Distribution and source of organic matter in surface sediment from the muddy deposit along the Zhejiang coast, East China Sea

To constrain organic matter compositions and origins, elemental (TOC, TN, C/N) and stable carbon (δ¹³C) and nitrogen isotope (δ¹⁵N) compositions are measured for surface sediments collected from muddy deposit along the Zhejiang coast, East China Sea. The results showed that the TOC, TN, C/N, δ¹³C, and δ¹⁵N were 0.19–0.67%, 0.03–0.09%, 6.76–9.22, − 23.43 to − 20.26‰, and 3.93–5.27‰, respectively. The δ¹³C values showed that the mixing inputs of terrigenous and marine organic matter generally dominated sedimentary organic matter in the west part, and the sedimentary organic matters were mainly influenced by the marine organic matter in the east part of the study area. A stable carbon isotope two end member mixing model estimates ~ 38% terrestrial -derived and ~ 62% marine-derived inputs to sedimentary organic matter. Microbial mineralization strongly controls δ¹⁵N values, and therefore cannot be used to identify the provenance of organic matter for the Zhenjiang coast. - Highlights: • δ¹³C could effectively identify the provenance of sedimentary organic matter. • Terrigenous organic matter dominated sedimentary organic matter in the west part. • Marine organic matter was mainly from the algal cells in the east part.