Arsenic in Puget Sound Sediments and Soils of Vashon and Maury Islands





[Update 12/20: DNR suspends harvesting in Poverty Bay's Redondo tract where Arsenic was detected by China. The Puyallup Tribe which had been harvesting in the area also agreed to suspend harvesting until further testing could be done.]

[Update 12/20: Point Reyes Light (PRL) in Marin County reports on the recreational shellfish harvesting ban in Tomales Bay, near Drakes Estero, due to a bloom of the algae causing PSP toxins in shellfish. Separate from the Chinese ban of west coast shellfish for Arsenic, California has banned recreational harvesting in the area for fear of shellfish poisoning. Of significance is the state noting: "It is the first time the toxin, which typically closes non-commercial harvest during summer months, has appeared in winter in the inner and middle sections of the bay." PRL also notes the California Department of Health saying there is no understanding of what causes the algal blooms and therefore no means of predicting the events.]

[Update 12/20: King TV also reported on the Vashon/Maury Islands' elevated levels of Arsenic and Lead in October. The broadcast can be seen by clicking here.]

 

"State begins wide soil cleanup effort"

(Vashon Maury Island Beachcomber, October 9,2013)

 

"...the state needs to do more soil sampling there

to better understand the extent of the contamination..."

 

Soils on parts of Vashon and Maury Islands

contaminated with Arsenic and Lead.

"Take it away and cover it up. It will be fine."

Area where past testing showed elevated levels

of Arsenic, Cadmium and Lead in

Puget Sound sediments and where

"geoduck of concern" came from.

 

Dig it up, take it away, put down more soil - good as new 
In October the state began a large "cleanup" of soils on Vashon and Maury Islands due to concerns over elevated levels of Arsenic and Lead discharged from the ASARCO plant. As reported in the Vashon Maury Island Beachcomber in October this year:

As soon as next summer, the state will remove the top 12 inches of soil in contaminated areas and replace it with fresh dirt, also replacing grass or other foliage removed in the process.

Unfortunately, Puget Sound sediments are not quite so easy to deal with.

Puget Sound's natural burial through sedimentation
In Puget Sound natural sedimentation lays down layers of sediments which creates a barrier which effectively seals contaminants in the lower layers (assuming no new contaminants are entering the waters). There is typically no need to add a foot of topsoil, although in some heavily contaminated areas a "cap" has been used. Usually the contaminants remain, a forgotten remnant of the past, unless disturbed by some activity, such as geoduck harvesting.

"Welcome back." Sediments churned

by geoduck harvesting bring unwanted

friends back to the surface again.

Impacts from geoduck harvesting - cumulative impacts at many levels

The Chinese and consumers of shellfish in the United States may want the state to consider expanding the testing of soils to include the sediments in all areas geoduck are being harvested from in Puget Sound. Poverty Bay is only one of many areas in Puget Sound where past discharges of industrial activity has resulted in contaminants buried in the deeper sediments. Modern urban runoff only adds to the risk. The "churning" of those sediments from "liquefication" and pulling of geoduck from 3' down in some cases may bring unwanted contaminants back to the surface where they drift in the water column which is indiscriminately filtered by shellfish, native or farmed. It is only one of the cumulative impacts which geoduck harvesting brings with it.

 

Farmed geoduck are not intelligent

Some in the industry state that only "wild" geoduck are a problem and that "farmed" are not. Unfortunately farmed geoduck are not "intelligent" enough to discriminate between algae which results in paralytic shellfish poisoning toxins and healthy "organically grown" algae. They do not know what a periodic table is nor what is harmful to humans but not them. They filter water and all that is contained in it just like their older wild siblings and they absorb whatever it happens to be, not really caring whether it is harmful to humans or not. Consumers have to rely on tax payer funded testing of shellfish to ensure it is safe, assuming safety takes precedence over jobs and economic gain.

 

A favor from the east - focus on your testing

The current ban which China has placed on shellfish from the United States helped bring focus to how shellfish are tested in Washington. As reported by KUOW (who originally broke the story) "there are no federal safety standards for arsenic in shellfish" so DOH rarely tests for it. As seen by the continued inability to control outbreaks of vibriosis from raw oysters harvested in Washington it is not the only thing which could use improvement - for consumers in China as well as the United States.