Institute of Ecosystem Studies

2009 BES Annual Meeting Presentation and Poster Abstracts

Sensor Technology Application: Measuring Soil CO2 Efflux
Xia, Lijun
Co-Authors: Lijun Xia,Yun Cheng, Katalin Szlavecz, Jayant Gupchup

Abstract: As an application of sensor technology used in environmental studies, this project is a study and measurement of soil CO2 efflux at an urban site at Cub Hill, Maryland, as well as a forest site at the Smithsonian Environmental Research Center (SERC). A wireless sensor network is deployed at each site to monitor CO2 concentration, soil temperature, and soil moisture remotely and continuously every 15 minutes. The data is collected remotely via the network’s radio transmitters. While sensors make it possible to measure CO2 concentration in the soil, the rate of CO2 production in the soil cannot be measured directly. The experiment utilizes two different methods for soil CO2 efflux measurement: the traditional “chamber method”, in which sensors measure CO2 concentration in an enclosed chamber on the soil surface over a period of time, as well as the “gas well method” in which measurements of CO2 concentration, soil temperature and soil moisture are taken at three soil depths. The main advantage of the gas-well method is its continuous sampling over time which allows for the observation and consideration of precipitation and other environmental changes in the data. In this experiment, the chamber method and gas well method showed comparable results in the measurement of soil CO2 efflux, showing the gas-well method to be an appropriate method. The gas-well method was able to show a positive correlation between soil CO2 efflux and moisture, with temperature having less of an effect. Furthermore, the CO2 efflux was shown to be unexpectedly more variable at the Cub Hill site than the SERC site possibly due to its urban terrain when compared to the isolated forest environment at the SERC site.