Oops! Deepwater Horizon Much Worse Than Though; Oil Spread To Keys, Cuba, North Carolina,
Florida Keys residents may not have seen massive tar balls and fish kills after the 2010 Deepwater Horizon oil spill, but small concentrations of toxic crude were still reaching the islands and potentially harming marine life, as the extent of the deadly disaster in the Gulf of Mexico was worse than originally thought, according to a University of Miami study.
Nearly a decade after the worst offshore oil spill in U.S. history killed 11 people and dumped 200 million gallons of crude into the ocean, researchers found discrepancies in the satellite footprint that was used to establish fisheries closures and data from sampling and field tests. They concluded that the real extent of the BP oil spill may have been 30 percent larger than originally estimated. After methane seeped into the rig and triggered an explosion on April 20, 2010, oil gushed from a pipe more than 4,000 feet below the ocean’s surface for 87 days.
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What researchers called “invisible oil” was crude in smaller and lighter concentrations that was flowing around the Gulf of Mexico, not thick enough to be detected by satellites. Though the oil was lighter in concentration than the crude that the National Response Team was cleaning up on the surface, it was toxic because of the interaction with ultraviolet light, Berenshtein said. “This photoinduced toxicity means that oil, even in very low concentrations, becomes more toxic than oil alone when UV light is also present,” he said.
For example, high levels of toxic chemicals called polycyclic aromatic hydrocarbons, or PAHs, released from the oil spill were found in red snappers’ livers, while researchers also observed an increase in cases of skin lesions in bottom-dwelling fish, the study said. Researchers also analyzed data showing that “fish larvae developed edema, decreased heart rates, and developmental abnormalities at low oil concentrations. “ Mike Forster, a longtime Islamorada restaurant owner who is also a backcountry angler, said he was recently speaking to lobster and crab fishermen about their slow catch this season, and he theorized it could be residual effects from the massive 2010 spill. “No, we didn’t see the tar balls and major fish kills of any magnitude,” Forster said. “But, you can’t make believe it didn’t have an effect on the eggs, nursery of anything living in the ocean, and specifically on the Gulf side.”
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https://www.miamiherald.com/news/local/community/florida-keys/article240263391.html?fbclid=IwAR3HG9p8258hw_7HuDKFuaAjtJH305KUmSBP15nyAE0NXIHH3uCLK1eYkvk
INTRODUCTION
The Deepwater Horizon (DWH) blowout was a mega oil spill, introducing ~795 million liters of live oil into the Gulf of Mexico (GoM) with oil slicks covering an estimated area of 149,000 km2 (1). As a result, vast areas of the GoM were closed for fishing, at one point reflecting a maximum of more than a third of the U.S. national exclusive economic zone (2). The application of the fishery closures was based on satellite and areal imagery by the National Environmental Satellite, Data, and Information Service (NESDIS), using mainly synthetic aperture radar (SAR), and tracking of the NESDIS footprints forward in time, predicting their approximated locations for up to 72 hours (3). The closures were reopened on the basis of a systematic seafood sampling, performing chemical and sensory testing in various seafood specimens (2).
The cumulative satellite oil slick footprint was largely accepted as the DWH oil spill extent from scientific, public, and management perspectives (2, 4, 5). Yet, accumulating field data support a much wider extent of the DWH spill beyond the satellite footprint, reaching the West Florida Shelf (WFS), the Texas Shores (TXS), the Loop Current (LC) system, and the Florida Keys (FK) (see regional map in fig. S1). Specifically, in the WFS, studies indicate high concentrations of oil, including toxic and mutagenic levels, in the water (6), in sediments (7), in sand patties (8), and on the coast (9). Furthermore, high levels of polycyclic aromatic hydrocarbons (PAHs) from DWH oil were found in red snappers’ livers, which co-occurred with a high frequency of skin lesions in bottom-dwelling fish (10). Last, satellite imagery and particle tracking showed that an oil slick present east of Pensacola (north WFS) was transported southeast along the WFS, reaching Tampa and the Dry Tortugas (FK) within a few weeks (11). In TXS, high and toxic levels of oil were found in the water (12) and in sediments (12, 13). In the LC system, the European Space Agency reported the presence of DWH oil during mid-May (14). Later, during early June, NESDIS satellite imagery revealed the presence of 12 oil slicks in the LC system, stretching from FK to the GoM interior. High concentrations of oil were reported in the LC between late June and mid-July west of the fishery closures (15). Furthermore, a deep intrusion (~1000 to 1300 m), which was documented (16) and represented in oil transport simulations (17), included toxic PAH concentrations within 13 km from the well and above-background concentrations extending southwest ~300 km beyond the satellite footprint and closure areas. Overall, these observations indicate that DWH oil extended beyond the satellite footprint and the fishery closures (18).
Oil transport models are effective tools for predicting and reconstructing marine oil spills. Numerous modeling efforts were previously carried out in an attempt to reconstruct spatiotemporal dynamics of the DWH oil spill. The surface oil movement was modeled using Lagrangian Coherent Structure (LCS) core analysis, successfully reconstructing the oil footprint from the satellite imagery (19). Similarly, the three-dimensional (3D) oil application of the Connectivity Modeling System (oil-CMS) (20) and the General NOAA (National Oceanic and Atmospheric Administration) Operating Modeling Environment (GNOME) (21) simulated the oiled coastline areas, both successfully reconstructing the observed beaching patterns (9). The GNOME was also used to conduct probabilistic Monte Carlo simulations, running hundreds of oil transport scenarios based on historical wind and currents data (22). While some of these models provided possible scenarios of the DWH spill, a robust spatiotemporal examination of the spill’s extent, resolving toxic and nontoxic concentrations, does not exist for the DWH. Similarly, the relationship between satellite detection and in situ oil concentrations was rarely examined. This is a key point because satellite detection is the main source of information used for determining the oil spill extent and the corresponding management actions, e.g., fishery closures (2). Having the capacity to quantify the toxic-to-biota extent, which is not necessarily equal to the satellite-detected extent, would improve the understanding and, therefore, the management of oil spills.
This is particularly important in light of photoinduced toxicity studies that have demonstrated that the combined effect of PAH and ultraviolet (UV) radiation can be two orders of magnitude more potent than PAH alone (4). This marked increase in hazard to early life stage was never considered in oil transport simulations thus far, and this is the first study to do so. The aim of this study was to examine the full extent of the DWH oil spill based on satellite/areal imagery, in situ measurements, and oil transport model, focusing on the oil fraction that is invisible to satellites and toxic to biota. To compute this fraction, we quantify the relationship between PAHs, which are associated with oil toxicity, and total petroleum hydrocarbons (TPHs), which closely represent the oil modeled in oil transport simulations (23). We then quantify the satellite detection threshold in terms of oil concentrations. Last, we apply these elements in an oil transport model, compute the total and toxic-to-biota extents of the DWH oil spill, and discuss their implications on the environment and public health.
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https://advances.sciencemag.org/content/6/7/eaaw8863
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