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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.

Introduction. General Mechanism of Action of Chemical Dispersants. Chemical Formulation of Dispersant Agents. Factors Affecting Chemical Dispersion of Oil and Its Measurement. Properties and Chemistry of Oil. Dispersant Composition. Dispersant Application. Mixing Energy. Dispersant-To-Oil Ratio (DOR). Oil-To-Water Ratio (OWR). Temperature. Salinity. Sampling and Analysis Method. Laboratory Testing of Dispersant Performance. Laboratory Testing Methods. Advantages and Disadvantages of Different Laboratory Tests. Rapid Field Tests for Estimating Dispersant Performance. Field Tests of Dispersant Applications. Summary and Recommendations-Laboratory Studies. References. Index. Appendix A: Preparation Approach for this Book.

Olefin-based synthetic-based drilling mud (SBM) was released into the Gulf of Mexico as a result of the Deepwater Horizon (DWH) disaster in 2010. We studied the composition of neat SBM and, using conventional GC-FID, the extent, concentration, and chemical character of SBM-derived olefins in > 3600 seafloor sediments collected in 2010/2011 and 2014. SBM-derived (C 14 –C 20 ) olefins occurred (up to 10 cm deep) within a 6.5 km 2 “footprint” around the well. The olefin concentration in most sediments decreased an order of magnitude between 2010/2011 and 2014, at least in part due to biodegradation, evidenced by the preferential loss C 16 and C 18 linear (α- and internal) versus branched olefins. Based on their persistence for 4-years in sediments around the Macondo well, and 13-years near a former unrelated drill site (~ 62 km away), weathered SBM-derived olefins released during the DWH disaster are anticipated to persist in deep-sea sediment for (at least) a comparable duration.

NO. 2017-167 As part of the Natural Resource Damage Assessment (NRDA) effort following the Deepwater Horizon (MC252) blowout and oil spill in 2010, over 5,300 water samples were forensically evaluated both as evidence of exposure and to validate oil fate and transport modelling. In addition to whole water-sample grabs, particulate-oil and dissolved-phase samples from the subsurface release were separated (filtered) in the field to provide detailed information on the partitioning behavior of oil droplets in a deepwater plume (1,000–1,400m) extending to the southwest (SW) of the wellhead. Offshore, the subsurface plume was visually observed and photographed using remotely operated vehicles (ROVs), and tracked in conductivity, temperature, and depth (CTD), dissolved oxygen (DO), and fluorometry profiles. The farthest reach of the plume was 412 km (250 mi) SW of the wellhead as confirmed by multiple lines of evidence (i.e., depth, fluorometry spikes, DO sags, and dispersant indicators) and out to 267 km as weathered, phase-discriminated, confirmed hydrocarbon profiles. With increasing time and distance from the wellhead, the plume’s polycyclic aromatic hydrocarbon (PAH) signal became diluted and eventually no longer detectible using selected-ion-monitoring (SIM) gas chromatography/mass spectrometry (GC/MS), although the plume was still discernible in the corroborating data. We hypothesize that microbial degradation at depth converted the PAH and aliphatics into oxygenated and polar products not detectible using SIM GC/MS methods. Near-surface oil samples showed evidence of substantial dissolution weathering as the oil droplets rose through the water column, and further evaporative losses of lower-molecular-weight n-alkanes and aromatic hydrocarbons occurred after the oil reached the surface. Surface oil also showed evidence of photo-oxidation of alkylated chrysenes and triaromatic steranes. Typical of surface oil dynamics, increases in dissolved and particulate-oil fractions were observed in the shallow sub-surface as a result of both dispersant effects and wave reentrainment of surface films. Dispersant treatment effects, both as surface applications and injected at the wellhead, showed uniquely enhanced-dissolution weathering patterns in PAH profiles with limited or delayed microbial degradation of saturated hydrocarbons (SHC) close to the wellhead. From an oil-fate-and-transport standpoint, these data document that the dispersant applications at depth were functionally effective in breaking up the oil droplets and thereby preventing some portion of the oil from reaching the surface.

