Metal Oxide Gas Sensors for Monitoring Regulated and Greenhouse Gas Fluxes From Manure Sources.

In recent years, public concern for regulated and greenhouse gas (RGHG) emissions from animal feeding operations (AFOs) has continued to increase as population expansion encroaches on rural farming areas. The need for defensible information on RGHG emissions from AFOs becomes a current major challenge to establish appropriate gas emission mitigation strategies, including developing gas emissions regulations for farming operations. With the advancement of modern solid state technology, solid state gas sensors have been extensively used for detection of a wide variety of gases at low ppm levels and can be applied in many different applications. We have recently engineered a multi-gas sensor system based on commercially available solid state sensors (Synkera Technologies Inc., Longmont, CO) initially targeting at NO_x, NH₃, CH₄, H₂S, and VOCs and thus potentially apply the system for long-term measurements and monitoring of RGHG fluxes from AFOs. The aim is to identify and evaluate detection limits, sensitivity and stability of each sensor by introducing a board range of known concentrations of the target gases into a calibration chamber. The laboratory experiments have been designed and set up for multi-gas sensor testing under humidity and temperature conditions anticipated during the field application. The governing elements for biological respiration and biochemical gas production in farmyard manure and manure-amended soils, including water content, oxygen level concentration and temperature are monitored during the laboratory experiments. In this presentation, we will discuss the framework for developing the multi-gas sensor, evaluation of sensor calibration and testing results as well as challenges in design and development of the multi-gas sensor prototype potentially enabling long-term monitoring capabilities for AFO gas emissions.