Research On Variation And Migration Characteristics Of Phosphorus Speciation In Shiwuli River

As an essential element for algae-growth, phosphorus is regarded as the major factor to the lake eutrophication. The serious pollution of Chaohu Lake basins is ascribed to the introduction of exogenous phosphorus pollutants. Hence, monitoring and investigating the phosphorus content especially bio-available and endogenous phosphorus in river channel will do great assistance to the control the lake eutrophication.As the west part of Chao Lake is in worse situation, Shiwuli River is one of the most important phosphorus input sources. In this article, the pattern of spatial and temporal distribution of phosphorus in water and sediments are analyzed as well as the primary source of phosphorus, from data which are all based on the Shiwuli River. SMT method is employed to the investigation of the morphology of phosphorus from sediments in different levels in drought period. DGT and conventional chemical analysis methods are also utilized to explore the migration and transformation rule of phosphorus on the interface of water-sediments as comparison. Besides, the influence of pH and disturbance on the release of phosphorus is theoretically simulated. Results showed that:1.13locations from Shiwuli River are examined every month in one year:the Shiwuli River is seriously polluted, and the water quality is worse than Grade V all the year around. The pollutants display an accumulation trend from upstream to downstream. The DIP and TP contents in water vary dramatically in seasons and reach to the peak in summer, resulted from exogenous factors including high temperature, pH and dissolved oxygen. Results indicate that the draining outlets from S2in Jinzhai Road, S4in Jinhe Bridge and S5in Shubei Bridge are the dominant phosphorus sources.2. Four kinds of BAP in sediments of Shiwuli River in March, August and December are analyzed, and they exhibit a concentration pattern of AAP>Olsen-P> WSP>RDP. The contents of AAP and Olsen-P which are representative for BAP are quite high, denoting large phosphorus release capacity of the sediments from Shiwuli River.3. SMT extraction method and particle detector are employed to the analysis of the sediments in drought period, results suggest that a hugh homology exists in TN, TP and organic pollutants; HCl-P is highly concentrated in upstream while NaOH-P content which is easily releasable in downstream after S8enhances gradually;The particle size decreases along the river, which is more easily to absorb pollutants and there is a huge potential for sediments in downstream of Shiwuli River to release phosphorus if under exogenous disturbance.4. DGT method is used to test the water and sediments from the river for BAP content, the results demonstrate that the BAP concentration maintains a high level with an accumulation tendency in24h, which is consistent with consults conducted by conventional chemical methods. DGT technique could serve as an efficient tool to research BAP on the interface-sediments from the Shiwuli River. The combinational results of DGT and centrifugation-extraction technique unravel that, phosphorus pollutants absorbed on sediments show an immigration trend to the superficial water layer apart from samples from S1Swan Lake and S2Jinzhai Road. In addition, the stream way in downstream widens along with lower current, it is quite possible for blue algae blooming, which needs more monitoring and controlling.5. The influence of pH and disturbance on the phosphorus release from sediments is investigated by theoretical simulation. It is concluded that both acid and alkaline superficial water of sediments would promote phosphorus release while hardly any effect exhibits in neutral condition doesn’t any. The release of TP is significantly stronger than DIP, besides, the amount and rate of phosphorus release accelerate violently with an increasing pH. The releasing time extended to24h at pH9and reached to a stable level afterwards. Disturbance could sharply boost the amount and rate of phosphorus release:DIP release reaches to the top amount in1h under the circumstance of60r/min; TP release is stable in early4-6h under different disturbance, after that, the amount and rate augment violently along with boosted vibration and eventually stay at relatively stable level.