[show abstract][hide abstract] ABSTRACT: We examine the concentrations and food web biomagnification of three cyclic volatile methylsiloxanes (cVMS) octamethylcyclotetrasiloxane (D4), decamethylcyclopentasiloxane (D5), and dodecamethylcyclohexasiloxane (D6) using aquatic biota collected from Lake Erie. Concentrations of cVMS in biota were within the range reported for other studies of cVMS in aquatic biota. Trophic magnification factors (TMF) were assessed in various food web configurations to investigate the effects of food web structure. TMF estimates were highly dependent on the inclusion/exclusion of the organisms occupying the highest and lowest trophic levels and were >1 for D4 and D5, indicating biomagnification, in only 1 of the 5 food web configurations investigated and were <1 in the remaining 4 food web configurations. TMF estimates for PCB180 were also dependant on food web configuration, but did not correspond with those obtained for cVMS materials. These differences may be attributed to environmental exposure and/or lipid partitioning differences between PCB180 and cVMS.
[show abstract][hide abstract] ABSTRACT: Ring doves were provided contaminated food spiked with [(13)C]-2,2',4,4',5,5'-hexachlorobiphenyl (PCB 153) over a period of 63 days. Animals were sacrificed after 0.33, 0.5, 1, 2, 4, 8, 18, 36 and 63 days following access to contaminated food. At each time point, chemical concentrations in blood, liver, brain, gonad, adipose and remaining whole carcass was determined. Whole body concentrations of PCB 153 increased linearly with time over the experiment indicating that the birds did not reach steady state with their food after 63 days. Tissue/plasma concentration ratios were plotted as a function of time to determine time to inter-tissue steady state for fast and slowly perfused tissues. Liver, brain and gonad achieved steady state concentrations with plasma in less than 3 days, whereas fat and carcass tissues required 9.7 and 11.5 days, respectively. The results indicate that inter-tissue distribution kinetics for PCBs in birds is relatively rapid and completed within a little over a week following exposure to a contaminated diet.
Bulletin of Environmental Contamination and Toxicology 07/2013; · 1.11 Impact Factor
[show abstract][hide abstract] ABSTRACT: Aquatic contaminants, specifically polychlorinated biphenyls (PCBs), a class of persistent organic contaminants, have been associated with sublethal effects on reproduction in fishes. Female brown bullhead (Ameiurus nebulosus) were used to assess variation in reproductive traits across eight populations differing in sediment sum PCB concentrations in the Lower Great Lakes region. Differences in maternal carotenoid allocation patterns among these populations were also examined. No significant associations were found between sediment sum PCB concentrations corrected for organic content (OC) and reproductive traits. However, egg diameter was negatively correlated with sediment PCB concentrations not corrected for OC, suggesting that observed relationships between sediment sum PCB concentrations and reproductive traits are driven by classes of environmental contaminants whose bioavailability are not predicted by OC, such as metals. An unexpected positive relationship was also found between egg carotenoid concentrations and sediment PCB concentrations. This positive relationship was explained by the maternal allocation of carotenoids based on a negative correlation between female muscle and egg carotenoid concentrations, where females from less contaminated locations had lower egg and greater muscle carotenoid concentrations than those from more contaminated locations. The results of this study identify sublethal effects of environmental contaminants on reproductive life-history traits in female brown bullhead, and investigations of adaptive mechanisms underlying this variation are warranted.
Archives of Environmental Contamination and Toxicology 07/2013; · 2.01 Impact Factor
[show abstract][hide abstract] ABSTRACT: Concentrations of selected heavy metals (Cd, Cu, Hg, Pb, Zn) and organic contaminants (PCBs, PAHs) were investigated in samples from the Detroit River (Great Lakes, North America) in 1999 and 2008/09 collected using a stratified random sampling design. Getis-Ord geospatial analysis was used to further establish locations of areas demonstrating significantly high and low contaminant concentrations in the river. Based on the stratified random sampling design, a majority of the examined metals and organic contaminants demonstrated little or no trends with respect to regional sediment concentrations and river-wide mass balances over the investigated time interval. The Getis-Ord analysis revealed local scales of contaminated and clean areas which did not conform to the original strata used in the geostatistical sampling design. It is suggested that geospatial analyses such as Getis-Ord be used in the design of future sediment quality surveys to refine locations of strata that can simultaneously address sediment recovery over system-wide, regional and local spatial scales.
