the original dataset of the sedimentary organic matter in the Gulf of Thailand
To elucidate the distribution and fate of organic matter deposited in tropical regime of the SE Asian, this study and dataset shows the concentration, composition of sedimentary organic carbon based on the bulk and molecular level from the estuary to the coastal margins, and depicts the modern transport patterns of organic matter in Gulf of Thailand. Results indicated the variability of OM inputs and selective transport of fine sediment resulting in preferential dispersal of terrigenous OM. The bulk organic carbon indices with low C/N ratios (5.26 ~ 20.51, 7.63 ± 1.96) and enriched δ13C values (-24.2‰ ~ -20.4‰, -21.4 ± 0.56‰) could be likely related to the presence of marine-derived OM and anthropogenic OM inputs. The analysis of Monte-Carlo based mixing model further clarified the significant contribution of soil-derived OM inputs within the upper GOT (36 ± 10%) and the modern depocenter (29 ± 5%) from the lower GOT. The n-alkanes ranged from 0.15 to 5.29 μg/g, with an average of 1.24 ± 0.97 μg/g. Based on these results, a significant contribution of soil-derived OM at the modern depocenter from the lower GOT by coupling with the presence of high molecular weight (HMW) lipid-molecular evidences, reflecting the effects of hydrodynamic sorting and selective dispersal and re-deposition of terrigenous SOM around this area. This dataset including the concentration and indices of bulk SOM and compositional patterns of n-alkanes with sediment grain size, the relative proportions for Marine-OM (%), Soil-OM (%) and Terrestrial C3-plant (%) based on the Monte Carlo simulation as well as the PCA results.