Sources and contribution of terrigenous organic carbon to surface sediments in the Gulf of Mexico

A study of terrigenous organic matter in offshore surface sediments in the Gulf of Mexico revealed that offshore sediments originate from grassland soils in the Mississippi River drainage basin and that nearshore sediments derive from coastal forests and swamps. The study examined the chemical and stable isotope signatures of oxidation from lignins in the organic matter. It enabled researchers to differentiate between matter which originated from plants which use the C4 mechanism in photosynthesis and those which use the C3 mechanism. These results significantly expand knowledge of the nature and fraction of terrigenous organic carbon in marine sediments.