[show abstract][hide abstract] ABSTRACT: The assimilation of polychlorinated biphenyls (PCBs) in round gobies (Neogobius melanostomus) after intraperitoneal (IP) injection was compared to PCBs bioaccumulated by the same fish through natural exposure ("native" PCBs). Lipid equivalent corrected dorsal muscle: whole body concentration ratios for native PCB 153 averaged 1.16 ± 0.77 and ranged from 1.19 to 1.24 for three IP dosed non-native PCBs within 6 h after dosing. Variation in tissue distribution of IP-dosed congeners was reduced after benchmarking to PCB 153, reinforcing that assimilation of the IP dose occurred into muscle rapidly after injection. Despite the use of small oil volumes during injection (<10 μL per fish), coefficients of variation of IP-dosed PCBs were equivalent to those observed for native PCBs. The results suggest that IP dosing provides a precise method to achieve target concentrations of hydrophobic chemicals in small fish and does not require several days to achieve assimilation into highly perfused tissues.
Bulletin of Environmental Contamination and Toxicology 06/2013; · 1.11 Impact Factor
[show abstract][hide abstract] ABSTRACT: Fall spawning pacific salmon provision large amounts of yolk to their eggs to allow survival of larvae during under the ice winter conditions. This yolk provisioning leads to maternal offloading of persistent organic pollutants (POPs) to eggs and larvae. Previous research has shown that Chinook salmon larvae exhibit limited capacity to eliminate POPs during the cold water period resulting in bioamplification of POP residues. This study compared POPs bioamplification in Chinook salmon larvae under a high food provisioning treatment and a non-fed treatment to test whether or not food availability attenuates POPs bioamplification via growth dilution. Results demonstrate that larvae in the food provisioning treatment did not gain weight until after day 129. Between hatching and day 129, fed and non-fed treatments exhibited similar decreases in whole body lipid content, negligible POPs elimination and POPs bioamplification factors approaching 1.6. By day 184 of the study, POPs bioamplification factors in the non-fed treatment were as high as 5.3 across chemicals but ranged from non-detectable to approaching 1 in the fed group. This study demonstrates that POPs bioamplification occurs in Chinook salmon larvae even under ideal rearing conditions but peaks after day 129, following which growth dilution can attenuate bioamplification relative to starved individuals.
[show abstract][hide abstract] ABSTRACT: The sorption behaviour of hydrophobic organic compounds (HOCs) 1,2,4,5-tetrachlor-obenzene (TeCB), pentachlorobenzene (PeCB) and hexachlorobenzene (HCB) to Aldrich humic acid (AHA) and municipal wastewater treatment plant (MWTP) influent colloidal organic carbon (COC) was investigated using the gas-stripping technique. Gas stripping assumptions of gas/water equilibrium and a constant volatilization rate were validated prior to calculation of partitioning parameters. The logKCOC coefficients determined for MWTP influent COC were 3.86, 3.89 and 3.19 for TeCB, PeCB and HCB, respectively. Due to the presence of COC, the mass transfer of TeCB, PeCB and HCB with the primary effluent to the secondary biological stage was predicted to increase 8.7%, 9.6% and 1.2%, respectively, based on the measured COC concentration and logKCOC values. The calculated increases in apparent solubility for TeCB, PeCB and HCB in the primary effluent were 14.4%, 22.0% and 6.5%, respectively. This partitioning did not follow the expected trend (TeCB < PeCB < HCB) based on hydrophobicity predicted by octanol/water partitioning. The trend observed differed from the current AHA standard and correlation-based trends derived from natural COCs. More experiments with other HOCs are needed to better understand and predict the magnitude and significance of MWTP influent COCs on the fate and transport of HOCs during the MWTP process.
