CO2 Emissions from Drainage Canals in Southeast Asian Peatlands

Southeast Asian peatlands hold 11-14% of peat carbon globally, but these carbon stocks are mobilizing following widespread land use change. While the loss of tropical peatland carbon via peat soil carbon dioxide (CO2) emissions has been estimated, a potential pathway for additional loss is through CO2 emissions from the water surface of the drainage canals covering these peatlands, emitting old peat carbon directly to the atmosphere. Here, we measured rates of CO2 emission from drainage canals in tropical peatlands surrounding the city of Pontianak, in West Kalimantan, Indonesia. CO2 emissions were measured using a floating chamber equipped with an SCD30 CO2 (Sensirion) sensor. Across the 13 sites surveyed, we found that CO2 emissions from drainage canals varied 10-fold and fell within the range of previously published estimates. In this survey, the size of canals was found to affect the emission rate, with the narrowest canals having the highest CO2 emission rates. Conversely, there was little discernable variation in emission rates across different land-use types, including oil palm plantation and mixed agricultural use. Given the limited number of CO2 emission estimates from drainage canals in Southeast Asia, the findings from this study helped identify which drainage canals emit more CO2 to the atmosphere. With greater understanding of the spatial patterns in CO2 emissions from drainage canals, we can better predict total peatland CO2 emissions in Southeast Asia.