Calculation of inorganic nitrogen fluxes in the Yangtze estuary tidal wetland

Based on the data of inorganic nitrogen fluxes at the sediment-water interface of eleven typical sectional sites in tidal wetland of the Yangtze estuary from 2002 to 2004, we established the inorganic nitrogen fluxes interpolation model and calculating model. Using these models, we studied the spatio-temporal distributing characteristics of inorganic nitrogen fluxes, and calculated the total fluxes in different sectional tidal wetlands and different seasons. The results show: (1) compared to IDS and Ordinary Kriging, the forecast precision of fluxes interpolation is better using revising GIDS interpolation model; (2) the sediment-water exchanges of inorganic nitrogen showed complicated spatial differences and seasonal variations; (3) when using revising GIDS model to interpolate, in order to improve calculating precision of fluxes, the spatial scale should adopt 1.2′ × 1.2′; (4) the Yangtze estuary tidal wetland releases inorganic nitrogen fluxes into water in spring, and the releasing quantity is 1.33 × 10⁴ t. In summer, autumn and winter, Yangtze estuary tidal wetland purifies inorganic nitrogen fluxes from water, and the purifying quantity is 4.36 × 10⁴ t, 6.81 × 10⁴ t and 2.24 × 10⁴ t, separately. All the year round, the Yangtze estuary tidal wetland purifies inorganic nitrogen fluxes from water, tand he purifying quantity is 12.1 × 10⁴ t; and (5) the purifying ratio is about 23.0%.