Summer hypolimnetic and whole‐lake under‐ice measurements in an experimentally acidified lake suggested that rates of in situ decomposition in sediments (measured as methane and inorganic carbon release) were unaffected over an epilimnetic pH range of 6.7–5.1. This was apparently because microbial processes kept the pH at 6.0 or above just a few millimeters below the sediment surface even after lake water had been acidified for 8 years. In laboratory studies where the pH of mixed, fresh lake sediment was controlled at reduced levels, decomposition rates of carbon that had been in the sediments for several months were unaffected at pH values as low as 4.0. However, decomposition rates of newly sedimented material began to decrease at pH 5.25–5.0. Decomposition processes were less affected during the acidification of Lake 223 than were higher life forms.

Kelly, C. A., Rudd, J. W. M., Furutani, A., & Schindler, D. W. (1984). Effects of lake acidification on rates of organic matter decomposition in sediments. Limnology and Oceanography, 29(4), 687–694. Portico.