[show abstract][hide abstract] ABSTRACT: Henry's law constant (HLC) is an important factor used in environmental risk assessment and fate and transport models to describe mass transfer of chemical between water and air. HLCs and structure-property relationships were assessed for 1,2,4,5-tetrachlorobenzene (TeCB), pentachlorobenzene (PeCB), and hexachlorobenzene (HCB). HLCs were determined using the volatilization rate (k(v)) of sparged chemical at 25°C. Despite the assumption that k(v) should be constant throughout the stripping duration, results indicated that k(v) decreased over time according to three separate slope regions. Results of ANCOVA indicate that k(v) is statistically different in the third slope region, which leads to the conclusion that use of the entire stripping data set would lead to biased HLCs. This decrease in k(v) may be attributed to desorption from sparger surfaces, which has not been considered widely in the literature. Statistical analysis was possible because of the robustness of the current experimental procedure which included numerous replications (15 total spargers) and extensive data points available to discern key slope changes. HLCs determined using the gas stripping technique were 57, 33, and 30Pam(3)mol(-1) for 1,2,4,5-TeCB, PeCB, and HCB, respectively. In comparison to literature values, current TeCB and HCB HLCs were within wide reference ranges spanning approximately an order of magnitude for each chemical. PeCB HLC of the current study was two times lower than the lowest reference data.
[show abstract][hide abstract] ABSTRACT: Natural organic matter from the aquatic environment passing a 1 kDa filter has been hypothesized to not contribute appreciably to hydrophobic organic compound (HOC) partitioning; however, to our knowledge this limit has not been verified experimentally for any sorbate/sorbent system. Presently, colloidal organic carbon (COC) < 1 kDa approached 70% of the total COC (< 1.5 µm) mass in primary effluent (PE) from a municipal wastewater treatment plant. Partitioning of HOCs 1,2,4,5-tetrachlorobenzene, pentachlorobenzene and hexachlorobenzene to COC for both 1.5 µm and 1 kDa filtrates of PE was investigated using the gas-stripping technique. Contrary to the hypothesis, significant HOC - COC partitioning to the 1 kDa filtrate was observed with organic carbon-normalized partitioning coefficients (logK(COC)) of 4.30, 4.36 and 3.74 for 1,2,4,5-TeCB, PeCB and HCB, respectively. Further, partitioning to COC < 1 kDa dominated the overall partitioning of the three chlorobenzenes in the 1.5 µm filtrate, and the partitioning behaviour did not follow the trend based on hydrophobicity (K(OW)). The results show that significant partitioning of HOC may occur to OC < 1 kDa and highlights the need for further experiments with other HOCs and COC characterization to better understand and explain the observed partitioning.
[show abstract][hide abstract] ABSTRACT: An assessment of polychlorinated biphenyls (PCBs) in water of the Detroit River, North America, was performed using mussel biomonitoring data generated between 1996 and 2010. The study included a temporal monitoring program at six locations and an enhanced spatial survey performed during 2002. Mussels were transplanted at biomonitoring stations and collected after 21-226d. A toxicokinetic model was used to perform steady state and control corrections followed by an equilibrium partitioning model to estimate bioavailable water concentrations of PCBs. Bioavailable water concentrations of PCBs were similar in magnitude and trends to dissolved water concentrations reported in previous studies using direct sampling approaches. PCB concentrations exhibited complex temporal patterns at the six biomonitoring stations with multi-year declines in PCB trajectories between 1996 and 2002 and less consistent trends occurring across stations in later years. Spatial patterns of PCBs during 2002 revealed significantly higher water contamination on the US side of the river (seasonal average mean±standard error (SE) sum PCB concentration of 0.63±0.11ngL(-1)) compared to the Canadian side (mean±SE sum PCB concentration of 0.09±0.01ngL(-1)). Spatial/temporal variability of bioavailable PCB concentrations was greatest between countries, followed by moderate variation across years and by river reach (upstream, midstream and downstream sections within a country) and lowest when comparing intra-seasonal variation.
