Flux chamber methods for quantifying greenhouse gas emissions from composting piles: Applicability, challenges, and future perspectives

The increasing concern over greenhouse gas (GHG) emissions from composting piles has underscored the need for accurate quantification methods.This review assesses the applicability of flux chamber techniques as reliable tools for measuring GHG emissions during composting.Flux chambers are widely used because of their practicality, cost-effectiveness, and straightforward design; however, their accuracy depends on several factors, including chamber dimensions, airflow rate, recovery efficiency, gas properties, and environmental conditions, such as moisture and temperature.Two main types (static and dynamic chambers) are discussed, along with their respective strengths and limitations.Reported studies show that flux chambers can achieve high accuracy, with recovery efficiencies of 97-100% when airflow rates are maintained between 2 and 5 L/min.Nevertheless, challenges remain in capturing spatial and temporal variability, which can lead to underestimations or overestimations.To address these issues, protocol standardization, calibration, and careful chamber placement are recommended in future studies.Emerging alternatives, such as passive diffusion flux chambers, may help overcome the limitations of traditional designs.Overall, the combination of flux chambers with complementary methods, such as micrometeorological or eddy covariance techniques, can enhance their reliability.These improvements can facilitate more accurate emission assessments and contribute to sustainable waste management and climate change mitigation strategies.