bluuebunny/crossref_metadata_2025 huggingface dataset:
Relative potencies of individual polychlorinated dibenzo-p-dioxin, dibenzofuran, and biphenyl congeners and congener mixtures based on induction of cytochrome P4501A mRNA in a rainbow trout gonadal cell line (RTG-2)
Authors: Zabel Erik W. , Pollenz Richard , Peterson Richard E.
Published: March 2010

Cytochrome P450-catalyzed enzyme activity in cell culture was investigated as a bioassay for 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) equivalents in environmental mixtures of polychlorinated dibenzo-p-dioxin (PCDD), dibenzofuran (PCDF), and biphenyl (PCB) congeners. A problem with the use of enzyme induction is that certain congeners are unable to induce P4501A enzyme activity to the same maximal level as TCDD. We sought to eliminate this problem by measuring mRNA induction rather than enzyme activity. Rainbow trout gonadal cells (RTG-2) were exposed to PCDD, PCDF, and PCB congeners and congener mixtures, and induction of cytochrome P4501A mRNA was measured. A high level of induction in cells treated with only a medium change was seen and was due to a component of the fresh medium. 2,3,7,8-Substituted PCDD and PCDF congeners and four non-ortho-substituted PCBs caused dose-related induction of P4501A mRNA. Di-ortho-substituted PCBs did not induce P450 mRNA, but three mono-ortho-substituted PCBs caused significant induction. Toxic equivalency factors determined in RTG-2 cells were generally higher than those in rainbow trout early life stages. Rainbow trout gonadal cell (RTG-2) bioassay TCDD equivalents (TEqs) for three environmental extracts were lower than those predicted by addition of individual congener TEqs, and the synthetic congener mixture acted additively.
Organic pollutants in the coastal environment off San Diego, California. 2. Petrogenic and biogenic sources of aliphatic hydrocarbons
Authors: Tran Kim , Yu Charlie C , Zeng Eddy Y
Published: March 2010

The results from the measurements of aliphatic hydrocarbons suggest that hydrocarbons in the Point Loma Wastewater Treatment Plant (PLWTP) effluents are mainly petroleum derived; those in the Tijuana River runoff have largely originated from terrestrial plants with visible petroleum contamination; and those in the sea surface microlayer, sediment traps, and sediments at various coastal locations off San Diego have mostly resulted from biogenic contributions with enhanced microbial products in the summer season. Rainfall in the winter season appeared to amplify the inputs from terrestrial higher plants to the coastal areas. The PLWTP discharged approximately 3.85 metric tons of n-alkanes (C10-C35) in 1994, well below the level (136 metric tons) estimated in 1979. The input of aliphatic hydrocarbons from the Tijuana River was about 0.101 metric tons in 1994. Diffusion, solubilization, evaporation, and microbial degradation seemed partially responsible for the difference in the concentrations and compositions of aliphatic hydrocarbons in different sample media, although the relative importance of each mechanism cannot be readily discerned from the available data. The results from analyses of aliphatic hydrocarbon compositional indices are generally consistent with those of polycyclic aromatic hydrocarbons.
Similarity analysis of PAH and PCB bioaccumulation patterns in sediment-exposedChironomus tentanslarvae
Authors: Wood Lindsey W , O'Keefe Patrick , Bush Brian
Published: March 2010

Larvae of the aquatic insect Chironomus tentans (Insecta: Diptera: Chironomidae) were exposed at the third or fourth instar stage to sediments collected near the outfalls of two aluminum foundries and an aluminum fabrication plant. Biota and sediment bioaccumulation factors (BFs), based on wet tissue weights and dry sediment weights, ranged from 0.07 to 0.27 for polycyclic aromatic hydrocarbons (PAHs) and from 0.22 to 1.42 for polychlorinated biphenyls (PCBs). A higher rate of metabolism of PAHs compared with PCBs could explain the differences in BF values for the two groups of chemicals. It was found, using community similarity procedures from the field of ecology, that the congener patterns for PAHs and PCBs bioaccumulated by the larvae differed from the pattern of the same compounds in the sediments to which they were exposed. Affinity analysis indicated that the larvae favored the higher molecular weight PAH and PCB congeners. Preferential ingestion of sediments with defined particle size ranges, metabolism, and octanol/water partition coefficients (log Kow) are factors that may have influenced the bioaccumulation patterns. However, no single factor could adequately account for the differences between the larval and sediment patterns.
Effect of application solvents on heterotrophic and nitrifying populations in soil microcosms
Authors: Miller Jerry L , Sardo Michael A , Thompson Thomas L , Miller Raina M
Published: March 2010

Agricultural practices may cause contamination of soil and ground water with a combination of organic compounds (pesticides and fuel) and nitrogen fertilizers. In coupled microcosm studies that monitored the mineralization of naphthalene and the nitrification of ammonia, it was observed that the solvent (dichloromethane) used to apply naphthalene to the soil inhibited nitrification, although there was no effect on naphthalene mineralization. Further studies were performed with a series of application solvents: methanol, acetonitrile, trichloromethane, and dichloromethane. Soil and solvent were allowed to equilibrate with ambient air for various times before capping and incubation of microcosms. Results indicated that dichloromethane equilibrated for 5 mins inhibited nitrification for at least 3 weeks relative to the control (water). Acetonitrile and trichloromethane similarly inhibited nitrification. Methanol and dichloromethane equilibrated for 60 mins also significantly delayed nitrification, although to a lesser extent. Inhibition of nitrification was not permanent, and nitrification activity was eventually restored in all systems tested. None of the solvents inhibited mineralization of the added carbon source. These results indicate that special care must be taken to ensure that applications solvents do not affect the activity of sensitive microbial populations, such as the nitrifiers, that may be part of a study.
Laboratory assay of sediment phytotoxicity using the macrophyte Vallisneria americana
Authors: Biernacki Maciej , Lovett-Doust Jon , Lovett-Doust Lesley
Published: March 2010

