Award: OCE-1634999

Microscopic photosynthetic organisms in the ocean called cyanobacteria are so numerous that blooms can be seen from space by satellites. Laboratory experiments suggest that cyanobacteria produce millions of tons of hydrocarbons, chemicals containing carbon and hydrogen, which have the potential to greatly affect the chemistry of our oceans and atmosphere. These hydrocarbons can serve as an energy source for other ocean bacteria that may be important in degrading oil spills. They also have the potential to evaporate into the atmosphere where they can impact air quality, cloud formation and precipitation, and climate. This project aimed to investigate how these hydrocarbons cycle through the marine environment. We were interested in four questions: 1) How much of these hydrocarbons are found in ocean water? 2) How quickly do bacteria consume these hydrocarbons? 3) How much of these hydrocarbons evaporates into the atmosphere? 4) Do these hydrocarbons sustain a population of other bacteria that can then degrade oil spills? In particular, our group’s role in this collaborative work was to measure hydrocarbons in the air and to examine the relationship between the measured hydrocarbons and the cyanobacteria present in different parts of the ocean. To accomplish this, we collected air and water samples during a three-week research cruise aboard the R/V/ Neil Armstrong in 2017 in the North Atlantic Ocean and measured hydrocarbon concentrations and counted cells of different species of cyanobacteria. We did not find evidence of the major hydrocarbons produced by cyanobacteria in our air samples, which means that the vast majority of these hydrocarbons remains in the water. However, we did see evidence that a species of cyanobacteria called Synechococcus may produce large amounts of a hydrocarbon called toluene that evaporates into the atmosphere. Toluene is highly reactive with other chemicals in the air and can form tiny particles called secondary organic aerosols. These aerosols have the potential to increase cloud formation over the ocean, which can impact precipitation patterns and climate, and can negatively impact human health if they are transported to populated downwind areas. This work involved several undergraduate students from an undergraduate university that serves a high number of first generation college students. The students not only received training in the use of scientific instrumentation and data analysis, but were also able to present their work at regional and national conferences, making contacts with potential employers and graduate school advisors, and to publish their work as undergraduate theses and as co-authors on future peer-reviewed manuscripts. Last Modified: 03/11/2020 Submitted by: Robert F Swarthout