bluuebunny/crossref_metadata_2025 huggingface dataset:
Time-dependent lethal body residues for the toxicity of pentachlorobenzene to Hyalella azteca
Authors: Landrum Peter F. , Steevens Jeffery A. , Gossiaux Duane C , McElroy Michael , Robinson Sander , Begnoche Linda , Chernyak Sergei , Hickey James
Published: November 2004

The study examined the temporal response of Hyalella azteca to pentachlorobenzene (PCBZ) in water-only exposures. Toxicity was evaluated by calculating the body residue of PCBZ associated with survival. The concentration of PCBZ in the tissues of H. azteca associated with 50% mortality decreased from 3 to 0.5 μmol/g over the temporal range of 1 to 28 d, respectively. No significant difference was observed in the body residue calculated for 50% mortality when the value was determined using live or dead organisms. Metabolism of PCBZ was not responsible for the temporal response because no detectable PCBZ biotransformation occurred over an exposure period of 10 d. A damage assessment model was used to evaluate the impact and repair of damage by PCBZ on H. azteca. The toxicokinetics were determined so that the temporal toxicity data could be fit to a damage assessment model. The half-life calculated for the elimination of PCBZ averaged approximately 49 h, while the value determined for the half-life of damage repair from the damage assessment model was 33 h.
Enhancing the attenuation of explosives in surface soils at military facilities: Combined sorption and biodegradation
Authors: Fuller Mark E. , Hatzinger Paul B. , Rungmakol Darin , Schuster Rachel L. , Steffan Robert J.
Published: November 2004

This research evaluated soil amendments designed to enhance the adsorption and biodegradation of explosives at military training facilities, thus minimizing their potential for transport to subsurface environments. Several carbon cosubstrates were tested in soil slurries for their ability to stimulate the biodegradation of 2,4,6-trinitrotoluene (TNT), hexahydro-1,3,5-trinitro-1,3,5-triazine (royal demolition exposive [RDX]), and octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (high-melting explosive [HMX]) by indigenous soil microorganisms. Crude soybean oil and molasses stimulated mineralization of RDX (30–40%) and HMX (∼10%). The TNT was not significantly mineralized in any of the treatments, but high-performance liquid chromatography (HPLC) analysis indicated extensive transformation of TNT to amino-containing compounds. The biodegradation of explosives was then examined in unsaturated soil microcosms amended with crude soybean oil and molasses combined with sphagnum peat moss and sawdust. Minimal TNT mineralization was observed, and HMX mineralization was only observed with molasses addition. In contrast, RDX mineralization was extensive in microcosms amended with soybean oil or molasses. The presence of peat moss decreased soybean oil-stimulated RDX mineralization by approximately 5%, but resulted in about 5% greater RDX mineralization compared with molasses only. Sawdust markedly decreased mineralization regardless of cosubstrate type. Mass balance results indicated that the formation of bound residues likely was occurring, especially for TNT. These results indicate that the application of inexpensive adsorbents and cosubstrates to soils may significantly improve the protection of groundwater resources underlying live fire ranges.
Impact of perfluorooctanoic acid on fathead minnow (Pimephales promelas) fatty acyl-coa oxidase activity, circulating steroids, and reproduction in outdoor microcosms
Authors: Oakes Ken D. , Sibley Paul K. , Solomon Keith R. , Mabury Scott A. , Van Der Kraak Glen J.
Published: November 2004

This study investigates reproductive impairment and biochemical changes in fathead minnow (Pimephales promelas) exposed for 39 d to varying concentrations of perfluorooctanoic acid (PFOA) under microcosm conditions. While the concentrations tested in this study were much higher than those normally found in the environment, no mortality was associated with PFOA exposure. Only modest changes were observed in condition factor and in relative liver and gonad size. Significant declines in circulating plasma steroids were observed, but these were accompanied by only limited increases in time to first oviposition and decreases in overall egg production. Peroxisome proliferation, as quantified by fatty acyl-CoA oxidase (FAO) activity, was elevated with low PFOA concentrations but attenuated with exposure to higher PFOA doses. Little evidence was seen of differential induction of peroxisome-associated enzyme activity with sex. Oxidative stress, as quantified by the 2-thiobarbituric acid reactive substances (TBARS) assay, was only modestly influenced by PFOA exposure and is not a significant consequence of FAO activity in fathead minnow. Perfluorooctanoic acid appears to be relatively nontoxic at environmentally relevant concentrations but may impact biochemical and reproductive endpoints under conditions associated with environmental spills.
Multiple mechanisms contribute to the biodegradation of benzo[a]pyrene by petroleum-derived multicomponent nonaqueous-phase liquids
Authors: Kanaly Robert A. , Watanabe Kazuya
Published: November 2004

