THE BIOAVAILABILITY OF BROMINATED DIPHENYL ETHERS FROM URBAN ESTUARINE SEDIMENTS TO DEPOSIT-FEEDING INVERTEBRATES

Brominated diphenyl ethers (BDEs) are organic chemicals used as flame retardants that have become ubiquitous in the environment. Sediment exposure assessments have not been conducted for BDEs and are necessary for understanding their potential impacts in coastal environments. Field studies and laboratory experiments were conducted to determine the bioavailability of BDEs from sediments to deposit-feeding invertebrates in order to investigate potential transfer to higher trophic levels in estuarine environments. In field studies, accumulation of congeners in the Penta-BDE mixture was similar to PCBs with similar Kow. BDE 209, the dominant congener in sediments, was not detected in invertebrates despite sediment concentrations up to 4000 ng/g dry weight. In 28 and 56 day exposures to Baltimore Harbor sediments, PCBs, PAHs, butyltins and metals were bioavailable to the polychaete worm Nereis virens and the amphipod Leptocheirus plumulosus. However, BDE accumulation was low and BDE 209 was not detected in either species despite sediment concentrations up to 300 ng/g dry weight. To elucidate the mechanism(s) limiting the bioavailability of BDE 209 and determine the relative bioavailability of congeners in the Penta-BDE and Deca-BDE (>97% BDE 209) commercial mixtures, 28 day bioaccumulation experiments were conducted in which N. virens were exposed to spiked sediments, spiked food or field sediments. Selective accumulation of congeners in the Penta-BDE mixture over BDE 209 and other components of the Deca-BDE mixture from spiked sediments support the prevalence of the Penta-BDE congeners reported in higher trophic level species. Bioaccumulation from the spiked substrates demonstrated that BDE 209 is capable of crossing the gut wall. Bioavailability was highly dependent on the exposure conditions however since accumulation of BDE 209 from field sediments did not occur in 28 days (<0.3 ng/g wet weight). When exposed to Deca-BDE in spiked sediments also containing the Penta-BDE commercial mixture and PCB 209, bioaccumulation of BDE 209 was reduced compared to exposure to Deca-BDE alone. The mechanism responsible for limiting accumulation of BDE 209 remains unclear but appears to involve characteristics of the sediment matrix and low transfer efficiency in the digestive fluid and across the gut wall

Environmental Emission of Pharmaceuticals from Wastewater Treatment Plants in the USA

The residual drugs, drug bioconjugates, and their metabolites, mostly from human and veterinary usage, are routinely flushed down the drain, and enter wastewater treatment plants (WWTP). Increasing population, excessive use of allopathic medicine, continual introduction of novel drugs, and existing inefficient wastewater treatment processes result in the discharge of large volumes of pharmaceuticals and their metabolites from the WWTPs into the environment. The effluent from the WWTPs globally contaminate ~25% of rivers and the lakes. Pharmaceuticals in the environment, as contaminants of emerging concerns, behave as pseudo-persistent despite their relatively short environmental half-lives in the environment. Therefore, residual levels of pharmaceuticals in the environment not only pose a threat to the wildlife but also affect human health through contaminated food and drinking water. This chapter highlights WWTPs as point-sources of their environmental emissions and various effects on the aquatic and terrestrial ecosystem

Bioavailability of Decabromodiphenyl Ether to the Marine Polychaete Nereis Virens

The flame retardant decabromodiphenyl ether (BDE 209) accumulates in humans and terrestrial food webs, but few studies have reported the accumulation of B DE 209 in aquatic biota. To investigate the mechanisms controlling the bioavailability of BDE 209. a 28-d bioaccumulation experiment was conducted in which the marine polychaete worm Nereis Wrens was exposed to a decabromodiphenyl ether (deca-BDE) commercial mixture (\u3e85% BDE 209) in spiked sediments, in spiked food, or in field sediments. Bioaccumulation from spiked substrate with maximum bioavailability demonstrated that BDE 209 accumulates in this species. Bioavailability depends on the exposure conditions, however, because BDE 209 in field sediments did not accumulate (\u3c0.3 ng/g wet weight; 28-d biota-sediment accumulation factors [BSAFs] \u3c0.001). When exposed to deca-BDE in spiked sediments also containing lower brominated congeners (a penta-BDE mixture), bioaccumulation of BDE 209 was 30 times lower than when exposed to deca-BDE alone. Selective accumulation of the lower brominated congeners supports their prevalence in higher trophic level species. The mechanisms responsible for limited accumulation of BDE 209 may involve characteristics of the sediment matrix and low transfer efficiency in the digestive fluid

