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DTSTAMP:20240516T165718Z
LOCATION:275-277
DTSTART;TZID=America/Chicago:20240514T133000
DTEND;TZID=America/Chicago:20240514T135000
UID:IOSC_IOSC 2024_sess137_PAPER225@linklings.com
SUMMARY:Comparative Risk Assessments of Dispersant and Other Oil Spill Res
 ponse Options Quantifies Oil Exposure Tradeoffs Weighed by Relative Abunda
 nce and Recovery Potential of Affected Biota
DESCRIPTION:Paper\n\nDeborah P. French-McCay, Melissa Gloekler, Matthew Fr
 ediani, Sandra Deeb, Lisa McStay, and Gabrielle McGrath (RPS Ocean Science
 , Tetra Tech)\n\nThe usefulness of subsea dispersant injection (SSDI) for 
 reducing environmental impacts of a deepwater oil and gas release continue
 s to be debated. Oil spill modeling has been used to evaluate tradeoffs of
  SSDI and other response measures when responding to a spill. For example,
  oil exposure assessments of the Deepwater Horizon (DWH) oil spill were mo
 deled as it occurred and with various response alternatives included or no
 t in the simulations. A quantitative Comparative Risk Assessment (CRA) met
 hodology was used to weigh the relative consequences of differing response
  application scenarios. Inclusion of SSDI reduced human and wildlife expos
 ure to volatile organic compounds (VOCs); dispersed oil into a large water
  volume at depth; enhanced biodegradation; and reduced surface water, near
 shore and shoreline exposure to floating oil and entrained/dissolved oil in
  the upper water column. Tradeoffs included increased exposures of benthic 
 and water column biota in deep offshore waters. The CRA method provided a 
 quantitative comparison of the relative exposures of Valued Ecological Com
 ponents (VECs) in the Gulf of Mexico ecosystem. Exposure areas and volumes
  of VECs are weighed by exposure duration, relative abundance across envir
 onmental compartments (ECs) occupied, and recovery potential. Since shorel
 ine habitats and wildlife (marine mammals, sea turtles and birds) are vuln
 erable to surfaced oil and relatively slow to recover, and organisms were 
 much less abundant at depth, overall exposure of VECs was minimized by use
  of SSDI. \nApplication of the CRA methodology to other deep water oil spi
 ll scenarios in the Gulf of Mexico and elsewhere resulted in similar concl
 usions. The reductions in exposures of wildlife, surface water biota, and 
 nearshore habitats are most sensitive to the oil droplet size distribution
 s of untreated and dispersant-treated oil. Droplet size distributions vary
  considerably with oil and gas release rates and the concentration of disp
 ersant in the SSDI application. The degree to which deep water VECs are af
 fected are also subject to spill location, current patterns at depth, and 
 presence of vulnerable deep water habitats downstream of a spill. In the C
 RA framework, the fractions of resources exposed, along with their recover
 y potential, inform decisionmakers using a Spill Impact Mitigation Assessm
 ent (SIMA) approach with objective and transparent quantitative estimates 
 of potential consequences of spills assuming various response alternatives
 , which they may consider along with stakeholder values.\n\nTag: Remediati
 on\n\nSession Chair: Doug Helton (Office of Response and Restoration)
URL:https://iosc2024.conference-program.com/presentation/?id=PAPER225&sess
 =sess137
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