Snapping turtle (
Chelydra serpentina) eggs were exposed to two concentrations of chemically- or physically-dispersed water accommodated fractions of weathered Arabian light crude oil (Low
=
0.5 and ...High
=
10
g oil/L water). Solutions were passed through nest substrate to simulate alterations in composition during percolation to egg depth. Hatchlings were raised for 13
months during which numerous endpoints were measured. Prior to percolation, total PAH (“tPAH”; the sum of 52 PAHs measured) in physically-dispersed oil fractions were similar (High, 43; Low 67
mg/L). Following percolation, tPAH was also similar in physically-dispersed fractions (High, 14; Low 24
mg/L). Addition of dispersant increased tPAH prior to percolation in the High treatment (302
mg/L) relative to Low (13
mg/L), but percolation resulted in nearly equal concentrations in both treatments (High, 30; Low, 22
mg/L) due to physical trapping of dispersed oil by the nest substrate. In both chemically- and physically-dispersed fractions, percolation reduced low molecular weight (MW) compounds such that embryos were exposed to primarily mid- to high MW compounds. Total PAH in eggs differed 15-fold between the chemically-dispersed High and physically-dispersed High treatments (560 and 36
µg/kg respectively), the former characterized by higher MW compounds than the latter. While eggs accumulated up to 560
µg/kg tPAH, we observed no effects on hatching success or hatchling/juvenile traits (DNA integrity, survival, growth, metabolism, energy storage, or behavior), our results demonstrate that PAH profiles are altered during percolation, suggesting that experiments with subsurface organisms should be designed to account for compositional changes that occur as the solutions percolate through the substrate.
Water from the Susquehanna River was collected and analyzed for polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyl (PCB) congeners to estimate seasonal and annual riverine loads to ...the Chesapeake Bay. Temporal variations in the chemical loads resulted from the large changes in the water flow rates and in the particle-associated contaminant concentrations. Concentrations of PCBs and PAHs in river particles (ng/g) were twice as great as those in the northern Chesapeake Bay, indicating that the Susquehanna River is an important source of these contaminants to the bay. The river carries a majority of its hydrophobic organic contaminants (HOCs) in the particulate phase. During periods of high flow, large amounts of suspended particles in the river result in elevated HOC levels and increased loadings of these contaminants to the bay. From 1997 to 1998, 60% of the total annual HOC loading occurred in the early spring coincident with high river flows. The total PCB and PAH annual loadings from the Susquehanna River to the Chesapeake Bay were 76 and 3160 kg/year, respectively and 75% of the loaded organic contaminants were in the particulate phase. Principal component analysis of PAH and PCB congener patterns in the particles reveals that the river suspended particles were dominated by autochthonous production in the summer and by resuspended sediment and watershed erosion during the winter and early spring.
The majority of the preference assessment literature focuses on applications with children and adults with developmental disabilities. To date, relatively few studies have focused on research related ...to preference and reinforcer assessments with the elderly population with cognitive impairment, despite the need for programmed access to preferred and reinforcing stimuli (Raetz, LeBlanc, Baker, & Hilton, 2013). This study assessed the predictive validity of engagement- and selection-based preference assessment formats with 2 types of reinforcer assessments: engagement-based and task-based. Three older adults, who attended an adult day program and who had a formal diagnosis of neurocognitive disorder, participated in the study. The first participant's most preferred items in the each preference assessment were validated in both reinforcer assessments. The second participant's most preferred items from each preference assessment were validated with the engagement-based reinforcer assessment, but the task-based assessment produced variable responding. The third participant's most preferred items from the MSWO were validated with both reinforcer assessments, but the most preferred item from the FO was validated with only the engagement-based reinforcer assessment. Results are discussed in terms of their implications for preference and reinforcer assessments and their utility with the population of elderly adults with cognitive impairments.