In contrast to their ecological importance, submersed rooted macrophytes have been overlooked in environmental science. Presently, the array of standard phytotoxic bioassays includes only one free-floating vascular macrophyte (Lemna) and several algal species. A short-term and inexpensive assay was studied for feasibility in evaluating sediment quality. Cloned ramets of the macrophyte Vallisneria americana were used to test phytotoxicity of sediments collected at different locations in the Detroit River. Ramets were planted in sediment samples and placed in greenhouse aquaria. After a week of exposure, ramets of V. americana were destructively sampled and preserved. The leaf and root surfaces areas were determined, and plant biomass was recorded for each ramet. An index of the leaf-to-root surface area ratio was a reliable predictor of sediment phytotoxicity; the ratio of leaf-to-root mass was also useful but proved less consistent. Ramets grown in sediments that were relatively less contaminated with organic compounds had lower values of the leaf-to-root surface area ratio, while plants grown in more contaminated sediments had greater values. Results of analyses of variance indicated that the index of leaf-to-root surface area ratio responded to sediment quality but was not significantly affected by either variation in plant genotype or interaction between sediment and plant genotype. There was a significant correlation (p < 0.001) between rank-ordered results of the present greenhouse study and results of leaf-to-root surface area ratios for plants previously surveyed in the field.
Interlaboratory comparison of a method to evaluate the effects of chemicals on fish growth
Authors: Mallett M J , Grandy N J , Lacey R F
Published: March 2010

A protocol for the evaluation of chemicals on the growth rate of juvenile rainbow trout (Oncorhynchus mykiss Walbaum) over a 28-day period has been evaluated by comparison of the test results obtained by 15 laboratories from seven countries in the European Union. Two test substances were used, 3,4-dichloroaniline (DCA) and linear alkylbenzene sulfonate (LAS). Fourteen test results were received for DCA and seven for LAS. The data were analyzed in two ways: the evaluation of the lowest observed effect concentrations (LOECs), and regression analysis to estimate the concentration of the substance causing a 25% reduction in growth relative to the controls (EC25). The latter method clearly provided a number of advantages over estimation of LOECs. These included less dependence of the result upon the spacing between exposure concentrations and upon the arbitrary choice of level of statistical significance. In addition it was possible to estimate an EC25 for more data sets than was possible for LOEC estimation. The sensitivity of the test was comparable with other chronic tests (Daphnia juvenile production and fathead minnow early life stage tests) for DCA and LAS. For DCA the overall mean EC25 was 223 μg/L the EC25s found by individual laboratories ranged from 100 to 390 μg/L. For LAS the EC25 ranged from 1,220 to 2,810 μg/L.
Results of zinc deprivation in daphnid culture
Authors: Caffrey Paula Barone , Keating Kathleen Irwin
Published: March 2010

Daphnia pulex Leydig (Cladocera), reared in circumstances of strictly controlled trace element exposure, were deprived of zinc. When zinc was withheld from both their liquid medium and solid (algal) food, D. pulex survived for more than 20 consecutive generations before the line ceased reproduction entirely. Through these generations zinc deprivation resulted in a somewhat irregular, but continuing, shortening of life span, a decrease in fecundity (both progeny per brood and number of broods were affected), and a loss of cuticle integrity. A distinct pattern of response was observed during the gradual, multigenerational decline of the animal line. The decline can be separated into three stages: initial (first five), minimal, but steady, increase in overt damage; intermediate (sixth through 19th), varying degrees of damage with apparent severity showing a distinct alternation from generation to generation; and final (last three generations), limited reproduction with ultimate elimination of the animal line by a total absence of reproduction in generation 23.
Effects of bacterial inoculation and nonionic surfactants on degradation of polycyclic aromatic hydrocarbons in soil
Authors: Madsen Torben , Kristensen Preben
Published: March 2010

The aim of the study was to examine the effects of introduced bacteria and nonionic surfactants on the degradation of polycyclic aromatic hydrocarbons (PAHs) in soil. Mineralization experiments were conducted with freshly added [14C]phenanthrene or [14C]pyrene, whereas other experiments focused on the degradation of selected PAHs present in a coal tar-contaminated soil. Inoculation of soil samples with phenanthrene-utilizing bacteria stimulated the mineralization of [14C]phenanthrene. This effect, however, was most notable in soil with a low indigenous potential for PAH degradation, and a large inoculum was apparently required to establish phenanthrene mineralization in the soil. Addition of alcohol ethoxylate and glycoside surfactants to soil samples enhanced the mineralization of [14C]phenanthrene and [14C]pyrene. The nonionic surfactants also enhanced the degradation of contaminant PAHs that were present in the soil coal tar. As an example, pyrene, benzo[b,j,k]fluoranthene, and benzo[a]pyrene were resistant to degradation in the absence of surfactants, whereas significant degradation of these PAHs was observed when surfactants were added. The surfactant-related enhancement of the degradation of PAH contaminants was less convincing when a rapidly degradable glycoside surfactant was used. This suggests that surfactants that are mineralized at moderate rates may be more applicable for increasing the availability of PAHs in soil.
The relative sensitivity of chicken embryos to yolk- or air-cell-injected 2,3,7,8-tetrachlorodibenzo-p-dioxin
Authors: Henshel Diane S , Hehn Brent , Wagey Ravenska , Vo Mylinh , Steeves John D
Published: March 2010

