本文關鍵詞：水體垂向擾動條件下溶質在沉積介質中的遷移研究　出處：《清華大學》2015年碩士論文　論文類型：學位論文

  更多相關文章： 垂向擾動 紊動壓強 對流遷移 自由擴散 非均勻結構

【摘要】：上覆水體的擾動對海洋、河流、湖泊等水體沉積物中物質的再懸浮和釋放已逐漸受到全球學者的關注。這種在水動力條件下導致的物質的遷移和再懸浮過程,尤其是污染物質的釋放過程嚴重的影響著水體的環境和生態平衡。為了研究在上覆水體擾動條件下物質在沉積介質中的遷移,本實驗建立了簡單的沉積物再懸浮發生裝置,并分別利用不同粒徑大小的沙粒作為均質沉積物,同時利用500μg·cm-3的溶解性羅丹明B作為示蹤劑,觀測研究在垂向紊流擾動條件下溶質在不同沉積介質中的遷移情況。實驗表明,在均勻沉積介質中,水流的垂向擾動主要影響溶質的垂向遷移,而溶質的水平對流遷移十分微弱。在200 r·min-1的擾動強度下,在平均粒徑為71μm介質中,溶質幾乎不發生對流遷移現象,以自由擴散遷移為主,且擴散的強度與埋深沒有直接關系;而該擾動強度對平均粒徑為154μm,311μm,503μm和646μm均勻沉積介質的擾動影響深度分別達到了7cm,10cm,12cm和13cm;在各均勻介質中最大遷移速率分別達到了0.8 mm·h-1、1.8 mm·h-1、2.9 mm·h-1和4.9 mm·h-1,且隨著埋深的加深,物質前遷移減弱。而在非均勻介質中,上覆水體的擾動將在非均勻介質中產生的橫向孔隙水紊動壓強增大,從而導致溶質隨著水流發生跨介質的橫向對流遷移,且一定范圍內隨著擾動的增強和顆粒粒徑的增大,溶質的這種橫向對流遷移也相應增強。當擾動強度達到300 r·min-1以上時,沉積層表層顆粒已發生了大量再懸浮-再沉淀現象,破壞了表層沉積層結構。研究還發現非均勻結構將會增大溶質在介質中的垂向遷移以及同一擾動強度對介質的影響深度,如200r·min-1的擾動強度對646μm均勻沉積介質影響深度為13cm,而對其各類非均勻結構的影響深度達到了15cm~16cm;并且對于同一種沉積介質,不同的非均勻組合對溶質遷移的影響也不同。同時,研究還表明,不同的沉積介質間存在著一個最利于溶質遷移的結構組合,在本實驗組中,646μm介質與311μm介質構成的非均勻結構在200r·min-1的擾動強度下最利于物質的遷移。另外,實驗發現在非均質邊界處,溶質在71μm介質中的擴散遷移大大增強,其最大擴散直徑增量幾乎是其它各點的1.5倍~2倍,說明擾動條件下非均勻結構對溶質的擴散遷移也有明顯的增強效果。由于自然條件下水動力條件十分復雜,不同的擾動環境對物質的遷移影響也存在著較大的差異,因此該論文得出的結論適用于水體的垂向擾動。
[Abstract]:The disturbance of overlying water has gradually attracted the attention of global scholars for the resuspension and release of material in marine, river, lake and other water sediments. The migration and resuspension of substances, especially the release of pollutants, seriously affect the environment and ecological balance of water under hydrodynamic conditions. In order to study the disturbance transfer conditions in sedimentary material medium in overlying water, this experiment established a simple sediment resuspension generator, and then different particle size of sand as homogeneous sediments, while using 500 g cm-3 dissolved Luo Danming B as tracer, observation and study of disturbance migration conditions the solute in different deposition medium to turbulent flow in the vertical. The experimental results show that the vertical migration of the solute is mainly influenced by the vertical disturbance of the flow in the homogeneous sedimentary medium, while the horizontal convection migration of the solute is very weak. In the perturbation strength 200 r min-1, the average particle size of 71 m in the medium, there is almost no solute convection phenomenon, migration dominated by free diffusion, and the diffusion of the strength and depth of no direct relationship; and the disturbance intensity on the average particle size of 154 m, 311 m, influence the depth of disturbance 503 m and 646 m respectively, the uniform deposition of medium 7cm, 10cm, 12cm and 13cm; in the homogeneous medium maximum migration rate reached 0.8 mm - H-1, mm - 1.8 H-1, 2.9 mm H-1 and 4.9 mm H-1, and with the depth of the material before deepened. Migration weakened. While in non homogeneous medium, transverse pore water turbulence disturbance of overlying water will result in inhomogeneous medium dynamic pressure increases, which leads to the solute water flow with transverse convection cross media migration, and within a certain range with the increasing of the size of the particle and enhance the disturbance, the migration of the solute is transverse convection the corresponding enhancement. When the intensity of the disturbance reaches more than 300 R. Min-1, a large number of re - suspension and re precipitation phenomena have occurred in the surface layer of the sedimentary layer, which destroys the structure of the surface layer. The study also found that non uniform structure will increase the solute in the medium vertical migration and the influence of disturbance intensity on the same medium depth, such as disturbance intensity of 200R - 646 m min-1 on the uniform deposition medium influence depth is 13cm, and the influence of various kinds of non uniform structure depth reached 15cm~16cm; and for the same the sedimentary medium, different non uniform combination effects on solute migration are different. Meanwhile, the study also shows that there is a structural combination that is most conducive to solute transport among different sedimentary media. In this experimental group, the non-uniform structure composed of 646 mu m medium and 311 m medium is most conducive to the migration of matter under the intensity of 200R min-1. In addition, it is found that the diffusion and transport of solute in the medium of 71 M can be greatly enhanced at the heterogeneous boundary. The maximum diffusion diameter increment is almost 1.5 times ~2 times of the other points, indicating that the heterogeneous structure has obvious enhancement effect on the solute diffusion and migration under the condition of disturbance. Because of the complexity of hydrodynamic conditions under natural conditions, the influence of different disturbance environments on material migration is also quite different. Therefore, the conclusions drawn in this paper are applicable to vertical disturbance of water bodies.
【學位授予單位】：清華大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：X52

