Ecology: Sediments Safe - at least the top two centimeters

Look a little deeper...

...you might find something else.



Top 2-3 centimeters cover a lot of history below
The Department of Ecology (DOE) has released an 8 page summary comparing 1999 and 2011 sample results  of the top two centimeters (one inch) of sediments in south Puget Sound. In the summary entitled "Sediment Quality in South Puget Sound, Changes from 1999 to 2011" DOE reports that exposure to chemical contaminants in this top one inch was "minimum" almost everywhere in south Puget Sound. On the other hand, if you are a bottom dwelling organism, you were "adversely affected in about 1/3 of South Sound." More important, the top 2-3 centimeters are little more than a cover over what's contained from past industrial discharges into Puget Sound, many discharges lasting for decades.

What's down there?

More than a geoduck.

Dig a little deeper
As the Chinese discovered, if you happen to be consuming geoducks from certain parts of Puget Sound, there may be more to concern yourself with. In the case of geoduck shipped to China, it was discovered by the Chinese that geoduck harvested from Poverty Bay had elevated levels of arsenic.  Most likely the result of the ASARCO discharges, it was these contaminants, buried in deeper sediments where geoduck were harvested from, which resulted in a banning of geoduck imported from Washington. After an initial response from the USA suggesting there was nothing to worry about and to simply not eat the outer skin, the Chinese responded:

“The U.S. system shows defects on regulating and monitoring the safety and hygiene for geoduck export to China,” the letter states. “Therefore, the geoduck originating from the USA poses high safety risk in terms of heavy metal arsenic.” [Note: The US is still  negotiating with China over the issue of arsenic found in geoduck. One of the more recent responses from a shellfish lobbyist was: “Maybe we can resolve this by including some kind of label that says not to eat the skin.” Another comment included: "We have arsenic in our geology here in the Northwest." It's not known how the Chinese feel about this.]

Wash off if in Oakland Bay
Another example of what lies below the top one inch of sediments is found in a recent study of deeper sediments (1 foot and below) in Oakland Bay, near Shelton. It was found that elevated levels of dioxins and other chemicals existed at levels higher than the upper one inch. In DOE's "Responsiveness Summary" they note:

The levels of dioxins found in Shelton Harbor and Oakland Bay are well above background levels for Puget Sound. Therefore Ecology agrees that dioxin in Oakland Bay needs to be addressed.

The Department of Health (DOH) noted in their Health Consultation that steps children and adults could take to minimize exposure to dioxins and other contaminants from sediments in Oakland Bay include:

Washing clams thoroughly before eating them (it did not mention whether Manila clam's neck skin should be removed); washing your hands and face after playing or working in the sediments, especially before eating; using a scrub brush to clean dirt from under your nails; and, to wash heavily soiled clothing separately. (page 17)

Stirring up the pot
Most important to all of the above is to take note what the Chinese brought to a head: there is a history of industrial discharge into Puget Sound which is contained in deeper sediments, below one inch. The ASARCO smelter discharged pollutants for decades into the air which traveled throughout the Puget Sound region, settling into the sediments, only to be buried and forgotten, until brought to the surface by geoduck aquaculture, and found by the Chinese. Oakland Bay's waters were once so polluted from industrial discharges the salmon would swim up Hammerlsey Inlet, only to turn over and die in Oakland Bay. Boaters used to anchor their boats in Oakland Bay so the polluted waters would kill the barnacles and other sea life growing on the bottom. Much of what was in those waters settled into the sediments, to be covered. It is not gone nor should it be forgotten because the top one inch of sediments appear safe.

[Update 3/29 (provides a link to an article not requiring a subscription): Northwest Public Radio has reported a possible solution to the Chinese ban of geoduck may be near. The US has proposed testing geoduck for arsenic. The Chinese will review the testing procedures and decide at a later date if it is adequate.]