The presence of multicomponent nonaqueous-phase liquids (NAPLs) on contaminated sites critically alters the biodegradation susceptibility of many target pollutants, including polycyclic aromatic hydrocarbons. This study investigated the effects of petroleum-derived multicomponent NAPLs on biodegradation of benzo[a]pyrene by a bacterial consortium in liquid culture. When high—boiling point diesel fuel distillate (HBD)-NAPL was added to liquid culture, the consortium initiated benzo[a]pyrene mineralization after a lag period of several days. This lag period was not observed in the mineralization of phenanthrene, anthracene, and chrysene by the same consortium with HBD. Nonaqueous-phase liquids added to cultures pregrown before experimentation largely affected the extent of benzo[a]pyrene mineralization and the duration of lag period in subsequent experiments, suggesting that NAPL presence was important for maintaining the efficiency of the mineralizing consortium. Experiments using further fractionated oil components suggested that stimulation of benzo[a]pyrene mineralization by NAPLs was fraction dependent; an alkylated aromatic fraction was more effective than aromatic and aliphatic fractions. The effect of NAPL on benzo[a]pyrene biodegradation was determined to be multimechanistic; that is, NAPL acted as a cosolvent for polycyclic aromatic hydrocarbon dissolution, as a substrate to induce cometabolic degradative pathways, and as an agent to formulate the effective microbial consortium. Data suggest that the third mechanism was of particular importance for rapid benzo[a]pyrene mineralization.
Assessment of the availability of polycyclic aromatic hydrocarbons from gasworks soil using different extraction solvents and techniques
Authors: Bergknut Magnus , Kitti Anna , Lundstedt Staffan , Tysklind Mats , Haglund Peter
Published: November 2004

This study was designed to assess the availability of polycyclic aromatic hydrocarbons (PAHs) present at a gasworks site to different soil remediation techniques. The study examined the effect on PAH availability of using different organic solvents, the degree of pretreatment, and the extraction time. In total, 25 PAHs (with two to six fused rings) and five carbonyl derivatives were measured. The results indicated that the PAHs and their derivatives were bound loosely to the surface of the studied soil and that there were no significant kinetic boundaries associated with the extraction of the PAHs. Furthermore, it was concluded that the studied soil was not suitable for bioremediation, as the concentration of PAHs with low molecular weight were limited. However, pressurized liquid extraction (PLE) with methanol as the solvent extracted 97% of all PAHs and PAH-derivatives, indicating that extraction may be effective as part of a soil remediation technique for old gasworks soils.
Cell-specific CYP1A expression and benzo[a]pyrene adduct formation in gills of rainbow trout (Oncorhynchus mykiss) following CYP1A induction in the laboratory and in the field
Authors: Jönsson Maria E. , Brunström Björn , Ingebrigtsen Kristian , Brandt Ingvar
Published: November 2004

The effect of cytochrome P4501A (CYP1A)induction on cell-specific benzo[a]pyrene (BaP) adduct formation was studied in rainbow trout (Oncorhynchus mykiss) gills. Fish preexposed to β-naphthoflavone (βNF) or caged in a polluted river were exposed to waterborne 3H-benzo[a]pyrene (3H-BaP). The 3H-benzo[a]pyrene adducts in the gill filaments were localized by autoradiography and CYP1A protein by immunohistochemistry. Ethoxyresorufin O-deethylase (EROD) activity was measured using a gill filament-based ex vivo assay. Branchial 3H-BaP binding and EROD activity were enhanced by exposure to βNF or to the river water, and completely blocked by the CYP1A inhibitor ellipticine. The predominant sites of adduct formation were in epithelium of the secondary lamellae and in epithelium of the efferent edge of the gill filament. In βNF-exposed fish, the strongest CYP1A immunoreactivity was observed in differentiating cells and in pillar cells. In fish caged in the polluted river, strong CYP1A immunoreactivity was found in most cells in the secondary lamellae, whereas the primary lamellae were almost devoid of immunoreactivity. Our results reveal a discrepancy between the localization of CYP1A protein and BaP adducts in the gill. Consequently, other factors, such as bioavailability of waterborne polycyclic aromatic hydrocarbons (PAHs) to the target cells, are important for the localization of PAH adducts in the gill.
Development of a whole-sediment toxicity test using a benthic marine microalga
Authors: Adams Merrin S. , Stauber Jennifer L.
Published: November 2004

An acute whole-sediment toxicity test with a benthic marine microalga was developed and optimized using flow cytometry to distinguish algae (based on their chlorophyll a autofluorescence) from sediment particles. Of seven benthic marine algae screened, the diatom Entomoneis cf punctulata was most suitable because of its tolerance of a wide range of water and sediment physico-chemical parameters, including salinity, pH, ammonia, and sulfide. A whole-sediment and water-only toxicity test based on inhibition of esterase activity in this species was developed. Enzyme activity rather than growth was used as the test endpoint, as nutrient release from sediments has previously been found to stimulate algal growth, potentially masking contaminant toxicity. The sensitivity of the bioassay to a range of metals (copper, zinc, cadmium, lead, arsenic, manganese) and phenol in water-only exposures was compared to the standard 72-h growth rate inhibition test. The esterase enzyme inhibition test was sensitive to copper, with a 3-h inhibitory concentration to cause a 50% (IC50) reduction in a fluorescein diacetate fluorescence value of 97 ± 39 μg Cu/L. A concentration-dependent response was also observed in the presence of sediment particles (copper tailings), with and without dilution, using a control clean sediment. The primary route of exposure to copper was via pore water rather than by direct contact with tailings particles. This is the first whole-sediment bioassay developed with a benthic alga suitable for sediment quality assessment in marine/estuarine systems, and its advantages and limitations are discussed.
Assessment of macrobenthos response to sediment contamination in the San Francisco Estuary, California, USA
Authors: Thompson Bruce , Lowe Sarah
Published: November 2004