Bioaccumulation Kinetics of Polybrominated Diphenyl Ethers from Estuarine Sediments to the Marine Polychaete, Nereis Virens

Polybrominated diphenyl ethers (PBDEs) are flame-retardant chemicals that have become ubiquitous environmental contaminants. Polybrominated diphenyl ether no-uptake rates from estuarine or marine sediments to deposit-feeding organisms have not yet been reported. In the present study, the marine polychaete worm Nereis virens was exposed to field-contaminated and spiked sediments containing the penta- and deca-BDE commercial mixtures in a 28-d experiment to characterize the relative bioavailability of PBDE congeners from estuarine sediments. A time series sampling regimen was conducted to estimate uptake rate constants. In both field-collected and laboratory-spiked sediment exposures, worms selectively accumulated congeners in the penta-BDE mixture over BDE 209 and other components of the deca-BDE mixture, supporting the prevalence of these congeners in higher trophic level species. Brominated diphenyl ether 209 was not bioavailable to N. virens from field sediment and was only minimally detected in worms exposed to spiked sediments in which bioavailability was maximized. Chemical hydrophobicity was not a good predictor of bioavailability for congeners in the penta-BDE mixture. Direct comparison of bioavailability from the spiked and field sediments for the predominant congeners in the penta-BDE mixture was confounded by the considerable difference in exposure concentration between treatments. Biota-sediment accumulation factors (BSAFs) for N. virens after 28 d of exposure to the field sediment were lower than the BSAFs for Nereis succinea collected from the field site, indicating that 28-d bioaccumulation tests using N. virens may underestimate the in situ concentration of PBDEs in deposit-feeding species. The bioavailability of PBDEs to N. virens indicates that these chemicals can be remobilized from estuarine sediments and transferred to aquatic food webs

A COMPARATIVE ASSESSMENT OF AZINPHOSMETHYL BIOACCUMULATION AND TOXICITY IN TWO ESTUARINE MEIOBENTHIC HARPACTICOID COPEPODS

Abstract—Aqueous, pore-water, and whole-sediment bioassays were conducted with meiobenthic copepods with different infaunal lifestyles to assess the acute and chronic toxicity of the organophosphorous pesticide azinphosmethyl (APM) and its bioaccumulation potential in sediments. Biota sediment accumulation factors were an order of magnitude higher for the deeper burrowing Amphiascus tenuiremis (26.6) than the epibenthic Microarthridion littorale (2.2). The female A. tenuiremis APM median lethal concentration (LC50; 3.6 mg/L) was twice the male LC50 (1.8 mg/L), in straight seawater exposures, and nearly 20 % higher than males in whole-sediment exposures (540 vs 456 ng/g dry weight). Amphiascus tenuiremis were 17 times more sensitive to sediment-associated APM than M. littorale. In pore-water–only exposures, the adult mixed-sex A. tenuiremis LC50 (5.0 mg/L) was nearly twice the seawater mixed-sex LC50 (2.7 mg/L). Dissolved organic carbon in pore water was five times higher (20 mg/L) than in seawater-only exposures (4 mg/L). Differences in acute toxicity within exposure media were driven by species- and sex-specific differences in lipid content. Amphiascus tenuiremis likely experienced greater exposure to sediment-associated toxicants via longer periods of direct contact with pore water than M. littorale and, therefore, exhibited correspondingly higher bioaccumulation and acute toxicity. Copepod reproduction was significantly reduced (.60%) in 14-d sediment culture exposures at sublethal APM levels, suggestin