional effect was observed when the exposure was increased to 2 and 4 d. Snake River communities pre-exposed to copper (1 mg/L) for 4 d prior to acute dose–response experiments showed no difference in AMR with respect to doses up to 10 mg/L, indicating the ability of the assay to detect adaptation. Several metal-contaminated streams in Idaho were used to field validate the CLPP approach for detecting impacts of metals in the environment. The response profiles of the bacterioplankton from two downstream sites receiving metal laden mine drainage were compared to those from reference sites upstream and further downstream of the location receiving the mine drainage. The AMR of the communities at the stream reference sites were greater than sites just below the mines. We ascribed this finding to acute physiological insult near the mines and subsequent recovery downstream. Multivariate analysis revealed differences in the pattern of carbon source utilization between chronically stressed (mine waters) and unstressed communities (reference stream sites). At the third site, treatment of mine drainage by an artificial wetland was assessed above and below the wetland; water exiting the treatment wetland had a higher AMR than water that was untreated. The CLPP approach has sufficient sensitivity to detect acute contaminant impact on physiological processes of the indigenous microbial community while providing data for evaluation of chronic stress-induced adaptations in microbial community structure.
Mechanistic quantitative structure–activity relationship model for the photoinduced toxicity of polycyclic aromatic hydrocarbons: I. Physical model based on chemical kinetics in a two-compartment system
Authors: Krylov Sergey N , Huang Xiao-Dong , Zeiler Lorelei F , Dixon D George , Greenberg Bruce M
Published: March 2010

A quantitative structure–activity relationship model for the photoinduced toxicity of 16 polycyclic aromatic hydrocarbons (PAHs) to duckweed (Lemna gibba) in simulated solar radiation (SSR) was developed. Lemna gibba was chosen for this study because toxicity could be considered in two compartments: water column and leaf tissue. Modeling of photoinduced toxicity was described by photochemical reactions between PAHs and a hypothetical group of endogenous biomolecules (G) required for normal growth, with damage to G by PAHs and/or photomodified PAHs in SSR resulting in impaired growth. The reaction scheme includes photomodification of PAHs, uptake of PAHs into leaves, triplet-state formation of intact PAHs, photosensitization reactions that damage G, and reactions between photomodified PAHs and G. The assumptions used were: the PAH photomodification rate is slower than uptake of chemicals into leaves, the PAH concentration in aqueous solution is nearly constant during a toxicity test, the fluence rate of actinic radiation is lower within leaves than in the aqueous phase, and the toxicity of intact PAHs in the dark is negligible. A series of differential equations describing the reaction kinetics of intact and photomodified PAHs with G was derived. The resulting equation for PAH toxicity was a function of treatment period, initial PAH concentration, relative absorbance of SSR by each PAH, quantum yield for formation of triplet-state PAH, and rate of PAH photomodification. Data for growth in the presence of intact and photomodified PAHs were used to empirically solve for a photosensitization constant (PSC) and a photomodification constant (PMC) for each of the 16 PAHs tested. For 9 PAHs the PMC dominates and for 7 PAHs the PSC dominates.
Joint acute toxicity of diazinon and chlorpyrifos to Ceriodaphnia dubia
Authors: Bailey Howard C , Miller Jeffrey L , Miller Michael J , Wiborg Lan C , Deanovic Linda , Shed Theodore
Published: March 2010

Diazinon and chlorpyrifos are two organophosphorous pesticides widely found in municipal, agricultural, and urban storm water discharges. Because they are often found concurrently, their relationship with respect to joint toxicity is of interest, particularly in regard to interpreting the results of toxicity identification evaluations (TIEs) that point to metabolically activated organophosphorous pesticide(s) as causes of toxicity. Joint toxicity was evaluated using static tests that incorporated 48- to 96-h exposure periods using laboratory water, natural water, and urban storm water. Chemical concentrations were verified analytically. Mortalities were measured at 24-h intervals and joint toxicity was calculated on the basis of toxic units (TUs) for every time interval (1 TU = median lethal concentration [LC50]). Forty-eight-hour LC50 values ranged between 0.26 and 0.58 μg/L for diazinon and between 0.058 and 0.079 μg/L for chlorpyrifos. The 96-h values were approximately 65% of their respective 48-h values. Under the assumption of strict additivity, the LC50 (as TUs) of the mixture should be the sum of the respective fractions of diazinon and chlorpyrifos and should total unity. These values were calculated for a total of 12 time intervals. The TUs associated with the mixtures in laboratory water ranged between 0.89 and 1.46, with an average of 1.13. The values for the natural and storm water samples were similar to those obtained with laboratory water. These data confirmed the results of TIEs that suggested that diazinon and chlorpyrifos exhibit additive toxicity when present together.
Woodlouse locomotor behavior in the assessment of clean and contaminated field sites
Authors: Bayley Mark , Baatrup Erik , Bjerregaard Poul
Published: March 2010

