<b>Phytoplankton carbon sequestration in inland waters can not benefit climate warming mitigation</b>

In inland waters, characterized by low salinity and shallower conditions, carbon dynamics are markedly different. In these environments, the organic carbon fixed by phytoplankton tends to decompose more rapidly due to higher microbial activity, releasing CH₄, a far more potent greenhouse gas than CO₂ . Even if a subset of the CO₂ fixed by phytoplankton in inland water environments is buried, this conversion of some of the carbon into CH₄ likely contributes to a warming effect. Whether the process by which phytoplankton fix CO₂ and subsequently convert it into CH₄ leads to a warming effect, as well as the magnitude of such an effect, depends on the efficiency of organic carbon decomposition (x) and the proportion of this organic carbon converted into CH₄(x₁).