bluuebunny/crossref_metadata_2025_split huggingface dataset:
Accumulation of polychlorinated biphenyls from floodplain soils by passerine birds
Authors: Neigh Arianne M. , Zwiernik Matthew J. , Bradley Patrick W. , Kay Denise P. , Jones Paul D. , Holem Ryan R. , Blankenship Alan L. , Strause Karl D. , Newsted John L. , Giesy John P. 
Published: May 2006

AbstractEggs, nestlings, and adults of the eastern bluebird (Sialia sialis) and house wren (Troglodytes aedon) were collected at a polychlorinated biphenyl (PCB)-contaminated site and a reference location on the Kalamazoo River (MI, USA). Eggs and nestlings of eastern bluebirds at the more contaminated location contained concentrations of 8.3 and 1.3 mg/kg, respectively, of total PCBs and 77 and 6.3 ng/kg, respectively, of 2,3,7,8-tetrachlorodibenzo-p-dioxin equivalents (TEQs). Eggs, nestlings, and adults of house wrens from the contaminated location contained 6.3, 0.77, and 3.2 mg/kg, respectively, of PCBs and 400, 63, and 110 ng/kg, respectively, of TEQs. Concentrations of total PCBs and TEQs in tissues at the more contaminated location were significantly greater than concentrations in tissues at the reference site for all tissue types of both species. Exposures of the two species studied were different, which suggests that terrestrial-based insectivorous passerine species, foraging in the same area, may have differential exposure to PCBs depending on specific foraging techniques and the insect orders that are targeted. Despite the greater accumulation of PCBs at the more contaminated location, the risk of exposure to PCBs did not exceed the threshold for adverse effects at either location.
Concentration of contaminants in breeding bird eggs from the Colorado River Delta, Mexico
Authors: García-Hernández Jaqueline , Sapozhnikova Yelena V. , Schlenk Daniel , Mason Andrew Z. , Hinojosa-Huerta Osvel , Rivera-Díaz Juan José , Ramos-Delgado Norma Alicia , Sánchez-Bon Gerardo 
Published: May 2006

Abstract
Organic contaminants (organochlorine [OC], organophosphorus [OP] pesticides and polychlorinated biphenyls [PCBs]), and metals (As, Cd, Hg, Pb, and Se) are a concern to avian health in the Colorado River delta, Mexico. We determined concentrations of contaminants in eggs of three breeding species of birds from the delta (mourning doves [Zenaida macroura], burrowing owls [Athene cunicularia], and marsh wrens [Cistothorus palustris]). We collected 27 eggs of mourning doves, eight eggs of burrowing owls, and 18 eggs of marsh wrens for analyses. Polychlorinated biphenyls, OC, and OP pesticides were analyzed by gas chromatography equipped with an electron capture detector, and metals were analyzed by inductively coupled plasma mass spectrometry. The non-ortho PCB congeners (PCB 77 and 126) were found in mourning dove and burrowing owl eggs at concentrations in which hatchability can be affected. Mean selenium concentration found in marsh wren eggs (5.6 μg/g dry wt) exceeded the level of concern. Arsenic and Cd were found at higher than normal concentrations, Hg concentrations did not exceed the level of concern in any of the species, and Pb concentrations were higher in eggs of species subject to hunting. With the exception of lead, marsh wren eggs contained the highest metal concentrations.
Dynamics of cadmium accumulation and effects in common carp (Cyprinus carpio) during simultaneous exposure to water and food (Tubifex tubifex)
Authors: Reynders Hans , Van Campenhout Karen , Bervoets Lieven , De Coen Wim M. , Blust Ronny 
Published: May 2006

Abstract
In this study, the influence of exposure time and concentration on the accumulation of cadmium and the occurrence of adverse effects was investigated when carp were simultaneously exposed through contaminated water and food. As exposure concentrations increased (9, 105, and 480 μg/L through water and 9.5, 122, and 141 μg/g dry weight through food) the accumulation pattern of cadmium changed, with progressively more cadmium being accumulated in the liver and especially the kidney and less in the gills and the intestine. A strong concentration- and time-dependent effect of cadmium exposure on plasma calcium concentrations was observed, leading to a decrease, with approximately 16% in the mid group and up to 50% in the group exposed to the highest cadmium concentration. Also at the highest exposure concentrations, sodium and chloride levels as well as plasma osmolality were significantly reduced, indicating a disturbed ion homeostasis. Furthermore, an increase in plasma alanine transaminase activity indicated liver damage caused by the cadmium accumulation in this organ. At the end of the experiment, general stress responses such as decreased hematocrit, growth, and mortality (17%) also were observed. All together, these results suggest that plasma hypocalcemia as an ion-disruptive phenomenon is the most sensitive effect during cadmium exposure, although the occurrence and magnitude both depend on exposure time and concentration.
Detoxifying toxicants: Interactions between sulfide and iron toxicity in freshwater wetlands
Authors: van der Welle Marlies Elizabeth Wilhelmina , Cuppens Mieke , Lamers Leon Peter Maria , Roelofs Jan Gisbert Maria 
Published: May 2006

