The nutrients distribution of the interstitial water and the exchange flux in the northeastern South China Sea

In order to study the distribution of the biogenic elements in the sediment and the impact on the marine ecological environment, the nutrients spatial distribution and the sediment-water exchange flux have been analyzed in the interstitial water in northeastern South China Sea during the period from October to November in 2014. The results showed that the average content of nutrients ( NH₄-N、NO₃-N、NO₂-N、PO₄-P、SiO₃-Si) were 25.20、11.62、3.05、7.42、305.8μmol/L in the sediment interstitial water, respectively. The SiO₃-Si and NH₄-N were the major components and the NH₄-N accounted for 57.4%~75.1% of DIN. Through the estimation of the exchange flux at the interface between the sediment and water, the results indicated that the average flux of NH₄-N、NO₃-N、NO₂-N、PO₄-P were 8.34、1.89、-0.89、0.41μmol/m²/d, respectively. The sediment as the source of nutrients (NH₄-N、NO₃-N and PO₄-P) provided a lot of NH₄-N、NO₃-N and PO₄-P constantly into the overlying water. We preliminarily discussed the geochemical behavior of nutrient in the process of early diagenesis, and the accumulation and transportation of the nutrient in sediment.