Evaluation of Contaminant Exposure and the Potential Impacts on Aquatic Habitat Quality in the Anchorage Area of the Cook Inlet Basin.

摘要

The primary motivation for this research was to determine the presence and potential toxicological significance of waterborne polycyclic aromatic hydrocarbons (PAHs), on fishery resources in urban streams of Anchorage, AK. This complex class of toxic chemicals originates from both petrogenic and pyrogenic sources. Only 16 are listed by the US EPA as priority pollutants (PP) but hundreds of PAHs are known to exist in the environment. Most PAHs are acutely toxic but a number of PAHs are also mutagenic and carcinogenic. In addition many PAHs exhibit greatly enhanced toxicity in the presence of UV radiation. In collaboration with USGS personnel of the Cook Inlet Basin NAWQA Unit, researchers at the Columbia Environmental Research Center, USGS, deployed lipid-containing semipermeable membrane devices (SPMDs) in six small urban streams for 56 days in Anchorage, Alaska. Because SPMDs mimic the bioconcentration of trace waterborne lipophilic contaminants by fishes, are not subject to most stressors affecting the health of biomonitoring organisms, and are highly reproducible, these devices are being used worldwide for passive in situ monitoring of hydrophobic organic contaminants such as PAHs. PP PAHs were only detected at one site (Chester Creek). However, the largest component of the detected residues was pyrene, which is known to have greatly enhanced toxicity in the presence of UV radiation. The estimated concentration of bioavailable pyrene in water (3.6 ng/L) was within the range known to cause adverse effects on some fingerling fishes. Also, non-PP PAHs were detected at all sites but were particularly high (40.7 ng/L) at Campbell Creek (C-Street). The toxicological significance of these compounds is unknown but the whole mixture toxicity can be screened with biomarker tests (see Dr. Johnson's report). To ensure a more holistic assessment of hydrophobic chemicals in Anchorage streams, additional screening of SPMD samples was performed for the presence of organochlorine pesticides (OCs). Numerous trace levels of OCs were found to be present at all study sites. However, levels of DDT and analogs (approx. 0.5 ng/L total), and pentachloroanisole (PCA, 0.17 ng/L) were quite high (e.g., relative to the Missouri River) at Ship Creek and Little Rabbit Creek, respectively. PCA is a microbial degradation product of pentachlorophenol, which is known to contain dioxins, and DDT and analogs are known to disrupt the endocrine system in some aquatic organisms. More definitive analysis of these research results requires mass spectrometric confirmation of detected residues.