求翻译：总氮和氨氮在产流初期，浓度较高，随着产流量的增大浓度逐渐降低，到产流后期，浓度又逐渐增大。是什么意思？

Total nitrogen and ammonia in the beginning of the runoff, the higher concentration decreased with the increasing concentration of runoff to the late runoff, the concentration is gradually increasing.

Total nitrogen and ammonia nitrogen in concentration is high in the early middle-class, with output declining flow of increasing concentration, concentration, and the middle-class late and is gradually increasing.

The total nitrogen and the ammonia nitrogen are producing flow the initial period, the density are high, along with produces the current capacity to increase the density to reduce gradually, to produces flows the later period, the density increases gradually.

Total nitrogen and ammonia in the early production flow, density is higher, as the flow increases the concentration of gradually reducing production, to a later runoff concentration gradually increases.

Technology Department, education, CAs, engineering and National Science Fund Committee,