We compared the relative sensitivity of chicken embryos exposed to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) injected either into the yolk or into the air cell. The TCDD was injected at the start of incubation (embryonic day 0) and the embryos were sacrificed at multiple times during embryonic development. A subset of embryos were allowed to hatch undisturbed. The chick embryo was significantly more sensitive to TCDD when injected into the yolk than when injected into the air cell. The resultant median lethal dose (LD50) (122 pg/g egg, determined by probit analysis; 146 pg/g egg determined by interpolation) was 60% lower than the LD50 (297 pg/g egg by probit; 255 pg/g egg determined by interpolation) for air-cell-injected TCDD. A significant decrease in hatch weight of embryos exposed to high concentrations of TCDD compared to controls occurred, and this decrease was even more pronounced at a lower concentration in the yolk-injected birds. Interestingly, during the period of embryonic days 11 through 15, the mean weight of the yolk-injected embryos was smaller than the mean weight of the air-cell-injected embryos. This difference was not noticably evident just before or just after this developmental period. Embryos exposed to high concentrations of TCDD injected into either the yolk or the air cell tended to die within the first 2 weeks of incubation. A number of TCDD-exposed embryos survived the entire 21-d incubation period, but only air-cell-injected embryos were able to hatch successfully. Because the injection site varies in studies reported by different laboratories, the relative sensitivity must be considered when comparing results from different studies.
A spreadsheet program for estimating low toxic effects
Authors: Caux Pierre-Yves , Moore Dwayne R J
Published: March 2010

A Mcrosoftt® Excel v. 5.0 spreadsheet program for estimating low toxic effects is described using an example data set consisting of herbicide effects on corn germination. Users are guided through each step in the program. Five model equations are illustrated in both their mathematical and spreadsheet forms and statistical procedures are described.
High induction of cytochrome p4501a activity without changes in retinoid and thyroid hormone levels in flounder (Platichthys flesus) exposed to 2,3,7,8-tetrachlorodibenzo-p-dioxin
Authors: Besselink H T , van Santen E , Vorstman W , Vethaak A D , Koeman J H , Brouwer A
Published: March 2010

Oal dosesof 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) were administered twice within 7 d (total concentration 0.01, 0.1, 1, 10, or 100 μg TCDD/kg body weight) to flounder (Platichthys flesus). After 10 d of exposure, flounder were sacrificed, and the effects of TCDD exposure on hepatic microsomal total cytochrome P450 content, 7-ethoxyresorufin-O-deethylase (EROD) activity, and glutathione-S-transferase activity were examined. In addition, plasma and hepatic retinoid and plasma thyroid hormone levels were analyzed. Overall a good correlation existed between the dose and liver concentrations of TCDD. However, only 0.75% of the total dose of TCDD was retained in the flounder liver. The TCDD caused a dose-related, statistically significant induction of the hepatic microsomal total cytochrome P450 content (4.4-fold; p < 0.001) and associated EROD activity (27-fold; p < 0.001), without obvious changes in body weight, liver weight, and condition factor. Total glutathione-S-transferase activity was not induced in livers of flounder exposed to TCDD. No TCDD-induced changes in liver retinoid, plasma retinol, and plasma thyroid hormone parameters were observed. These results indicate that the flounder is an aryl hydrocarbon (Ah) receptor-responsive species with respect to CYP1A induction but not with respect to other mammalian Ah receptor-associated responses.
Influence of body fat on trifluralin toxicokinetics in rainbow trout (Oncorhynchus mykiss)
Authors: Schultz Irvin R , Hayton William L
Published: March 2010

We previously characterized the toxicokinetics of trifluralin (TF) in rainbow trout (Oncorhynchus mykiss) and found a large steady-state volume of distribution (Vss) that was attributed to a large, poorly perfused peripheral storage compartment. Because adipose tissue was expected to be an important peripheral storage tissue for this lipophilic herbicide, we studied its toxicokinetics in trout that differed in body fat content. Large, hatchery-reared rainbow trout and adult summer-run steelhead trout were fitted with an aortic cannula and given a 1-mg/kg dose of TF. The steelhead were studied approximately 3 weeks prior to spawning and after a 9-month fasting period. The total lipid content of the steelhead after removal of the reproductive organs averaged 1.2% of body weight, whereas that of the hatchery trout was 8%. Toxicokinetic analysis of the plasma concentration-time profile using a three-compartment model found the Vss in steelhead to be reduced significantly (p < 0.01) compared with the hatchery trout (1.3 vs. 5.7 L/kg). Other parameters that differed were the maximum plasma concentration, which was higher in steelhead (p < 0.05), and the elimination t1/2,β and mean residence time, which were reduced (p < 0.05) in steelhead. Although several physiological factors are probably involved, examination of the relationship between Vss and lipid content supported the hypothesis that the distribution of TF in trout was largely influenced by the lipid content of the fish.
The effects of hexachlorobenzene on mink in the Canadian environment: An ecological risk asssessment
Authors: Moore Dwayne R J , Breton Roger L , Lloyd Karen
Published: March 2010