A multimetric benthic assessment method was developed for two benthic assemblages in the San Francisco Estuary (USA) using data from several monitoring programs collected over five years. Assessment indicators used were total number of taxa, total abundances, oligochaete abundances, number of molluscan taxa, number of amphipod taxa, and Capitella capitata and Streblospio benedicti abundances. Exceedances of the maximum or minimum indicator values in reference samples were used to assess test samples using a weight-of-evidence to obtain an assessment value. Only 2.5% of the samples from the deeper, offshore sites had benthic impacts, 14.3% of the samples from near wastewater discharges had impacts, and 78.3% of the samples from the estuary margins and channels were impacted. Impacted samples from both assemblages had significantly higher mean effects range-median quotient values (mERMq) than reference samples, total organic carbon (TOC) was significantly higher in the impacted samples from the mesohaline assemblage, and percent fines was significantly higher in the impacted samples from the polyhaline assemblage, reflecting the close associations of contaminants with fine sediments and organic material. In samples with mERMq below 0.050, there were no benthic impacts. The incidence of impacts remained low (9.4%) at mERMq below 0.146, but when mERMq was above 0.146, 68.2% of the samples had benthic impacts, and samples with mERMq above 0.740 were always impacted.
Effect of maternal exposure to tributyltin on reproduction of the pearl oyster (Pinctada fucata martensii)
Authors: Inoue Suguru , Oshima Yuji , Nagai Kiyohito , Yamamoto Takashi , Go Jyoji , Kai Norihisa , Honjo Tsuneo
Published: November 2004

We examined the effect of tributyltin (TBT) on reproduction of the pearl oyster (Pinctada fucata martensii). In a maternal exposure test, five female pearl oysters were exposed to TBT at measured concentrations of 0 (control), 0.092, or 0.191 μg/L at 25°C for one week, and the embryo developmental success (the ratio of normal D-larvae to all larvae) was measured. The embryo developmental success was significantly decreased in the 0.191-μg/L treatment group (65.5%) compared to that in the control group (82.5%; p = 0.031). Concentrations of TBT in the ovary reached 0.088 μg/g in the 0.191-μg/L treatment group. In a waterborne exposure test, inseminated eggs were exposed to TBT at measured concentrations of 0 (control), 0.020, 0.045, 0.091, 0.192, or 0.374 μg/L for 24 h. The embryo developmental success also was significantly decreased in the 0.192-μg/L treatment group (78.3%; p = 0.020) and no development at all was observed in the 0.374-μg/L treatment group compared with that in the control group (95.4%). These results clearly demonstrate that TBT accumulating in the bodies of bivalves has the potential to inhibit reproduction.
Physical and biochemical interactions of soil fungi with asbestos fibers
Authors: Martino Elena , Cerminara S TEFANO , Prandi Laura , Fubini Bice , Perotto Silvia
Published: November 2004

Iron, a structural component of most asbestos, is thought to play a crucial role in asbestos toxicity. Surface iron favors fiber uptake by mammalian cells and promotes the generation of free radicals with consequent DNA and lipid damage. In some cases, chemical removal of iron from asbestos fibers has reduced several cellular responses to asbestos. Since iron represents an essential element for soil microorganisms, many of them have developed mechanisms to scavenge this element from poorly soluble forms. We have investigated the ability of some soil fungi to produce iron chelators capable of extracting iron from crocidolite (blue asbestos). Many of the species/isolates investigated could remove significant amounts of iron from crocidolite fibers, Fusarium oxysporum being the most effective. The fungal responses following exposure to asbestos fibers also have been investigated with morphological and biochemical approaches. In liquid cultures, the fibers were visibly cleared from the suspension because they were tightly bound to the fungal hyphae. Modifications in the fungal protein profiles were observed following exposure to asbestos fibers. By binding the fibers and depriving them of iron, selected species/strains of soil fungi might represent interesting tools for the bioremediation of asbestos-contaminated soils.
Developmental toxicity of p,p′-dichlorodiphenyltrichloroethane, 2,4,6-trinitrotoluene, their metabolites, and benzo[a]pyrene in Xenopus laevis embryos
Authors: Saka Masahiro
Published: November 2004

Since 1995, high incidences of deformed frogs have been documented in Kitakyushu, Japan. In this area, relatively high concentrations of DDT, trinitrotoluene (TNT), their metabolites (p,p′-dichlorodiphenyldichloroethylene [DDE], p,p′-dichlorodiphenyldichloroethane [DDD], 2-amino-4,6-dinitrotoluene [2ADNT], and 4-amino-2,6-dinitrotoluene [4ADNT]), and benzo[a]pyrene [BaP]) have been identified from field samples. I used a standardized assay with Xenopus laevis embryos (frog embryo teratogenesis assay—Xenopus, FETAX) to examine the developmental toxicity of these compounds. Both DDE and BaP were considered nearly nontoxic in embryonic development because they induced low (<10%) mortality and malformation incidence even at the highest concentrations tested (DDE, 393 μM; BaP, 13.2 μM). The DDD (96-h median lethal concentration [LC50] = 44.1 μM, 96-h median effective concentration [EC50] for malformation = 14.9 μM) was more lethal and teratogenic than its parent compound, DDT (96-h LC50 = 101 μM, 96-h EC50 = 41.5 μM). Predominant symptoms observed were axial malformations (DDT and DDD) and irregular gut coiling (DDT). However, DDT and DDD should not act as major lethal or teratogenic toxicants in the aquatic environment within a short-term exposure via water because their 96-h LC50 and 96-h EC50 values were extremely high, considering their low solubility in water. The TNT (96-h LC50 = 16.7 μM) was more lethal than 2ADNT (96-h LC50 = 166 μM) or 4ADNT (96-h LC50 = 115 μM). Although 4ADNT (96-h EC50 = 85.8 μM) induced various tadpole malformations, it was a weak teratogen compared with TNT (96-h EC50 = 9.78 μM) and 2ADNT (96-h EC50 = 16.9 μM). The most typical malformations observed were axial malformations, eye abnormalities (TNT), edema, and irregular gut coiling (2ADNT and 4ADNT). The 96-h LC50 and 96-h EC50 values of TNT, 2ADNT, and 4ADNT were lower than their saturated concentrations in water. Therefore, these nitroaromatic compounds may show lethal or teratogenic effects on aquatic animals if their habitats are severely contaminated with TNT.
Acute and chronic toxicity of the new explosive CL-20 to the earthworm (Eisenia andrei) exposed to amended natural soils
Authors: Robidoux Pierre Yves , Sunahara Geoffrey I. , Savard Kathleen , Berthelot Yann , Dodard Sabine , Martel Majorie , Gong Ping , Hawari Jalal
Published: November 2004