AbstractIn many Dutch freshwater wetlands, concentrations of sulfate in the surface water and groundwater have increased. It is especially in peaty areas that this can lead to problems, including the reduction of sulfate to toxic sulfide. Our aquarium experiments showed that even low sulfide concentrations of 50 μmol/L are toxic to the freshwater macrophyte Nitella flexilis and the freshwater oligochaete Ophidonais serpentina. Sulfide toxicity can be modified by the availability of free iron in soil moisture or sediment from iron-rich groundwater discharge. The iron precipitates the sulfide, thereby immobilizing it and decreasing its toxicity. However, iron itself can be a toxicant as well. We found a detoxifying effect of moderate iron concentrations on sulfide toxicity, as well as a toxic effect of high iron concentrations on the growth of Potamogeton acutifolius. At the intermediate range, the formation of metal sulfides can simultaneously decrease metal and sulfide toxicity. Results of the experiments are discussed in relation to hydrological changes in freshwater wetlands.
Chronic toxicity of silver to the sea urchin (Arbacia punctulata)
Authors: Ward Timothy J. , Kramer James R. , Boeri Robert L. , Gorsuch Joseph W. 
Published: May 2006

Abstract
The chronic toxicity of silver to the seaurchin (Arbacia punctulata) was determined in 30%o salinity seawater during a three-part study: A fertilization test (1-h sperm exposure), a 48-h embryo test, and a 30-d adult test. Combined data from the three tests resulted in a lowest-observed-effect concentration of 19 μg/L, a no-observed-effect concentration of 8.6 μg/L, and a maximum acceptable toxicant concentration of 13 μg/L, based on measured concentrations of dissolved silver. The 96-h median effective concentration was 40 μg/L, and the acute to chronic toxicity ratio was 3.1. During the tests, measured concentrations of free ionic silver (Ag+) were only 0.0027 to 0.0046% of dissolved silver concentrations, as predicted by ion-speciation theory. Some measured Ag+ concentrations were lower than predicted, indicating the presence of other ligands in the seawater test media. These strong sulfide ligands were exuded by the exposed sea urchins into the seawater (where Ag-sulfide complexes formed) in amounts that increased in direct proportion to the silver concentration during the toxicity test. This suggests a toxicity-defense mechanism that functioned by modifying the chemistry of the surrounding external medium.
The fate of chiral organochlorine compounds and selected metabolites in intraperitoneally exposed arctic char (Salvelinus alpinus)
Authors: Wiberg Karin , Andersson Patrik L. , Berg Håkan , Olsson Per-Erik , Haglund Peter 
Published: May 2006

Abstract
The fate of chiral organochlorine compounds (OCs) and selected metabolites in exposed Arctic char (Salvelinus alpinus) was investigated. The contaminants α-hexachlorocyclohexane (α-HCH), cis-chlordane, 13C4-heptachlor, o,p′-DDT, and the atropisomeric chlorinated biphenyls (CBs) 95, 132, 136, 149, and 174 were solved in peanut oil and injected into the peritoneal cavity. The exposed fish were sampled three times during a five-week period, and the OC residues and detected metabolites (heptachlor-exo-epoxide) were quantified in muscle and liver tissues by chiral and achiral gas chromatography-mass spectrometry and gas chromatography-electron-capture detection. Peak concentrations were reached after one to two weeks, and thereafter, the levels declined. At the end of the experiment, liver concentrations had decreased 76 to 92% relative to peak concentrations, whereas muscle concentrations showed a moderate decline (5–38%), with the exception of α-HCH (91%). Hydrophobicity and steric hindrance were shown to influence the assimilation process, and a significant linear relationship between the product of the steric hindrance coefficients and the inverse of the octanol-water partition coefficients (Kow) versus peak concentration was found for the CBs (r2 = 0.86, p = 0.02). The assimilation of the contaminants into muscle and liver tissues generally resulted in racemic mixtures, whereas elimination was enantioselective for α-HCH, cis-chlordane, o,p′-DDT, CB-132, and CB-136. The chiral heptachlor metabolite 13C4-heptachlor-exo-epoxide was formed in the fish. The enantiomeric composition of the formed metabolite indicated racemic formation, whereas the elimination process appeared to be enantioselective.
Spatial trends and associated biological responses of organochlorines and brominated flame retardants in hatchlings of North Atlantic kittiwakes (Rissa tridactyla)
Authors: Murvoll Kari Mette , Skaare Janneche Utne , Moe Børge , Anderssen Endre , Jenssen Bjorn Munro 
Published: May 2006

