Dry and Wet Fluxes of Nutrients

There is still lacking complete knowledge of the atmospheric deposition in the YS and the ECS from the data available up until now. Therefore, it is necessary to deeply analyze the flux of nutrient elements via the atmosphere to the ocean. Wan et al. (2003) reported the following results of dry and wet fluxes of nutrients in the SYS. 

The dry deposition velocity of particles depends on many factors, such as the size of particles, wind speed, relative humidity and the stability of the surface layer atmosphere. So there are many difficulties in estimating the dry deposition velocity accurately. It is assumed that the dry deposition velocity of nutrient elements is 2.0 cm/s according to the research results. 

The concentrations of aerosols in each season are shown in Table 3.8 (Wan et ah, 2003) and estimated by weighted average of data from representative stations. Silicate aerosol is not taken into account here, since the silicate concentration observed in aerosol is too low in the YS. Cheju Island (33° 17 N, 126° 10 E) is taken as the representative station in the southern YS but, for lack of information on phosphate aerosol, its concentration is estimated using observed data from its vicinity. The concentrations of phosphate in aerosol is about 0.06 pg/m over the Xiamen area and about 0.307 pg/m in northeastern China. 

In summer the flows are from southern China and Japan, Pacific maritime conditions. In addition, summer is the wettest season and rain scavenging also contributes to the summer minimums. It tends to be the minimum in the summer time. Nitrate also shows a similar cycle. According to the concentrations of nutrients and sulphate described above, the dry deposition fluxes can be obtained in each season. The seasonal variability of dry deposition fluxes is similar to that of its concentration. The dry deposition flux of nitrate in the southern YS is at a maximum in spring and reaches a minimum in summer. Other nutrient elements in the southern YS have similar seasonal cycles to that of nitrate. 

From the concentrations in precipitation and monthly rainfall data in Table 3.10, we can easily conclude the monthly average wet deposition fluxes in the southern YS (Table 3.10, Wan et al., 2003). The seasonal variability of wet deposition fluxes in the southern YS is contrary to that of dry deposition fluxes. It tends to reach a maximum in summer and a minimum in winter. Though the concentrations are relatively low in summer, the wet deposition fluxes are still the greatest in the whole year due to enormous rainfall. By comparing dry and wet deposition fluxes, it can also be found that the wet 

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