Work

Effect of nitrogen pollution input on carbon cycling in mangrove constructed wetlands

Year: 2026

Type: article

Abstract: Nitrogen pollution can disrupt nitrogen cycling processes in mangrove wetlands, its effects on carbon (C) cycling are poorly understood. This study investigated the effects of varying nitrogen pollution on C input in Kandelia obovata , and disentangled the distinct impacts of microbes versus K. obovata - microbe interactions on C metabolism. Under high N pollution, K. obovata enhanced photosynthesis but suppressed root exudation ( R DOC ) and altered exudate composition, which inhibited microbial gluconeogenesis and TCA cycle activity, accompanied by higher greenhouse gas (GHG, including CO 2 and N 2 O) emissions and reduced soil C pool stability. Notably, independent microbial treatment maintained a more stable C pool compared with K. obovata - microbe interactions. Conversely, low nitrogen pollution decreased photosynthetic C input but stimulated the release of R DOC and dissolved organic C, and this pollution might suppress anaplerotic reactions, TCA cycle, and gluconeogenesis of K. obovata - microbe. Furthermore, soil C pool was particularly influenced by interactions between K. obovata and microbes, despite resulting in lower GHG emissions. Medium N pollution provided an appropriate environment characterized by moderate photosynthesis and CO 2 release, along with the lowest N 2 O emissions. Moreover, compared to the effects of independent microbial, the influence of K. obovata - microbe contributed more significantly to maintaining the stability of soil C pools, which related to a decreased intensity of anaplerotic reactions, the TCA cycle, and gluconeogenesis. This study can provide a theoretical reference for local authorities to mitigate GHG emissions and preserve C sink functions of mangrove wetlands under N pollution stress.

Source: Marine Pollution Bulletin

DOI: 10.1016/j.marpolbul.2026.120463