Dominance of terrigenous particulate organic carbon in the high-turbidity Shuangtaizihe estuary

Suspended sediment samples were collected from the high-turbidity Shuangtaizihe estuary to analyze particulate organic carbon (POC) and stable carbon isotope composition (δ13C) of organic materials. The POC values of the Shuangtaizihe estuary are relatively low (1.2–1.4%) but remain stable over the whole salinity range sampled, which suggests the predominance of a terrigenous source over the mass transport of organic materials in the estuary. The δ13C values of particulate organic materials (−25.0 to −23.5‰) are heavy compared to detritus of higher plants (e.g. tree leaves), but similar to other Chinese rivers. The compositional characteristics of POC and δ13C indicate a large and isotopically constant material source from the organic matter reservoir of soils over the drainage basin.