Project: Deepwater Horizon Oil Spill, Marine Snow and Sedimentation

The accident at the BP oil well in the Gulf of Mexico in April 2010 resulted in an oil spill of unprecedented magnitude and consequences. Preliminary data collected in the beginning of May at the site of the accident show very high concentrations of marine snow in the water, especially in close proximity to the oil/ dispersants. The goal of this project is to evaluate the role these large marine snow-like particles play in the ecosystem during the following weeks to months. Neither the formation mechanisms nor the aggregate composition are known. These investigators will monitor the distribution of marine snow, characterize these particles and measure sedimentation rates to try to understand the role of snow formation and sedimentation in the ecosystem response.

This project examined the effects of the Deepwater Horizon oil spill in the Gulf of Mexico. During a field investigation on the RV Oceanus we began investigating how the oil and dispersants impact the carbon cycle and, specifically, aggregation and sedimentation of particles. First results indicate signals which were consistent with the presence of oil at around 1000 m depth at many stations. Oil-like material was also observed in the upper layers of many sediment cores. Marine snow concentrations did not seem exceptional anymore, although they were high at stations near the spill site. We deployed a time series sediment trap in the area of the accident, which will continue to sample over the next year, allowing us to collect continuous data on sedimentation rates in the area.

Intellectual Merit
The characteristics and the potential fate of these marine snow like aggregates, which may potentially sink or float, be grazed, degraded or remain suspended in the water for a long period of time, is unknown. This accident is an opportunity to evaluate and expand our knowledge on reactions of marine ecosystems to such large disturbances in general and more specifically to study the role of aggregation and sedimentation in the process. Marine snow formation and its sedimentation are an essential component of elemental cycling. It has been postulated that sedimentation of material "cleans" the water column from particles. Marine snow is also thought to be hotspots of microbial activity. Potentially this oily marine snow could not only represent hotspots of activity for oil degrading organisms, but may also function to isolate oil into small volumes. However, rapid sedimentation of such oil aggregates may lead to anoxia at depths. Scientifically we do not understand the possible interactions between marine snow, marine particles, oil and dispersant.

Tasks performed during the investigate the formation of marine snow and sedimentation patterns in the aftermath of the oil spill:
1. Deploy floating, VERTEX type sediment traps (8 to 12 columns per trap array) at 8 stations for about 36 hours each at 150 or 180 m depth. Two columns filled with polyacrymyl gels for microcosmical investigation of sinking particle types and sizes
2. Deploy 1 time series trap at 28 42.360N; 88 25.325W (about 2.5 nmiles SW of the spill site) at about 1400 m from August 2010 for about 1 year.
3. Determine marine snow distribution in the water column
4. Experiments on the formation mechanisms of marine snow