Specimens of the woodlouse Oniscus asellus were collected at four clean field sites and from a recently closed iron foundry heavily contaminated with zinc, lead, chromium, and nickel. Each of the 30 woodlice per group was housed individually and acclimatized to laboratory conditions for 2 d on a humid plaster of paris substrate. Thereafter, the locomotor behavior of each animal was measured for 4 h employing automated computer-aided video tracking. Linear discriminant analysis of five locomotor parameters revealed average velocity and path length as the principle components separating the polluted site and control animals. Post hoc analysis of the discriminant variable for animals from all five sites showed that the animals from the polluted site where significantly hyperactive when compared to all controls. Further, control animals collected from sites separated by several hundred kilometers were remarkably similar in their locomotor behavior. This preliminary study highlights the potential utility of quantitative analysis of animal locomotor behavior in environmental monitoring.
Cytochrome P450 and organochlorine contaminants in black-crowned night-herons from the Chesapeake Bay region, USA
Authors: Rattner Barnett A , Melancon Mark J , Rice Clifford P , Riley Walter , Eisemann John , Hines Randy K
Published: March 2010

Black-crowned night-heron (Nycticorax nycticorax) offspring were collected from a relatively uncontaminated coastal reference site (next to Chincoteague National Wildlife Refuge, VA, USA) and two sites in the Chesapeake Bay watershed (Baltimore Harbor, MD and Rock Creek Park, Washington, DC, USA). Hepatic microsomal activities of benzyloxyresorufin-O-dealkylase and ethoxyresorufin-O-dealkylase were significantly elevated (up to sixfold and ninefold induction, respectively) in pipping embryos from the Baltimore Harbor colony compared to the reference site, whereas values in embryos from the Rock Creek Park colony were intermediate. Concentrations of organochlorine pesticides and metabolites in pipping embryos from both sites in the Chesapeake watershed were greater than at the reference site but below the known threshold for reproductive impairment. However, concentrations of 10 arylhydrocarbon receptor-active polychlorinated biphenyl (PCB) congeners and estimated toxic equivalents were up to 37-fold greater in embryos collected from these two sites in the Chesapeake Bay region, with values for toxic congeners 77 and 126 exceeding those observed in pipping heron embryos from the Great Lakes. Monooxygenase activity of pipping embryos was associated with concentrations of several organochlorine pesticides, total PCBs, arylhydrocarbon receptor-active PCB congeners, and toxic equivalents (r = 0.30–0.59), providing further evidence of the value of cytochrome P450 as a biomarker of organic contaminant exposure. Organochlorine contaminant levels were greater in 10-d-old nestlings from Baltimore Harbor than the reference site but had no apparent effect on monooxygenase activity or growth. These findings demonstrate induction of cytochrome P450 in pipping black-crowned night-heron embryos in the Chesapeake Bay region, probably by exposure to PCB congeners of local origin, and the accumulation of organochlorine pesticides and metabolites in nestling herons from Baltimore Harbor. Bio-monitoring with additional waterbird species (e.g., bald eagle, common tern, great blue heron) that appear to be more sensitive to PCBs than black-crowned night-herons is recommended to document health of waterbirds and remediation of the Chesapeake Bay.
A culture-based assessment of the effects of chlorpyrifos on multiple meiobenthic copepods using microcosms of intact estuarine sediments
Authors: Chandler G Thomas , Coull Bruce C , Schizas Nicholaos V , Donelan Teresa L
Published: March 2010

Miobenthos occur at densities of >106/m2 in almost every uncontaminated estuarine sediment of the world, yet few studies have explored their utility for a multiple-species chronic bioassay of sediment contaminant effects. A new approach using laboratory-reared, whole-sediment meiobenthic microcosms was developed to holistically test the sublethal effects of chlorpyrifos on benthic copepod survival, age structure, and reproduction. Entire sediment-dwelling meiofaunal communities from a pristine estuarine preserve were cultured (i.e., net population gains were achieved in controls) for at least a full generation to the known 96-h copepod adult 25% lethal concentration and larval 50% lethal concentration of sediment-associated chlorpyrifos (21–33 μg/kg sediment). As an internal bioassay control, we added and cultured 100 gravid benthic copepods (Amphiascus tenuiremis) in each microcosm to assess the exact rather than relative effects of chlorpyrifos on population growth and dynamics. All but one copepod species reproduced and was cultured successfully for at least 21 d using these techniques. We found no chlorpyrifos effects on total meiobenthic copepod densities, but the predominant naturally occurring copepod Microarthridion littorale, known to be a major prey item of many juvenile fish, was significantly reduced in some chlorpyrifos-spiked microcosms. Other naturally occurring copepods were either unaffected or their growth was enhanced in the presence of chlorpyrifos. Amphiascus tenuiremis, known to be adversely affected at this concentration in 96-h static bioassays, increased dramatically in every microcosm. Species-specific responses of endemic copepods were masked when combined into the more commonly used coarse taxonomic category of total copepods.
Fate of chlorpyrifos in outdoor pond microcosms and effects on growth and survival of bluegill sunfish
Authors: Giddings Jeffrey M , Biever Ronald C , Racke Kenneth D
Published: March 2010

