模拟太湖底泥疏浚对氮磷营养物释放过程的影响研究

通过模拟太湖底泥疏浚,研究了不同水土比与不同环境因素条件下,底泥中氮、磷等营养物的释放规律与较长时期的模拟疏浚环境效果。结果表明,底泥中细小颗粒物、较高的水温、置水和厌氧条件等是促进底泥中磷释放的主要环境因素。从模拟太湖底泥的淤积现状上看,以平均模拟疏浚深度为25cm环境效果最佳,在沉积物粒度较细的湖区,可以适当加深;底泥疏浚应在冬季等水温低的季节进行,这样可以有效地防止其中营养物向上覆水体的释放。

Effects of Simulating Sediment-dredging on the Release of N and P Nutrients in Taihu Lake's Sediment

Eutrophication of water-body now is one of the main environmental phenomena all over the world, which results from the out input of pollutants and the release of nitrogen and phosphorus nutrients in sediment, especially, the release from inner resource when the out input of pollutants controlled effectively, so sediment dredging is a broadly adoptive engineering measure. The past researches on the release of nitrogen and phosphorus nutrients in sediment were focused on the same proportion of water to sediment, but no dynamic affects of environmental factors on the release of nutrients after sediment dredging. The release of nitrogen and phosphorus nutrients in sediment from Taihu Lake and long-time effects of simulation dredging under different proportion of water to sediment were studied. The results indicated that the smaller size particles in sediment, higher water temperature, water exchanging and anaerobic condition were all the key factors to increase the release of nitrogen and phosphorus nutrients in sediments, but their effects varied greatly with the proportions of water to sediment. All the conditions considered, 25 cm simulation depth of sediment dredging was best, but it could be more in the area covered by the sediment of smaller size particles. The lower the water temperature, the less the release of nitrogen and phosphorus nutrients in sediment, and winter was the best season for sediment dredging with lower release nitrogen and phosphorus nutrients from sediment to water.