Enhanced burial of land-based organic matter under climate change and human pressure: A tropical coastal sediment perspective
Description
Carbon cycling and anthropogenic interference are more extensive in tropical margins than in other regions of the world. In this study, bulk organic carbon (OC) and molecular markers, including n-alkanes and polycyclic aromatic hydrocarbons (PAHs), were analyzed in a sediment core obtained from the lower Gulf of Thailand to trace centennial-scale OC inputs under the combined impacts of natural processes and anthropogenic pressure. Analyses of the records of bulk OC and n-alkane contents revealed remarkable changes in the contribution of terrestrial OC since the 1980s, associated with variation in the regional climate regime. The synchronously increasing trends of molecular imprints such as that of perylene and the carbon preference index indicated that enhanced inputs of more degraded land-based organic matter were related to the destruction of a mangrove ecosystem and extensive coastline retreat. Higher PAH deposition fluxes before the 1980s reflected a significant increase in PAHs of petroleum origin, due to the increased burning of fossil fuels. Differences in the PAH records around the margins of Southeast Asia (Thailand, Philippine, Indonesia, and Malaysia) were consistent with large regional changes in energy consumption structures over the past century.