Carbon, nitrogen geochemical character and organic matter source study in the coastal sediment of Yellow River Estuary

Carbon, nitrogen geochemical character and the sources of organic matter were studied in the coastal sediment of Yellow River Estuary.The concentration of total organic carbon (TOC) and total nitrogen (TN), C/N, δ¹³C, δ¹⁵N was (0.40±0.19)%、(0.049±0.018)%、7.92±1.48、(-23.94±0.69)‰、(7.06±0.72)‰ respectively.The concentration of TOC decreased significantly as distance from the river mouth increased offshore(P < 0.05), whereas δ¹³C increased very significantly(P < 0.01).In the study area, the organic matters in the sediment were constituted of terrestrial, estuarine and marine organic carbon.The contribution of terrestrial, estuarine and marine organic carbon to TOC pool was (44.6±6.5)%, (6.5±5.5)% and (48.9±6.1)% respectively.The contribution of terrestrial organic carbon to TOC pool decreased significantly as distance from the river mouth increased offshore(P < 0.05), whereas contribution of marine organic carbon to TOC pool increased significantly(P < 0.05).The bury rate of terrestrial organic carbon was 171~214 t/(km²·a)in the study area.And nearly 20% terrestrial organic carbon transported via estuary was buried in that area.Not only the sources but also the fates of organic matters were impacted by transportation of Yellow River.