Unsteadiness of NH3-N Pollutant in the Middle-Upper Minjiang River

This paper explores and identifies the rules of the unsteady evolution of NH₃-N pollution in the upper and middle reaches of Minjiang River through multi-scale analysis on the weekly NH₃-N pollution data for the last five years provided by the water quality monitoring station, Minjiang River Bridge, Leshan City, Sichuan Province. The results of wavelet analysis indicate that the NH₃-N pollution index oscillates alternatively and differently at each time-scale in a 1 year cycle, and the density of NH₃-N, subject to the runoff volume, the effects of Wenchuan earthquake and agricultural seeding, etc., is high in winter and spring, mild in summer and autumn.