Two different scientific papers caught my eye this past week. Neither involve research conducted in the Pacific Northwest, but both are worth reviewing in light of the fish consumption debate raging in Washington right now. The first is an upcoming article by a group of Spanish researchers in the Proceedings of the National Academy of Sciences on the amount of plastic pollution in the world’s oceans. The second is research by USGS scientists on mercury concentrations in fish in four lakes in Voyageurs National Park in Minnesota.
How do these two studies relate to Washington’s efforts to revise its water quality standards to account for greater fish consumption rates of various populations in the state? Both studies highlight the difficulty of reducing toxics in fish using the regulatory scheme of the Clean Water Act. As I’ve written in the past, I am skeptical that lowering water quality standards for toxics by increasing the fish consumption rate used in deriving those standards will result in any measurable change or environmental benefit. This is because, for many of the contaminants that are of concern, we’ve reached the point in regulating end-of-pipe and non point sources of those contaminants where revising water quality standards downward won’t reduce toxics in fish because many of those toxics are no longer coming from regulated sources.
The study on plastics in the Pacific emphasizes this point for organic contaminants in salmon, one of the species of fish often referred to as “contaminated” in the rhetoric that is flying around the fish consumption debate (but the one species that most clearly is not impacted by local water quality conditions because of the time spent growing in the open ocean). The researchers modeled fluxes of plastics to the world’s oceans and then compared the amount of plastics thought to be entering the world’s oceans to the amount observed in five subtropical gyres or convergence zones where the plastic accumulates. What the researchers documented is a large amount of “missing” plastic, i.e., what was calculated to be entering the oceans did not match what was observed. The researchers concluded that the fate of this plastic is unknown, but one hypothesis the researchers put forth in the paper is the possibility that plastics are rapidly nan0-fragmented in the oceans, where those nano-fragments are then integrated into the ocean’s foodweb.
How does this relate to toxics in salmon in the Pacific Northwest?Continue Reading What Can Washington Learn from Plastics in the Pacific and Mercury in the Midwest?
