Joel E. Baker

Polybrominated diphenyl ethers and polychlorinated biphenyls in sediments of southwest Taiwan: Regional characteristics and potential sources

Very little information is available on the contamination of coastal sediments of Taiwan by PBDEs and PCBs. In this study, we determined the concentrations of 19 PBDE and 209 PCB congeners in 57 surface sediment samples to identify the possible sources of PBDEs and PCBs. The total PBDE and PCB concentrations ranged from below detection limit to 7.73 ng/g and 0.88-7.13 ng/g, respectively; these values are within the ranges observed for most coastal sediments worldwide. The PBDE congeners were dominated by BDE-209 (50.7-99.7%), with minor contributions from penta- and octa-BDEs. The signatures of PCB congeners suggested that PCB residues in Kaohsiung coast may be the legacy of past use or the result of ongoing inputs from the maintenance, repair and salvage of old ships. Principal component analysis of the congener-specific composition of PBDEs and PCBs revealed distinct regional patterns that are related to the use of commercial products.

Seasonal variation in the biogeochemical cycling of seston in Grand Traverse Bay, Lake Michigan

Abstract This study describes the biogeochemical cycling of seston in Grand Traverse Bay, Lake Michigan. Seston was characterized by carbon and nitrogen elemental and isotopic abundances. Fluorescence, temperature, light transmittance, and concentrations of dissolved inorganic nitrogen were also determined. PCBs were analyzed from surface (10 m) seston and Σ PCB was calculated by summing all of the congeners quantified in each sample. The vertical and seasonal trends in the δ 13 C values of seston exhibited a broad range from −30.7 to −23.9‰. Low δ 13 C values that occur concurrently with a peak in fluorescence below the thermocline reflect uptake of 13 C depleted respiratory CO 2 and/or the accumulation of 13 C depleted lipids by phytoplankton. High δ 13 C values late in the season likely result from a reduction in photosynthetic fractionation associated with a decrease in the CO 2 pool. Seasonal δ 15 N values of seston were high in the spring and declined through August. The δ 15 N values of seston reflect a balance between fractionation during assimilation of NH 4 + or NO 3 − and degradative processes. The seston Σ PCB and fluorescence were both high in the spring and subsequently declined, suggesting that the concentrations of PCBs in seston were associated with labile material derived from primary productivity. The strong seasonal trends in the organic geochemical characteristics of seston and concentrations of PCBs emphasize the complex nature of particle cycling in aquatic environments.

Influence of Baltimore's Urban Atmosphere on Organic Contaminants over the Northern Chesapeake Bay

Air and precipitation samples were collected along an urban to over-water to rural transect across the northern Chesapeake Bay as a preliminary investigation into the spatial extent of elevated atmospheric concentrations of urban-derived persistent organic pollutants. Air samples were collected daily from June 3-9, 1996, along the transect as part of the Atmospheric Exchange over Lakes and Oceans project. Total (gas + particle bound) atmospheric polycy-clic aromatic hydrocarbon concentrations [∑-PAH] ranged from 0.4 to 114 ng/m3, and gas phase polychlorinated bi-phenyl concentrations [∑-PCB] ranged from 0.02 to 3.4 ng/m3. Strong concentration gradients were found for both PAHs and PCBs, with the highest concentrations in the city and the lowest at the downwind rural site. Gas and particle bound PAHs varied independently in the city, possibly due to strong but geographically separated emission sources. A precipitation event collected during westerly winds contained fourfold higher ∑-PAH and twelvefold higher ∑-PCB concentrations at the over-water site than at the rural background location, further indicating that the urban plume extends from Baltimore, MD, over the northern Chesapeake Bay over a spatial scale of approximately 30 km.