Hexachlorobenzene (HCB) is a persistent substance that accumulates in tissues and biomagnifies up the food chain suggesting that biota at higher trophic levels (e.g., predatory birds and piscivorous mammals) are at the greatest risk of exposure. Although widespread, the highest levels of HCB in Canada are found in the Great Lakes and connecting channels. Because mink (Mustela vison) are piscivorous mammals known to be particularly sensitive to the effects of organochlorine substances, we assessed whether mink populations in the Great Lakes area are experiencing adverse effects as a result of exposure to HCB. A deterministic, deliberately hyperconservative analysis indicated that recent levels of HCB in air, water, and aquatic organisms are unlikely to pose a significant risk to mink living near Lakes St. Clair, Erie and Superior. The hazard quotients for the St. Clair River area near Sarnia and Lake Ontario, however, indicated potential risks. We conducted Monte Carlo simulations to estimate the probability that mink exposed to HCB in these areas are experiencing reproductive impairment. The results of these analyses indicate: (1) a moderate to high probability that mink in the St. Clair River area are experiencing 5 to 20% declines in reproductive success due to HCB exposure, and (2) a low probability (<15%) that mink near Lake Ontario are experiencing even modest declines in reproductive fecundity (>5%).
A reformulated, reconstituted water for testing the freshwater amphipod, Hyalella azteca
Authors: Smith Mark E , Lazorchak James M , Herrin Lori E , Brewer-Swartz Sandra , Thoeny William T
Published: March 2010

Toxicity testing with the freshwater amphipod, Hyalella azteca, has routinely been conducted using nonstandard waters. Four waters were tested for acceptability for aqueous reference toxicant testing with H. azteca. These included three formulated (standardized) waters: moderately hard reconstituted water (MHRW), reformulated moderately hard reconstituted water (RMHRW), and 25% dilute mineral water (DMW). The water used for comparison was a nonstandard, in-house culture water mixture of well water and dechlorinated tap water, diluted with Super-Q® deionized water to a hardness of 100 mg/L, as CaCO3 (LL/SQ). Control survival was less than the 90% minimum control survival criteria in all tests with MHRW. Two of five tests with DMW also failed to pass the minimum control survival criteria. All five tests with the RMHRW passed the control survival criteria. The mean 50% lethal concentration (LC50) for the tests in RMHRW was 320 mg/L KCl, with a coefficient of variation of 8.5%. Concurrent tests with the in-house water yielded control survival greater than 90% and a mean LC50 of 216 mg/L KCl with a coefficient of variation of 13.4%. Tests in an interlaboratory study yielded similar results. Whole-sediment toxicity tests conducted using RMHRW as the overlying water routinely exceed the 80% minimum survival criteria in the control and reference sediments. The failure of MHRW and DMW to produce acceptable results, as well as the inability of other laboratories to produce LL/SQ, makes RMHRW the best candidate for a standard water for H. azteca testing.
Polychlorinated biphenyls in eggs and chorioallantoic membranes of American alligators (Alligator mississippiensis) from coastal South Carolina
Authors: Cobb George P , Wood Pattie D , O'Quinn Michael
Published: March 2010

Assessing chemical exposure in threatened or endangered wildlife species presents unique analytical problems. Chorioallantoic membranes (CAMs) have been proposed as surrogate tissues for evaluation of polychlorinated biphenyl (PCB) exposure in oviparous species. Research was undertaken to determine the extent of PCB accumulation in alligators (Alligator mississippiensis) at sites along the coast of South Carolina and to evaluate the utility of CAMs as surrogate tissues for determining PCB concentrations in whole alligator eggs. Polychlorinated biphenyls were found in eggs and CAMs of alligators from both sites examined. Concentrations of PCBs were higher in CAMs (p = 0.02) and eggs (p = 0.001) from sites known to contain chlorinated hydrocarbons than from more pristine sites. Total PCBs partitioned predictably (r2 > 0.59; p < 0.02) between egg and CAM tissues indicating the utility of CAMs to serve as surrogate tissues when comparing total PCB concentrations in whole eggs. Tetrachloro through octachloro biphenyl homologues and total PCBs in CAMs from reference areas were correlated with concentrations of these homologues in eggs. At contaminated sites, total PCB concentrations in CAMs were correlated with total PCB concentrations in eggs.
Terrestrial wildlife risk assessment for TCDD in land-applied pulp and paper mill sludge
Authors: Meyn Ossi , Zeeman Maurice , Wise Michael J , Keane Susan E
Published: March 2010

A risk assessment was performed to evaluate the potential effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) in land-applied pulp and paper mill sludge on terrestrial wildlife. Three representative bird and mammal species were assessed for potential individual risk of adverse effects. A dietary model was used to estimate TCDD exposures of adult birds and mammals, and a pharmacokinetic model was used to estimate exposure for avian embryos. Using the quotient method, modeled exposure levels were compared to published no-observed-adverse-effect levels (NOAELs) for birds and mammals to calculate risk. Monte Carlo analysis was used to consider the variability and uncertainty in the risk estimates. The results suggest that TCDD in land-applied pulp and paper sludge may pose significant individual risks to terrestrial wildlife under certain circumstances. Shrews were found to be most at risk due to their high consumption rate of food items that are expected to bioconcentrate the TCDD from soil at the application sites. Of all possible pathways, only dietary exposure was considered in this investigation. The analysis centered on parameter uncertainty and does not include an assessment of alternative models, although this could be a significant source of uncertainty.
Cytochrome P4501A immunoassay in freshwater turtles and exposure to PCBs and environmental pollutants
Authors: Yawetz Aminadav , Benedek-Segal Michal , Woodin Bruce
Published: March 2010

