Composition and sources of sediment organic matter in a western Iberian salt marsh: Developing a novel prediction model of the bromine sedimentary pool.

Salt marshes are sensitive highly productive habitats crucial for carbon cycling. This study presents a comprehensive analysis of organic geochemical indicators and geochronology in the Mira salt marsh (SW Portugal) over eight centuries. The closely intertwined carbon and bromine (Br) biogeochemical cycles in these environments can influence the fluxes of volatile compounds such as ozone-depleting methyl bromide, emphasizing the importance of understanding sediment organic matter (OM) origin, budget, and composition in salt marshes.

Refractory organic matter in coastal salt marshes-effect on C sequestration calculations.

The age and ability of salt marshes to accumulate and sequester carbon is often assessed using the carbon isotopic signatures (ΔC and δC) of sedimentary organic matter. However, transfers of allochthonous refractory carbon (C) from the watershed to marshes would not represent new C sequestration. To better understand how refractory carbon (C) inputs affect assessments of marsh age and C sequestration, ΔC and δC of both total organic carbon (TOC), C, and non-C organic matter fractions were measured in salt marshes from four contrasting systems on the North Atlantic coast.