Study of carbon content tracing sediment diffusion bound after water-sediment regulation in the Yellow River estuary

The particulate organic carbon content(POC)and particulate inorganic carbon content(PIC)in total suspended solid(TSS)are used to trace sediments diffusion bound in Bohai after the fourth test of water-sediment regulation of the Yellow River,the result indicates that POC and PIC in sediment are both stable with season changing,their mean content are(1.75×0.28)% and(0.51×0.08)% respectively.When TSS concentration is below 30 mg/L,PIC in TSS decrease swiftly to 0, whereas POC in TSS increase promptly.According to the analysis of chlorophyll-a and mineral in TSS,when TSS is less than 30 mg/L,phytoplankton increases,but the sediment from the Yellow River decreases in TSS.Simultaneously,ΣC₂₀^-/ΣC₂₀⁺ and carbon proponderance index(CPI)of n-alkane increase and decrease obviously.TSS=30 mg/L can be regarded as the effective boundary between the allochthonous TSS and autochthonous TSS.The sediment from the fourth test of water-sediment regulation of the Yellow River diffuses to southern river-mouth at surface layer;While at bottom layer,sediments diffusion range concentrates at northern and southern river-mouth of the Yellow River.the central section of Laizhou bay is likely to be the habitation of sediment from the fourth test of water-sediment regulation of the Yellow River.