Photodegradation of polychlorinated biphenyl congeners using simulated sunlight and diethylamine

Abstract Photodegradation of polychlorinated biphenyls (PCBs) can be an important natural decomposition mechanism. As most PCB congeners do not strongly absorb wavelength above 300 nm, sensitizers are used in the transfer of light energy to the PCB molecule in order to enhance their degradation. The objectives of this study were to determine the rate-order of reaction and the photodegradation rates of PCB congeners by simulated sunlight in the presence of diethylamine. Five PCB congeners (66, 101, 110, 118, and 138) with diethylamine were exposed to simulated sunlight from 0, 1, 2, 4, 8, to 24 hr. These five congeners constitute 45.45 % of all the Aroclor 1254 congeners. Half-lives of these congeners, after exposure to simulated sunlight and diethylamine, ranged from 3.4 to 9.9 hr. The photodegradation rate constant of the PCB congeners varied from 0.07±0.01 to 0.20±0.04 hr−1. The photodegradation rate was proportional to the concentration of the PCB congener suggesting a pseudo first order reaction of PCB photodegradation. The data also indicated that the photodegradation is independent of the concentration of diethylamine. Degradation of congener 101 was 5 times faster with simulated than with natural sunlight. The product quantum yield of PCB congeners ranged from 2.6±0.3 to 7.5±0.2 × 10−4 in the presence of diethylamine.

Accumulation and maternal transfer of polychlorinated biphenyls in snapping turtles of the upper Hudson River, New York, USA

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.

Internal recycling of particle reactive organic chemicals in the Chesapeake Bay water column

Hydrophobic organic contaminants (HOCs) may be used as tracers of particle dynamics in aquatic systems. Internal cycling of polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs) were studied in the mesohaline Chesapeake Bay to assess the role of resuspension in maintaining particle and contaminant inventories in the water column, and to compare settling and suspended particle characteristics. Direct measurements of sediment resuspension and settling conducted in conjunction with one of the sediment trap deployments indicate reasonable agreement between measurements of particle flux using the two different methods. Organic carbon and PCB concentrations in settling solids collected in near-surface sediment traps were remarkably lower than concentrations in suspended particles collected by filtration during the trap deployments, but higher PAH concentrations were found in the settling particles. The different behaviors of PAHs and PCBs in the settling particles are due to their different source types and association to different types of particles. Sediment trap collections in near bottom waters were dominated by resuspension. Resuspension fluxes of HOCs measured 2 m above the bay bottom were as high as 2.5 μg/m2 day for total PCBs and 15 μg/m2 day for fluoranthene, and were 25 and 10 times higher than their settling fluxes from surface waters, respectively. HOC concentrations in the near bottom traps varied much less between trap deployments than HOC concentrations in the surface traps, indicating that the chemical composition of the resuspended particles collected in the near bottom traps was more time-averaged by repeated resuspension than the surface particles.

Effects of activated carbon on reductive dechlorination of PCBs by organohalide respiring bacteria indigenous to sediments

Polychlorinated biphenyls (PCBs) have accumulated in aquatic sediments due to their inherent chemical stability and their presence poses a risk due to their potential toxicity in humans and animals. Granular activated carbon (GAC) has been applied to PCB contaminated sediment sites to reduce the aqueous concentration by sequestration thus reducing the PCB exposure and toxicity to both benthic and aquatic organisms. However, it is not known how the reduction of PCB bioavailability by adsorption to GAC affects bacterial transformation of PCBs by indigenous organohalide respiring bacteria. In this study, the impact of GAC on anaerobic dechlorination by putative organohalide respiring bacteria indigenous to sediment from Baltimore Harbor was examined. It was shown that the average Cl/biphenyl after dehalogenation of Aroclor 1260 was similar between treatments with and without GAC amendment. However, GAC caused a substantial shift in the congener distribution whereby a smaller fraction of highly chlorinated congeners was more extensively dechlorinated to mono- through tri-chlorinated congeners compared to the formation of tri- through penta-chlorinated congeners in unamended sediment. The results combined with comparative sequence analysis of 16S rRNA gene sequences suggest that GAC caused a community shift to putative organohalide respiring phylotypes that coincided with more extensive dechlorination of ortho and unflanked chlorines. This shift in activity by GAC shown here for the first time has the potential to promote greater degradation in situ by promoting accumulation of less chlorinated congeners that are generally more susceptible to complete mineralization by aerobic PCB degrading bacteria.

