Wavelet Analysis on NH3-N Pollution Index Changes of the Middle-Upper Minjiang River during Last 6 Years

This paper explores and identifies the rules of the unsteady evolution of NH3-N in the upper and middle reaches of Minjiang River through multi-scale analysis on the weekly NH3-N data for the last six 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 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 and industrial construction, etc., is high in winter and spring, mild in summer and autumn.