模拟再清淤对南淝河底泥氮磷释放的影响研究

Releases of Nitrogen and Phosphorus from Sediments from Nanfei River After Simulated Follow-up Dredging

为掌握南淝河清淤效果和进一步改善南淝河水污染现状,利用柱状采样器采集南淝河清淤后的底泥,并在室内柱状反应器中对采集的原状底泥进行模拟再清淤后污染物释放的试验研究,通过定期检测上覆水中氮、磷污染物浓度随时间的变化,来反映清淤及模拟再清淤后底泥中氮、磷污染物的释放状况。结果表明,模拟再清淤后的底泥和实际清淤后的底泥对氮、磷污染物均表现为以7 d为周期的释放与吸附的交替变化,且一个月后污染物释放量与沉降量达到平衡。对南淝河位于合作化路桥至长丰路桥段实际清淤后的底泥进行模拟再清淤试验,清淤深度在5.9 cm时,短期内可有效降低底泥中氮、磷污染物的释放。

Water quality monitoring has shown that nitrogen and phosphorus pollution is still severe in Nanfei River even if dredging has been conducted. Here a simulation experiment was carried out to examine the effect of follow-up dredging on the releases of nitrogen and phosphorus from the sediments using intact columns of the sediments that were previously in situ dredged. In the simulated dredging experiment, nitrogen and phosphorus in in situ dredged sediments showed alternative release and adsorption pattern with an interval of 7 d, and reached stability after one month. Our results indicate that follow-up dredging at a depth of 5.9 cm could restrain the releases of nitrogen and phosphorus from the sediments during the short term.