Award: OCE-1756667

Natural oil seeps are found throughout the world's oceans.These seeps are a constant source of oil to the water column and form sheens at the water surface. They support marine ecosystems by providing a source of carbon and other elements for marine microbes, which, in turn, support higher organisms. Measuring the amount of oil coming from natural oil seeps is challenging and has previously relied on aerial or satellite observations of surface sheens. Our project focused on developing a new method to measure the rate of oil seepage and understanding the impacts that this oil has on microbial populations. To accomplish this, we designed an uncrewed aerial vehicle (UAV) based air sampling method to measure concentrations of oil chemicals in the air above natural oil seeps and collected fresh oil at the seafloor using the Alvin deep-sea submersible at seep locations in the Gulf of Mexico. Using these two groups of samples we were able to quantify the amount of oil being released. We also collected water samples to investigate the impact of the oil on the microbes present throughout the water column. Intellectual merit: Our work is the first to use our UAV vertical profiling method to estimate oil release rates from natural seeps. Future use of the methods we developed will allow for additional ground truthing of estimates relying exclusively on satellite and aerial survey observations and the uncertain relationships between oil sheen color and oil thickness. Greater accuracy in estimates of natural oil seep emission rates will enhance our understanding of the fate of petroleum hydrocarbons in the water column at seep sites and the role of these hydrocarbons in oceanic nutrient cycling in impacted areas. The UAV based sampling methodology developed and validated in our work provides a useful tool for estimating emission fluxes from other diffuse sources. This could have implications for quantifying transport of pesticides to non-target areas or hazardous air pollutants to downwind population centers. Broader impacts: This project allowed for multiple educational and training opportunities for students at Appalachian State University. We created a laboratory experience for undergraduate students in a Global Biogeochemical Cycles course that leverages the methodology developed. Over 40 students per course explore fundamental concepts of atmospheric emissions and transport during this lab and measure atmospheric fluxes of pollutants. They then use these calculations in a simple biogeochemical model to estimate impacts on downwind locations. The project has also provided rich datasets for nine undergraduate research students at to use in capstone research courses in chemistry and environmental science. These students had the opportunity to present their work at national and regional conferences and network with potential graduate school advisors and employers. Last Modified: 09/04/2024 Submitted by: RobertFSwarthout