Contamination Characteristics And Release Phosphate For Qu Jiang South Lake

With the continuous development of social economy, the life quality and ecological environment has been enhanced more and more, waterscape is an important part of urban landscape. The urban landscape water not only beautify urban environment but also could improve the micro climate surrounding the water. However, the landscape water quality deterioration and eutrophication phenomenon, at the same time brings many new environmental problems in recent years. In this paper, Qu jiang South Lake was chosen as the study object, based on the typical sampling points and everal related works were carried out, such as water quality monitoring, basic properties of sediment monitoring and simulation research of the phosphorus release characteristics in sediment.The hydrochemical characteristics of Qujiang South Lake as well as the temporal and spatial distribution of different forms of N and P were investigated. Qujiang South Lake’s characteristics was high turbidity,low salinity and alkaline landscape. HCO3-and Ca2+ were main anion and cation, ion content characteristic was Ca2+>Mg2+>Na+ > K+, HCO3-> SO42-> Cl-. The hydrochemicaln of Qu jiang South Lake is Bicarbonate-Na-Ⅰtype. Nitrogen and phosphorus in water with the seasons change showed that concentrations of total nitrogen were low in both summer and spring, which much high in both winter and autumn. The high contentration of nitrate was recorded in autumn and winter, the maximum contentration of Ammonia and nitrite was recorded in summer. The concentration of phosphorus reached its maximum in spring and summer, its minimum in autumn and winter. Seen from space, the nitrogen and phosphorus in the form of higher than on lake, under the relative distribution; the evaluation results of fuzzy comprehensive evaluation method indicated that the water quality of Qujiang South Lake isⅣclass and total nitrogen as the main pollutants.The study results showed that:the sediment of Qujiang South Lake p H value is 7.50~8.07, containing high moisture content and low organic pollution. Its sediments of total nitrogen content is 494.86~823.12 mg/kg and organic nitrogen cleaner Ⅱ class level; total phosphorus content is 280.56~543.55 mg/kg. The distribution of various forms of P in the sediment surface and bottom of Qujiang South Lake was investigated by SMT method. The result showed that the Ca-P was the main form. The characteristics of phosphorus forms change were explored by simulation experiment under different environmental conditions which was temperature, p H dissolved oxygen(DO) and disturbance. The Al-P and Ca-P were dissolved quickly under acidic conditions. The NH4-P of the maximum release amount under the disturbance of the external force. The Fe-P and Org-P were greatly influenced by DO, p H and temperature. Its adsorption and release capacity had significant differences and the effect of eutrophication on water can not be ignored. It is the first time to investigate the water environmental pollution and analyze its characteristics. Meantime, the behaviors of P desorption on the sediments were studied. This study provided evidences for pollution source identification and for the water quality improvement and management.