Finding caffeine in waters just off a coastline heavy with coffee shops may not be surprising. What a new NOAA-funded study does reveal is that traces of caffeine in Pacific Northwest waters point to a likely source of the stimulant: septic tanks and sewer overflows.
Results of the study, funded in part by Oregon Sea Grant and NOAA, were published in the July 2012 Marine Pollution Bulletin. The study was conducted by scientists at Portland State University and Washington State University, Vancouver.
This research, the first to look at caffeine contamination off the Oregon coast, found elevated levels of caffeine at several sites in Pacific Ocean waters off the coast of Oregon—though not necessarily where researchers expected.
Starting in spring 2010, scientists collected and analyzed samples from 14 Oregon coastal locations and seven adjacent water bodies as far north as Astoria and as far south as Brookings. Researchers identified locations as potentially polluted if they were near wastewater treatment plants, large population centers, and rivers and streams emptying into the ocean.
The study found high caffeine levels near Carl Washburne State Park in Florence, and at Cape Lookout – two areas not near the potential pollution sources. Meanwhile, the researchers also measured low levels of caffeine near large population centers like Astoria/Warrenton and Coos Bay. They also found that caffeine levels spiked following a late-season storm of wind and rain that triggered sewer overflows.
The results suggest that wastewater treatment plants are effective at removing caffeine, but that high rainfall and combined sewer overflows flush the contaminants out to sea. The results also suggest that septic tanks, such as those used at the state parks, may be less effective at containing pollution.
"Our study findings indicate that, contrary to our prediction, the waste water treatment plants are not a major source of caffeine to coastal waters," said Elise Granek, assistant professor of environmental science and management at Portland State University. "However, onsite waste disposal systems may be a big contributor of contaminants to Oregon’s coastal ocean and need to be better studied to fully understand their contribution to pollution of ocean waters."
Caffeine is found in many food and beverage products as well as some pharmaceuticals, and caffeine in waterways is directly related to human activity. Although many plant species produce caffeine, there are no natural sources of the substance in the Pacific Northwest. The presence of caffeine in ocean water may also signal additional pollution such as pesticides and pharmaceuticals, Granek said.
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Portland State University news release: http://pdx.edu/news/CoastalCaffeineWaters