Monocyclic nitramine explosives such as 1 3,5-trinitro-1,3,5-triazacyclohexane (RDX) and octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) are toxic to a number of ecological receptors, including earthworms. The polycyclic nitramine CL-20 (2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane) is a powerful explosive that may replace RDX and HMX, but its toxicity is not known. In the present study, the lethal and sublethal toxicities of CL-20 to the earthworm (Eisenia andrei) are evaluated. Two natural soils, a natural sandy forest soil (designated RacFor2002) taken in the Montreal area (QC, Canada; 20% organic carbon, pH 7.2) and a Sassafras sandy loam soil (SSL) taken on the property of U.S. Army Aberdeen Proving Ground (Edgewood, MD, USA; 0.33% organic carbon, pH 5.1), were used. Results showed that CL-20 was not lethal at concentrations of 125 mg/kg or less in the RacFor2002 soil but was lethal at concentrations of 90.7 mg/kg or greater in the SSL soil. Effects on the reproduction parameters such as a decrease in the number of juveniles after 56 d of exposure were observed at the initial CL-20 concentration of 1.6 mg/kg or greater in the RacFor2002 soil, compared to 0.2 mg/kg or greater in the SSL soil. Moreover, low concentrations of CL-20 in SSL soil (˜0.1 mg/kg; nominal concentration) were found to reduce the fertility of earthworms. Taken together, the present results show that CL-20 is a reproductive toxicant to the earthworm, with lethal effects at higher concentrations. Its toxicity can be decreased in soils favoring CL-20 adsorption (high organic carbon content).
Adsorption of polycyclic aromatic hydrocarbons at the air-water interface and its role in atmospheric deposition by fog droplets
Authors: Valsaraj Kalliat T.
Published: November 2004

This review addresses the significance of air-water interfacial adsorption in the fate and transport of polycyclic aromatic hydrocarbons (PAHs) in dispersed systems, such as fog droplets in the atmosphere and air bubbles in wastewater systems. The equilibrium (partition constants) and transport (mass accommodation coefficients) parameters in dispersed systems are discussed. Specific cases where the air-water interfacial adsorption makes a significant impact, such as uptake of naphthalene by fog droplets in a falling droplet reactor and of pyrene removal on air bubbles in a solvent sublation reactor, are discussed as illustrations. The consequence of the air-water interface in atmospheric wet deposition of PAHs by fog droplets is analyzed mathematically.
Toxicokinetics of three polychlorinated biphenyl technical mixtures in rainbow trout (Oncorhynchus mykiss)
Authors: Buckman Andrea H. , Brown Scott B. , Hoekstra Paul F. , Fisk Aaron T.
Published: November 2004

Accumulation and depuration parameters of polychlorinated biphenyls (PCBs) in fish have been reported only for a few congeners. As well, there is little information on the ability of fish to biotransform PCBs. To address these issues, juvenile rainbow trout (Oncorhynchus mykiss) were exposed to dietary concentrations of three Aroclor® mixtures (1248, 1254, 1260) in food for 30 d followed by an additional 160 d of nonspiked food at 8°C. Accumulation, depuration, and potential biotransformation of 92 PCB congeners were assessed. Half-lives (t1/2) of PCB congeners ranged from 79 to 182 d, assimilation efficiencies ranged from 40 to 50% and biomagnification factors (BMF) ranged from 2.9 to 6.9. No evidence of significant biotransformation of any PCB congeners was found. All 92 congeners fell on the same t1/2 to Kow relationship as 16 preselected PCB congeners previously shown to persist in fish and no hydroxylated PCB metabolites (OH-PCBs) were detected in the plasma after 30 d of exposure. These findings suggest that OH-PCBs observed in feral fish may be accumulated from sources other than internal metabolism of the parent congeners, at least for juvenile fish at cool temperatures. Because t1/2s in this experiment were slower than t1/2s reported in other work, water temperature also may be an important factor in determining the t1/2s of all PCB congeners in fish.
Testosterone and energy metabolism in the estuarine mysid Neomysis integer (Crustacea: Mysidacea) following exposure to endocrine disruptors
Authors: Verslycke Tim , Poelmans Sofie , De Wasch Katia , De Brabander Hubert F. , Janssen Colin R.
Published: November 2004

