【摘要】 采用室内模拟试验,研究了不同曝气深度(分别为泥水界面上方5 cm和下方0、5、10和15 cm处,依次记为A+5、A0、A-5、A-10和A-15)对城市河道沉积物中氮的释放及上覆水中氮形态的影响。结果表明,试验期间,对照组(不曝气)的沉积物始终在向上覆水中释放NH+4-N并形成累积;对水体曝气可抑制沉积物中NH+4-N的释放,并促进上覆水中的NH+4-N向硝态氮转化;对沉积物曝气时,上覆水中的NH+4-N浓度在第3天达到最大,并且A-15>A-10>A-5>A0,大量释放的NH+4-N在硝化作用下转化成硝态氮;曝气组在曝气阶段均出现了NO-2-N的累积现象,并随着曝气深度的增加,上覆水中的NO-2-N累积量亦增加,累积时间也越长;深层曝气(泥水界面以下5 cm)对沉积物扰动剧烈,使沉积物中的有机质大量释放,满足了系统反硝化所需的碳源,停止曝气后系统静置分层,反而影响了反硝化速率;从长时间尺度来看,在相同曝气条件下处理污染河道,对沉积物曝气比对水体曝气可以更好地抑制沉积物中氮素的释放,并且沉积物曝气深度越深,处理效果就越好,第60天试验结束时,A-15中上覆水的NH+4-N浓度为1.24 mg/L。更多还原

【Abstract】 Putting the aerator 5 cm above,and 0 cm,5 cm,10 cm and 15 cm below the watersediment interface,and marking them as A+ 5,A0,A- 5,A- 10and A- 15,the effect of aeration depth on nitrogen release from urban river sediments and nitrogen forms in overlying water was studied based on indoor simulation. The results indicated that nitrogen released in the form of NH+4- N from sediments in the control group( no aeration) could accumulate in the overlying water; water aeration could not only inhibit the release of NH+4- N from sediments into the overlying water,but also promote the transformation of NH+4- N to nitrate nitrogen; the concentration of NH+4- N increased to the highest level on the third day after the sediment aeration was launched,and specifically,A- 15 > A- 10 > A- 5 > A 0. A large amount of released NH+ 4- N were transformed into nitrate nitrogen through nitrification. The NO-2- N accumulation took place in overlying water under the aerating conditions. NO-2- N accumulation and accumulation time increased with aeration depth. Deep aeration at 5 cm below the water-sediment interface severely perturbed sediments,resulting in high release of organic matter from sediments,which provided a carbon source for denitrification. Meanwhile static layering phenomenon occurred after aeration stopped,thus affecting the denitrification rate. In the long run,the sediment aeration could inhibit release of NH+ 4- N from sediments into the overlying water. Moreover,the deeper the aeration depth,the better the results. The NH+ 4- N concentration in the overlying water reached 1. 24 mg / L when the experiment finished after 60 days.更多还原