Peatland ecosystems store large quantities of carbon in their soils and are a significant source of methane to the atmosphere. Methane production in peatlands is believed to proceed primarily via either an acetoclastic pathway or a hydrogenotrophic pathway. It has been suggested that a methylotrophic pathway, in which methanogens produce methane from methylated substrates, is also viable. As part of an effort to test the significance of this pathway, methods were developed to measure a range of potential substrates at the nanomolar level in peatland porewaters. Potential substrates include methanol, methylamines and dimethylsulfide. A solid-phase microextraction gas chromatography-mass spectrometry method (SPME-GC/MS) was developed to measure mono, di, and tri methylamine and a purge and trap gas chromatography-mass spectrometry method (PT-GC/MS) was developed to measure dimethylsulfide and methanol. In all cases detection limits were at the low nanomolar level. To validate the methods, substrate concentrations were measured in porewaters from a number of peatland sites across a range of depths. Dimethyl sulfide levels were always below measurement detection limits. Methanol levels ranged from 33 to 1226 nM across all sites and depths and average mono, di and tri methyl amine concentrations were 368±183, 30±42, and 24±10 nM respectively. Methods and some preliminary data will be discussed.

Methanol, dimethylsulfide, and methylamine concentrations in peatland porewaters

2019 Fall National Meeting

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