【參考文獻】

相關期刊論文 前10條

1 王瑩;王道瑋;李輝;趙世民;李兆欣;潘學軍;;內陸湖泊富營養化內源污染治理工程對比研究[J];地球與環境;2013年01期

2 張雷;古小治;邵世光;胡海燕;鐘繼承;范成新;;河蜆(Corbicula fluminea)擾動對湖泊沉積物性質及磷遷移的影響[J];環境科學;2011年01期

3 ;The role of sediment resuspension duration in releaseof PAHs[J];Chinese Science Bulletin;2008年18期

4 尤本勝;王同成;范成新;朱龍喜;鐘繼承;李寶;尹洪斌;胡春華;;太湖沉積物再懸浮模擬方法[J];湖泊科學;2007年05期

5 SEYMOUR Brian;;Ocean waves propagating over a porous seabed: Residual and oscillatory mechanisms[J];Science in China(Series E:Technological Sciences);2007年01期

6 ;The nutrient forms, cycling and exchange flux in the sediment and overlying water system in lakes from the middle and lower reaches of Yangtze River[J];Science in China(Series D:Earth Sciences);2006年S1期

7 劉臣煒;汪德r;;湖泊富營養化內源污染的機理和控制技術研究[J];農業環境科學學報;2006年S2期

8 李九發;李為華;應銘;時連強;陳沈良;戴志軍;;黃河三角洲飛雁灘沉積物顆粒度分布和粒度參數特征及水動力解釋[J];海洋通報;2006年03期

9 黃冠華;黃權中;詹紅兵;陳靜;熊云武;馮紹元;;均質介質中污染物遷移的分數微分對流-彌散模擬[J];中國科學(D輯:地球科學);2005年S1期

10 ;Particle flux through the Huanghai Sea cold water mass[J];Acta Oceanologica Sinica;2005年05期

相關博士學位論文 前3條

1 忻海平;海洋資源價值及開發戰略研究[D];中國地質大學（北京）;2008年

2 員美娟;多孔介質中流體的若干流動特性研究[D];華中科技大學;2008年

3 周守為;中國海洋石油開發戰略與管理研究[D];西南石油學院;2002年

相關碩士學位論文 前1條

1 王同成;極端風情下湖泊沉積物—上覆水之間的物質交換[D];河海大學;2007年

，

本文編號：1346256