Distribution, characterization, and exposure of MC252 oil in the supratidal beach environment

Abstract

The distribution and characteristics of MC252 oil:sand aggregates, termed surface residue balls (SRBs), were measured on the supratidal beach environment of oil-impacted Fourchon Beach in Louisiana (USA). Probability distributions of 4 variables, surface coverage (%), size of SRBs (mm(2) of projected area), mass of SRBs per m(2) (g/m(2)), and concentrations of polycyclic aromatic hydrocarbons (PAHs) and n-alkanes in the SRBs (mg of crude oil component per kg of SRB) were determined using parametric and nonparametric statistical techniques. Surface coverage of SRBs, an operational remedial standard for the beach surface, was a gamma-distributed variable ranging from 0.01% to 8.1%. The SRB sizes had a mean of 90.7 mm(2) but fit no probability distribution, and a nonparametric ranking was used to describe the size distributions. Concentrations of total PAHs ranged from 2.5 mg/kg to 126 mg/kg of SRB. Individual PAH concentration distributions, consisting primarily of alkylated phenanthrenes, dibenzothiophenes, and chrysenes, did not consistently fit a parametric distribution. Surface coverage was correlated with an oil mass per unit area but with a substantial error at lower coverage (i.e., <2%). These data provide probabilistic risk assessors with the ability to specify uncertainty in PAH concentration, exposure frequency, and ingestion rate, based on SRB characteristics for the dominant oil form on beaches along the US Gulf Coast.

Input of organic matter enhances degradation of weathered diesel fuel in sub-tropical sediments

“…Following the 2010 Deep Water Horizon (DWH) oil spill in the northern Gulf of Mexico, the restoration of coastal ecosystems has focused national attention on the importance of these vital ecological locales (Allan et al, 2012;Lin and Mendelssohn, 2012;Mortazavi et al, 2013a). Although reports following the DWH spill indicated that natural attenuation processes were occurring at many sites (Allan et al, 2012;Beazley et al, 2012), weathered oil may remain trapped in the area sediments, posing potential long-term risks to the environment (Allan et al, 2012;Lemelle et al, 2014;Elango et al, 2014).…”

Formation, Fate, and Impacts of Microscopic and Macroscopic Oil‐Sediment Residues in Nearshore Marine Environments: A Critical Review

“…Due to the magnitude of SOA and SOM contamination along the northern Gulf coast following the Deepwater Horizon spill, several studies have been carried out to understand the distribution, transport dynamics, and physical and chemical characteristics of these agglomerates, most notably in Louisiana (Elango et al, ; Lemelle et al, ; Urbano et al, ), Alabama (Clement et al, ; Hayworth et al, ; Wang & Roberts, ; Yin et al, ), and some in Florida (Wang & Roberts, ). SOAs resulting from this spill were typically found on the range of 0.5–8 cm in diameter, while SOMs spanned up to several meters in length and were up to 20 cm thick (Dickey & Huettel, ; Hayworth et al, ; Michel et al, ).…”

“…The persistence of toxic PAHs within SOAs and SOMs is of particular concern and has been the subject of several studies related to Deepwater Horizon residues (Elango et al, ; John et al, ; Lemelle et al, ; Liu et al, ; Stout et al, ; Urbano et al, ; Yin et al, ). Yin et al () compared SOA samples from Alabama beaches with a first‐arrival mousse samples as well as with a reference MC252 crude oil sample.…”

“…Since the release of the OSAT‐2 report, studies have shown that SOAs and SOMs have persisted in the nearshore environment, increasing the background oil contamination level by several orders of magnitude (Clement et al, ). Additional studies have shown concerns about the toxicity of SOAs, specifically because of the continued presence of some toxic compounds including PAHs (John et al, ; Lemelle et al, ; Yin et al, ), environmentally persistent free radicals (EPFRs) (Kiruri et al, ), genotoxic and carcinogenic metals (Liu et al, ; Wise et al, ), oxygenated compounds (Aeppli et al, ; Huba & Gardinali, ; White et al, ), and human pathogens such as Vibrio vulnificus (Tao et al, ). A recent study on the neurotoxic effects of residues from the Deepwater Horizon spill showed that the water accommodated fraction from SOM fragments can lead to the generation of reactive oxygen species, which can negatively impact cell membrane integrity and permeability that can lead to programmed cell death.…”

Seafood and Beach Safety in the Aftermath of the Deepwater Horizon Oil Spill

“…Beginning in 2011, samples of buried oil sand layers contained 7% to 9% oil, SRBs 4% to 13%, and SOM 9% to 17% (OSAT, 2011). Because SRBs are relatively stable in the beach environment, presumably because of the properties of resins that provide cohesion to the oil and sand particles ( Lemelle et al, 2014;Warnock et al, 2015), they now are the primary form of oil observed on Gulf beaches. As a result of cleanup teams' removal of oiled sediments, the monthly amounts of SRBs collected decreased (Dalyander et al, 2014), although SOMs that formed in protected areas and near inlets still persist to the present day and act as sources for petroleum hydrocarbons that wash up on beaches as "new" SRBs after storm events .…”