AbstractPersistent organic pollutants (POPs), such as polychlorinated biphenyls (PCBs), some organochlorinated pesticides (OCPs), polybrominated diphenyl ethers (PBDEs), and hexabromocyclododecane (HBCD), were analyzed in yolk sacs of kittiwake (Rissa tridactyla) hatchlings from Kongsfjorden at Svalbard (Norwegian Arctic; 79°N) and from Runde, an island on the coast of Norway (62°N). Retinol (vitamin A), retinyl palmitate, and α-tocopherol (vitamin E) were measured in plasma and liver of the hatchlings to examine whether these vitamins were associated with the POPs. Higher levels of PCBs and OCPs were found in hatchlings from Kongsfjorden than in hatchlings from Runde. However, HBCD levels were significantly lower in hatchlings from Kongsfjorden compared to those in hatchlings from Runde. No differences between the two populations of kittiwake hatchlings were found regarding levels of PBDEs. In comparison with seabirds from other European waters and the Canadian Arctic, the kittiwakes seemed to have relatively high levels of PBDEs and HBCD. No effects on morphological variables or vitamin levels by the POPs were revealed, but multivariate regression indicated that liver tocopherol levels may be influenced by POPs.
Uptake and elimination of ionizable organic chemicals at fish gills: I. Model formulation, parameterization, and behavior
Authors: Erickson Russell J. , McKim James M. , Lien Gregory J. , Hoffman Alex D. , Batterman Sharon L. 
Published: May 2006

AbstractA mechanistic model for the uptake and elimination of ionizable organic chemicals at fish gills is presented. This model is a modification of a previous model for nonionizable organic chemicals that addressed the transport of chemical to and from gill surfaces in water and blood, diffusion of chemical across epithelial cells, and binding of chemical to components in water and blood. For ionizable chemicals, three additional processes are included. First, excretory products alter the pH at gill surfaces, affecting the relative amounts of neutral and ionized molecules compared with that in the bulk exposure water. Second, ionized molecules support chemical flux to and from epithelial cell membranes and help maintain high diffusion gradients of neutral molecules across these membranes, thereby contributing to uptake and elimination even if the membranes are impermeable to ionized molecules. Third, membrane barriers are not completely impermeable to ionized molecules, and even limited permeability can have appreciable effects on chemical flux. Approaches for model parameterization are discussed. Model-predicted relationships of uptake and elimination rates to exposure water pH, alkalinity, and chemical properties are presented and discussed in terms of model processes. The model is shown to predict important features of reported effects of pH on uptake rates of weak organic acids.
Uptake and elimination of ionizable organic chemicals at fish gills: II. Observed and predicted effects of pH, alkalinity, and chemical properties
Authors: Erickson Russell J. , McKim James M. , Lien Gregory J. , Hoffman Alex D. , Batterman Sharon L. 
Published: May 2006