Full text
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CEKLJ, FFLJ, NUK, ODKLJ, PEFLJ
We conducted field studies over three years to assess body burdens and maternal transfer of polychlorinated biphenyls (PCBs) as well as indices of sexual dimorphism in snapping turtles (Chelydra ...serpentina) of the upper Hudson River (NY, USA.) We collected adult turtles in areas known to be contaminated with PCBs and in nearby reference areas for measurement of body size, precloacal length, and penis size. We analyzed PCB concentrations in eggs collected over three years and in whole blood from adults in one year. Total PCB concentrations (mean ± standard error) in eggs were 2,800 ± 520 and 59 ± 5 ng/g wet weight in the contaminated area and the reference area, respectively. Eggs from the contaminated area were significantly enriched in tri‐, penta‐, and hepta‐PCBs relative to the reference area. Blood from adults in the contaminated area averaged 475 ± 200 and 125 ± 34 ng/g wet weight for males and females, respectively. In the reference area, blood PCB concentrations were 7 ± 3 and 4 ± 1 ng/g wet weight for males and females, respectively. Significant positive relationships were found between carapace length and blood PCB concentration for both sexes in the contaminated area; however, only a marginal relationship was found between female carapace length and concentration of PCBs in their eggs. Our results suggest that PCB contamination of the upper Hudson River presents risks of establishing high body burdens and of maternal transfer of PCBs to eggs, although our measures of gross morphology revealed no discernable expression of abnormal sexual development or reproduction.
A dynamic model that couples air−water exchange and phytoplankton uptake of persistent organic pollutants has been developed and then applied to PCB data from a small experimental lake. A sensitivity ...analysis of the model, taking into account the influence of physical environmental conditions such as temperature, wind speed, and mixing depth as well as plankton-related parameters such as biomass and growth rate was carried out for a number of PCBs with different physical−chemical properties. The results indicate that air−water exchange dynamics are influenced not only by physical parameters but also by phytoplankton biomass and growth rate. New phytoplankton production results in substantially longer times to reach equilibrium. Phytoplankton uptake-induced depletion of the dissolved phase concentration maintains air and water phases out of equilibrium. Furthermore, PCBs in phytoplankton also take longer times to reach equilibrium with the dissolved water phase when the latter is supported by diffusive air−water exchange. However, both model analysis and model application to the Experimental Lakes Area of northwestern Ontario (Canada) suggest that the gas phase supports the concentrations of persistent organic pollutants, such as PCBs, in atmospherically driven aquatic environments.
Gaseous and dissolved concentrations of polychlorinated biphenyls (PCBs) and hexachlorobenzene (HCB) were measured in the ambient air and water of Kaohsiung Harbor lagoon, Taiwan, from December 2003 ...to January 2005. During the rainy season (April to September), gaseous PCB and HCB concentrations were low due to both scavenging by precipitation and dilution by prevailing southwesterly winds blown from the atmosphere of the South China Sea. In contrast, trace precipitation and prevailing northeasterly winds during the dry season (October to March) resulted in higher gaseous PCB and HCB concentrations. Instantaneous air–water exchange fluxes of PCB homologues and HCB were calculated from 22 pairs of air and water samples from Kaohsiung Harbor lagoon. All net fluxes of PCB homologues and HCB in this study are from water to air (net volatilization). The highest net volatile flux observed was +
172 ng m
−
2 day
−
1
(dichlorobiphenyls) in December, 2003 due to the high wind speed and high dissolved concentration. The PCB homologues and HCB fluxes were significantly governed by dissolved concentrations in Kaohsiung Harbor lagoon. For low molecular weight PCBs (LMW PCBs), their fluxes were also significantly correlated with wind speed. The net PCB and HCB fluxes suggest that the annual sums of 69 PCBs and HCB measured in this study were mainly volatile (57.4
×
10
3 and 28.3
×
10
3 ng m
−
2 yr
−
1
, respectively) and estimated yearly, 1.5 kg and 0.76 kg of PCBs and HCB were emitted from the harbor lagoon surface waters to the ambient atmosphere. The average tPCB flux in this study was about one-tenth of tPCB fluxes seen in New York Harbor and in the Delaware River, which are reported to be greatly impacted by PCBs.