Diffusive exchange of PAHs across the air–water interface of the Kaohsiung Harbor lagoon, Taiwan

Instantaneous air-water polycyclic aromatic hydrocarbons (PAHs) exchange fluxes were calculated in 22 pairs of ambient air and water samples from Kaohsiung Harbor lagoon, from December 2003 to January 2005. The highest net volatilization (3135 ng m(-2) day(-1)) and absorptive (-1150 ng m(-2) day(-1)) fluxes in the present study were obtained for the three-ring PAH phenanthrene on 7 April and 27 January 2004, respectively. All PAH diffusive fluxes for three-ring PAHs except phenanthrene were mainly volatilization exchange across the air-water interface. Phenanthrene and the four-ring PAHs were absorbed primarily from the atmosphere and deposited to the surface water, although some minor volatilization fluxes were also observed. Differences in flux magnitude and direction between the dry and wet seasons were also evident for PAHs. Strong absorptive/weaker volatilization PAH fluxes occurred in the dry season, but the opposite was found in the wet season. The mean daily PAH diffusive fluxes were an in flux of -635 ng m(-2) day(-1) in the dry season and an efflux of 686 ng m(-2) day(-1) in the wet season. The integrated absorbed and emitted fluxes of PAHs for harbor lagoon surface waters in the dry and wet seasons were 3.1 kg and 3.4 kg, respectively. Different from water bodies located in temperate zone, phenanthrene diffusive fluxes in Kaohsiung Harbor lagoon was favored in volatilization from surface waters during the wet season (April to September) because of scavenging by precipitation and dilution by prevailing southwesterly winds. In addition, this study used both of salinity and temperature to improve estimation of Henrys law constants (H) of PAHs in a tropical coastal area and show that correction for salinity produced 13-15% of differences in H values.

Seasonality of diffusive exchange of polychlorinated biphenyls and hexachlorobenzene across the air-sea interface of Kaohsiung Harbor, Taiwan.

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 x 10(3) and 28.3 x 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.

Seasonal Dynamics of PCB and Toxaphene Bioaccumulation within a Lake Michigan Food Web

Seasonal variations in PCB and toxaphene concentrations were measured in bulk zooplankton, mysid shrimp, benthic amphipods, alewife, and bloater chub collected from Grand Traverse Bay, Lake Michigan between April and September of 1997 and 1998. Concentrations of PCBs in the dissolved phase of the water column were consistent over time; however, seasonal changes in contaminant concentrations within the biota were significant. Seasonal changes were most pronounced in zooplankton, which displayed highest PCB burdens in April and decreased by as much as 75% through September, coincident with changes in phytoplankton biomass, species composition, and changes in the particulate pools of PCBs within the water column. Mysis sp. display a similar PCB trend as zooplankton, while Diporeia sp. displayed maximal PCB concentrations in late summer during 1997. PCB trends in the primary forage fish alewife (Alosa pseudoharengus) and bloater (Coregonus hoyi) were correlated more to shifts in lipid content and seasonal diet preferences. PCB concentrations were higher (p < 0.01) in bloater (310 ± 98 ng/g wet weight) than alewife (233 ± 70 ng/g wet weight), however alewife possessed higher toxaphene burdens (198 ± 72 ng/g wet weight) than bloater (88 ± 36 ng/g wet weight). Alewife contaminant burdens were high in spring and fall of both years, decreasing by as much as 60% in midsummer, and were reflective of changes measured in their lipid content associated with gamete production and spawning. These results suggest that despite invariant concentrations of the dissolved pool of PCBs within the lake, accumulation of PCBs by the biota on seasonal scales is controlled appreciably by growth and lipid dynamics, and foraging behavior.