Where k is decay rate of ammonia, q is correction factor (q > 1), T is
water temperature, k20 is the decay rate whenwater temperature is
20. From the Eq. (16), it indicates that the decay rate will be raise
with the rise of water temperature. The higher water temperature
can accelerates the decay rate of ammonia. The Songhua River
system has obvious seasonal dynamics, the difference of average
water temperature between summer and winter exceeds 30, so
water temperature of the river is the main reason for the distribution
of the k.