Our previous measurements of the temperature de pendencies of Henry's law constants of 26 polychlorinated biphenyls (PCBs) showed a well-defined linear relationship between the enthalpy and the ...entropy of phase change. Within a homologue group, the Henry's law constants converged to a common value at a specific isoequilibrium temperature. We use this relationship to model the temperature dependencies of the Henry's law constants of the remaining PCB congeners. By using experimentally measured Henry's law constants at 11 °C for 61 PCB congeners described in this paper combined with the isoequilibrium temperatures from our previous measurements of Henry's law constants of 26 PCB congeners, we have derived an empirical relationship between the enthalpies and the entropies of phase change for these additional PCB congeners. A systematic variation in the enthalpies and entropies of phase change was found to be partially dependent on the chlorine number and substitution patterns on the biphenyl rings, allowing further estimation of the temperature dependence of Henry's law constants for the remaining 122 PCB congeners. The enthalpies of phase change for all 209 PCB congeners ranged between 10 and 169 kJ mol-1, where the enthalpies of phase change decreased as the number of ortho chlorine substitutions on the biphenyl rings increased within homologue groups. These data are used to predict the temperature dependence of Henry's law constants for all 209 PCB congeners.
Sediment cores were collected from two sites in Grand Traverse Bay, Lake Michigan in May 1998, dated using 210Pb geochronology, and analyzed for polychlorinated biphenyl (PCB) congeners, polycyclic ...aromatic hydrocarbons (PAHs), and toxaphene. The extraordinarily high sediment focusing and accumulation rates in these cores relative to other Great Lakes sediments allowed quantification of high-resolution temporal trends in the burial of hydrophobic organic contaminants. The focus-corrected accumulation rate of total PCBs (sum of 105 congeners) in 1998 was 0.50 ng/cm2-year at both sites. Toxaphene and total PAH (t-PAH; sum of 33 compounds) surficial accumulations varied at each site and ranged from 0.08 to 0.41 ng/cm2-year for toxaphene and 25 to 52 ng/cm2-yr for t-PAHs at the two sites. The maximum t-PAH accumulation rate was in sediment dated from 1942, and PAH accumulation decreased from 1942 to 1980 with a first-order rate of decline 0.017 yr-1. Both toxaphene and t-PCB accumulations peaked in sediment deposited in 1972, after which their accumulations decreased with nearly identical rates of decline (0.027 yr-1 and 0.028 yr-1, respectively).
As part of the Atmospheric Exchange Over Lakes and Oceans Study (AEOLOS), air−water exchange fluxes of polychlorinated biphenyls (PCBs) were determined along a transect in the Baltimore Harbor from ...the Inner Harbor of Baltimore, MD, to the mainstem of the northern Chesapeake Bay to assess the overall contributions of urban source PCBs through air−water exchange and their impacts on coastal waters. Six sites were sampled during three intensive sampling periods in June 1996, February 1997, and July 1997 and at two sites (urban and rural) every ninth day between March 1997 and March 1998 to measure spatial and temporal variability in the PCB air−water exchange fluxes. During the intensive sampling campaigns, net total PCB (t-PCBs) volatilization fluxes ranged between 5 and 2120 ng m-2 day-1, varying on both temporal and spatial scales. Volatilization fluxes were highest in February, driven by high winds and elevated dissolved PCB concentrations. Throughout the annual sampling period, t-PCB volatilization fluxes were similar between urban (130 μg m-2 yr-1) and rural (120 μg m-2 yr-1) sites. Approximately 10% of the dissolved t-PCB inventory in the water column in Baltimore Harbor exchanges with the atmosphere each day. From air−water exchange alone, the estimated residence time of dissolved t-PCBs in the harbor is approximately 10 days (estimated hydraulic residence time of water in the harbor is between 7 and 14 days), indicating that air−water exchange is an efficient removal mechanism of t-PCBs from urban coastal waters. Furthermore, the annual flux of t-PCBs volatilizing from Baltimore Harbor is approximately 12% of the gas-phase t-PCB inventory over the water, and at the northern Chesapeake Bay site, the t-PCB flux is approximately 40% of the gas-phase t-PCB inventory. This suggests that air−water exchange of t-PCBs has the potential to be a significant source of PCBs to the rural atmosphere.
