Nutrients in the South Yellow Sea Sediments

The distributions of different forms of nitrogen in the SYS surface sediments are shown in Fig. 3.30, from which the distribution characteristics of different forms of nitrogen may be obtained. The four forms of extractable nitrogen are 

Nitrogen in weak acid extractable form (WAEF-N) the content of WAEF-N is the lowest among all the nitrogen forms, and ranges from 0.44 to 1.25 

The distributions and forms of nitrogen are affected by many factors. Both circumstances and sediment characteristics can become the determinant under a certain condition. Table 3.12 shows the correlation coefficients (r) among the contents of different forms of nitrogen and environmental parameters and fine sediment ( 31 pm) proportions of the SYS surface sediments. The correlation between the contents of different forms of nitrogen and the affecting factors are discussed as follows. 

Forms Region I Region II Region III Whole area 

The DIN exchange flux at sediment-water interface was 1.31 mmol/(m -d) (from sediment to overlying water) by simulating examination in Chung et al. (1999). Assuming the DIN flux of fine sediment ( 31 fim), medium sediment (Sl GS jum) and coarse sediment ( 63 im) full flux, 1/2 of full flux and 1/8 of full flux respectively, that of natural sediments in different regions could be obtained from the formula (Song et ah, 2003) 

---