Nitrogen in the North Yellow Sea Sediments

Five core sediment samples were collected with the box sampler, and then cut at 2 cm intervals. The sediments location was as shown in Fig. 3.32. Four exchangeable forms of nitrogen were analyzed in every sub-sample, including lEF-N, WAEF-N, SAEF-N, and SOEF-N. 

SAEF-N The primary form of SAEF-N was Fe-Mn oxide combined form, whose formation and distribution were affected by the oxidation-reduction characteristics of the sediment environment. The average concentrations in 5 cores were 9.18 pmol/g in Cl, 11.95 j,mol/g in C2, 5.66 pmol/g in C3, 6.27 pmol/g in C4, and 4.71 j,mol/g in C7, reflecting the difference in the oxidation-reduction characteristics in the 5 cores. SAEF-N concentrations presented complex variations with depth, as well as the ratios of NO3-N to NH4-N (Table 3.20). 

The grain size and components of sediments played important roles in the distribution of elements in the sediments, and affected the local biogeochemical 

The concentrations of all forms of nitrogen in sediments varied with the sediments texture. Generally, fine-grained components directly affect the form, content, and distribution of nitrogen in natural sediments. The distributions of 4 exchangeable nitrogen forms in different components of sediments were listed in Table 3.23. It was noticeable that the concentrations of 4 exchangeable 

Station Grain size lEF-N WAEF-N SAEF-N SOEF-N TN 

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