Geology topics

G.V. Irvine

Publications and source records attributed to G.V. Irvine.

4 recordsLinked to original sources

USGS2011

An improved understanding of the Alaska coastal current: The application of a bivalve growth-temperature model to reconstruct freshwater-influenced paleoenvironments

Shells of intertidal bivalve mollusks contain sub-seasonally to interannually resolved records of temperature and salinity variations in coastal settings. Such data are essential to understand changing land-sea interactions through time, specifically atmospheric (precipitation rate, glacial meltwater, river discharge) and oceanographic circulation patterns; however, independent temperature and salinity proxies are currently not available. We established a model for reconstructing daily water temperatures with an average standard error of ???1.3 ??C based on variations in the width of lunar daily growth increments of Saxidomus gigantea from southwestern Alaska, United States. Temperature explains 70% of the variability in shell growth. When used in conjunction with stable oxygen isotope data, this approach can also be used to identify changes in past seawater salinity. This study provides a better understanding of the hydrological changes related to the Alaska Coastal Current (ACC). In combination with ??18Oshell values, increment-derived temperatures were used to estimate salinity changes with an average error of 1.4 ?? 1.1 PSU. Our model was calibrated and tested with modern shells and then applied to archaeological specimens. As derived from the model, the time interval of 988-1447 cal yr BP was characterized by ???1-2 ??C colder and much drier (2-5 PSU) summers. During that time, the ACC was likely flowing much more slowly than at present. In contrast, between 599-1014 cal yr BP, the Aleutian low may have been stronger, which resulted in a 3 ??C temperature decrease during summers and 1-2 PSU fresher conditions than today; the ACC was probably flowing more quickly at that time. The shell growth-temperature model can be used to estimate seasonal to interannual salinity and temperature changes in freshwater-influenced environments through time. ?? 2011 SEPM (Society for Sedimentary Geology).

Palaios↗

USGS2007

Slightly weathered Exxon Valdez oil persists in Gulf of Alaska beach sediments after 16 years

Oil stranded by the 1989 Exxon Valdez spill has persisted in subsurface sediments of exposed shores for 16 years. With annualized loss rates declining from &sim;68% yr -1 prior to 1992 to &sim;4% yr -1 after 2001, weathering processes are retarded in both sediments and residual emulsified oil (“oil mousse”), and retention of toxic polycyclic aromatic hydrocarbons is prolonged. The n -alkanes, typically very readily oxidized by microbes, instead remain abundant in many stranded emulsified oil samples from the Gulf of Alaska. They are less abundant in Prince William Sound samples, where stranded oil was less viscous. Our results indicate that, at some locations, remaining subsurface oil may persist for decades with little change.

Environmental Science & Technology↗

USGS2001

Persistence of oiling in mussel beds after the Exxon Valdez oil spill

Persistence and weathering of Exxon Valdez oil in intertidal mussel ( Mytilus trossulus ) beds in Prince William Sound (PWS) and along the Gulf of Alaska was monitored from 1992 to 1995. Beds with significant contamination included most previously oiled areas in PWS, particularly within the Knight Island group and the Kenai Peninsula. In sediments, yearly mean concentrations of total petroleum hydrocarbons ranged from <60 μg/g in reference beds to 62,258 μg/g wet wt., or approximately 0 to 523 μg/g dry wt. total polynuclear aromatic hydrocarbons (TPAHs). In mussels, mean TPAH concentrations ranged up to 8.1 μg/g dry wt. Hydrocarbon concentrations declined significantly with time in some, but not all mussels and sediments, and should reach background levels within three decades of the spill in most beds. In 1995, mean hydrocarbon concentration was greater than twice background concentration in sediments from 27 of 34 sites, and in mussels from 18 of 31 sites.

Alaska↗

USGS1996

Persistence of oiling in mussel beds three and four years after the Exxon Valdez oil spill

Dense beds of the mussel Mytilus trossulus affected by Exxon Valdez crude oil in Prince William Sound and along the Kenai and Alaska peninsulas were intentionally left untreated during shoreline cleanup activities in 1989-1991. In 1992 and 1993, mussels and sediments from 70 mussel beds in Prince William Sound and 18 beds along the Kenai and Alaska peninsulas were sampled to establish the geographic extent and intensity of Exxon Valdez oil persisting in mussel beds. Substantial residual Exxon Valdez oil persists in sediments underlying mussel beds in the area affected by the spill. Residual crude oil is a source of chronic contamination of mussels and their predators.

Alaska↗