SiO3-Si/PO4-P was decreasing appreciably, NO2-N/DIN, NH4-N/DIN, NO3-N/DIN, DIN/PO4-P and SiO3-Si /DIN all kept steady.

• SiO3-Si/PO4-P比值略有所减小,NO2-N/DIN,NH4-N/DIN,NO3-N/DIN,DIN/PO4-P和SiO3-Si/DIN的比值均保持稳定。