Computer programming – commonly referred to as “coding” by the cool kids – is the art of creating applications or software. These programs allow us to do everything from solve simple math problems and watch our favorite YouTube videos (I can’t get enough of skydiving bulldogs) to destroying hordes of rampant aliens in our favorite video games and even launching a real-life spaceship into outer space.

Welcome back budding hero! Looks like you’ve had a long day of homework, chores, and, of course, fighting crime. Now all that is left to do is eat your vegetables, put away your dishes, and for the love of God man, brush those teeth!

Welcome back intrepid hero! One thing you should know about super heroes and villains (especially villains) – they tend to rather worry. Thankfully, this chapter is all about increasing your abilities and granting you the new super power to handle all things text and text-related!

Sometimes fighting crime can make you feel like you are running around in circles. Day in and day out you seem to have to tackle the same struggles: a bank robber here, a cat stuck in a tree over there, an evil genius trying to take over the universe. It is almost as if you are stuck in some sort of…loop.

Now that we have officially created our first ever, full-blown Python application (back in Chapter 6 if you are skipping around!), it is time to begin learning how to truly harness our programming powers and becoming the best programmers we can be.

Now that are we are all suited up in our metaphorical capes and super hero outfits (i.e., we have installed Python and learned how to use the IDLE), it is time to put our new super powers to the test! Our first villain? Perhaps one of the most nefarious, vile, contemptuous beasts of all time; a criminal of the school system, running rampant and threatening to destroy – or bore – every student in its path. The villain’s name?

You’ve come a long way thus far. You started off being bitten by a radioactive programmer when you made the unfortunate mistake of trying to grab his microwaveable pizza bites. From there, your powers began to blossom and you proved yourself a worthy sidekick. But now it is time to truly test your knowledge and your l33t cod3r skillz. Are you up for the challenge?

Up to this point, we have covered some pretty standard programming language features and practices. This chapter will continue this tradition; however, the subject matter may be a little tougher to grasp at first glance. Don’t worry though – you have come this far, and we have watched you morph from stumbling sidekick to full-on, beastly hero.

It is only appropriate that we have a chapter where we discuss creating video games in Python – after all, it is that very interest that got me started programming all those years ago when I was a kid. Things have progressed a lot since then; at the time, PC games were text-based with the only images consisting of really poor quality graphics or, worse, made out of ASCII characters.

Chemical analysis of sediment cores collected up to 8 km from the Macondo well in 2010/2011 demonstrates the extent of weathering of the Macondo oil deposited in deep-sea sediments following the Deepwater Horizon disaster. On average, dissolution and biodegradation of the oil on the seafloor increased with distance from the well indicating that weathering occurred rapidly and overwhelmingly during the oil's transport as dispersed oil droplets within the deep-sea plume. Beyond about 5 km from the well, the oil deposited on the seafloor had lost most mass below C 25 , was relatively enriched in n -C 25 + n -alkanes and C 3 – and C 4 -alkylated benz[ a ]anthracenes/chrysenes, the latter owing to 95% depletion of total PAHs. Biodegradation of C 28 and C 29 tricyclic terpanes, C 34 and C 35 17α(H),21β(H)-homohopanes, C 27 13β(H),17α(H)-dia and C 27 14β(H),17β(H)-steranes and dissolution of C 26 to C 28 triaromatic steroids occurred. The results provide a means to distinguish Macondo oil in deep-sea sediments from naturally-occurring seep oils and pervasive ambient background hydrocarbons.