Three series of outdoor pond microcosms were treated with the organophosphorous insecticide chlorpyrifos to determine the fate of this compound and its ecological impact on an aquatic community. A variety of application regimes were used, including a one-time surface spray, three soil-water slurry applications, and combinations of spray and slurry applications. Maximum chlorpyrifos concentrations in microcosm water ranged from 0.03 to 2.58 μg/L. Chlorpyrifos disappeared rapidly after each spray application, probably due to volatilization from surface water, with an initial half-life of about 1 d. In slurry-treated microcosms, and in spray-treated microcosms after initial volatilization, half-lives in water were consistently around 6 d. A small fraction (generally less than 10%) of the chlorpyrifos applied went to the sediment, where it was more persistent than in the water column. The mean length and weight of individual bluegill sunfish (stocked as juveniles before chlorpyrifos application) were unaffected by chlorpyrifos exposure. Survival and total biomass of bluegill were reduced in microcosms exposed to the highest chlorpyrifos concentrations. The inhibition concentrations (IC25) for bluegill survival and total biomass were about 0.4 to 1.9 μg/L, based on maximum measured concentrations or maximum 96-h average concentrations. Bluegill survival and total biomass were unaffected by repeated exposures to chlorpyrifos if the maximum concentrations remained below these levels.
The relative importance of water hardness and chloride levels in modifying the acute toxicity of silver to rainbow trout (Oncorhynchus mykiss)
Authors: Galvez Fernando , Wood Chris M
Published: March 2010

Static-renewal 7-d toxicity tests for silver nitrate (AgNO3) were performed with juvenile rainbow trout (Oncorhynchus mykiss Walbaum). The relative influences of calcium and chloride concentrations on median lethal time (LT50) were assessed. Calcium concentrations were controlled by adding either Ca(NO3)2 or CaSO4, whereas chloride concentrations were adjusted with either NaCl or KCl. For both calcium salts, a 100-fold elevation in concentration increased the LT50 approximately 10-fold. However, a 100-fold elevation in KCl ameliorated silver (Ag) toxicity at least 100-fold, while NaCl protected against Ag toxicity even more substantially, demonstrating the much greater protective effect of chloride relative to calcium. In a separate series of bioassays, fish were exposed to 0.92 μM Ag (100 μg/L as AgNO3) with varying amounts of NaCl titrated into each tank to alter the free [Ag+]. The 7-d LC50 occurred at a [NaCl] of 2,500 μM. Using MINEQL+ (a geochemical speciation program), the predicted free [Ag+] at this LC50 value is 0.0285 μM. Further bioassays were performed in which [chloride] was maintained at either 50 or 225 μM, while total [Ag] was independently varied from 0.0092 to 0.0694 μM (1.0–7.5 μg/L). The 7-d LC50 value was calculated at 0.0294 μM Ag (3.18 μg/L) at a chloride concentration of 50 μM, very similar to the free [Ag+] value of 0.031 μM calculated from an earlier LC50 test at a fixed [chloride] of 730 μM. According to MINEQL+, the estimated [Ag+] at this LC50 value is 0.0289 μM. Although a 7-d LC50 value could not be determined at 225 μM chloride, it was estimated at slightly above 0.0277 μM Ag+. Elevating chloride concentrations from 50 to 225 μM did not alter the accumulation of Ag in the liver. In addition, there were no significant differences in hepatic Ag accumulation between any of the Ag-exposed fish, irrespective of the total Ag concentration used during the exposure. Overall, Ag accumulated to approximately 185 μmol/kg wet weight in all Ag-exposed groups (approximately a 10-fold increase above controls). These results, together with a reanalysis of published data, suggest that Ag toxicity can be correlated with the free Ag ion [Ag+], and that any factors altering Ag+ availability (i.e., chloride) will be expected to modify acute Ag toxicity.