Ka. Kvenvolden et al., UBIQUITOUS TAR BALLS WITH A CALIFORNIA-SOURCE SIGNATURE ON THE SHORELINES OF PRINCE WILLIAM SOUND, ALASKA, Environmental science & technology, 29(10), 1995, pp. 2684-2694
Although tile shorelines of Prince William Sound still bear traces of
the 1989 Exxon Valdez oil spill, most of the flattened tar balls that
can be found today on these shorelines are not residues of Exxon Valde
z oil. Instead, the carbon-isotopic and hydrocarbon-biomarker signatur
es of 61 tar ball samples, collected from shorelines throughout the no
rthern and western parts of the sound, are all remarkably similar and
have characteristics consistent with those of oil products that origin
ated from the Monterey Formation source rocks of California. The carbo
n-isotopic compositions of the tar balls are all closely grouped (delt
a(13)C(PDB) = -23.7 +/- 0.2 parts per thousand), within the range foun
d in crude oils from those rocks, but are distinct from isotopic compo
sitions of 28 samples of residues from the Exxon Valdez oil spill (del
ta(13)C(PDB) = -29.4 +/- 0.1 parts per thousand). Likewise, values for
selected biomarker ratios in the tar balls are all similar but distin
ct from values of residues from the 1989 oil spill. Carbon-isotopic an
d biomarker signatures generally relate the tar balls to oil products
used in Alaska before similar to 1970 for construction and pavements.
How these tar balls with such similar geochemical characteristics beca
me so widely dispersed throughout the northern and western parts of th
e sound is not known with certainty, but the great 1964 Alaska earthqu
ake was undoubtedly an important trigger, causing spills from ruptured
storage facilities of California-sourced asphalt and fuel oil into Pr
ince William Sound.