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Environment: Scientists find widespread contamination of food web in Columbia River

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The Columbia River Basin, courtesy NASA Earth Observatory.

Some chemicals exceed limits set to protect human health

By Summit Voice

FRISCO — Even the Northwest’s mighty Columbia River isn’t immune to persistent chemical pollution federal scientists said last week, publicizing a new study that found fish with traces of pesticides and PCBs at levels that raise health concerns.

The data have been sent to state health officials in Oregon and Washington who will evaluate the new information to determine exactly how much of the resident fish are safe to eat.

The researchers measured contaminants, including pesticides, flame retardant compounds, and ingredients from common household products in the water and osprey eggs at 10 different locations along the Columbia River.

The study then focused in on three primary locations that best reflected a range in chemical exposure, such that researchers could more intensively sample the contaminants and measure their effects on resident fish and other aquatic organisms over that exposure range.

The contamination was worse farther downstream where more urban runoff enters the river. These results shed light on some of the effects of chemicals of emerging and of legacy concern on food webs in a large aquatic ecosystem that is not well understood.

Earlier research showed that several different contaminants are widespread in the bed sediments of the lower Columbia River and its tributaries. The new study showed those pollutants, including endocrine disrupting compounds, are entering the aquatic food web  through bottom-dwelling organisms such as aquatic insects and algae in a process known as biomagnification.

The Columbia River provides critical habitat for a number of threatened and endangered salmonid species and various resident fish, such as the largescale sucker. Over time, aquatic organisms can be exposed to a variety of environmental contaminants from many sources, including municipal and industrial permitted discharges, atmospheric deposition, urban and industrial nonpoint source pollution, accidental spills of petroleum products and hazardous materials, and runoff from agricultural and forested areas and other upstream sources.

Along with testing for contaminants, this study developed a sediment transport and habitat model to predict how sediment and contaminants would be distributed under different stream flow scenarios. These models help identify potential management applications that track wastewater effluent and chemical spills.

Although evaluating water quality with respect to environmental benchmarks was not the focus of the study, concentrations of the chemicals were compared to ODEQ screening level values for carcinogens in fish tissues for human and wildlife consumption. ODEQ Acceptable Tissue Levels were exceeded for several contaminants including some legacy pesticides and polychlorinated biphenyls or PCBs.

The USGS Columbia River Contaminants and Habitat Characterization Study is an interdisciplinary project investigating transport pathways, chemical fates, and the effects of flame retardants and other endocrine disrupting chemicals in water, sediments, and the food web in the lower Columbia River from Bonneville Dam to the mouth.

Results of the food web study have been published in the journal Science of the Total Environment. Results of the earlier study have been reported in the Journal of the American Water Resources Association.

 

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