AbstractEffects of exposure-water pH on chemical uptake at rainbow trout (Oncorhynchus mykiss) gills were investigated for nine weakly acidic, chlorinated phenols with different ionization constants and hydrophobicities and for a moderately hydrophobic, nonionizable reference chemical (1,2,4-trichlorobenzene). Uptake rates for all chemicals varied little from pH 6.3 to 8.4, despite ionization of the chlorinated phenols ranging from less than 1 to greater than 99.9% among these pH values and chemicals. At pH 9.2, uptake rates were reduced substantially for the chlorinated phenols but not for the reference chemical. These results indicate greater bioavailability of neutral chemical forms but also considerable bioavailability of ionized forms that varies with pH. Three mechanisms were evaluated regarding such ionized chemical bioavailability. First, reduced pH at the gill surface causes net conversion of ionized molecules to more readily absorbed neutral molecules. This mechanism was tested by increasing exposure-water alkalinity, which increased gill surface pH and reduced uptake of the chlorinated phenols but not of the reference chemical. Magnitudes of these effects were close to predictions from a mathematical model for chemical exchange at fish gills that incorporated this mechanism. Second, ionized molecules contribute to uptake by maintaining high gradients of neutral molecules across epithelial membrane barriers, even if the barriers are impermeable to these ions. This mechanism was demonstrated to explain the similarity of uptake among pH values and chemicals at pH less than 8.4 and the degree to which uptake declined at pH 9.2. Third, membrane barriers can have some permeability to the ionized forms, but this was not important for the chemicals and conditions of the present study. Increased exposure-water pH also was demonstrated to increase elimination rates of these chemicals, which also was in accord with model expectations.
Emission of legacy chlorinated pesticides from agricultural and orchard soils in British Columbia, Canada
Authors: Bidleman Terry F. , Leone Andi D. , Wong Fiona , van Vliet Laurens , Szeto Sunny , Ripley Brian D. 
Published: May 2006

AbstractAir samples were collected above agricultural fields in the Fraser Valley and orchards in the Okanagan Valley, British Columbia, Canada, to investigate volatilization of organochlorine pesticides used in the past. Concentrations of pesticides in air were elevated over soils that contained higher residues. Soil/air fugacity ratios at sites with the higher soil residues were calculated relative to air sampled at 40 cm height and background air. The fugacity ratios in the first case indicated net volatilization or soil-air equilibrium for most compounds and occasional net deposition for p,p′-dichlorodiphenyldichloroethene (p,p′-DDE), whereas those in the second case showed a strong potential for net volatilization of all compounds. The enantiomer fraction (EF) of chiral compounds α-hexachlorocyclohexane (α-HCH), trans-chlordane, cis-chlordane, and o,p′-DDT were determined in overlying air samples and soils. Enantiomer fractions in air corresponded to those in soils at fields in which soil concentrations were high but were decoupled from soil signatures at fields with low soil residues. Mean EFs in air sampled over soils were significantly (p &lt; 0.001) nonracemic for α-HCH and the chlordanes and agreed with published EFs in regional ambient air. The mean EF of o,p′-DDT for all air samples did not show a significant deviation from racemic EFs (p &gt; 0.2), but EFs of individual samples reflected the ambivalent nature of o,p′-DDT degradation, sometimes preferring the (+) enantiomer and other times the (−) enantiomer. The study indicates that soils are continuing to emit “legacy” pesticides into the regional atmosphere.
The persistent DDT metabolite, 1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene, alters thyroid hormone-dependent genes, hepatic cytochrome P4503A, and pregnane × receptor gene expressions in atlantic salmon (Salmo salar) parr
Authors: Mortensen Anne S. , Arukwe Augustine 
Published: May 2006

AbstractThe present study investigated the effects of 1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene (DDE) on the thyroid and steroid-metabolizing system in Atlantic salmon (Salmo salar) parr. Fish were exposed to waterborne DDE and thyroxine (T4), both singly and in combination, for 5 d. Thyroid-stimulating hormone (TSHβ), T4 deiodinase (T4ORD), thyroid receptors (TRα and TRβ), and insulin-like growth factor type 1 receptor (IGF-1R) were analyzed using quantitative (real-time) polymerase chain reaction in liver, brain, and kidney, whereas cytochrome P4503A (CYP3A) and pregnane × receptor (PXR) mRNA levels were analyzed only in the liver. Exposure to DDE and T4, both singly and in combination, inhibited TSHβ expression in the brain. The DDE induced TSHβ in the liver, and T4 inhibited TSHβ in the liver and kidney, both singly and in combination with DDE. The DDT-metabolite DDE induced T4ORD expression in the kidney and liver, and combined exposure with T4 inhibited T4ORD expression in the brain, kidney, and liver. The IGF-1R and TRα expressions were induced by DDE and T4 singly in the brain, whereas combined exposure with both compounds did not affect IGF-1R and TRd transcript levels. Whereas T4 inhibited TRβ expression in the liver, exposure to DDE, both singly and in combination with T4, induced TRβ transcript levels in the liver. Exposure to T4 and DDE, both singly and in combination, resulted in a parallel pattern of CYP3A and PXR mRNA induction in the liver. These results indicate that DDE alters thyroid hormone–dependent genes and hepatic CYP3A and PXR levels. The hepatic modulation of CYP3A and PXR transcript levels by DDE represents a novel aspect of DDE toxicity that, to our knowledge, has not been demonstrated previously in fish. Therefore, the present study demonstrates some possible physiological and endocrine consequences from exposure to endocrine-disrupting chemicals for salmon parr during smoltification.
Changes in antibacterial activity of triclosan and sulfa drugs due to photochemical transformations
Authors: Wammer Kristine H. , Lapara Timothy M. , McNeill Kristopher , Arnold William A. , Swackhamer Deborah L. 
Published: May 2006

