Influence of Ocean CO2 Sequestration on Bacterial Elemental Cycling

Abstract

Emissions of atmospheric CO2 from combustion of fossil fuels and alterations in land use have contributed to increases in global surface air temperatures over the past century. Carbon dioxide in the atmosphere is a major greenhouse gas. Increasing atmospheric concentrations are believed to be responsible for a gradual warming of the Earth. International research teams are working on a variety of strategies to sequester CO2, and one of those efforts involves the deep ocean. An international collaboration to conduct a field experiment on CO2 ocean sequestration was initiated in December 1997. The goal of this project is to evaluate the feasibility of transporting and containing anthropogenic CO2 in the deep ocean. This chapter focuses on studies being conducted as part of the field experiment assessing the influence of decreased pH from CO2 dissolution on bacterial production in the ocean. A preliminary analysis of the variation in bacterial production under different values of pH and temperature, conducted in July 1999, indicated that there was no measurable effect on the microbial population in the first 24 hrs of the experiment. However, there was a rapid decline in bacterial production with decreases in pH over a 96 hour incubation period. In addition, the impact of reduced pH was more pronounced when the bacteria were grown at warmer temperatures—that is, with a more rapid production rate.