Assessing Contributions of Synthetic Musk Compounds from Wastewater Treatment Plants to Atmospheric and Aquatic Environments.

The high environmental concentrations, persistence, and toxicity of synthetic musk compounds (SMCs) necessitate a better grasp of their fate in wastewater treatment plants (WWTPs). To investigate the importance of WWTPs as pathways of SMCs to the environment, air and wastewater samples were collected at four WWTPs in Ontario, Canada. Polycyclic musks (PCMs) were present at higher concentrations than nitro musks (NMs) and macrocyclic musks (MCMs). Three PCMs [galaxolide (HHCB), tonalide (AHTN), and iso-E super (OTNE)] were the most abundant compounds (0.30-680 ng/m3 in air, 0.40-15 µg/L in influent, and 0.007-6.0 µg/L in effluent). Analyses of multiyear data suggest that risk management measures put in place have been effective in reducing the release of many SMCs into the environment. The highest removal efficiency, up to almost 100% of some SMCs, was observed for the plant with the longest solid retention time. A fugacity-based model was established to simulate the transport and fate of SMCs in the WWTP, and good agreement was obtained between the measured and modeled values. These findings indicate that the levels of certain SMCs discharged into the atmospheric and aquatic environments were substantial, potentially resulting in exposure to both humans and wildlife.

Determination of linear and cyclic volatile methylsiloxanes in blood of turtles, cormorants, and seals from Canada.

We measured the concentrations of linear and cyclic volatile methylsiloxanes (VMS) concentrations in the blood plasma of turtles, cormorants, and seals collected from Canadian freshwater and marine ecosystems. A modified quick, easy, cheap, effective, rugged, and safe (QuEChERS) method was developed to quantify the levels of linear and cyclic VMS in the plasma samples. The cyclic VMS of hexamethylcyclotrisiloxane (D3), octamethylcyclotetrasiloxane (D4), decamethylcyclopentasiloxane (D5), and dodecamethylcyclohexasiloxane (D6) were present in the plasma of all three species. Linear VMS compounds were observed only in seal plasma from one contaminated site. There was no statistically significant difference among species and locations for D3, D4, and D6 concentrations. Average D5 concentrations ranged from 0.143 to 7.39ngg-1; these concentrations appeared to be associated with diffuse/urban sources. Snapping turtles, cormorants, and seals all exhibited elevated D5 concentrations in contaminated sites relative to the reference sites. Our data indicate that local urban sources of VMS contributed significantly to the observed D5 concentrations in free-ranging wildlife. The presence of cyclic VMS in the plasma of the three species from Canada demonstrates that these chemicals are ubiquitous in aquatic biological systems. This finding raises concerns regarding their persistence in freshwater and marine environments. To the best of our knowledge, this study reports the first measurements of VMS compounds in the plasma of reptiles, birds, and mammals.

Probing the debromination of the flame retardant decabromodiphenyl ether in sediments of a boreal lake.

After decades of use of polybrominated diphenyl ethers (PBDEs) as flame retardants, a large reservoir of these toxins has accumulated in ecosystems worldwide. The present study used an innovative approach to examine whether the fully brominated PBDE decabromodiphenyl ether (decaBDE) degrades to more toxic congeners in aquatic environments. The authors incubated intact sediment microcosms with high-purity [(13)C]decaBDE in a remote boreal lake to assess its debromination under ambient conditions. Although the addition of [(13)C]decaBDE increased total PBDE concentrations in sediment more than 10-fold, the relative amount of [(13)C]decaBDE in sediment did not change significantly over a 1-mo incubation. However, observation of small quantities of lower-brominated [(13)C]BDEs lent support to the hypothesis that decaBDE is slowly debrominated. The authors observed a significant increase in octaBDEs and nonaBDEs in profundal, but not littoral, sediment over 30 d. A second experiment in which sediment was incubated under different light and oxygen regimes yielded a surprising result-oxygen significantly stimulated the formation of octaBDEs and nonaBDEs. The authors also conducted a large-scale in situ enclosure experiment in which they followed the fate of experimentally added decaBDE in sediment over 26 mo, but that study yielded little evidence of decaBDE debromination. Overall, the authors suggest that the debromination of decaBDE occurs very slowly, if at all, in natural sediment of boreal lakes, in contrast to the rapid degradation kinetics reported by most laboratory-based studies, which are usually conducted by dissolving decaBDE in organic solvents. The findings reinforce the need for field studies on contaminant fate to inform environmental policy decisions.