In-situ burning during the Deepwater Horizon oil spill generated tens of thousands of barrels of in-situ burn (ISB) residues in the northern Gulf of Mexico (GoM), most or all of which eventually sank to the seafloor. Chemical analyses showed that floating and sunken (~ 1400 m deep) ISB residues (1) exhibited distinct n-alkanes and UCM profiles inconsistent with vapor-pressure driven evaporation, (2) were relatively enriched in pyrogenic PAHs, particularly less stable (mostly) linear PAH isomers formed during burning, and (3) had lost petroleum biomarkers, relative to their volatility. PAH concentrations in ISB residues indicate that between 26,800 and 37,800 kg of total PAHs (TPAH51) and 2880 and 4060 kg of 16 Priority Pollutant PAHs were potentially deposited on the seafloor in discrete ISB residue particles. Despite this additional benthic impact, ISB reduced the total mass loadings of PAH from the burned oil to the GoM by 89% (ignoring any re-deposition from atmospheric emissions).

This book covers research completed between 1981 and May 1985 and includes: reviews of recent studies, sitings and investigations at spills-of-opportunity as well as results of recent arctic and sub-Arctic oil weathering experiments and observations on the behavior of crude oil in the presence of ice. Topics covered include the following: laboratory studies of formation and stability of water-in-oil emulsions; selected case histories of the more detailed chemistry studies of mousse behavior and long term fate in near-coastal and open ocean oil spills/blowouts; tar ball formation and distribution; and algorithms and computer programs to simulate the formation of water-in-oil emulsion.

As analytic instruments and methods have improved over the decades, so too, have insights into the fate and behavior of oil–water mixtures. Particularly relevant are understanding and documenting oil phase signatures that, while yielding forensic insights in our early studies, have led to the recent development of phase-specific methods appropriate for the forensic study of oiled water. The forensic applications of these methods include source matching, weathering, deconfounding background contaminants, distinguishing dissolved and particulate phases within whole water samples, and documenting chemical dispersant effects on polycyclic aromatic hydrocarbons (PAH) profiles. These methods, when collectively applied to deep-sea water of the Gulf of Mexico following the Deepwater Horizon (DWH) blowout, were used to ultimately track the subsurface plume of DWH-impacted water 412 km across the Gulf of Mexico to a final sample confirmed with only a trace dissolved-PAH pattern and supporting information.

During the Deepwater Horizon blowout, unprecedented volumes of dispersant were applied both on the surface and at depth. Application at depth was intended to disperse the oil into smaller microdroplets that would increase biodegradation and also reduce the volumes buoyantly rising to the surface, thereby reducing surface exposures, recovery efforts, and potential stranding. In forensically examining 5300 offshore water samples for the Natural Resource Damage Assessment (NRDA) effort, profiles of deep-plume oil droplets (from filtered water samples) were compared with those also containing dispersant indicators to reveal a previously hypothesized but undocumented, accelerated dissolution of the polycyclic aromatic hydrocarbons (PAH) in the plume samples. We interpret these data in a fate-and-transport context and conclude that dispersant applications were functionally effective at depth.

Forensic chemistry assessments documented the presence of Macondo (MC252) oil from the Deepwater Horizon (DWH) spill in offshore water samples collected under Natural Resource Damage Assessment (NRDA) protocols. In ocean depths, oiled water was sampled, observed, photographed, and tracked in dissolved oxygen (DO) and fluorometry profiles. Chemical analyses, sensor records, and observations confirmed the shifting, rising oil plume above the wellhead while smaller, less buoyant droplets were entrapped in a layer at ~1000–1400 m and advected up to 412 km southwest. Near-surface oil samples showed substantial dissolution weathering from oil droplets rising through the water column, as well as enhanced evaporative losses of lighter n-alkanes and aromatic hydrocarbons. Dispersant effects from surface applications and injected at the wellhead were seen in oil profiles as enhanced weathering patterns (increased dissolution), thus implying dispersants were a functionally effective mediation treatment. Forensic assessment methods are detailed in the Supplemental information (SI).