[show abstract][hide abstract] ABSTRACT: The gastrointestinal magnification (GI-magnification) model was calibrated in ring doves and Japanese koi using matched data on dietary assimilation and fecal depuration of polychlorinated biphenyls (PCBs). Mass transport parameters describing PCB flux from gut contents to organism (D'(og); mol d(-1) Pa(-1)) and organism to gut contents (D(og); mol d(-1) Pa(-1)) were quantified to test the hypothesis that the ratio of these two terms approached unity. For birds, D'(go)/ D(og) ranged from 2.9 to 6.3 and for fish the ratios ranged from 0.7 to 3.1. In both species, the ratio commonly exceeded 1. The GI-magnification model was used to predict maximum PCB biomagnification factors (BMF(max)) for each species which ranged from 18.5 to 33.8 for ring doves and 7.9 to 14.8 for Japanese koi. Chemical losses via respiration reduced steady state biomagnification factor (BMF(ss)) estimates by a negligible amount in birds, whereas for fish, predicted BMF(ss) decreased to values from 0.5 to 7.2. This study demonstrated that chemical transfer efficiency during assimilation exceeds organism/feces transfer which contributes to elevated PCB biomagnification potentials in birds and fish. Combined with reduced losses of chemical across respiratory surfaces, higher D'(go)/ D(og) ratios of birds contribute to elevated biomagnification in birds over fish.
[show abstract][hide abstract] ABSTRACT: The maternal provisioning of yolk to eggs transfers significant quantities of persistent organic pollutants (POPs). As yolk utilization progresses via metabolic activity, there is a potential to realize further increases in POP concentrations if yolk lipids are depleted at a faster rate than POPs, a condition referred to as bioamplification. This study investigated the bioamplification of POPs in Chinook salmon ( Oncorhynchus tshawytscha ) eggs and larvae. Chinook eggs were sampled from the Credit River, ON, Canada, and brought to an aquaculture facility where they were fertilized, incubated, and maintained posthatch until maternally derived lipid reserves became depleted (approximately 168 days). The loss of chemicals having an octanol-water partition coefficient (log K(OW)) greater than 5.8 was slow to negligible from days 0-135. However, during the increase in water temperatures in early spring, K(OW)-dependent elimination of POPs was observed. Bioamplification was maximized for the highest log K(OW) POPs, with an approximate 5-fold increase in lipid equivalents concentrations in 168 day old larvae as compared to newly fertilized eggs. This study demonstrates that later yolk-sac Chinook larvae (before exogenous feeding) are exposed to higher lipid equivalents POP concentrations than predicted by maternal deposition, which could lead to underestimates in the toxicity of critical life stages.
[show abstract][hide abstract] ABSTRACT: One adaptive mechanism aquatic populations use to facilitate tolerance to environmental contaminants is acclimation. Polychlorinated biphenyls (PCBs) are a globally ubiquitous class of persistent organic contaminants that have been linked to reproductive impairments in fish. The authors used female brown bullhead (Ameiurus nebulosus) to test whether acclimation of reproductive life-history traits occurs in response to changes in sum PCB exposure. They compared egg diameter, gonadosomatic index (GSI), and fecundity of fish directly caught from wild populations exposed to a range of contaminant concentrations (acute), to those collected from the same populations a year before, which were placed in a clean environment to clear their contaminants throughout that year (cleared). Sum PCB concentrations were also determined for each individual. Brown bullhead from acute treatments had significantly greater sum PCB concentrations compared with cleared treatments. Egg diameter and GSI metrics were greater in cleared treatments compared with acute treatments (by 6 and 14%, respectively). Treatment effect (i.e., acute or cleared), as opposed to where the fish were collected from, accounts for 72 to 89% of the variation in the reproductive life-history trait variables. No difference in fecundity was found between acute and cleared treatments. The authors found support that acclimation of reproductive life-history traits occurs to changes in sum PCB concentration. To their knowledge, the present study is the first experimental test of acclimation responses of female life-history traits to contaminants in wild populations.
