A low-cost automated trap to measure bubbling gas fluxes

Abstract

We describe a trap that can be used for automated, high temporal resolution measurement of ebullition fluxes in aquatic environments. The trap comprises a submerged cone connected to a transparent PVC pipe that serves as a collection chamber. A differential pressure sensor at the top of the pipe measures the pressure caused by gas accumulation in the chamber. The sensor circuit consists of low-power electronics and can function for longer than 6 months on two high-capacity AA lithium batteries. The circuit, batteries, and a commercial data logger that records the measurements are enclosed in a custom-made, 10-cm diameter waterproof housing. The trap is designed to be fabricated economically and easily so that many units can be deployed for greater spatial coverage. We have used several of these automated traps to measure bubbling fluxes at a lake, and have collected data continuously at a resolution of 5 or 10 min over 6 months. © 2010, by the American Society of Limnology and Oceanography.