Oct 7, 2013

Sears Island: Testing biota for HoltraChem mercury.

 Locations for testing and Recommended actions (see recs at end of essay).
AT ISSUE Reports suggest that the majority of mercury in Penobscot Bay has come down Penobscot River from spills, leaks and dumping of the element by the riverside Holtra Chem Plant  in Orrington.  History of plant.

QUESTIONS
* Can mercury be detected in the plant and animal biota of Sears Island?
 * Can it be  measured? Is it moving through island or intertidal foodwebs?

Likely origins, transport vectors, and on island-locations of mercury 
"The pattern of 
contamination of the sediments of the Penobscot River and estuary was....

consistent with a large source from the HoltraChem site at Orrington.....
"The spatial pattern of contamination of various species of biota, such as periwinkles, 
mussels, lobsters, tomcod (fish) and cormorants (birds) was also consistent with 
 
elevated inputs of Hg to the lower Penobscot River below the Veazie dam". 
.....
 [T]hese results indicate that the
 most severe contamination of the Penobscot system is between Brewer on the lower
 
river and about Fort Point or Sears Island in the upper estuary."
(Note: see maps of  study sample sites in the river and bay on page 20 of thPenobscot River Mercury Study Phase I)

SEARS ISLAND MERCURY DEPOSITION LOCATIONS
Bathymetry & hydrology questions. Does Sears Island's shape, location, hydrology and bathymetry influence where mercury might accumulate on the island?

Larger image click here
TESTING LOCATIONS
In what locations would what Sears Island biota, including intertidal and upland) be likely to absorb mercury? Particularly methyl mercury. What species might have it in detectable quantities? 

Changes in Sears Island Hydrology 
The Sears Island causeway has halted the flow of water around the island since the 980s (See a 1970s picture of causeway-free Sears Island from mainland. (courtesy  Maine Historic Preservation Commission).  Has this changed the sites of mercury deposition?

 The Jellison Channel between Sears Island and Cape Jellison was surveyed in 1999 by the NOAA vessel Rude (pronounced "Rudy"), at the request of Penobscot Bay Watch. The Rude produced this image of the channel floor (full size) The image shows that currents continue to sweep the floor of the channel clean of mud. Are those currents bringing mercury into Stockton Harbor?

Intertidal flats and beaches on the east or west sides of Sears Island

Penobscot River Mercury Study Phase 2: Upper Penobscot Bay.  Belfast lobsterman Mike Dassatt gathered sample lobsters from the upper Bay area under a special license from DMR  for mercury examination (Red triangle).
Click here for fullsized image
 The  report has yet to be released.   Dassatt described the lobsters  collected inside the red triangle (quotes are his words
"There is a  pretty heavy concentration of mercury" along the line between the II Buoy and the Gong 1 Buoy. (the long edge of the triangle). 

"But the very hottest  reach is the shoal edge above  the deeper water east of  the DMP buoy", (the shoal edge is the wiggly line inside the red triangle) Mike said that while he did not take sample lobsters from the exact bay floor the Army Corps of Engineers wants to dredge, which is northeast of the DMP buoy, he is confident that the same elevated mercury will be found in that area if they do test lobsters there for it. 

Marine fog deposition of upwelling mercury onto upland vegetation.
This has not been examined in Maine to the best of our knowledge. (See 2012 UCSC paper Total and monomethyl mercury in fog water from the central California coast, Peter S. Weiss-Penzias, et al. 2012 and these  "general public" articles
According to that study: "[U]sing a standard fog water collector, depositions of HgT [elemental mercury] and MMHg [methylmercury] via fog were found to range from 42–4600 and 14–1500 ng m−2 y−1, which accounted for 7–42% of HgT and 61–99% of MMHg in total atmospheric deposition (fog, rain, and dry deposition), estimated for the coastal area." 

There are several prominent upwelling areas in the upper Penobscot Bay that could carry out that action: The top of the channel   According to lobsterman Mike Dassatt,  if mercury tainted sediments are dumped in the Rockland Disposal Site  prevailing bottom currents will transport it up both sides of Islesboro and back to the upper bay. 

RECOMMENDATIONS  
1.  Sample or collect plant, animal & algae species, driftwood and sediments in  intertidal areas on both sizes and both ends of Sears Island.

2. Sample or collect samples from trees and other vegetation & fungi species and soils in a transect across  Sears Island to determine if mercury deposition from fog is significant.

3. Use mercury detection  paper test strips for initial onsite  test results

4. Test for mercury and methylmercury in Unity College lab. Compare results to  mercury test strips' results.

5. Use results and determine  if initial questions can be answered:  
*  Can mercury be detected in the plant and animal biota of Sears Island?
 * Can it be  measured? Is it moving through island or intertidal foodwebs?

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