Date of Award

Winter 2014

Project Type

Thesis

Program or Major

Earth Sciences

Degree Name

Master of Science

First Advisor

Ruth Varner

Second Advisor

Michael Palace

Third Advisor

Mark Hines

Abstract

Ebullition, or bubbling, is one pathway of methane (CH4) emission to the atmosphere from wetland ecosystems. Rates of ebullition vary spatially and temporally according to dominant vegetation type, peat density and time of year or season. We studied the continuous and episodic nature of ebullition and how it varies with species composition using six acoustic and manual sensors deployed in a temperate wetland, Sallie's Fen, Barrington, NH, in 2011 and 2012. Six additional sensors were installed in June 2013 and all sensors ran from typically June to October. A subsample of the manual bubble collections at each sensor was analyzed for 13C-CH4 to help us determine whether fractionation was occurring during the formation of bubbles. Our results indicate that the sedge-dominated and shrub-dominated sites show seasonal patterns and variability from year to year, but higher rates of ebullition in the shrub-dominated sites occurred in two of the three years. Methane in bubbles from both vegetation types does not appear to undergo fractionation while it is being formed into a bubble.

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