| Eutrophication is a very important problem in recent water environment study. The reasons for eutrophication lie not only in the pollution outside of water body, but also the sediment in it. Sediment can release large quantities of phosphorus in some conditions, which causes internal pollution. So it has significant meaning to study on the laws of move and transformation of phosphorus between overlying water and sediment so as to resolve eutrophic problems.This study has discussed the types, distribution characteristics and influencing factors of phosphorus by analyzing the overlying water and sediment in the rivers of the campus and Suzhou city.The results show that the river overlying water of the campus is eutrophied all the time. Temperature, algae including branches and leaves fell into river are the important factors which affect phosphorus content in river overlying water of the campus. The three sorts of phosphorus TP (Total Phosphorus), TDP (Total Dissolved Phosphorus), SRP (Soluble Reactive Phosphorus) in overlying water are well correlated. Basically, they all have extremely significant level. Many factors have effect on phosphorus of sediment and the correlation between each sort of phosphorus is complicated. Generally, the correlations among TP, IP (Inorganic Phosphorus) and NAIP (Non-Apatite Inorganic Phosphorus) are stable, which presents extremely significant level. However, it has bad correlation between OP (Organic Phosphorus) and the other types of phosphorus.Relatively, the most important factor that influences the phosphorus content in sediment is temperature. If it changes, other factors will change. For instance, the growth and death of algae are strongly related to temperature. Most phosphorus in river sediment of the campus exists as IP and there is more NAIP in IP, but some sediment has more AP (Apatite Phosphorus).The TP content in the river sediment of Suzhou city proper is high. It's about 1000mg/kg, which is far beyond the soil background value and more than the content in most rivers home and abroad. The phosphorus pollution in sediment has covered the whole city proper. The major phosphorus pollution in city proper sediment is IP pollution, which is the same as in the campus. IP is constituted by NAIP and AP,and its content equals to the sum of them. The contents and ratios of NAIP and IP differ from sample spots. NAIP prevails in the undredged rivers while AP is more in the dredged ones.Most overlying water in Suzhou city proper is worse than Class V requirement. Comparatively, the river water quality of the campus is a little bit better than others'. It varies among rivers of the urban district, from Classâ…£requirement to high Class V requirement. It's commonly bad in the Grand Canal and higher than Class V requirement, that's because the Grand Canal water body is frequently influenced by disturbing which can increasingly prompt sediment to release phosphorus.There is close phosphorus exchange between overlying water and sediment. The SRP in overlying water doesn't have obvious correlation with any type of sediment phosphorus, which indicates SRP does not come from the sediment phosphorus directly. However, the TP from overlying water has extremely significant correlation with the AP, NAIP, IP and TP from sediment, which explains the TP in overlying water mainly comes from the IP release from sediment. |
