Abstract: Abiotic nitrogen transformation processes can generate N₂O in estuarine wetlands. The abiotic processes of hydroxylamine (NH₂OH) and nitrite (NO₂^-) can produce N₂O, but production potential and affecting factors remain unclear. We conducted an experiment with three treatments (without nitrogen addition (CK), NH₂OH and NO₂^- additions) to determine N₂O production rates from abiotic processes in wetland soils of Min River Estuary. The results showed that N₂O production rates significantly differed among three treatments (P<0.05). The potential production rates of N₂O from abiotic processes under NH₂OH addition, NO₂^- addition, and without nitrogen treatments ranged from 16.88 to 307.99, -0.50 to 27.51 and -1.20 to 2.97 ng·g^-1·h^-1, respectively. The contributions of N₂O production from abiotic processes of NH₂OH and NO₂^- additions were 20.74%-98.73% and 1.27%-79.26%, respectively. Average N₂O production rates of abiotic processes for all the five soil types varied significantly among the three treatments (P<0.05). The average N₂O production rates of abiotic process of NO₂^- were in the order of Kandelia candel>Spartina alterniflora>Phragmites australis>Scirpus mariqueter>Cyperus malaccensis, while the rates of abiotic processes of NH₂OH were S. mariqueter>S. alterniflora>P. australis>C. malaccensis>K. candel. These results suggest that abiotic processes of NH₂OH have higher N₂O production rates compared to NO₂^-, and the N₂O production from abiotic processes of soil NH₂OH and NO₂^- varied largely among different vegetation soils. Soil pH, NO₂^-, NO₃^-, Fe²⁺， Fe³⁺  and C/N ratio were crucial factors affecting N₂O production rates from abiotic processes of NH₂OH and NO₂^-.

Key words: hydroxyamine, nitrite, abiotic process, nitrous oxide, Min River Estuary.