Ancillary Variables, N2O Concentrations, and N2O Diffusive Fluxes in the Subtropical Mariculture Ponds in Southeast China

We examined the plot-scale spatial variations of dissolved N2O concentrations in water and N2O fluxes across the water-air interface in the subtropical shrimp ponds in southeast China using the headspace equilibration and the gas transfer methods. Our results showed that the dissolved concentrations and diffusive fluxes of N2O in the shrimp ponds ranged from 2.26 to 19.20 nM and from 16.43 to 589.65 nmol m-2 h-1, respectively, over the culture period. Significant variations of N2O concentrations and fluxes were observed within ponds, with higher values being observed in the aeration area that could be attributed to the enhanced nitrification and denitrification. Also, N2O concentrations and fluxes varied significantly among the three studied ponds as a result of the difference in N-NO3- and N-NH4+ concentrations in water. The large fine-scale spatial variations of N2O concentrations and fluxes in our aquaculture ponds suggest that management practices such as aeration and bait feeding could greatly affect the influence of aquaculture activity on N2O emissions and climate change