An oil droplet size model was developed for a variety of turbulent conditions based on non-dimensional analysis of disruptive and restorative forces, which is applicable to oil droplet formation under both surface breaking-wave and subsurface-blowout conditions, with or without dispersant application. This new model was calibrated and successfully validated with droplet size data obtained from controlled laboratory studies of dispersant-treated and non-treated oil in subsea dispersant tank tests and field surveys, including the Deep Spill experimental release and the Deepwater Horizon blowout oil spill. This model is an advancement over prior models, as it explicitly addresses the effects of the dispersed phase viscosity, resulting from dispersant application and constrains the maximum stable droplet size based on Rayleigh-Taylor instability that is invoked for a release from a large aperture.

Following the Deepwater Horizon oil spill, the spilled Macondo oil was severely weathered during its transport within the deep-sea plume as discrete particles, which were subsequently deposited on the seafloor. The Macondo oil deposited in deep-sea sediments was distinguished from ambient (background) hydrocarbons and naturally-seeped and genetically-similar oils in the Mississippi Canyon region using a forensic method based upon a systematic, multi-year study of 724 deep-sea sediment cores collected in late 2010 and 2011. The method relied upon: (1) chemical fingerprinting of the distinct features of the wax-rich, severely-weathered Macondo oil; (2) hydrocarbon concentrations, considering a core's proximity to the Macondo well or to known or apparent natural oil seeps, and also vertically within a core; and (3) results from proximal cores and flocculent material from core supernatants and slurp gun filters. The results presented herein establish the geographic extent of “fingerprintable” Macondo oil recognized on the seafloor in 2010/2011.

After a spill, oil is present in water as both dissolved and particulate (oil-droplet) phases due to entrainment and dissolution/weathering processes. The two phases, capable of physically separating and remixing in a body of water, complicate forensic evaluations but also contribute information on waterborne fate and transport. Identifying and tracking each phase in field samples has high forensic value in developing interpretive scenarios of weathering and exposure processes and for providing data germane to modeling and toxicology studies in damage assessments. Samples can be parsed into phase components either physically in the field using portable filtration equipment or later with data evaluation methods developed to parse out unfiltered samples using a weathered particulate-oil reference series generated from a few field-filtered samples. If done properly, sampling the water column for oil hydrocarbons during or after an oil spill can be highly insightful but the task is challenging and technically demanding with multiple opportunities to get it wrong, especially without feedback until weeks or months later when the data come back from the lab. This chapter presents water-sampling issues (and solutions), methods of forensically assessing quantified data, and adaptive sampling strategies that prove effective in tracking a deep submerged plume.

Oil-spill fate and transport modeling may be used to evaluate water column hydrocarbon concentrations, potential exposure to organisms, and impacts of oil spills with and without dispersant use. Important inputs to transport modeling for such analyses are current velocities and turbulent dispersion coefficients. Fluorescein dye studies off San Diego, California, were used to calibrate an oil transport model by hindcasting movement and dispersion of dye. The oil spill model was then used to predict subsurface hydrocarbon concentrations and potential water column impacts if oil were to be dispersed into the water column under similar conditions. Field-collected data included surface currents calculated from high-frequency radar data (HF-Radar), near-surface currents from drifter measurements drogued at several depths (1m, 2m, 4m or 5m), dye concentrations measured by fluorescence, spreading and dye intensity measurements based on aerial photography, and water density profiles from CTD casts. As the dye plume quickly extended throughout an upper mixed layer (7–15m), the horizontal dye movements were better indicated by the drifters drogued to a depth near the middle of that layer than the HF-Radar, which measured surface (∼top 50 cm) currents (including wind drift). Diffusion rates were estimated based on dye spreading measured by aerial photography and fluorescence-depth profiles. The model used these data as inputs, modeling of wind-forced surface water turbulence and drift as a function of wind speed and direction (based on published results of fluid dynamics studies), and Stokes law for droplet rise/sinking rates, to predict oil transport and dispersion rates within the water column. Use of such diffusion rate data in an oil fate model can provide estimates of likely dispersed oil concentrations under similar conditions, which may be used to evaluate potential impacts on water column biota. However, other conditions with different patterns of current shear (due to background currents, tidal currents, and wind stress) should be examined before these results can be generalized.