Environmental Toxicology and Chemistry 01/2012; 31(4):863-9. · 2.62 Impact Factor
[show abstract][hide abstract] ABSTRACT: Ephemeral emergent insects, such as mayflies (Hexagenia spp.), are commonly used as biomonitors of persistent organic pollutants (POPs) and provide a vector for aquatic-terrestrial contaminant transfer. Mayflies bioaccumulate sediment-associated contaminants by bioconcentration and biomagnification during the aquatic stage and concentrate POP residues postemergence due to bioamplification, which occurs as a result of weight and lipid loss without contaminant loss. The present study quantified polychlorinated biphenyl (PCB) bioamplification in male and female emergent mayflies at three sites. Male mayflies used 36 to 68% of their lipids during emergence, with the exception of caged males that were prevented from flight. Females did not lose lipid content between pre-emergent nymph and emerged life stages. Mass balance indicated no PCB elimination between life stages. The mean PCB bioamplification factor, expressed as the ratio of lipid-equivalent PCB concentrations across life stages, was 2.05 ± 0.38 for male imagos/nymphs and 1.91 ± 0.18 for male imago/subimago life stages. For females, bioamplification factors were close to unity. Wildlife consumers of imago stages of emergent mayflies can potentially increase their total daily intake of PCBs by 36% depending on the sex-ratio composition of their diet relative to animals that feed predominantly on nymph or subimago stages during mass emergence events.
Environmental Toxicology and Chemistry 06/2011; 30(9):2167-74. · 2.62 Impact Factor
[show abstract][hide abstract] ABSTRACT: Evaluation of dredged material for aquatic placement requires assessment of bioaccumulation potentials for benthic organisms using standardized laboratory bioaccumulation tests. Critical to the interpretation of these data is the assessment of steady state for bioaccumulated residues needed to generate biota sediment accumulation factors (BSAFs) and to address control correction of day 0 contaminant residues measured in bioassay organisms. This study applied a novel performance reference compound approach with a pulse-chase experimental design to investigate elimination of a series of isotopically labeled polychlorinated biphenyl ((13)C-PCBs) in the polychaete worm Nereis virens while simultaneously evaluating native PCB bioaccumulation from field-collected sediments. Results demonstrated that all (13)C-PCBs, with the exception of (13)C-PCB209 (> 80%), were eliminated by more than 90% after 28 d. The three sediment types yielded similar (13)C-PCB whole-body elimination rate constants (k(tot)) producing the following predictive equation: log k(tot) = - 0.09 × log K(OW) - 0.45. The rapid loss of (13)C-PCBs from worms over the bioassay period indicated that control correction, by subtracting day 0 residues, would result in underestimates of bioavailable sediment residues. Significant uptake of native PCBs was observed only in the most contaminated sediment and proceeded according to kinetic model predictions with steady-state BSAFs ranging from 1 to 3 and peaking for congeners of log K(OW) between 6.2 and 6.5. The performance reference compound approach can provide novel information about chemical toxicokinetics and also serve as a quality check for the physiological performance of the bioassay organism during standardized bioaccumulation testing.
