Methane and nitrous oxide fluxes in the polluted Adyar River and estuary, SE India

We measured dissolved N₂O, CH₄, O₂, , and on 7 transects along the polluted Adyar River–estuary, SE India and estimated N₂O and CH₄ emissions using a gas exchange relation and a floating chamber. High implied some nitrification of a large anthropogenic pool. In the lower catchment CH₄ was maximal (6.3±4.3×10⁴ nM), exceeding the ebullition threshold, whereas strong undersaturation of N₂O and O₂ implied intense denitrification. Emissions fluxes for the whole Adyar system ∼2.5×10⁸ gCH₄ yr⁻¹ and ∼2.4×10⁶ gN₂Oyr⁻¹ estimated with a gas exchange relation and ∼2×10⁹ gCH₄ yr⁻¹ derived with a floating chamber illustrate the importance of CH₄ ebullition. An equivalent CO₂ flux ∼1–10×10¹⁰ gyr⁻¹ derived using global warming potentials is equivalent to total Chennai motor vehicle CO₂ emissions in one month. Studies such as this may inform more effective waste management and future compliance with international emissions agreements. [Copyright &y& Elsevier]