Natural (Background) Hydrocarbon Contamination in Gulf of Alaska Sediments
As a continuation of work begun in 1989 by Paul Carlson (CMG, Emeritus), Keith Kvenvolden
(CMG), and others, new research has recently been undertaken to understand the sources and
fate of hydrocarbons in Prince William Sound, Alaska (Fig. 1). Whereas the earlier work of
Carlson, Kvenvolden, and others focused primarily on the effects of anthropogenic pollution
(such as the Exxon Valdez oil spill), this new study addresses the natural, or background,
influx of hydrocarbons to the Gulf of Alaska and Prince William Sound. Understanding the source
and magnitude of these natural occurrences is necessary to provide a "baseline" against which
the impact of human activities on the ecosystem can be measured. Specifically, the new research
is directed toward understanding the role of particulate coal in the transport of hydrocarbons
(including polycyclic aromatic hydrocarbons, PAHs, which are known carcinogens). Large coal
deposits exist in southeastern Alaska, and the Bering and Malaspina Glaciers (Fig. 1, below) likely
erode particulate coal from coal-bearing formations. Coal particles have recently been observed
in strand lines on a Gulf of Alaska beach at Katalla (near the Bering Glacier, Fig. 2).
Figure 2. Beach
near Katalla, Alaska; dark strand lines (indicated by arrows) contain particulate coal.
Objectives of this study are to identify sources of particulate coal found in Gulf of Alaska and
Prince William Sound sediments and to evaluate the effects of such influx on sediment hydrocarbon
levels. This research is funded by the Exxon Valdez Trustee Council and is a collaborative effort
between the USGS and the National Oceanic and Atmospheric Administration (NOAA). During Spring
2000, Jon Kolak (CMG) and Jeff Short (NOAA) participated in a one-week cruise to collect benthic
sediments from the Gulf of Alaska and Prince William Sound. In Fall 2000, samples of suspended and
riparian sediments were collected from streams located between the Bering and Malaspina Glaciers.
Samples from both trips are being analyzed at USGS and NOAA laboratories.
Figure 1. Map of study area.
At the USGS, a heavy-liquid separation technique was developed to isolate coal particles from
bulk sediments. Using this technique, coal has been isolated from the benthic sediment samples,
implying that (1) longshore transport may be an important mechanism in dispersing particulate coal,
and (2) particulate coal contributes to the background hydrocarbon influx observed in Gulf of Alaska
and Prince William Sound sediments.
in this issue:
Natural Hydrocarbons in Gulf of Alaska
Black History Month
Glacial Floods Video
Coastal Marsh Die-Back in Gulf of Mexico
Carbonate Beaches 2000
USGS Information: Electronic Age
CMG Program Webmasters
Leaky Coastal Margins / Karst Interest Group
Nat'l Sand & Gravel
Ordnance Mine Burial
Earthquake Hazards Video
March Publications List