Environmental Toxicology and Chemistry 03/2011; 30(6):1366-75. · 2.62 Impact Factor
[show abstract][hide abstract] ABSTRACT: The study discusses the role of natural and anthropogenic factors influencing dispersal of both inorganic and organic pollutants in the sediments based on findings for different aquatic sub-systems (fluvial, deltaic, lacustrine) joined into one waterway (Huron-Erie Corridor, North America). Bottom current velocity, finest fraction (
[show abstract][hide abstract] ABSTRACT: This research investigated dose-dependent whole body and fecal elimination of 39 polychlorinated biphenyl (PCB) congeners spanning a range of chemical hydrophobicities (log Kow) by the Japanese koi (Cyprinus carpio). Both whole body (ktot) and fecal (keg) PCB congener elimination rate coefficients were negatively correlated with log Kow and observed to be dose independent. PCB congener ktot values determined for koi were representative of those generated for fish species of similar size and reared at near optimal temperatures. For persistent and metabolized-type PCB congeners, no significant difference was observed between the regressions describing the relationships between ktot and log Kow for these congeners. Individual PCB congener keg coefficient estimates ranged between 1% and 20% of their respective ktot values but averaged only 5% of the magnitude of ktot over a log Kow range of 5.7-7.8. These results verify first-order kinetics of PCB elimination by a fish species and demonstrate that the relative contribution of keg to ktot is negligible, even for highly hydrophobic (log Kow>6.5) compounds. It was concluded that gill elimination is the primary mechanism of elimination for persistent organic pollutants such as PCBs by Japanese koi.
[show abstract][hide abstract] ABSTRACT: The influence of diet on polychlorinated biphenyl (PCB) assimilation was investigated by measuring dietary assimilation efficiencies (AEs) for 47 PCB congeners in juvenile koi (Cyprinus carpio) fed five experimental diets. Two of the diets were naturally contaminated and were obtained by collecting mayflies from Lake Erie (ON, Canada) and emerald shiners from the Detroit River (MI, USA). The remaining diets consisted of commercial fish pellets (lipid contents from 6.7 to 24%) that were contaminated by spiking with a PCB mixture. Experimental fish were held individually to quantify the amount of food consumed per fish and, following a 48-h fasting period to facilitate food digestion and assimilation; AEs were determined by mass balance. Fish fed the benthic invertebrate food exhibited the highest PCB AEs (70-101%) and were significantly elevated compared to the other diet treatments (AEs ranging from 23 to 87%). The PCB AEs for fish fed emerald shiners did not differ from those fed pellet formulations. Variation among PCB AEs was not related to diet lipid content. For all diet treatments, PCB AEs were significantly related to chemical hydrophobicity. The relationship between chemical AE and n-octanol/water partition coefficient (K(OW)) was best explained by a linear model compared to a two-phase resistance model. Overall, PCB AEs were observed to be dependent on both diet type and chemical hydrophobicity, with both factors contributing nearly equally to the variation measured in this toxicokinetic parameter.
Environmental Toxicology and Chemistry 02/2010; 29(2):401-9. · 2.62 Impact Factor
[show abstract][hide abstract] ABSTRACT: The bioaccumulation and toxicokinetics of 42 polychlorinated biphenyls (PCBs) was determined in male Amrican kestrels exposed to an Aroclor®-contaminated diet for 120 d followed by a 348-d depuration period. The birds were housed under ambient outdoor temperatures to permit normal fluctuations in body weight during the study. Whole body PCB clearance, plasma/fat distribution coefficients, and plasma PCB clearance constants were determined for individual PCBs to calibrate a two-compartment rate constant model in order to describe PCB elimination in the birds. Plasma/fat partition coefficients (KPF) averaged 0.0060 ± 0.0001 for all congeners of study, were not dependent on chemical hydrophobicity, and did not change in summer versus winter sacrificed animals. Plasma clearance constants (k′pc) for PCBs were observed to be dependent on both chlorine substitution patterns and congener hydrophobicity. Polychlorinated biphenyl congeners categorized as readily cleared congeners contained vicinal meta–para hydrogen substituents on at least one phenyl ring, while slowly cleared congeners were chlorine hindered at these positions. A general equation was derived to predict plasma clearance constants for all tri- to octachlorobiphenyls based on the presence of an open meta–para site on one of the phenyl rings and from the n-octanol–water partition coefficient of the chemical. The equation was validated by comparing predicted versus measured relative biomagnification factors of PCBs determined in birds at the end of the dosing period. The two-compartment model calibrated for PCB elimination in American kestrels may be used to describe PCB toxicokinetics in wild birds provided that seasonal fluctuations in the fat content of the modeled population is known.