Geology Reports⌕ Search

Geology topics

Geoffrey S. York

Publications and source records attributed to Geoffrey S. York.

3 recordsLinked to original sources
USGS2006

Persistent organic pollutants in Alaskan ringed seal ( Phoca hispida ) and walrus ( Odobenus rosmarus ) blubber

Since 1987, the Alaska Marine Mammal Tissue Archival Project (AMMTAP) has collected tissues from 18 marine mammal species. Specimens are archived in the National Institute of Standards and Technology's National Biomonitoring Specimen Bank (NIST-NBSB). AMMTAP has collected blubber, liver and/or kidney specimens from a number of ringed seals ( Phoca hispida ) from the areas near Nome and Barrow, Alaska and walruses ( Odobenus rosmarus ) from several locations in the Bering Sea. Thirty-three ringed seal and 15 walrus blubber samples from the NIST-NBSB were analyzed for persistent organic pollutants (POPs). The compounds determined included PCBs (28 congeners or congener groups), DDT and related compounds, hexachlorobenzene (HCB), hexachlorocyclohexane isomers (HCHs), chlordanes, dieldrin, and mirex. POP concentrations in ringed seal blubber were significantly higher in Barrow than in Nome when statistically accounting for the interaction of age and gender; HCB, however, was not statistically different between the two locations. Unlike males, POP concentrations and age were not significantly correlated in females probably as a result of lactational loss. POP concentrations in walrus blubber were lower than in ringed seal blubber for ΣPCBs, chlordanes, and HCHs, but higher for dieldrin and mirex. POP concentrations in ringed seals and walrus from Alaska provide further evidence that the western Arctic tends to have lower or similar POP concentrations compared to the eastern Canadian Arctic.

Alaska↗
USGS2004

Using Forward Looking Infrared (FLIR) imagery to detect polar bear maternal dens: Operations manual

Recent research has shown that Forward Looking Infia-Red (FLIR) imagery can detect polar bear dens despite total snow cover over their deming habitat. FLIR imagers detect a AT or difference in temperature between objects in the imager's field of view. During the Arctic winter, the groundlsnow surface is typically cold, providing a dark background in the FLIR imager. Sources of heat appear as lighter or white areas. Dens, in particular, appear as small bright "hotspots", usually with kzy boundaries (Appendix 1). Most commonly, since bears chose deep snow drifts for deming, dens can be distinguished from the normally dark (cold) band of drifted snow surrounding them. This innovation has the potential to prevent human activities fiom disturbing deming polar bears by allowing managers to discover dens before potentially disruptive activities begin. This is important because expanding resource extraction in Alaska's Arctic regions may threaten the welfare of polar bears and their habitat. In recent years, exploration and development activities have expanded east and west of the original oil fields of Prudhoe Bay. Hydrocarbon extraction is now occurring or planned along much of the central Beaufort Sea coast. As development continues into the National Petroleum Reserve, the scope of expansion could include 213 of the northern coastal region of Alaska. Industrial activities are a potential threat to polar bears, especially as they might disturb bears in maternal dens (Lentfer and Hensel 1980, Stirling 1990, Stirling and Andriashek 1992, Amstrup 1993, Amstrup and Gardner 1994). As the number of humans and their activities have increased in recent years, there has been a concurrent increase in the number of female polar bears deming on land (Amstrup and Gardner 1994). Therefore, the probability of disrupting maternal deming can be expected to increase in the future. Using FLIR surveys to detect bears in dens could reduce or eliminate that probability. The purpose of this manual is to provide agency and private sector land managers with the information necessary to perform effective FLIR surveys to detect maternal dens. A list of personnel who can provide additional information is provided in Appendix 2.

BOEM↗