A diverse set of reference compounds suspected of having an endocrine-disrupting mode of action (i.e., testosterone, flutamide, ethinylestradiol, precocene, nonylphenol, fenoxycarb, and methoprene) were tested for acute toxicity to the estuarine mysid Neomysis integer (Crustacea: Mysidacea). Neomysis integer was very sensitive to all tested compounds, with 96-h median lethal concentrations in a narrow range between 0.32 and 1.95 mg/L. The pesticides methoprene and fenoxycarb, both synthetic insect juvenile hormone analogs, were most toxic to N. integer. In addition, the short-term sublethal effects of methoprene and nonylphenol (an estrogen agonist) on the energy and steroid metabolism of N. integer were evaluated. Both compounds significantly affected energy and testosterone metabolism of N. integer at concentrations below acute toxicity levels. Energy consumption in methoprene- and nonylphenol-exposed mysids was significantly induced at 100 μg/L, resulting in a lower cellular energy allocation in these animals. Testosterone phase I metabolism was affected at 10 μg/L, whereas glycosylation was the most important phase II pathway affected in mysids exposed to 100 μg/L of both compounds. Methoprene exposure resulted in a concentration-dependent increase in the metabolic androgenization ratio. Mysids exposed to nonylphenol at 10 μg/L had a significantly higher metabolic androgenization ratio. The present study indicates that energy and testosterone metabolism of mysids, as endpoints, are able to detect endocrine-disruptive activity of chemicals after short-term exposure to environmentally realistic levels of endocrine disruptors.
Degradation and sorption of selected organophosphate and carbamate insecticides in urban stream sediments
Authors: Bondarenko Svetlana , Gan Jianying
Published: November 2004

Monitorings studies show that urban surface streams in the United States are commonly contaminated with pesticides, and contamination by organophosphates and carbamates is of particular concern because of their aquatic toxicity. The degradation and sorption of four common organophosphate and carbamate insecticides were studied in urban creek sediments from southern California, USA. In sediment, malathion was quickly degraded under either aerobic or anaerobic conditions, with a half-life (t1/2) <3 d. Diazinon and chlorpyrifos were moderately persistent under aerobic conditions (t1/2 = 14–24 d). However, persistence of chlorpyrifos increased significantly under anaerobic conditions, and t1/2 was prolonged to 58 to 223 d. The greatest effect of redox potential was found with carbaryl. Although rapid dissipation occurred under aerobic conditions (t1/2 = 1.8–4.9 d), carbaryl became virtually nondegradable under anaerobic conditions (t1/2 = 125–746 d). The sorption coefficient consistently increased with time for all pesticides, and chlorpyrifos displayed greater sorption potential than the other pesticides. This study indicates that pesticides in sediment may become less available with time because of increased sorption, and pesticide persistence in sediment may vary greatly among compounds and with redox conditions. Under anaerobic conditions, long persistence may occur even for nonpersistent compounds.
Effects of sedimentary sootlike materials on bioaccumulation and sorption of polychlorinated biphenyls
Authors: Jonker Michiel T. O. , Hoenderboom Annemarie M. , Koelmans Albert A.
Published: November 2004

Bioaccumulation of hydrophobic organic chemicals from sediments containing soot or sootlike materials has been hypothesized to be limited by strong sorption of the chemicals to the soot matrixes. To test this hypothesis, we quantified bioaccumulation of 11 polychlorinated biphenyls (PCBs) into the aquatic oligochaete Limnodrilus sp. exposed to spiked sediment with and without the sootlike materials coal and charcoal. In addition, sorption experiments with sediment containing varying amounts of coal or charcoal were performed to elucidate the accumulation mechanism. Results showed that coal and charcoal (at realistic levels of 1.5% on a dry-wt basis) reduced PCB accumulation in worms 1.2 to 8.5 times when expressed on a mass basis. Moreover, whereas bioaccumulation from pure sediment increased with molecular planarity of the PCBs (toxic potency), it decreased in case of sediments containing coal and charcoal. In contrast to this advantageous effect, it was hypothesized that coal and charcoal had an adverse influence on the habitat quality of oligochaetes: Organisms inhabiting sediment containing coal or charcoal had significantly reduced lipid contents as compared to organisms from pure sediment. Because of these reduced lipid contents, lipid-normalized PCB concentrations in worms and biota-to-sediment accumulation factors (BSAFs) for most PCBs were higher in sediments containing the sootlike materials as compared to those for reference sediment. Also, measured BSAFs for coal- and charcoal-containing sediments appeared to be much higher than estimated on the basis of equilibrium partitioning theory. Sorption experiments revealed that this was caused by much weaker sorption to the sediment-coal/charcoal mixture than calculated assuming linear additivity of sorption capacities of the distinct phases. It was hypothesized that this weaker sorption resulted from competition between PCBs and dissolved organic carbon molecules for sorption sites on coal/charcoal. This points to a sorption process that is much more complicated than generally assumed.
Importance of black carbon in distribution and bioaccumulation models of polycyclic aromatic hydrocarbons in contaminated marine sediments
Authors: Vinturella Amy E. , Burgess Robert M. , Coull Brent A. , Thompson Kimberly M. , Shine James P.
Published: November 2004