This is the result of a comparative study of cytochrome P4501A (CYP1A) induction in liver microsomes from three species of freshwater turtles. CYP1A induction in turtle hepatic microsomes was compared to CYP1A induction in microsomes from the alligator, Alligator mississippiensis. Treatment of two species of freshwater turtles with four consecutive intraperitoneal injections of 100 mg/kg Aroclor 1254 caused a four- to five-fold increase in P4501A in hepatic microsomes of Chrysemys picta picta and Chrysemys picta elegans. The same treatment administered to another freshwater turtle, Mauremys caspica rivulata, resulted in a very low but significant (p < 0.01) induction of P4501A in hepatic microsomes. Specimens of M. caspica rivulata collected from an organic waste oxidation pond near the petrochemical industry area of the city of Ashdod exhibited normal levels of total hepatic microsomal cytochrome P450 but no detectable level of induction of cytochrome P4501A. The lack of P4501A1 induction could have resulted from two possible reasons. The first possibility is that the turtles were not exposed to residues of petrochemical waste in the pond. More likely, the apparent lack of induction resulted from the low response to CYP1A inducers found in this species. Induction of cytochrome P4501A was evaluated immunohistochemically in liver tissue of C. picta picta pretreated with Aroclor 1254 (400 mg/kg) or (124 mg/kg) 3,3′,4,4′-tetrachlorobiphenyl. The most intensive staining was exhibited by sections of liver from a 3,3′,4,4′-tetrachlorobiphenyl-treated turtle. Staining of P4501A in liver sections from Aroclor 1254-treated turtles was relatively moderate. In induced turtles, staining of the hepatocytes concentrated near the cell membranes and nuclear membranes, but stained granules were observed throughout the cytoplasm. The presence of inducible CYP1A enzymes in turtles is of importance from an evolutionary point of view and has potential ecological relevance.
Reduction of selenium oxyanions by Enterobacter cloacae strain SLD1a-1: Reduction of selenate to selenite
Authors: Losi Mark E , Frankenberger William T
Published: March 2010

Reduction of selenate ( SeO2−4) to selenite ( SeO2−3) by Enterobacter cloacae strain SLD1a-1 (ATCC 700258), a facultative anaerobe isolated from agricultural drainage water, was studied in microcosm experiments using washed cell suspensions. The washed cell suspension removed 92% of added SeO2−4 (at 127 μM) from solution over 10.5 h using glucose as the electron donor. A method was developed that allowed for the assessment of factors affecting only reduction of SeO2−4 to SeO2−3, the first step in the reduction of SeO2−4 to Se0 and/or Se2−. The method consisted of treating the cell suspensions with 2,4-dinitrophenol (DNP), after which SeO2−4 reduction proceeds relatively unimpeded but SeO2−3 reduction is inhibited and SeO2−3 accumulates in solution and is quantified. Optimum pH was found to be 6.5–7.0, and an electrical conductivity of 10 dS m−1 and greater inhibited the reaction. Reduction of SeO2−4 at 127 μM by SLD1a-1 was unaffected by NO3−, NO2−, SO2−4, AsO3−4, and Fe3+ at equimolar concentrations but was inhibited by NO3− and SO2−4 at levels 5 and 236 times greater, respectively, than the SeO2−4 concentration and by CrO2−4 and SO2−3 at concentrations equimolar with that of SeO2−4. It was found that the more easily an electron donor enters the glycolytic pathway, the greater its propensity to promote SeO2−4 reduction. In addition, initially growing the organism in the presence of lactose and maltose enhanced the organism's subsequent use of these electron donors in reduction of SeO2−4. Optimum temperature for the reaction was 30°C, and lowering the oxygen level enhanced SeO2−4 reduction and removal of Se from solution. Our results provide useful information for optimization of a bioreactor using E. cloacae SLD1a-1 to treat Se-contaminated water.
Role of ground water on hexachlorocyclohexane (lindane) detections in surface water in western Canada
Authors: Donald David B , Block Howard , Wood John
Published: March 2010

Interrelationships between surface water and groundwater dynamics of α- and γ-hexachlorocyclohexane (HCH) were investigated by determining their detection frequency and concentrations in surface water that originated primarily from surface runoff of snow and rain and in surface water that originated from ground water. In the prairie ecozone in Saskatchewan, where lindane (γ-HCH) is currently used, lindane and α-HCH were detected in about 50% of water samples taken from lakes and ponds that are recharged primarily by surface runoff (N = 43 sites). Maximum concentrations for lindane and α-HCH were 0.011 and 0.004 μg/L, respectively. Isomers of HCH were not detected in any of the eight prairie springs that were examined (N = 10 samples). These springs originate from ground water located beneath agricultural lands. In the montane ecozone of Alberta where lindane is not used for agricultural purposes, only α-HCH was detected frequently in the Waterton and Athabasca rivers. From 1976 to 1992, α-HCH was detected in 81% of water samples from the Waterton River with no significant difference in detection frequency through the year (χ2 for 12 months = 14.6, d.f. = 11, p = 0.20, N = 163 samples). The site on the Waterton River is located downstream from a series of large lakes with multiyear storage of surface water. In contrast, discharge for the Athabasca River originates primarily from surface water during summer and ground water during winter. Detection frequency for α-HCH during these seasons was 53% and 2%, respectively, with the annual pattern a normal distribution. These results indicate that HCH isomers were not detected frequently in surface waters that originate from ground water.
Use of various acute, sublethal and early life-stage tests to evaluate the toxicity of refinery effluents
Authors: Sherry James , Scott Brian , Dutka Bernard
Published: March 2010

