Abstract:

This project is designed to follow the transformation and distribution of the crude oil and the applied dispersants in the impacted region of the Gulf of Mexico and the projected path of the oil plume, using a novel fluorescent technique combined with computer modeling. Several optical sensors were used to determine crude oil fluorescence and CDOM fluorescence in a Turner Cyclops platform. Both sensors were used continuously, gathering data every 10 minutes during the entire cruise. The hydrocarbon levels of the hydrocarbon in seawater in the Gulf of Mexico were monitored using fluorescence sensors. Results showed that the oil fluorescence near the DeSoto Canyon was more elevated than the fluorescence near the Deepwater Horizon site. This is indicative of possible oil northeast transport from the 2010 Deepwater Horizon oil spill location. There is also an observed elevated oil fluorescence west of the southwest Florida Shelf. CDOM fluorescence showed similar fluorescence in the same stations. Because of this result, the presence of oil in this sampling track cannot be confirmed. The collected seawater samples using multi-dimensional fluorescence and GC-MS will be compared to confirm the source and composition of any oil present in these sampling sites.

Suggested Citation:

Mendoza, Wilson, Daniel Riemer, and Rod Zika. 2014. Distribution of subsurface crude oil during the Deepwater Horizon oil spill using an in-situ fluorescence-based sensor, LA to FL shelf break and deep, October 2011.. Distributed by: GRIIDC, Harte Research Institute, Texas A&M University–Corpus Christi. doi:10.7266/N7N58J9Q

Purpose:

This project is designed to help elucidate the transformation and distribution of crude oil components and added dispersants in strategic areas of the Gulf of Mexico and along the plumes' projected trajectories using fluorescence and GCMS techniques.

Data Parameters and Units:

Date (MM/DD/YYYY) Station Sampling Depth (m) Bottom depth (m) Time GMT (hh:mm) Latitude (decimal degrees) Longitude (decimal degrees) True wind (knots) Wind Dir (degrees) Waves (sea state) CTD Pressure (dbar) CTD Temp (degrees Celsius) CTD Sal (psu) CTD Oxygen (mg/L) CTD Fluor (mg/m^3) CTD CDOM (mg/L) TSG Temp (degrees Celsius) TSG Sal (psu) TSG Fluor (mg/m^3) TSG CDOM (mg/L) C7 CDOM (mg/L) C7 Turb (ntu nephelometric tubidity units) C7 Crude Oil (mg/L) C7 Temp (degrees Celsius) Remarks. Stations: Underway Station, Longitude (degrees and minutes), Latitude (degrees and minutes).

Methods:

Several optical sensors were used to determine crude oil fluorescence and CDOM fluorescence in a Turner Cyclops platform. Both sensors were used continuously, gathering data every 10 minutes during the entire cruise. Sampling started from south of the Florida Keys, then head up to the DeSoto Canyon, and made a loop back crossing the Deepwater Horizon sites. Water column samples and CDOM were collected by CTD/Rosette with a total of 19 deep casts.

Instruments:

Two EPA Standard Methods for extraction and concentration of the oil from seawater samples were used: (1) liquid/liquid extraction and (2) EMPORE solid phase discs. The EMPORE SPE used the EPA 1664.

Error Analysis:

Sea surface samples were collected continuously every four hours on a flow-through system during the October 3-13, 2011 aboard the R/V Walton Research Vessel.

Individual Files: