Abstract: To clarify spatial and temporal dynamics of N₂O concentration in agricultural watershed, water samples in the Jurong Reservoir watershed were collected from October 2015 to September 2016. By measuring the headspace gaseous N₂O concentration using the method of headspace balance-gas chromatography, the N₂O concentration in water was calculated. In combination with parameters of water quality, factors influencing aquatic N₂O concentration were analyzed. Results showed that the water N₂O concentration in Jurong Reservoir watershed varied from 5.04 to 61.83 nmol·L^-1. The concentrations of N₂O in rivers, ponds, and the reservoir peaked in winter, with values being （30.26±12.33）, （21.28±5.98）, and （18.56±2.27） nmol·L^-1, respectively. The average N₂O concentrations in different water types were in order of rivers (25.93±11.60） nmol·L^-1, ponds (20.03±9.57） nmol·L^-1, and the reservoir (16.17±4.72） nmol·L^-1. The aquatic N₂O concentration was significantly positively correlated with dissolved oxygen (DO), redox potential (ORP), ammonium nitrogen (NH₄⁺-N), nitrate nitrogen (NO₃^--N), nitrite nitrogen (NO₂^--N), and dissolved inorganic nitrogen (DIN), and negatively related to water pH.

Key words: spatial mapping, urban protected area, non-monetary value evaluation, cultural ecosystem services value, public participation GIS