Atmospheric
concentrations of methane have increased ∼2.4
fold since the industrial revolution with wetlands and inland waters
representing the largest source of methane to the atmosphere. Substantial
uncertainties remain in global methane budgets, due in part to the
lack of adequate techniques and detailed measurements to assess ebullition
in aquatic environments. Here, we present details of a low cost (∼$120
US per unit) ebullition sensor that autonomously logs both volumetric
ebullition rate and methane concentrations. The sensor combines a
traditional funnel bubble trap with an Arduino logger, a pressure
sensor, thermal conductivity methane sensor, and a solenoid valve.
Powered by three AA batteries, the sensor can measure autonomously
for three months when programmed for a sampling frequency of 30 min.
For field testing, four sensors were deployed for six weeks in a small
lake. While ebullition was spatially and temporally variable, a distinct
diurnal trend was observed with the highest rates from mid-morning
to early afternoon. Ebullition rates were similar for all four sensors
when integrated over the sampling period. The widespread deployment
of low cost automated ebullition sensors such as the iAMES described
here will help constrain one of the largest uncertainties in the global
methane budget.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.