The California Department of Fish and Game Office of Spill Prevention and Response (CA OSPR) is utilizing oil-spill fate and transport modeling to develop the time and spatial scales, and equipment needs, for a formal Dispersed Oil Monitoring Plan (DOMP). When fully implemented, the DOMP will aid in documenting hydrocarbon concentrations in the water column, potentially exposed organisms (zooplankton), and the impacts of entrained oil and dissolved hydrocarbons with and without dispersant applications. Fluorescein dye studies off San Diego, California (USA) have been completed to test the operational framework for repeated sampling of dispersed oil plumes as outlined in the DOMP, to allow evaluation of high-frequency radar (HP-Radar) for providing surface current input data to oil spill models, and to provide verification of model-predicted movement of subsurface oil (dye) by comparison with drogue movement and measured dye concentrations over three dimensions and time. Aerial photodocumentation, subsurface drogues, dye transport, and HF-Radar were used to measure near-surface current fields at varying depths. High-resolution subsurface dye-plume structure was mapped using an in situ GPS-coupled towed fluorometer equipped with pressure sensors to provide dye concentration data as a function of time, position, and depth. In addition, data from the more traditional Special Monitoring of Applied Response Technology (SMART) protocols utilized by the U.S. Coast Guard (USCG) were compared with the in situ towed-fluorometer measurements, and conventional CTD data were collected to determine the mixed layer depth, an important variable in monitoring dispersion of oil in the water column. As a result of these efforts, significant progress has been made on developing and testing sampling protocols for the DOMP, and nearly continuous and synoptic data have been obtained from seven cruises conducted over a 12-month period. These data sets (available on-line through the Coastal Response Research Center (CRRC) website: http://www.crrc.unh.edu/) are being analyzed and integrated to support oil spill model development and verification with direct applicability to spill response decision making, net environmental benefit analysis, natural resource damage assessments, and educating the spill community and public.

We compared hydrocarbons in water, suspended particulate matter (SPM), and riparian sediment collected from coastal watersheds along the Yakataga foreland with corresponding hydrocarbons in Gulf of Alaska benthic sediments. This comparison allows an evaluation of hydrocarbon contributions to marine sediments from natural oil seeps, coal and organic matter (e.g., kerogen) associated with eroding siliciclastic rocks. The samples from oil seeps show extensive loss of low-molecular weight n -alkanes ( n -C 14 ) and the presence of large, bimodal unresolved complex mixtures (UCMs), in contrast to the hydrocarbon fingerprints on the SPM and riparian sediment samples collected upstream from the oil seeps. After entering the fluvial systems, hydrocarbons from seep oils are rapidly diluted, and associate with the SPM phase as oil-mineral-aggregates (OMA). Johnston Creek, the watershed containing the most prolific seep, conveys detectable seep-derived hydrocarbons to the Gulf of Alaska, but overall seep inputs are largely attenuated by the (non-seep) petrogenic hydrocarbon content of the high SPM loads. In contrast to the geochemical signature of seep oil, Gulf of Alaska benthic sediments are characterized by abundant alkylated naphthalene homologues, relatively smooth n -alkane envelopes ( n -C 9 through n -C 34 , but with elevated levels of n -C 27 , n -C 29 , and n -C 31 ), and small UCMs. Further, hydrocarbons in benthic sediments are highly intercorrelated. Taken together, these characteristics indicate that seep oil is a negligible petrogenic hydrocarbon source to the Gulf of Alaska continental shelf. Coaly material separated from the benthic sediment samples using a dense liquid (∼2.00 g cm −3 ) also accounted for a minor portion of the total PAH (1–6%) and total n -alkanes (0.4–2%) in the benthic samples. Most of the hydrocarbon burden in the sediments is found in the denser sediment fraction and likely derives from organic matter contributed by denudation of siliciclastic formations in the Yakutat terrane. We therefore conclude that previous investigations relying on source allocation models have considerably overestimated oil seeps as a hydrocarbon source to the Gulf of Alaska.

