资源环境科技发展态势分析平台

To improve estimation of the dry deposition flux (F_d) of nitrogen and phosphorus over the ocean, the concentrations of NO₂⁻, NO₃⁻, NH₄⁺, and PO₄³⁻ in aerosol particles were measured from 2005 to 2017, and their deposition rates (V_d) were modeled over the marginal seas of China and the northwest Pacific (NWP). Combined with the modeled rates and the measured size distribution, the V_d values of NO₂⁻, NO₃⁻, NH₄⁺, and PO₄³⁻ over the studied ocean region were calculated to at 0.92 ± 0.06, 0.95 ± 0.08, 0.68 ± 0.03 and 0.65 ± 0.06 cm·s⁻¹ on average, respectively. The spatial variation in V_d for these species was dependent on the wind speed and mass concentration size distribution. Based on the multiyear observations over the region, the average concentrations of atmospheric NO₂⁻, NO₃⁻, NH₄⁺, and PO₄³⁻ were 2.07 ± 1.58 nmol·m⁻³, 58.5 ± 44.3 nmol·m⁻³, 107.9 ± 56.7 nmol·m⁻³ and 1.13 ± 1.10 nmol·m⁻³, respectively. The estimated F_d of NO₂⁻ was lower than 1 μmol·m²·d⁻¹ in most ocean regions, although the F_d of NO₃⁻, NH₄⁺ and PO₄³⁻ were 42.74 ± 25.02, 57.40 ± 29.50 and 0.66 ± 0.72 μmol·m²·d⁻¹, respectively. Except for the South China Sea, the F_d values of NO₃⁻ and NH₄⁺ were 3–6 times higher over the marginal seas than the NWP while the PO₄³⁻ flux was only high over the Yellow and Bohai Seas. The dissolved N/P ratio influx varied from 84 to 338, indicating that N was equivalent to the relative abundance of P during the atmospheric input to the China marginal seas and the NWP. Our results showed that the long-term input of atmospheric anthropogenic nutrients would cause different influences on the stoichiometric ratios of nutrients and primary productivity between marginal seas and open ocean.