Time Trends of Polybrominated Diphenyl Ethers (PBDEs) in Antarctic Biota.

Polybrominated diphenyl ethers (PBDEs) are "emerged" contaminants that were produced and used as flame retardants in numerous consumer and industrial applications for decades until banned. They remain ubiquitously present in the environment today. Here, a unique set of >200 biotic samples from the Antarctic was analyzed for PBDEs, including phytoplankton, krill, fish, and fur seal milk, spanning several sampling seasons over 14 years.

Persistent organic pollutants in the Atlantic and southern oceans and oceanic atmosphere.

Persistent organic pollutants (POPs) continue to cycle through the atmosphere and hydrosphere despite banned or severely restricted usages. Global scale analyses of POPs are challenging, but knowledge of the current distribution of these compounds is needed to understand the movement and long-term consequences of their global use. In the current study, air and seawater samples were collected Oct.

Polychlorinated biphenyls and organochlorine pesticides as intrinsic tracer tags of foraging grounds of bluefin tuna in the northwest Atlantic Ocean.

Researchers have utilized chemical fingerprints in the determination of habitat utilization and movements of the aquatic animals. In the present effort, we analyzed polychlorinated biphenyl (PCB) congeners and organochlorine pesticides in the samples of juvenile bluefin tuna caught offshore of Virginia, and in larger bluefin tuna from the Gulf of Maine and near Nova Scotia. For a given specimen, or a given location, PCB concentrations were highest, followed by DDTs, and chlordanes.

Inter-annual variation of persistent organic pollutants (POPS) in an Antarctic top predator Arctocephalus gazella.

Persistent organic pollutants (POPs), contaminants that may bioaccumulate in upper trophic level organisms, were detected in the milk of a top predator, the Antarctic fur seal (Arctocephalus gazella). Multiparous females had significantly lower concentrations of certain POPs (trans-nonachlor, p,p'-DDE, and several PCBs) in their milk than primiparous females, likely due to the annual lactational transfer of the POP burden from mother to pup. Furthermore, there were significant interannual differences in POP concentrations in multiparous females' milk from five breeding seasons between 2000 and 2011.

Aerosol-mediated transport and deposition of brominated diphenyl ethers to Antarctica.

Brominated diphenyl ethers (BDE47, 99, 100, and 209) were measured in air, snow and sea ice throughout western Antarctica between 2001 and 2007. BDEs in Antarctic air were predominantly associated with aerosols and were low compared to those in remote regions of the northern hemisphere, except in Marguerite Bay following the fire at Rothera research station in Sept 2001, indicating that this event was a local source of BDE209 to the Antarctic environment. Aerosol BDE47/100 reflects a mixture of commercial pentaBDE products; however, BDE99/100 is suggestive of photodegradation of BDE99 during long-range atmospheric transport (LRAT) in the austral summer.

Atlantic bluefin tuna (Thunnus thynnus) population dynamics delineated by organochlorine tracers.

Atlantic bluefin tuna (ABFT) are highly valued and heavily exploited, and critical uncertainties regarding their population structure hinder effective management. Evidence supports the existence of two breeding populations of ABFT; a western population in the Gulf of Mexico and an eastern population in the Mediterranean Sea; both of which migrate and mix in the North Atlantic. Conventional tagging studies suggest low rates of trans-Atlantic migrations; however, electronic tagging and stable isotopes in otoliths indicate stock mixing up to 57% between management zones delineated by 45 degrees W longitude.

Changes in sediment and organic carbon accumulation in a highly-disturbed ecosystem: the Sacramento-San Joaquin River Delta (California, USA).

We used the Sacramento-San Joaquin River Delta CA (Delta, hereafter) as a model system for understanding how human activities influence the delivery of sediment and total organic carbon (TOC) over the past 50-60 years. Sediment cores were collected from sites within the Delta representing the Sacramento River (SAC), the San Joaquin River (SJR), and Franks Tract (FT), a flooded agricultural tract. A variety of anthropogenic tracers including (137)Cs, total DDE (Sigma DDE) and brominated diphenyl ether (BDE) congeners were used to quantify sediment accumulation rates.

Organochlorine pesticide air-water exchange and bioconcentration in krill in the Ross Sea.

Mean hexachlorobenzene (HCB) and hexachlorocyclohexane (HCH) concentrations, measured in seawater and air samples, confirmed the decline in levels of these compounds in Antarctic air and water. However, low alpha/gamma-HCH ratios in air at the beginning of the sampling period suggest a predominance of fresh lindane entering the Antarctic atmosphere during the Austral spring probably due to current use in the Southern Hemisphere. Water-air fugacity ratios demonstrate the potential for HCH gas deposition to coastal Antarctic seas, while the water-air fugacity ratios for HCB imply that volatilization does not account for the observed decrease of HCB in surface seawater.