Abstract
Sulfa drugs and triclosan represent two classes of antibacterials that have been found in natural waters and for which photodegradation is anticipated to be a significant loss process. Parent antibacterial compounds and the products of photolysis reactions were compared for three sulfa drugs and triclosan to determine the extent to which photolysis affects their antibacterial potency on Escherichia coli DH5α. Sulfathiazole (median effective concentration [EC50] = 20.0 μM), sulfamethoxazole (EC50 = 12.3 μM), and sulfachloropyridazine (EC50 = 6.9 μM) inhibited bacterial growth but did not affect respiratory activity. Photolysis products of these sulfa drugs did not retain any measurable ability to inhibit growth. Triclosan inhibited both the growth (EC50 = 0.24 μM) and respiratory activity of E. coli DH5α. Triclosan photolysis products also exhibited no measurable effect on growth or respiratory activity. These experiments indicate that the products of triclosan and sulfa drug photolysis are unlikely to possess antibacterial activity in natural waters. The rapid screening method used for these two classes of compounds will be useful for helping to identify photolabile antibacterial compounds, for which photoproducts could require further investigation.
Sampling methods to determine the spatial gradients and flux of arsenic at a groundwater seepage zone
Authors: Gan Ping , Yu Ran , Smets Barth F. , MacKay Allison A. 
Published: May 2006

Abstract
Sampling techniques with centimeter-scale spatial resolution were applied to investigate biogeochemical processes controlling groundwater arsenic fate across the groundwater-surface water interface at a site characterized by fine sediments (40% sand, 46% silt, 14% clay). Freeze-core sediment collection gave more detailed and depth-accurate arsenic and iron contaminant and microbial distributions than could be obtained with the use of a hand auger. Selective chemical extractions indicated that greater than 90% of the arsenic was strongly sorbed to very amorphous iron oxyhydroxides. These solids accounted for more than 80% of the total iron in the sediments. Microbial enrichments indicated that iron-oxidizing bacteria (IOB) were up to 1% of the total bacterial abundance, whereas iron-reducing bacteria (IRB) were about two orders of magnitude less abundant than IOB. The abundance of IRB mirrored the IOB depth profile. Push-point pore-water sampling captured large amounts of sediment fines, even with controlled (20 ml/min) water withdrawal, thereby necessitating filtration before water quality analysis. Bead columns containing glass media enabled short-term (29 d) characterization of pore water-to-sediment transfer of arsenic and iron. Bead columns indicated quantitative capture of groundwater arsenic and iron during 2003, suggesting that freeze-core inventories corresponded to 2 to 20 years of accumulation, depending on location.
Ecological effects of the insecticide imidacloprid and a pollutant from antidandruff shampoo in experimental rice fields
Authors: Sánchez-Bayo Francisco , Goka Kouichi 
Published: May 2006

AbstractEcological changes caused by the insecticide imidacloprid and a pollutant from antidandruff shampoos (zinc pyrithione) were monitored in experimental paddies throughout a cultivation period. A total of 88 species were observed, with 54 of them aquatic. Plankton, nekton, benthic, and terrestrial communities from imidacloprid fields had significantly less abundance of organisms compared with control and shampoo-treated fields, either for the entire period or during early stages. The absence of Chironomus yoshimatsui and typical paddy ostracods from imidacloprid fields was most remarkable; as a consequence, green algae blooms (Spirogyra sp.) developed, which in turn hampered the establishment of weeds. Such changes occurred while residues of imidacloprid in water were present at levels greater than 1 μg/L. The overall diversity was similar in all fields and increased constantly until the end of the study. Phytophagous insects dominated in early communities, gradually giving way to predators and scavengers during late stages, but imidacloprid fields had a lower proportion of the latter trophic group. Multivariate analyses helped to describe and differentiate the communities between treatments and control. Hazard- and risk-assessment methods overestimated the effects of zinc pyrithione but failed to predict imidacloprid impacts, probably because of deficiencies in the exposure and relevant toxicity data used.