The toxicities of effluents from three Ontario, Canada, refineries were assessed with microbes, plants, invertebrates, and fish. Acute toxicity was assessed by the Microtox™ test, an assay based on electron transport activity in submitochondrial particles, and Daphnia magna (water flea) and Oncorhynchus mykiss (rainbow trout, 96-h exposure) bioassays. Short-term toxic effects were measured with bioassays of growth and survival of Pimephales promelas (fathead minnow) larvae; survival and reproduction of Ceriodaphnia dubia (water flea); growth of Selenastrum capricornutum (alga); growth of Lemna minor (aquatic plant); germination of Lactuca sativa (nonaquatic plant); survival, growth, and maturation of Panagrellus redivivus (nematode); and genotoxicity in the SOS-Chromotest. Only the Microtox test and the submitochondrial particle test detected acute toxicity in the effluent samples. Reduced survival and sublethal responses were caused by some effluents, but not all effluents were toxic, and none caused a response in all of the tests applied. The results suggest that the effluent treatment systems used at Ontario refineries have largely eliminated acute toxicity to the organisms in our test battery. Although reduced survival and sublethal effects were detected in some of the effluents, the effects were minor. Some of the tests provided evidence, albeit weak, of variations in the responses of the test organisms to a temporal series of effluent samples. Not unexpectedly, there were also minor differences in the responses of the tests to effluents from the three refineries. The fathead minnow test seems to be a sensitive indicator of the sublethal toxicity of Ontario refinery effluents.
Polychlorinated biphenyls and chlorinated pesticides in southern Ontario, Canada, green frogs
Authors: Russell Ronald W , Gillan Katherine A , Haffner G Douglas
Published: March 2010

Green frogs were collected from seven southern Ontario, Canada, locations and analyzed for chlorinated organicchemicals to establish the relative distribution of these chemicals at specific sites. At Hillman Marsh, a wildlife reserve in an agricultural area, green frogs accumulated significantly greater amounts of highly chlorinated Polychlorinated biphenyls (PCBs) than green frogs from all other collection sites. The source of PCBs is unknown. At Ancaster, 1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene (DDE) accumulated in green frogs to a significantly greater extent than at all other sites. This was attributed to the presence of agriculture at Ancaster and the historic use of 1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane (DDT) in agriculture. Chemical concentrations measured in green frogs from all locations were considerably lower than reported levels in other species resulting in observable effects. Specific data relating chronic effects in amphibians to environmental exposure to DDE and PCBs is lacking. Contaminant accumulation in southern Ontario amphibians may be an important factor contributing to amphibian declines only at specific sites.
Mechanistic quantitative structure–activity relationship model for the photoinduced toxicity of polycyclic aromatic hydrocarbons: II. An empirical model for the toxicity of 16 polycyclic aromatic hydrocarbons to the duckweed Lemna gibba L. G-3
Authors: Huang Xiao-Dong , Krylov Sergey N , Ren Lisha , McConkey Brendan J , Dixon D George , Greenberg Bruce M
Published: March 2010

Photoinduced toxicity of polycyclic aromatic hydrocarbons (PAHs) occurs via photosensitization reactions (e.g., generation of singlet-state oxygen) and by photomodification (photooxidation and/or photolysis) of the chemicals to more toxic species. The quantitative structure–activity relationship (QSAR) described in the companion paper predicted, in theory, that photosensitization and photomodification additively contribute to toxicity. To substantiate this QSAR modeling exercise it was necessary to show that toxicity can be described by empirically derived parameters. The toxicity of 16 PAHs to the duckweed Lemna gibba was measured as inhibition of leaf production in simulated solar radiation (a light source with a spectrum similar to that of sunlight). A predictive model for toxicity was generated based on the theoretical model developed in the companion paper. The photophysical descriptors required of each PAH for modeling were efficiency of photon absorbance, relative uptake, quantum yield for triplet-state formation, and the rate of photomodification. The photomodification rates of the PAHs showed a moderate correlation to toxicity, whereas a derived photosensitization factor (PSF; based on absorbance, triplet-state quantum yield, and uptake) for each PAH showed only a weak, complex correlation to toxicity. However, summing the rate of photomodification and the PSF resulted in a strong correlation to toxicity that had predictive value. When the PSF and a derived photomodification factor (PMF; based on the photomodification rate and toxicity of the photomodified PAHs) were summed, an excellent explanatory model of toxicity was produced, substantiating the additive contributions of the two factors.
Comparative ecotoxicity of interstitial waters in littoral ecosystems using Microtox® and the rotiferBrachionus plicatilis
Authors: Del Valls T Ángel , Lubián Luis M , Forja Jesús M , Gómez-Parra Abelardo
Published: March 2010

