MP7 Advances in Analysis and Measurements
201 Oregon Ballroom
1:20 PM - 4:40 PM, Monday
() A tiered approach measures the aerial extent of PAH contaminated shoreline sediments at historic industrial sites in Prince William Sound, Alaska.
Page, D1, Boehm, P2, Brown, J2, Bence, A3, Neff, J4, Wooley, C5, 1 Bowdoin College, Brunswick, ME, USA2 Battelle, Waltham, MA, USA3 ExxonMobil Upstream Research Co, Houston, TX, USA4 Battelle, Duxbury, MA, USA5 Chumis Cultural Resource Services, Anchorage, AK, USA
ABSTRACT- Prince William Sound (PWS), Alaska, the site of the 1989 Exxon Valdez oil spill, has an extensive industrial history of mining, fish processing, and logging that involved the use of large quantities of fossil fuels and attendant shoreline discharges. Recent studies found oil spill remnants at some spill-path locations and considered their impact on wildlife and fish populations, but did not consider sites of past human activity (HA) that contribute to the pre-spill hydrocarbon background of PWS. This 2003 study identified 45 HA sites, primarily in western PWS and assessed 9 in detail. Assessment steps at each site were to (1) locate visual evidence of oil/tar, (2) construct a 10m-spacing sampling grid and prepare site map, (3) excavate pits on the grid, (4) perform on-site colorimetric test at each pit for total hydrocarbon concentration (THC), (5) select 20 samples for same-day shipboard PAH immunoassay, (6) select 5 samples for PAH lab analysis, and (7) collect mussels and clams for PAH bioavailability assessment. Nine acres of PAH-contaminated sediments with THC >2500 ng/g (total PAH range 9 - 385,000 ng/g) were mapped at the 9 sites. The contaminants are mixtures of non-spill petroleum products (2-3 ring PAH) and combustion products (4-6 ring PAH). Mussel and clam total PAH ranges are 7 - 3063 and 8 - 490 ng/g dry wt., respectively. Sources of the contamination are relict oil tanks and works located above and within the tide zone. Contamination in some locations extends throughout the intertidal zone into the sub-tidal. Inputs are chronic and, without human intervention, will not be mitigated by time. These findings are compared to those of a 2001 NOAA shoreline study of sites oiled by the 1989 PWS oil spill that found 1.6 acres of middle and upper intertidal subsurface sediments contaminated with oil residues and an oil loss rate of 20-26% per year. The TPAH range for mussels sampled in 2002 at the oiled 2001 study sites was 2 - 634 ng/g. This presentation shows how a tiered approach can be used to quantify and map PAH sources at intertidal sites as a key element in evaluating long-term oil spill effects.
Key words: baseline, site assessment, exxon valdez, PAH