This illustrates that RS incorporated
into soil was subject to fast C mineralization. RS
probably served as a substrate (CH3COOH, for CH4 and CO2
production) as well as an electron donor for CH4 formation
(CO2 reduction to CH4), the last terminal electron acceptor in
typical flooded soil. Along with the drop of Eh, pH simultaneously
increased to 6.5 to 8.7 (Figure 3b) encompassing the
optimal pH of 7.5 to 8.5 for methanogenesis