Study On Pollutant Release And Multi Phase Interface Between Water And Sediment

The endogenous pollution becomes the principal facter which has bad effect on source water quality after the extraneous pollution has been effectively eliminated. Therefore, the study in this field has great significance. The two main focuses are as follows: the multi phase interface character and the adsorption/release mechanisms of some nutrient substance such as phosphorous and nitrogen.The multi phase interface, the most important environmental boundary-layer, has witnessed the paramount mass exchange between water and sediment. The structural model, composed of overlying water, sediment and the biofacies extensively existed between them, for this complicated interface was established in this study to research on the mutual relationship and the mutual influences between the multi phases and the ecological environment. Based on the above the characteristics of this structural model such as complexity, particularity, systematicness, continuity, spatial expansivity and seasonal variability were also discussed. And furthermore the laboratory researching method for simulating the natural interface between water and sediment of lake and reservoir with great depth was studied, i.e. a neotype simulating reactor was designed.In order to explore the microorganism effects on phosphorus circulation and conversion in the multi-phase interface between water and sediment. Three conditions, i.e. aerobic, anaerobic and adding reductant, were investigated in a series of simulated water-sediment reactor system using sediments from Fenhe Reservoir. The results showed that the release of endogenous phosphorus and ferrous didn't happen under aerobic condition. While under anaerobic condition (DO < 0.5mg/L) microbial activities significantly activated the phosphorus and ferrous release by reducing the oxidation-reduction potential (ORP) value of surrounding environment, during which the releasing rate of phosphorous changed from 0.42mg/(d·m~2 ) to 2.09mg/ (d·m~2 ) and the concentration of ferrous changed from 0.2mg/L to 1.3mg/L. And the release of phosphorus and ferrous had obvious positive correlation with the average correlation coefficient of 0.936. But in the reactor which didn't contain microorganism similarly under anaerobic condition the release of endogenous phosphorus and ferrous only happened after adding strong reductant. And it was also found that the Fe-P and O-P are more easily released under the microbial activates.The research results of Heihe Jinpen Reservoir water quality showed that there is obvious layered phenomenon in the waters and the contents of total nitrogen (TN), ammonia nitrogen (NH3-N), COD, phosphorous (P), Mn and so on in the waters near the multi phase interface are above-norm, which will worsening the superficial layer waters quality when each layers overturn and mix up in seasonal reversal. The testing results of sediment indicated that the contents of some pollutants (such as total phosphorous and total organic substances) in the sediment are a little higher than the moderate level. The laboratory simulating experiments outcome illuminated that it cost 58.5h, 34.5h and 106.5h respectively for ammonia nitrogen, total nitrogen and total phosphorous, Fe, Mn, COD to reach the release utmost and the ultimate concentrations of these pollutants were more than ten times as the intial ones. Thus endogenous pollutants release has great potential dangers to the water quality of Heihe Jinpen Reservoir.