Organic matter

• Dissolved organic carbon content is higher in deeper soil layers.
• The deep dissolved organic matter is older and more humified than at the surface.
• The vertical gradients studied are amplified during neap tides.
• Cr and Mn follow the dissolved organic carbon vertical gradient.
• Ni and Mo follow an opposite vertical gradient to dissolved organic carbon.

In June 2026, TROPECOS scientists from BOREA, iEES, UFF, MPEG and UFPA have sampled sediments cores, litters and litter bags in two Amazonian mangroves, Marapanim a preserved site and Salinopolis a site impacted by urbanization and sewage loads. In addition, forest inventories were performed in Marapanim.  

TROPECOS scientists involved in WP3 reveal that the composition of dissolved organic matter (DOM) in mangrove soils is strongly influenced by mangrove species and their biological traits, including mycorrhizal associations.

This is crucial because DOM plays a key role in carbon cycling and nutrient export from mangroves. These findings highlight that understanding species-specific DOM dynamics is essential to better assess carbon fluxes and the functioning of atoll mangrove ecosystems.

The second TROPECOS field work in mangroves of Rio de Janeiro (Mamangua and Itacoatiara) 24 May 2025 – 7 June 2025, involved 14 TROPECOS research scientists and students from BOREA, LPG, UFF and UFPA. We measured gas fluxes in mangrove soils and waters, dissolved carbon concentrations and water current in tidal creeks, and high resolution dissolved redox species in sediments using 2D gels.