Anthropogenically sourced low concentration PAHS: In situ bioavailability to juvenile Pacific salmon.

Gill 7-ethoxyresorufin O-deethylase (EROD) activity of juvenile Chinook salmon caged in Auke Lake, AK was used as a biomarker of polycyclic aromatic hydrocarbon (PAH) exposure. Biomarker measurements in conjunction with a comprehensive sampling program that included grab water and sediment samples, and passive sampling devices were used to determine PAH concentrations, source(s), bioavailability, and resulting biological response. PAHs were detected at all lake locations except the reference site upstream of anthropogenic activity. Water samples were the best predictor of a biological response and EROD activity correlated to corresponding parts per trillion water pyrene concentrations (r(2)=0.9662; p=0.0004). Sediment samples yielded the clearest indication of PAH sources and amalgamated contaminant magnitude, and passive samplers served as accumulators of retrospective aqueous conditions. Results suggest that salmon stocks are being exposed to chronic low-concentrations of anthropogenically sourced PAHs during sensitive life-stages, which may be in part a contributor to their declining numbers.

Semipermeable membrane devices link site-specific contaminants to effects: PART II - A comparison of lingering Exxon Valdez oil with other potential sources of CYP1A inducers in Prince William Sound, Alaska.

We deployed semipermeable membrane devices (SPMDs) on beaches for 28 days at 53 sites in Prince William Sound (PWS), Alaska, to evaluate the induction potential from suspected sources of cytochrome P450 1A (CYP1A)-inducing contaminants. Sites were selected to assess known point sources, or were chosen randomly to evaluate the region-wide sources. After deployment, SPMD extracts were analyzed chemically for persistent organic pollutants (POPs) and polycyclic aromatic hydrocarbons (PAH). These results were compared with hepatic CYP1A enzyme activity of juvenile rainbow trout injected with the same extracts prior to clean-up for the chemical analyses. Increased CYP1A activity was strongly associated with PAH concentrations in extracts, especially chrysene homologues but was not associated with POPs. The only apparent sources of chrysene homologues were lingering oil from Exxon Valdez, asphalt and bunker fuels released from storage tanks during the 1964 Alaska earthquake, creosote leaching from numerous pilings at one site, and PAH-contaminated sediments at Cordova Harbor. Our results indicate that PWS is remarkably free of pollution from PAH when nearby sources are absent as well as from pesticides and PCBs generally.

Spilled Oils: Static Mixtures or Dynamic Weathering and Bioavailability?

Polynuclear aromatic hydrocarbons (PAHs) from sequestered MV Selendang Ayu oil were biologically available in 2008, 3.6 y after it was spilled along Unalaska Island, Alaska. Thermodynamically driven weathering was the most probable mechanism of organism exposure to PAHs. Alkane and PAH composition in oil changed over time as smaller constituents were preferentially lost, indicative of weathering. In contrast, composition of the largest compounds (biomarkers) including triterpanes, hopanes, and steranes remained unchanged. Smaller molecules (the PAHs) lost from stranded oil were observed in indigenous mussels and passive samplers deployed in July 2008. Concentration and composition of PAHs were significantly different than in a non-oiled reference area and patterns observed in mussels were repeated in passive samplers deployed in three zones (intertidal, subtidal, and water). Thus, hydrocarbons lost from one compartment (sequestered whole oil) were detectable in another (mussels and passive samplers) implying aqueous transfer. Quantities of mobile oil constituents were small, yielding uptake concentrations that are likely inconsequential for mussels, but the sensitivity provided by bioaccumulation and passive sampler uptake ensured that dissolved hydrocarbons were detectable.

Monitoring polynuclear aromatic hydrocarbons in aqueous environments with passive low-density polyethylene membrane devices.

Low-density polyethylene membranes, typically filled with triolein, have been previously deployed as passive environmental samplers designed to accumulate nonpolar hydrophobic chemicals from water, sediments, and air. Hydrocarbons in such samplers, known as semipermeable membrane devices (SPMDs), diffuse through pores in the membranes and are trapped in the central hydrocarbon matrix, mimicking uptake by living organisms. Here, we describe laboratory and field verification that low-density polyethylene membrane devices (PEMDs) without triolein provide reliable, relatively inexpensive, time-integrated hydrocarbon sampling from water. For comparison, polynuclear aromatic hydrocarbon (PAH) uptake in SPMDs and pink salmon eggs also was studied. Total concentrations of PAH accumulated by PEMDs were highly correlated with concentrations in water (r2 > or = 0.99) and linear over the range tested (0-17 microg/L). Higher-molecular-mass PAH preferentially accumulated in PEMDs and in pink salmon eggs, but the source of oil in PEMDs remained identifiable. Accumulations of PAH were highly similar to those in SPMDs. The PEMDs retained approximately 78% of accumulated total PAH for 40 d in clean water. Thus, a simple plastic membrane can be conveniently used for environmental monitoring, particularly during situations in which contaminant concentrations are low (in the parts-per-billion range), variable, and intermittent.