Challenges in the measurement of emissions of nitrous oxide and methane from livestock sector

Abstract

Over the past two decades, the interest to decrease the emission levels of greenhouse gases (GHGs) has increased. The livestock sector has been put under continuous supervision and regulation because it is an important source of GHG emissions. In 2012, it was estimated that 3.46 Gton CO2-eq was released from this sector, methane (CH4) being the gas with the highest contribution (43 %), followed by nitrous oxide (21 %). In order to determine real emissions, it is necessary to use precise and reproducible measuring methods which can be complex and expensive. The challenges in these methods are focused on achieving an accurate assessment and monitoring of gas emissions, developing monitoring systems for the continuous measurement and implementation of methodologies for their validation in field in order to understand the complex nature of environmental variables affecting gas production. Different techniques for the measurement of CH4 and nitrous oxide (N2O) emissions are reviewed and discussed in this research. The passive flux sampling to measure emissions of these GHGs has been identified as an interesting alternative technique because it is practical, low cost and robust. This kind of sampler is highly adequate to measure emissions of N2O and CH4 originating from some sources of the livestock sector, but at this moment, no prototypes are commercially available and thus more research is necessary in this field.