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Sub-Surface Water Trajectories from USF Ocean Circulation Model

400 m

1000 m

Motivation for cruise:

- Pelican cruisesuggested subsurfaceoil to the SW

-Ocean circulationmodels suggested limbof subsurface oil shouldbe entrained in thecurrents to the NE

-Trajectories to the NEhas the potential toimpact the continental

slope and shelf

Goals of cruise:-Search for subsurfaceoil to the NE of DWH

wellhead

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Weatherbird II Cruise May 22 - 28, 2010Surface and Subsurface Sampling Sites

Ship track

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DWH -Riser Fluid/M252Oil

April 28, 2010

C18

C22

C28

Surface OilMay 28, 2010

n

-alkanes

Intensity

Time

Intensity Typical GC trace of hydrocarbons from light

crude oil (BP M252) Smooth abundance distribution, L & HMW

n-alkanes, >C7 to C-42, Thermally mature oil

Altered GC trace from DWH BP M252 crude oil

Loss of LMW hydrocarbons including alkanes

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DSH01- 1000 m ParticulatesClean Water, No HydrocarbonsFlorida Waters

C18

C22

C28

Surface Oil

n-alkanes

Intensity

Time

Comparison of Surface Oil with Clean Sub-Surface (1000 m) Particles

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Site 07- 400 m Particulates

Site 08- 400 m Particulates

Site 09- 1000 m Particulates

C32

C28C37

C32

C32

C37

C28

C28

Site 01- 1000 m ParticulatesClean Water

Comparison of Deep Water Column Particulatesand Floridas Clean Deep Waters

Unusual distribution for modern POM

Traces of algal inputs, C-17 to C-20

HMW n-alkanes not from plant inputs- No odd/even predominance- Trace of C-23.C-25 and C-27

Complete loss LMW n-alkanes

Smooth abundance distribution >C-30

Peak at C-32, not biological

Looks like physically fractionated(processes at wellhead including

addition of dispersants) and/orbiodegraded oil

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Site 07- 400 m Particulates

Site 08- 400 m Particulates

Site 09- 1000 m Particulates

C32

C28

C37

C32

C32

C37

C28

C28

Comparison of n-alkanes in 400 m and 1000 m Particulates

C24

C37

30

20

10

0

3020

10

0

7050

30

10

All particulatesamples have a HCdistributioncharacteristic ofphysicallyfractionated and/orbiodegraded oil

HCs range from~200 to 750 ppb

1000 m sample has

~2x amount of HCswrt 400 m

HC gradient in

water column infersa source from depth

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Weatherbird II Cruise May 22 - 27, 2010Surface and Subsurface Sampling Sites

Sampled Area of

Biodegraded Oils

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Site 07- 400 m Particulates

Site 08- 400 m Particulatesmild-moderate biodegradation

Site 09- 1000 m ParticulatesModerate biodegradation

C32

C28C37

C32

C32

C37

C28

C28

C24

C37

30

20

100

C18

C22

C28

Degraded Surface OilMay 28, 2010mild biodegradation

DWH - Riser Fluid/Oil

April 28, 2010

No biodegradation

Comparing Degree of Degradation:DWH BP-M252 Oil, Surface Oil & Subsurface Oils

Degradation Sequence:-Alkanes before aromatics-LMW before HMW-Short before long-chain

Comparison of Samples- See progressive loss ofshort-chain n-alkanes

- Biodegraded oils suggestsactive microbial consumption(see 15N signals associatedwith hydrocarbons)-Dispersants could be cause

of selective loss of LMWcompounds- Physical chemical reactionof petroleum emitted

Signal

Signal

Signal

Signal

Time and/or Temperature

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Initial Conclusions: Organic Geochemistry Biodegraded oil, as micron sized particles (invisible to naked eye) was found

at multiple depth below the surface and in deep water samples.

The molecular organic geochemistry of the deep water sample at 1000 m wasidentical to the 400 m samples.

The deep sample at 1000 m had higher hydrocarbon concentrations (~2-fold)than the shallower 400 m sub-surface.

Origins of hydrocarbon are likely from a deep-sea source

With additional research cruises and with information from BP on the oilcomposition and its concentration coming out the wellhead we can:

-determine whether the sub-surface oil is from natural seeps or fromthe leaking Deep Water Horizon.

-calculate length of time these potentially toxic molecules, such assaturated and aromatic hydrocarbons, can persist inthe environment.