Melting glaciers: a probable source of DDT to the Antarctic marine ecosystem.

Persistent organic pollutants reach polar regions by long-range atmospheric transport and biomagnify through the food web accumulating in higher trophic level predators. We analyzed Adélie penguin (Pygoscelis adeliae) samples collected from 2004 to 2006 to evaluate current levels of sigmaDDT (p,p'-DDT + p,p'-DDE) in these birds, which are confined to Antarctica. Ratios of p,p'-DDT to p,p'-DDE in Adélie penguins have declined significantly since 1964 indicating current exposure to old rather than new sources of sigmaDDT.

Atmospheric concentrations and air-water flux of organochlorine pesticides along the Western Antarctic Peninsula.

Air, seawater, sea ice, and snow were collected during the austral winter (September-October 2001) and summer (January-February 2002) along the Western Antarctic Peninsula. Hexachlorobenzene (HCB) > heptachlor > alpha- and gamma-hexachlorocyclohexane (HCH) and heptachlor epoxide, were the most frequently detected organochlorine pesticides in air. HCB and HCH levels declined over the past 20 years, with a half-life of 3 years for sigmaHCH in Antarctic air.

Polycyclic aromatic hydrocarbons in a highly industrialized urban estuary: inventories and trends.

The abundance and composition of polycyclic aromatic hydrocarbons (PAHs) in sediments of the main stem and southern branch of the Elizabeth River (VA, USA), a highly industrialized urban estuary in the Chesapeake Bay (USA) watershed, were examined relative to historical and toxic effects levels. Total PAH concentrations in Elizabeth River sediments exceeded those observed in Baltimore Harbor and the Anacostia River, two other regions of concern in the Chesapeake Bay. The sigmaPAH concentrations from samples collected in the vicinity of two former wood-treatment facilities in the Elizabeth River had the highest sigmaPAH when compared to coastal and estuarine systems around the world.

Fractionation of stable isotope-labeled organic pollutants as a potential tracer of atmospheric transport processes.

To test the potential for using stable isotope fractionation to examine the atmospheric transport of semivolatile organic compounds (SOCs), we conducted simplified distillation experiments in the laboratory and a tracer-release experiment using mixtures of stable isotope-labeled (D and 13C) and unlabeled SOCs. Perdeuterated phenanthrene and alpha-hexachlorocyclohexane were transported more slowly via air-water gas exchange in our laboratory experiments, resulting in significant isotope fractionation of perdeuterated/unlabeled compound mixtures. In contrast, isotope fractionation of 13C6-labeled SOCs was much lower.

Persistent organic pollutants at the base of the Antarctic marine food web.

Various organochlorine pesticides and brominated diphenyl ethers (BDE-47, -99, and -100) were measured in sea ice algae, water column plankton, and juvenile and adult krill collected in the Palmer Long-Term Ecological Research (LTER) region west of the Antarctic Peninsula during late austral winter and midsummer, 2001-2002. BDEs were 100-1000 times higher in ice algae and 2-10 times higher in phytoplankton than the most abundant organochlorine pesticide, hexachlorobenzene (HCB), reflecting the current production and use of BDEs versus organochlorine pesticides. However, concentrations of HCB and BDEs were significantly lower in summer plankton than in ice algae indicating lower atmospheric inputs, removal from the water column, and/or biodilution of persistent organic pollutants at the base of the food web during summer.

Variations in alpha-hexachlorocyclohexane enantiomer ratios in relation to microbial activity in a temperate estuary.

Changes in the enantiomer ratios (ERs) of chiral pollutants in the environment are often considered evidence of biological alteration despite the lack of data on causal or mechanistic relationships between microbial parameters and ER values. Enantiomer ratios that deviate from 1:1 in the environment provide evidence for the preferential microbial degradation of one enantiomer, whereas ER values equal to 1 provide no evidence for microbial degradation and may mistakenly be interpreted as evidence that biodegradation is not important. In an attempt to link biological and geochemical information related to enantioselective processes, we measured the ERs of the chiral pesticide alpha-hexachlorocyclohexane (alpha-HCH) and bacterial activity (normalized to abundance) in surface waters of the York River (VA, USA) bimonthly throughout one year.

Spatial and temporal variation in hexachlorocyclohexane isomers in a temperate estuary.

Hexachlorocylcohexanes (HCHs) are pesticides that persist in air and water of the Northern hemisphere. To understand the spatial and temporal variability in HCH levels in estuarine surface waters we measured concentrations of two HCH isomers (alpha-HCH and gamma-HCH) at six sites in the York River estuary at bimonthly intervals for a year. Bacterial abundance and activity were also monitored using acridine orange direct counts and uptake of tritiated substrates, respectively.