This study is aimed at understanding the effect of the ongoing Deepwater Horizon oil spill on chemical distributions in the affected area. Because of the ongoing nature of the oil spill as well as the uncertainty of it course (i.e., it could stop at any time or continue indefinitely), sampling this event now is critical. Metals, nutrients, and organic matter all play important roles in the geochemical processes affecting the biota. The oil spill region is an important fishery and thus understanding how the spill is affecting chemical distributions is a vital aspect of understanding its impact on the food chain.
With funding through this Grant for Rapid Response Research (RAPID), investigators at the University of Southern Mississippi will examine how and to what extent metal and nutrient distributions are affected by the oil spill. This includes both direct effects (e.g., Ni is enriched in crude oil) as well as indirect effects wherein the spill could affect some other factor or process that they affects metals and nutrients (e.g., via oxygen depletion). They will conduct surveys in the affected area using both boats available to the university as well as ships of opportunity. They will also analyze samples collected in the past week in the oil spill area. The principal investigator's laboratory already has pre-spill baseline data for much of the affected area. Thus, thus they have a context for understanding and interpreting the data that will be gathered.
Broader Impacts Little is known about the impact of oil spills on trace element distributions. Thus, a broader impact of this work lies in helping understand some of the impacts of a serious oil spill which is contaminating an important fishery. The investigators will also involve a student in this work. Because of the wide interest in the impact of the oil spill, the results will not only be disseminated in the reviewed literature, but the findings are also likely to picked up by the popular media.
The Deepwater Horizon oil well blowout resulted in approximately 4 million barrels of oil released into the northern Gulf of Mexico along with a similar amount (on a carbon atom basis) of methane. Besides the obvious toxic effects of the oil, there are other chemical environmental effects we sought to investigate. First, because there are metals naturally present in the oil, we examined whether the oil directly increased the metal dissolved load of the water column near the wellhead. Second, we conducted experiments to determine whether the oil might affect the natural dissolved-particulate partitioning of metals. Also, because the oil and gas can serve as food for various micro-organisms, we examined whether consumption of these materials resulted in uptake of nutrients, oxygen, and metals. We also collected samples for organic matter analysis, including the analysis of polycyclic aromatic hydrocarbons (PAH’s)...a persistent and toxic component of the oil. We found that this particular oil has lower concentrations of metals than is typically found in crude oil. Thus, most metals did not show enrichment in the water. And, where enrichment was observed (e.g., cobalt), the effect was still generally minor and localized. Likewise, the anomalies we observed in nutrients and oxygen tended to be minor and localized. Complicating the interpretation of the metal profiles is the dynamic nature of this region along the continental slope where natural inputs of material from the bottom as well as Mississippi River inputs to surface waters can alter the metal distributions. Our data have been combined with those of other workers in the region to provide a more comprehensive look at the geochemical effects of the oil spill. Several graduate students were involved in this project and we also provided interviews to the media regarding our work. A supplement to this grant also allowed to involve an undergraduate student in this work. That student continues to work in our lab.
