T94 Hydrogeology, Geochemistry, and Wetland Processes I: A Session in Honor of the Career of Donald I. Siegel

Monday, 23 October 2017
8:00 AM - 12:00 PM
Room 618/619/620

IDENTIFYING ENVIRONMENTAL PREDICTORS AND QUANTIFYING METHANE AND CARBON DIOXIDE FLUX FROM FOUR VERNAL POOLS, MAINE USA

Paper number: T94-6
Program: Technical Sessions
Time: 9:15 AM – 9:30 AM

Authors

Abstract

Vernal pools are small seasonal wetlands that are a common landscape feature of significant ecological importance in northeastern North American forests. However, even basic information about their biogeochemical functions, such as carbon cycling, is largely unknown. In this study, we estimated greenhouse gas fluxes from four vernal pools in central and eastern Maine, USA, with distinctly different geologic substrates and hydroperiods. Dissolved gas concentrations (CH4, CO2) and other water chemistry parameters (i.e. ortho-P, NH4+, SO42-) were monitored weekly at the bottom and surface of each pool between April and August 2016. The vernal pools were supersaturated with respect to CH4 and CO2 at all sampling dates and locations. Concentrations of dissolved CH4 and CO2 ranged from 0.4 to 2.1´102 μmol L-1 and 72 to 2.3´103 μmol L-1, respectively. Evaporative fluxes of CH4 and CO2 into the atmosphere ranged from 0.2 to 73 mmol m-2 d-1, and 30 to 5.9´102 mmol m-2 d-1, respectively; CH4 and CO2 flux increased over the season. Mass balance calculations showed that the pools had a relatively small capacity for gas storage, and that the produced gases evaporated into the atmosphere. During the study period, the vernal pools emitted between 0.2 to 5.9 kgC m-2 and 11 to 1.4´102 kgC m-2 of CH4 and CO2, respectively. Both CH4 and CO2 were positively correlated with surface temp, ortho-P, NH4+, DOC, alkalinity, and precipitation, and negatively correlated with pool volume, surface area and depth. Methane concentrations were best predicted by alkalinity and temperature. Carbon dioxide concentrations were best predicted by alkalinity, temperature, and dissolved oxygen. Carbon dynamics and greenhouse gas emissions are key to understanding how vernal pools fit into the global carbon budget and how their carbon cycles compare to other wetlands.

Geological Society of America Abstracts with Programs. Vol. 49, No. 6

doi: 10.1130/abs/2017AM-305369

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