Auke Bay Laboratory (ABL)

Habitat Program

Innovative Passive Samplers Assess Source and Origin of Hydrocarbons

Conventional passive sampling devices for monitoring pollution input often prove cost prohibitive when the spatial and temporal scales being assessed are very large. The Kenai River, a major salmon producing river in Alaska, served as the perfect laboratory to test the utility of polyethylene membrane devices (PEMD) developed at the AFSC to determine the spatial and temporal fluctuations in chronic nonpoint source inputs to fisheries habitat. Comparison of the relative levels of polycyclic aromatic hydrocarbons (PAH) at 71 locations over a 3-year period allowed us to assess the significance and potential source of these compounds in the river.

Concentrations of PAH were greatest near urban areas and peaked during the late winter when streams flows and attendant dilution were low. Vessel activity and PAH levels on the river peaked in July and were heaviest in the lower 16 km of the river where fishing activity was concentrated. Nearly one-third of the engines observed on the river were two-stroke engines, which release a higher proportion of unburned fuel into the water than the cleaner burning four-stroke engines.

The low concentrations of hydrocarbons upriver of the boat traffic suggest very little remote delivery of these contaminants to the watershed. These devices proved to be an excellent low-cost tool for determining the patterns of PAH in large fisheries watersheds.

By Adam Moles

AFSC Quarterly
Research Reports Oct-Dec 2005