The toxic effects of sediment interstitial waters collected from seven littoral sites in the Gulf of Cádiz were tested with the Microtox® assay and a 7-d Brachionus plicatilis (Rotifera) decline test. Dissolved organic carbon (DOC), nutrients (ammonia, phosphate, nitrate, nitrite, and silicate), the heavy metals (Fe, Mn, Zn, Cu, Pb, Cr, and Cd), and the linear alkylbenzensulfonate (LAS) concentrations in the interstitial water were measured. The results of assays were compared in a dose-response relationship between sites. This comparison has demonstrated a general agreement between toxicity values determined by Brachionus plicatilis and Photobacterium phosphoreum, except in the case of interstitial water toxicity from mixtures of heavy metals. Data derived from interstitial water chemistry and bioassays were assembled by multivariate statistical techniques (principal components analysis). Positive prevalence of these components in cases studied was used to establish those ranges in chemical concentrations associated with adverse effects. The interstitial water guidelines, in terms of concentrations at or below which biological effects have been shown to be minimal (mg/L), are: DOC, 12.8; phosphate, 0.28; LAS, 80.4; ammonia, 12.1; chromium, 0.0045.
Sensitivity of glochidial stages of freshwater mussels (Bivalvia: Unionidae) to copper
Authors: Jacobson Peter J , Neves Richard J , Cherry Donald S , Farris Jerry L
Published: March 2010

The sensitivity of glochidial stages of unionid mussels was evaluated in a series of exposures to aqueous copper. Glochidia held within marsupia of gravid Villosa iris (I. Lea, 1829) exhibited no observable effect following a 30-d copper exposure at levels up to 19.1 μg Cu/L. Similarly, transformation of encapsulated glochidia of Actinonaias pectorosa (Conrad, 1834), Pyganodon grandis (Say, 1829), and V. iris to the juvenile stage was unaffected by 12- to 20-d copper exposures of largemouth bass, Micropterus salmoides (Lacepede), at levels up to 200 μg Cu/L. In contrast, released glochidia of all species were sensitive to copper at comparatively low concentrations. The median lethal concentrations (24-h) for Lampsilis fasciola (Rafinesque, 1820) ranged from 26 to 48 μg Cu/L, from 36 to 80 μg Cu/L for V. iris, from 37 to 81 μg Cu/L for Medionidus conradicus (I. Lea, 1834), from 42 to 132 μg Cu/L for A. pectorosa, and from 46 to 347 μg Cu/L for P. grandis. Copper sensitivity varied with changes in test conditions, including length of exposure, water temperature, and water hardness. Although sensitivity of released glochidia to copper was comparable to previously reported values for juvenile mussels, the juveniles may be at greater risk given their residency in benthic sediments where toxicants such as metals may be sequestered at high levels. An evaluation of this risk is an urgent priority for further research.
Wildlife and endocrine disrupters: Requirements for hazard identification
Authors: Campbell Pamela M. , Hutchinson Thomas H
Published: March 2010

The increasing demands of the global economy and our growing human population exert profound effects on the ecosystem. As a species, we have an essential need for quality air, water, and soil and a diversity of living organisms, so any vision of a sustainable future must be formulated on the basis of their protection. Decisions on the most effective ways to protect ecosystems must be prioritized on the basis of science and our understanding of the most important factors that affect wildlife populations. In the case of endocrine disrupters, it is important that further research be conducted (1) to determine the status and trends of wildlife populations and the evidence for a widespread effect of endocrine disrupters, (2) to determine the extent to which species differences in the mechanisms that control reproduction and development will affect their sensitivity to endocrine disrupters, and (3) to ensure full validation and refinement of new test methods for assessing the effects of endocrine disrupters across diverse species. Premature implementation of testing and assessment methods for endocrine disrupters, without appropriate consideration of the above points, may result in assessment schemes that placate public opinion but neither alleviate the major factors affecting wildlife populations nor protect diverse species with distinctive endocrine systems.
A multivariate biological and chemical characterization of industrial effluents connected to municipal sewage treatment plants
Authors: Andrén Cecilia , Eklund Britta , Gravenfors Erik , Kukulska Zofia , Tarkpea Maria
Published: March 2010

Effluents from middle-sized industries, connected to municipal treatment plants in two cities in Sweden were sampled daily during 1 week and were characterized chemically and biologically. The results were evaluated mainly with multivariate statistics to find relations between chemistry and toxicity. The principal component analysis (PCA) overview of the chemical variables displayed three main clusters: nitrogen fractions, metals, and organic parameters. An overview of the biological responses showed that inhibition of nitrification was not correlated to the other biological tests. Bivariate statistics found significant correlations existing between different endpoints of Microtox®. In the partial least squares in latent structures (PLS) models created for the biological toxicity tests (Microtox, inhibition of nitrification, and algal growth test with Selenastrum capricornutum), two significant groups causing toxicity were detected, namely inorganic metals and organic pollutants detected by adsorbable organic halogens, chemical oxygen demand, and total organic carbon. When characterizing these industrial effluents, the chemical determinations and the various biological toxicity tests complement each other and none can be excluded.
Individual variation in the swimming performance of fishes: An overlooked source of variation in toxicity studies
Authors: Kolok Alan S. , Plaisance Eric P P , Abdelghani Assaf
Published: March 2010