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 approximately 68% yr(-1) prior to 1992 to approximately 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 samplesfrom 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.

Chemical analysis of large populations of floating (n=62) and stranded (n=1174) Macondo oils collected from the northern Gulf of Mexico sea surface and shorelines during or within seven weeks of the end of the Deepwater Horizon oil spill demonstrates the range, rates, and processes affecting surface oil weathering. Oil collected immediately upon reaching the sea surface had already lost most mass below n-C8 from dissolution of soluble aliphatics, monoaromatics, and naphthalenes during the oil's ascent with further reductions extending up to n-C13 due to the onset of evaporation. With additional time, weathering of the floating and stranded oils advanced with total PAH (TPAH50) depletions averaging 69±23% for floating oils and 94±3% for stranded oils caused by the combined effects of evaporation, dissolution, and photo-oxidation, the latter of which also reduced triaromatic steroid biomarkers. Biodegradation was not evident among the coalesced floating oils studied, but had commenced in some stranded oils.

Sampling zooplankton is a useful strategy for observing trace hydrocarbon concentrations in water because samples represent an integrated average over a considerable effective sampling volume and are more representative of the sampled environment than discretely collected water samples. We demonstrate this method in Port Valdez, Alaska, an approximately 100 km 2 basin that receives about 0.5–2.4 kg of polynuclear aromatic hydrocarbons (PAH) per day. Total PAH (TPAH) concentrations (0.61–1.31 μg/g dry weight), composition, and spatial distributions in a lipid-rich copepod, Neocalanus were consistent with the discharge as the source of contamination. Although Neocalanus acquire PAH from water or suspended particulate matter, total PAH concentrations in these compartments were at or below method detection limits, demonstrating plankton can amplify trace concentrations to detectable levels useful for study.

Buried oil residues in selected beaches that were heavily contaminated by the 1989 Exxon Valdez Oil Spill (EVOS) continue to leach oil-contaminated suspended particulate material (SPM) and dissolved-phase polycyclic aromatic hydrocarbons (PAH) into interstitial- and near-shore waters. Both are bioavailable forms of hydrocarbons that can be absorbed or consumed. On selected intertidal beaches in Prince William Sound (PWS) during June 2002, nearshore- and interstitial-water samples were collected during outgoing tides, first from a water depth of 10–15 cm above undisturbed sediments at water's edge and then from pits dug just above the waterline. At the time of collection, all samples were vacuum-filtered through 0.7-µm pore-size, glass-fiber filters using a Portable Large Volume Water Sampling System (PLVWSS) to separate dissolved- and oil-contaminated SPM fractions for detailed hydrocarbon analyses and fingerprinting. From intertidal pits at oil-impacted sites, interstitial water and SPM displayed strong oil signatures and elevated (albeit variable) PAH and n-alkane levels compared to the trivial non-petrogenic signatures seen at the reference sites. The dissolved-phase samples at the oil-impacted sites were typically characterized by water-soluble, lower-molecular-weight PAH, while the SPM/oil-phase contained the relatively-insoluble, higher-molecular-weight PAH and n-alkanes. Water's-edge samples (collected before any pits were excavated) typically showed a diluted- and degraded-compositional signature traceable to the interstitial water from higher tide levels. Interstitial-water dissolved-phase concentrations (average 1,200 ng/L.; 76–4,600 ng/L vs. 18–27 ng/L for reference sites) were above those reported to cause impacts to herring and salmon eggs (