The roles and relative importance of nonpyrogenic organic carbon (NPOC) and black carbon (BC) as binding phases of polycyclic aromatic hydrocarbons (PAHs) were assessed by their ability to estimate pore water concentrations and biological uptake in various marine sediments. Sediment bioaccumulation tests were performed with the marine polychaete Nereis virens, using a polyethylene device to estimate pore water concentrations of PAHs. Using existing partitioning data for pyrene and phenanthrene, it was found that the traditional Equilibrium Partitioning model, which assumes all organic carbon is NPOC (EqPOC), overestimated the measured pore water concentrations in the test sediments by one to three orders of magnitude. Instead, the measured pore water concentrations were better predicted from a distribution scenario that uses both BC and NPOC (EqPNPOC,BC). When comparing actual worm body burdens of pyrene and phenanthrene with the two model estimates of worm tissue concentrations, the EqPOC model tended to overestimate actual body burdens by three orders of magnitude, while the EqPNPOC,BC model came much closer to the true body burden values. The observed distribution of PAHs in the test sediments was used to calculate BC partition coefficients for five PAHs, which were one to two orders of magnitude higher than their corresponding organic carbon–normalized distribution coefficients, or KOCs. Together, these results suggest that, in certain situations, adding black carbon to distribution models may be necessary to predict accurately the bioavailability of PAHs.
Ammonium perchlorate effects on thyroid function and growth in bobwhite quail chicks
Authors: Mcnabb F. M. ANNE , Larsen Calvert T. , Pooler Penelope S.
Published: November 2004

Bobwhite quail chicks were used to investigate ammonium perchlorate (AP; NH4ClO4) effects on thyroid function and growth. Beginning at 3 to 4 d posthatch, we evaluated organismal thyroid status (circulating hormones), activation of the hypo-thalamic-pituitary-thyroid axis (thyroid wt) and thyroidal hormone content over a wide range of AP concentrations (50 μg/L — 4,000 mg/L) in drinking water, for relatively short (2-week) and longer (8-week) exposures. Thyroidal thyroxine (T4) content, the most sensitive index of decreased thyroid function, decreased markedly in response to increasing perchlorate exposure. Thyroid weight and plasma T4 were less sensitive indicators and similar in their ability to detect thyroid changes. Growth measurements (body wt and skeletal growth) were very insensitive indices. Because thyroids contain large hormone stores, with low exposures or short time periods, these stores can be used to maintain circulating hormones, at least temporarily. Most depletion of thyroidal T4 occurred during the first two weeks of AP exposure. Subsequent decreases were at a slower rate presumably because thyrotropin stimulation of the thyroids at least partially compensated for some of the perchlorate effect. Additional studies of the interactions between AP concentration and exposure time are needed for understanding the complex nature of thyroid responses to perchlorate.
A phytoplankton growth assay for routine in situ environmental assessments
Authors: Moreira-Santos Matilde , Soares Amadeu M.V.M. , Ribeiro Rui
Published: November 2004

This study proposes an ecologically relevant and cost-effective phytoplankton growth assay for routine in situ toxicity assessments. Assay procedures were developed applying, to the extent possible, the rationale behind the design of standard algal assays. Chlorella vulgaris was selected as test species because it grows well immobilized in alginate beads and has a wide geographic distribution. The performance of the assay in a freshwater system impacted by acid mine drainage demonstrated the suitability of assay chambers and procedures. The test system, made of inexpensive materials, allowed the rapid and easy deployment of the assay. The deployment of extra chambers at reference sites provided the ability to periodically check whether algal growth had already reached recommended growth criteria (time at which the assay should end). By deploying chambers filled with control medium at all sites, temperature was identified to explain 95% of the variation in growth. By using an artificial nutrient source shown capable of promoting algal growth according to recommended standards, toxicity from the mine effluent was distinguish from in situ nutrient limitation effects. The very good agreement (r2 = 90%) between mean in situ growth rates estimated by microscopy and by spectrophotometry and their similar coefficient of variation showed the latter to be a suitable straightforward methodology for assay endpoint estimation.
Relationships among exceedences of metals criteria, the results of ambient bioassays, and community metrics in mining-impacted streams
Authors: Griffith Michael B. , Lazorchak James M. , Herlihy Alan T.
Published: November 2004

If bioassessments are to help diagnose the specific environmental stressors affecting streams, a better understanding is needed of the relationships between community metrics and ambient criteria or ambient bioassays. However, this relationship is not simple, because metrics assess responses at the community level of biological organization, while ambient criteria and ambient bioassays assess or are based on responses at the individual level. For metals, the relationship is further complicated by the influence of other chemical variables, such as hardness, on their bioavailability and toxicity. In 1993 and 1994, U.S. Environmental Protection Agency (U.S. EPA) conducted a Regional Environmental Monitoring and Assessment Program (REMAP) survey on wadeable streams in Colorado's (USA) Southern Rockies Ecoregion. In this ecoregion, mining over the past century has resulted in metals contamination of streams. The surveys collected data on fish and macroinvertebrate assemblages, physical habitat, and sediment and water chemistry and toxicity. These data provide a framework for assessing diagnostic community metrics for specific environmental stressors. We characterized streams as metals-affected based on exceedence of hardness-adjusted criteria for cadmium, copper, lead, and zinc in water; on water toxicity tests (48-h Pimephales promelas and Ceriodaphnia dubia survival); on exceedence of sediment threshold effect levels (TELs); or on sediment toxicity tests (7-d Hyalella azteca survival and growth). Macroinvertebrate and fish metrics were compared among affected and unaffected sites to identify metrics sensitive to metals. Several macroinvertebrate metrics, particularly richness metrics, were less in affected streams, while other metrics were not. This is a function of the sensitivity of the individual metrics to metals effects. Fish metrics were less sensitive to metals because of the low diversity of fish in these streams.
Effect of grasses on herbicide fate in the soil column: Infiltration of runoff, movement, and degradation
Authors: Belden Jason B. , Coats Joel R.
Published: November 2004

