Salt marsh sediment organic matter decomposition in response to nitrate

We used a controlled flow though experiment to examine the role of nitrate on salt marsh organic matter decomposition and changes in microbial community composition through sequencing of the 16S rRNA gene. Marsh sediments were collected from Spartina alterniflora habitat at depths: 0-5 cm, 10-15 cm, and 20-25 cm and homogenized before loading into reactors. The experiment was run for 90 days under anaerobic conditions, during which we measured changes in nitrate, ammonium, dissolved inorganic carbon, rates of denitrification and dissimilatory nitrate reduction to ammonium, and changes in percent organic matter, carbon, and nitrogen.