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Spatial Variations of N 2 O Fluxes Across the Water‐Air Interface of Mariculture Ponds in a Subtropical Estuary in Southeast China
Author(s) -
Yang Ping,
Wang Dongqi,
Lai Derrick Y. F.,
Zhang Yifei,
Guo Qianqian,
Tan Lishan,
Yang Hong,
Tong Chuan,
Li Xiaofei
Publication year - 2020
Publication title -
journal of geophysical research: biogeosciences
Language(s) - English
Resource type - Journals
eISSN - 2169-8961
pISSN - 2169-8953
DOI - 10.1029/2019jg005605
Subject(s) - estuary , mariculture , water column , environmental science , nitrification , aeration , aquaculture , subtropics , flux (metallurgy) , hydrology (agriculture) , sediment , environmental chemistry , nitrogen , oceanography , chemistry , ecology , biology , fishery , geology , geomorphology , geotechnical engineering , organic chemistry , fish <actinopterygii>
While aquaculture ponds are potentially important sources of atmospheric N 2 O, the magnitude and variability of N 2 O concentrations and fluxes both within and across the ponds remain poorly understood. In this study, we examined the small‐scale spatial variations of dissolved N 2 O concentrations in water and N 2 O fluxes across the water‐air interface from three mariculture ponds in a subtropical estuary in southeast China. Our results showed that the dissolved concentrations and diffusive fluxes of N 2 O in the shrimp ponds ranged between 2.3–19.2 nM and 16.4–589.7 nmol m −2 hr −1 , respectively, over the culture period. Significant variations of N 2 O concentrations and fluxes were observed within the ponds, with higher values being observed in the aeration area that could be attributed to the high rates of nitrification in the water column, as well as sediment N 2 O production and diffusive flux into the overlying water. Also, N 2 O concentrations and fluxes varied significantly among the three ponds as a result of the difference in N‐NO 3 − and N‐NH 4 + concentrations in the water column. The large fine‐scale spatial variations of N 2 O concentrations and fluxes observed in our aquaculture ponds suggested that management practices such as aeration and bait feeding could largely affect the extent that aquaculture activities have on N 2 O emissions and climate change through their influence on the physicochemical environment (e.g., oxygen and N‐NH 4 + concentrations) of the ponds.