The objective of the present study was to evaluate if the presence of grass or the type of grass influences the environmental fate of herbicides within a soil column. Intact soil columns were planted with either smooth brome, big bluestem, tall fescue, switchgrass, or a mixture of prairie grasses or were left unvegetated. Artificial runoff containing atrazine, metolachlor, and pendimethalin was applied to the columns and allowed to infiltrate, and the resulting leachate was collected at the bottom of the soil column. This process was repeated on day 7 with herbicide-fortified runoff and on days 14 and 21 with water only. Following the leaching experiments, soil from the columns was fortified with either [14C]atrazine or [14C]metolachlor to measure pesticide degradation potential. The mean time necessary for infiltration of the artificial runoff decreased from 7.5 h for unvegetated to 3.4 h for grassed soil columns, and the type of grass did not have a significant effect. Neither the type of grass nor the presence of grass caused a significant change in the total amount of herbicide that leached through the columns. However, the presence of some grasses did decrease the amount of herbicide that leached in the final two events (i.e., additions not fortified with herbicide). Fescue was the least effective, reducing the amount of leached atrazine and metolachlor by 13% and 33% respectively, and mixed prairie grass was most effective, with reductions of 43% and 44%, respectively. In addition, atrazine and metolachlor degraded more rapidly in soil vegetated by some grasses. Mixed prairie grass had the greatest effect, increasing atrazine mineralization by 260% and formation of metolachlor-bound residue by 760%.
Integrated fate modeling for exposure assessment of produced water on the Sable Island Bank (Scotian Shelf, Canada)
Authors: Berry Jody A. , Wells Peter G.
Published: November 2004

Produced water is the largest waste discharge from the production phase of oil and gas wells. Produced water is a mixture of reservoir formation water and production chemicals from the separation process. This creates a chemical mixture that has several components of toxic concern, ranging from heavy metals to soluble hydrocarbons. Analysis of potential environmental effects from produced water in the Sable Island Bank region (NS, Canada) was conducted using an integrated modeling approach according to the ecological risk assessment framework. A hydrodynamic dispersion model was used to describe the wastewater plume. A second fugacity-based model was used to describe the likely plume partitioning in the local environmental media of water, suspended sediment, biota, and sediment. Results from the integrated modeling showed that the soluble benzene and naphthalene components reach chronic no-effect concentration levels at a distance of 1.0 m from the discharge point. The partition modeling indicated that low persistence was expected because of advection forces caused by tidal currents for the Sable Island Bank system. The exposure assessment for the two soluble hydrocarbon components suggests that the risks of adverse environmental effects from produced water on Sable Island Bank are low.
Determination of optimized protocols for the extraction of anticholinesterasic compounds in environmental samples containing cyanobacteria species
Authors: Barros LÉLIA PACHECO CORRĚIA , Monserrat José Maria , Yunes JoãO Sarkis
Published: November 2004

The effects of temperature and pH during extraction of toxin(s) from the cyanobacterial genus Anabaena were studied. Different extracts were compared for their anticholinesterase potency against purified eel acetylcholinesterase. A lyophilized powder from Anabaeba spiroides cells was dissolved in ethanol, sonicated, and filtered. This solution was then evaporated at three different temperatures (40, 60, or 80°C), resuspended in chloroform, and washed in deionized water at three different pH values (3.3, 5.0, or 8.5). At 40°C, the estimated 50% inhibition concentration (IC50) was 2.06, 2.19, and 8.64 mg lyophilized A. spiroides cells ml−1 for the extraction pH of 3.3, 5.0, and 8.5, respectively. At 60°C, the values were 4.82, 3.06, and 12.0 mg/ml at increasing pH values. Finally, at 80°C, the IC50 values were 3.52, 4.35, and 30.1 mg/ml at the same pH values. These results indicate that pH 3.3 and a temperature of 40°C should be employed to preserve toxin content. The optimized protocol was employed to evaluate the anticholinesterase potency of environmental samples of water containing different numbers of filaments of cyanobacterial species. Registered inhibition ranged from 5.11 to 11.1%, supporting the feasibility of the method.
Degradation of petroleum hydrocarbons in two sub-antarctic soils: Influence of an oleophilic fertilizer
Authors: Coulon Frédéric , Pelletier Emilien , Gourhant Lénaïck , Louis Richard St. , Delille Daniel
Published: November 2004

In order to determine the long-term effects of fertilizer on the degradation rate and the toxicity of hydrocarbons in sub-Antarctic soils contaminated by petroleum hydrocarbons, a field study was initiated in December 2000 on two different soils of the Kerguelen Islands (69°42′E, 49°19′S). The number of hydrocarbon-degrading bacteria (HDB) increased greatly after crude-oil and diesel-fuel contamination, and the fertilizer addition had a favorable effect on HDB growth and activity. Hydrocarbon-degrading bacteria counts remained high until the end of the experiment although the total hydrocarbon content in all contaminated soils was reduced to 80 to 90% of their initial value after 330 d. Degradation of n-alkanes was enhanced significantly in the presence of the fertilizer, while the degradation of polycyclic aromatic hydrocarbons (PAHs) was only barely enhanced. Toxicity results showed a noticeable reduction with time, although toxicity remained present and important in both soils at the end of the experiment. In addition, fertilized plots showed a toxic signal greater than unfertilized ones. Overall results clearly show that fertilizer addition improves the rate of degradation of both oil contaminants. However, remaining toxic residues may constitute a drawback of the fertilizer-assisted biodegradation process at low temperatures.
Temperature effects on very slow desorption of native chlorobenzenes from sediment to water
Authors: ten Hulscher Th. E. M. , Vrind Bea A. , van Noort Paul C. M. , Govers Harrie A. J.
Published: November 2004

