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Following the 1989 Exxon Valdez oil spill (EVOS), the Prince William Sound Regional Citizens' Advisory Council began the Long-Term Environmental Monitoring Program (LTEMP) in 1993 to track oil hydrocarbon chemistry of recovering sediments and mussel tissues along the path of the spill in Prince William Sound (PWS) and across the Northern Gulf of Alaska (NGOA) region. The program also samples sites near the Alyeska Marine Terminal (AMT) within Port Valdez, primarily to monitor tanker operations and the resulting treatment and discharge of oil-contaminated tanker ballast water. Over the last 28 years, the program has documented EVOS oil's disappearance at the spill-impacted sites (albeit buried oil still exists at a few unique sheltered locations in PWS). Within the Port, a few tanker- and diesel-spill incidents have been documented over the years, but all were minor and with recovery times of < 1 yr. Of highest concern has been the permitted chronic release of weathered oil from tankers' ballast-water that is treated and discharged at the Alyeska Marine Terminal (AMT). In earlier years (1980s–90s), with discharge volumes reaching 17–18 MGD, up to a barrel of finely dispersed weathered oil would be released into the fjord daily. Over the last two decades, total petrogenic inputs (TPAH43) into the Port have declined as measured in the monitored mussels and sediments. This trend reflects a combination of decreased Alaska North Slope (ANS) oil production and thus, less tanker traffic, plus less ballast from the transition to double-hulled tankers with segregated ballast tanks, and improved treatment-facility efficiency in removing PAH. From the 2018 collections, mussel-tissue hydrocarbon concentrations from all eleven LTEMP stations (within Port Valdez as well as PWS and NGOA regions) were below method detection limits and similar to laboratory blanks (TPAH43 < 44 ng/g dry wt.). At these low background levels, elevated TPAH values from a minor 2020 spill incident at the Terminal were easily detected at all three Port Valdez stations.

Source oil characterization and its subsequent identification and quantification in different receiving environments are integral components of a natural resource damage assessment (NRDA) following a spill. When the M/V New Carissa broke up on the Oregon coast in February 1999, it released an estimated 70,000 gallons of two bunker fuels and two diesel fuels. Numerous oil, water, sediment, and tissue samples were subsequently analyzed for the standard suite of aliphatic and polynuclear aromatic hydrocarbon (PAH) fractions, as well as steranes and triterpanes to use in chemical fingerprinting in support of the NRDA process. The fingerprinting task was uniquely complex with this spill because of the four major source oils of highly disparate compositions and additional compositional changes occurring as a result of partial in situ burning and release of residual fuels onboard the vessel during the response effort. Also unique to NRDA process was the segregated sampling of dissolved-phase and dispersed-oil droplet fractions from the water column, information that proved invaluable in the fingerprinting process. To assist with the complex data analysis in identifying New Carissa oil in environmental samples, a combination of multivariate principal-component analyses and hierarchical agglomerative-cluster analyses, conventional double-ratio analyses of selected PAH, and custom computer displays to allow comparison of multiple graphs on a single page was developed. Results show two different mechanisms of hydrocarbon uptake into affected organisms: direct uptake of dissolved-phase PAH from the water column into crab tissues, and accumulation of aliphatic and aromatic constituents from dispersed oil droplets and oiled suspended particulate material (SPM) by filter-feeding organisms. From the combined statistical and fingerprinting process, it was possible to differentiate New Carissa oil from background combustion-derived (and sediment-associated) PAH in selected clam and oyster tissue samples from inside Coos Bay. Also documented was interstitial water contamination of otherwise clean and unoiled sandy beach substrates by offshore dissolved-phase PAH, and the accumulation of hydrocarbons from the surface microlayer by diatoms.

Oil-weathering processes in ice-free subarctic and Arctic waters include spreading, evaporation, dissolution, dispersion of whole-oil droplets into the water column, photochemical oxidation, water-in-oil emulsification, microbial degradation, adsorption onto suspended particulate material, ingestion by organisms, sinking, and sedimentation. While many of these processes also are important factors in ice-covered waters, the various forms of sea ice (depending on the active state of ice growth, extent of coverage and/or decay) impart drastic, if not controlling, changes to the rates and relative importance of different oil-weathering mechanisms. Flow-through seawater wave-tank experiments in a cold room at ?35°C and studies in the Chukchi Sea in late winter provide data on oil fate and effects for a variety of potential oil spill scenarios in the Arctic. Time-series chemical weathering data are presented for Prudhoe Bay crude oil released under and encapsulated in growing first-year columnar ice through spring breakup.

During the emergency phase of an oil or hazardous material spill, natural resource managers and trustees must quickly develop and implement study plans to collect ephemeral data on the extent and degree of contamination and the potential biological injury resulting from the spill. Manuals and guidelines have been developed by various groups, yet these documents have proven to be too difficult to use during the chaotic, early days of a spill emergency. To provide better guidance, a series of brief (two-page) protocol summaries have been prepared for the types of sampling activities likely to be conducted during the emergency phase of spill, supporting both response and natural resource damage assessment (NRDA) objectives. Protocols have been prepared for collection of samples of the source oil(s), water samples, intertidal sediments, subtidal sediments, and shellfish tissues for chemical and histopathological analysis. Protocols are also being prepared for procedures to measure salt marsh injury, visual estimates of abundance and percent cover in quadrats, and quantitative measurements of infaunal abundance.

In the past 2 years, winter field programs have been conducted along the northeast coast of the Chukchi Sea to study the formation and fate of very cold and salty water produced during fall freeze up and lead refreezing processes. These programs, headed by Lon E. Hachmeister of Envirosphere Company, Bellevue, Wash., and James R. Payne of Science Applications International Corporation, La Jolla, Calif., have been funded by the National Oceanic and Atmospheric Administration Outer Continental Shelf Environmental Assessment Program (NOAA/OCSEAP) to better understand physical processes in arctic coastal regions in regard to potential impact bv oil and gas development.