A commonly used indicator of sublethal stress in fish is impaired swimming performance. Analysis of performance data usually employs a simple comparison, in which the mean of a stressed group of fish is compared to that of a control group. Although such a comparison is satisfactory in many cases, a comparison emphasizing individual variation in performance can yield valuable information unattainable by a means comparison. In this experiment, we determined critical swimming speeds of subadult male fathead minnows before and after exposure to contaminated sediments from Devil's Swamp, Louisiana, USA. The data were then analyzed using a means comparison and an individual approach to illustrate the differences in explanatory power between the two approaches.
Trophic transfer of silver to marine herbivores: A review of recent studies
Authors: Fisher Nicholas S , Wang Wen-Xiong
Published: March 2010

We review recent progress in understanding the trophic transfer of silver (Ag) in marine herbivores, especially mussels that have been extensively used as biomonitors of coastal contamination. A bioenergetic-based kinetic model is invaluable in predicting the trophic transfer and bioaccumulation of Ag in aquatic animals. Critical parameters that need to be quantified in predicting trophic transfer include Ag assimilation efficiency (AE) from ingested food particles, animal feeding rates, and Ag efflux rates. Silver AEs in marine herbivores are generally low (< 30%). Assimilation efficiencies from ingested sediments tend to be lower than those from ingested phytoplankton. Various biological and chemical factors, including Ag distribution in phytoplankton cytoplasm, gut passage time, importance of intracellular versus extracellular digestion, and metal desorption at lowered pHs typical of invertebrate guts, all influence Ag assimilation from ingested particles. Many experimental studies show that uptake from the dissolved phase exceeds uptake via ingestion in the overall Ag bioaccumulation in aquatic animals. However, these results are probably not predictive of field situations due to their simplistic experimental conditions in which fluctuations of feeding conditions of animals and physicochemistry of Ag are not considered. In mussels, the kinetic model predicts that either the solute or particulate pathway can dominate Ag overall uptake in nature, and this is dependent on Ag partition coefficients for suspended particles and Ag AE. Silver is the only metal that varies substantially in the importance of different uptake pathways due to its very high particle reactivity and high uptake rate from the dissolved phase. Total suspended solids (TSS) loads can sharply affect Ag bioaccumulation in mussels because high TSS loads can dilute Ag concentrations in both dissolved and particulate phases. Processes affecting Ag trophic transfer and bioaccumulation are discussed.
Effects of laboratory test conditions on the toxicity of silver to aquatic organisms
Authors: Erickson Russell J , Brooke Larry T , Kahl Michael D , Venter Fred Vende , Harting Sandra L , Markee Thomas P , Spehar Robert L
Published: March 2010

The effects of various chemical manipulations of test water on acute toxicity of silver to fathead minnows (Pimephales promelas) were investigated. Increases in hardness and organic carbon substantially reduced toxicity. Toxicity was also inversely related to pH and alkalinity when these parameters were jointly changed by addition of strong acid or base. The addition of 2 meq/L sodium sulfate had no significant effects, but the addition of 0.2 meq/L sodium chloride increased toxicity, perhaps related to the formation of the dissolved AgCl0 complex. We also evaluated the effects of static versus flow-through test conditions, feeding during exposure, and aging of test solutions before exposure on the acute toxicity of silver to fathead minnows and Daphnia magna. Static conditions and feeding reduced toxicity, likely as a result of accretion of organic carbon. Aging of test solutions had little effect. For both juvenile fathead minnows and D. magna, silver was much less toxic in water from the St. Louis River than in our normal laboratory water, presumably because of the much higher organic carbon content of the river water. This study identified some aspects of test conditions that are important in assessing the risk of silver to aquatic biota, but improved assessments will require information for more conditions, species, and endpoints. More importantly, if toxicity test results are to be extrapolated among waters with different chemistries, adequate characterization of the chemical speciation of silver and a better understanding of the mechanisms of silver toxicity and its relationship to silver speciation and other chemical factors are needed.
Impact of humic constituents on microbial dechlorination of polychlorinated dioxins
Authors: Barkovskii Andrei L , Adriaens Peter
Published: March 2010

We recently reported on the ability of a microbial consortium eluted from dioxin-contaminated Passaic River sediments to dechlorinate polychlorinated dibenzo-p-dioxins (PCDDs) through peridechlorination of 2,3,7,8-substituted hepta- to penta-CDDs resulting in the transient production of 2,3,7,8-tetra-CDD and through perilateral dechlorination pathway of non-2,3,7,8-substituted congeners. The dechlorination of PCDDs under combined reductive activities of the same microbial community and model humic constituents (MHCs) (resorcinol, 3,4-dihydroxybenzoic acid [3,4-DHBA], and catechol) was investigated. Model humic constituents alone caused reductive dechlorination of PCDDs, resulting in the production of hepta-, hexa-, and tetra-CDD congeners. Whereas abiotic MHC-stimulated dechlorination ceased at the tetra-CDD group of congeners, microbial activity caused further dechlorination to tri-, di-, and mono-CDDs. Combined with the microbial community, MHCs effected the appearance of a new profile of tetra through mono-CDD congeners that was distinguishable from either microbially or MHC-stimulated processes alone. An important overall trend could be discerned: the peridechlorination of PCDDs was promoted by MHCs, resulting in both a relative and an absolute (except for 3,4-DHBA) increase of 2,3,7,8-tetra-CDD relative to either microbially or MHC-stimulated dechlorination. This study indicates that, aside from direct deposition, the increase of 2,3,7,8-tetra-CDD concentrations in the environment may result from combined biotic and abiotic PCDD dechlorination.