Formate, acetate, and propionate as substrates for sulfate reduction in sub-arctic sediments of Southwest Greenland.

摘要: Volatile fatty acids (VFAs) are key intermediates in the anaerobic mineralization of organic matter marine sediments. We studied role VFAs carbon and energy turnover sulfate reduction zone sediments from sub-arctic Godthabsfjord (SW Greenland) adjacent continental shelf NE Labrador Sea. VFA porewater concentrations were measured by a new two-dimensional ion chromatography-mass spectrometry method that enabled direct analysis without sample pretreatment. low surprisingly constant (4-6 µmol L-1 for formate acetate, 0.5 propionate) throughout zone. Hence, turned over while maintaining stable concentration is suggested to be under strong microbial control. Estimated mean diffusion times acetate between neighboring cells <1 second, whereas increased several hours at sediment surface years bottom Thus, was not limiting turnover. Despite concentrations, Gibbs energies (Gr) VFA-dependent decreased downcore, -28 -16 kJ (mol formate)-1, -68 -31 acetate)-1, -124 -65 propionate)-1. Gr