Shellfish, fish, birds, and marine mammals in the Puget Sound regions have all been measured with high levels of toxic chemicals. Tried and true methods track known chemicals of concern, but scientists and conservation experts believe there may be other potentially harmful chemicals present in the water.
"Historically we've done a decent job of categorizing legacy chemicals in Puget Sound, but we also know there are a lot more chemicals that get into the water every day," said senior author C. Andrew James, a research scientist at the Center for Urban Waters at UW Tacoma. "If we can understand what's there and at what concentrations it's occurring, then we can start to figure out which chemicals will likely impact the health of fish, killer whales and other marine organisms."
In fact, James, Zhenyu Tian and colleagues at the University of Washington and UW Tacoma identified 64 chemicals not previously detected in the Puget Sound, including eight at potentially hazardous concentrations. The key to detection was the non-targeted high-res mass spectrometry (HRMS) method the researchers used.
“The benefit of the HRMS method is that we don’t need to pre-define our target compound list, and we can identify the contaminants without having reference standards. This allows for a wide-range screening for chemicals,” Tian explained to Laboratory Equipment.
In 78 samples taken from the Puget Sound’s nearshore, the researchers detected at least 205 chemicals, including pesticides, herbicides, food additives, pharmaceuticals and compounds related to vehicles. The researchers then compared the maximum detected concentration to the predicted non-effect concentration (PNEC), and calculated a risk quotient. If a chemical was detected in high concentration but the PNEC was low, the chemical was considered harmful.
The researchers found the eight concerning chemicals were localized to specific “hot spots” in the Sound, and not always present in different samples from the site. This is in contrast to other chemicals the team found in almost all of the samples but deemed less of a concern, such as the artificial sweetener Splenda and a pharmaceutical used to treat seizures and bipolar disorder.
“The information we got from the ‘hot spots’ was that our original assumption about the major pollution sources in Puget Sound might not be correct” Tian said. “We assumed that wastewater effluent was the predominant source, and the high concentration contaminants should be wastewater-derived. However, the chemicals in the hot spots disproved the assumption, and calculations and models pointed to sources other than wastewater. This suggested we should pay more attention to the non-point sources.”
Next, the research team plans to further evaluate what the chemical data mean for the Sound’s diverse marine life. Tian said the team is also working on the screening of contaminants in biological tissues and creek water samples.
Photo credit: Ryan Moriarty/UW Tacoma