Geology topics

G.V. Irvine

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

6 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↗

USGS2008

Monitoring lingering oil from the Exxon Valdez spill on Gulf of Alaska armored beaches and mussel beds sixteen years post-spill

Final Rept. ; Prepared in Cooperation With Alaska Univ., Fairbanks. Inst. of Arctic Biology. Sponsored By National Marine Fisheries Service, Juneau, Ak. Alaska Fisheries Science Center. ; Stranded Exxon Valdez Oil Has Persisted for 16 Years At Boulder- Armored Beach Sites Along National Park Coastlines Bordering the Gulf of Alaska . These Sites Are Up to 640 Km From the Spill Origin and Were Contaminated By Oil Mousse, a Viscous Water-in- Oil Emulsion. Although Surface Oil Has Continued to Decline, Subsurface Oiling Persists in Patches. Especially Striking Is the General Lack of Weathering of Stranded Oil on Armored Beaches Over the Last 16 Years . At Three of the Four Sites Where Oil Was Sampled in 2005, the Oil Was Compositionally Similar to 11-Day Old Exxon Valdez Oil , Even After 16 Years . The Formation of Mousse Allowed Less-Weathered Oil to Be Transported Long Distances. The Sequestration of the Oil Beneath a Boulder Armor, Coupled With the Stability of the Boulder Armoring (Investigated By Examining Movement of Marked Boulders), Had Contributed to the Lengthy Persistence of This Stranded Oil. Opportunistic Sampling of Several Previously Studied Oiled Mussel Beds Indicates Continued Contamination of At Least One of the Sites By Not Very Weathered Exxon Valdez Oil. Long-Term Persistence of Oil in These Habitats Should Cause Reconsideration of Response Activities After Spills, and May Influence the Environmental Sensitivity Indices Applied to These Habitats.

Report↗

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↗

USGS2000

Persistence of spilled oil on shores and its effects on biota

Over two million tonnes of oil are estimated to enter the world's oceans every year. A small percentage, but still a large volume, of this oil strands onshore, where its persistence is governed primarily by the action of physical forces. In some cases, biota influence the persistence of stranded oil or the rate of its weathering. Oil's deleterious effects on biota are frequently related to the persistence and degree of weathering of the oil, with long-lasting effects in low-energy environments such as salt marshes and coastal mangroves, or in higher-energy environments where oil is sequestered. However, an oil spill can have disproportionately large biological effects when it affects key species or processes (e.g., structurally important species, predators, prey, recruitment, or succession). In these cases, the continuing presence of oil is not always a prerequisite for continuing biological effects. There are relatively few long-term studies of the effects of oil spills; data from these suggest that oil can persist for decades in some environments or situations, and that biological effects can be equally persistent. Broad-based, integrated studies have been the most revealing in terms of the importance of direct and indirect effects, spillover effects between different parts of the environment, and continuing linkages between residual oil and biologic effects. Clean-up and treatment techniques applied to spilled or stranded oil can also have significant, long-lasting effects and need to be carefully evaluated prior to use.

Seas at the millennium - an environmental evaluati↗

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↗