The temperature dependence of the kinetics of very slow desorption of eight chlorobenzenes was studied in laboratory batch experiments on a field-contaminated sediment from Lake Ketelmeer, The Netherlands. The observed rate constants for very slow desorption averaged (1.5 ± 0.4) × 10−4/h at 10°C, (2.9 ± 1.0) × 10−4/h at 20°C, (5.8 ± 2.4) × 10−4/h at 35°C, and (6.4 ± 3.0) × 10−4/h at 45°C over all eight compounds. Activation energies for desorption to water were close to the enthalpy for dissolution of the pure solid in water. The activation energies ranged from 18 to 53 kJ/mol with an average of 36 ± 11 kJ/mol. These values confirm earlier reported activation energies for very slow desorption to water. They are much less than values for activation energies for desorption to the gas phase. That difference can be explained in terms of rate limiting desorption from carbonaceous adsorption sites.
Toxicity of binary mixtures of cadmium-copper and carbendazim-copper to the nematode Caenorhabditis elegans
Authors: Jonker Martijs J. , Piskiewicz Anna M. , Castellà Núria Ivorra I , Kammenga Jan E.
Published: November 2004

For ecological risk assessment, the additive model may be used to empirically predict toxic mixture effects. Detailed toxicity tests were performed to determine whether effects of mixtures of copper-cadmium and copper-carbendazim on Caenorhabditis elegans were similar to the effects of the individual compounds. Effects on the course of reproduction, the length of the juvenile period, the length of the reproductive period, and body length were analyzed. Dose–response data were compared to the additive model and tested for four deviation patterns from additivity: No deviation, synergistic/antagonistic deviation, dose ratio-dependent deviation, dose level-dependent deviation. During the exposure, the cadmium-copper effect on reproduction changed from a synergistic, to a dose ratio-dependent deviation from additivity. More cadmium in the mixture decreased the toxicity and more copper increased the toxicity. The effect of copper-carbendazim on reproduction was synergistic at low dose levels and antagonistic at high dose levels and independent of time. Mixture effects on the juvenile and reproductive period were similar to single component effects. It was concluded that the observed time-dependence of toxic interactions was small and that interactions on the timing of reproduction were not found. The additive model underestimated mixture effects on reproduction and body length.
Differential tolerance among cryptic species: A potential cause of pollutant-related reductions in genetic diversity
Authors: Rocha-Olivares Axayácatl , Fleeger John W. , Foltz David W.
Published: November 2004

Differential mortality of cryptic species (i.e., morphologically similar but genetically distinct sibling species) may contribute to observed reductions in genetic diversity at contaminated sites if the members of a complex of cryptic species exhibit differential responses to the contaminants that are present. We conducted toxicity bioassays with both polynuclear aromatic hydrocarbon and metal contamination on Cletocamptus fourchensis and C. stimpsoni from two intensively sampled locations. Previous molecular and detailed morphological analyses segregated these as cryptic species from the cosmopolitan C. deitersi. We found that these species occur together at two field sites and that they exhibit unique toxic responses to heavy metals, suggesting differential tolerances at contaminated sites. These findings suggest that reported losses of genetic diversity at contaminated sites may represent a reduction in species diversity rather than a loss of the presumed less-tolerant genotypes within a species. They also suggest that members of a cryptic species complex should not be used in laboratory toxicity tests unless populations are genetically characterized. Future studies using genetic diversity as a marker of contaminant effects should consider the possibility of undetected cryptic species.
Arsenic speciation in tissues of the mediterranean polychaete Sabella spallanzanii
Authors: Fattorini Daniele , Regoli Francesco
Published: November 2004

Arsenic toxicity is strictly related to its chemical form and marine organisms are known to accumulate this element mostly as organoarsenic nontoxic molecules. Contrasting with this general trend, the presence of moderately toxic to toxic arsenic compounds recently has been reported in some polychaete species, showing a completely different profile of represented chemical species. In this work the presence and distribution of arsenic were characterized in the Mediterranean polychaete Sabella spallanzanii, by analyzing total levels in different tissues and subcellular fractions and the occurrence of various arsenical compounds. Further investigations on arsenic accumulation in S. spallanzanii were based on the capability of this species to regenerate the branchial crown both in laboratory and field conditions. Though basal levels of arsenic in the thorax were similar to those already described for most polychaetes and invertebrate species, branchial crown revealed a remarkable accumulation of this element with concentrations higher than 1,000 μg/g. Arsenic mainly was localized in a soluble form within the cytosol and dimethyl-arsinate (DMA) appeared the most represented chemical species. Experiments on bioaccumulation of arsenic in regenerating branchial crowns confirmed the environmental origin of this element and the time-dependent appearance of various As compounds suggested a methylation pathway more than a degradation process for the elevated content of DMA. The accumulation of this moderately toxic compound in the more vulnerable tissues of the polychaete might represent an antipredatory strategy, as indicated by some feeding trials where fish ate the thorax but rejected the branchial crowns.