疏浚深度和光照对海河表层沉积物氮磷释放的实验研究

采用混合均匀的海河表层底泥并以自来水为上覆水进行室内沉积物氮、磷静态释放模拟实验，研究了疏浚深度和光照对沉积物总磷和氨氮释放的影响。结果表明，实验期间（2007年7月20日至2008年1月8日），无论光照与否，与未疏浚相比，完全疏浚能使上覆水总磷平均浓度从0．27～0．41mg·L^-1显著降低至0．02～0．03mg·L^-1（P〈0．05），但疏浚深度对上覆水氨氮浓度无显著性影响（乃0．05）。与避光组相比，光照可使部分疏浚组和未疏浚组上覆水总磷平均浓度分别降低0．05和0．26mg·L^-1，但对沉积物氨氮释放的影响不明显（光照组氨氮浓度略高于避光组）。其余水质指标监测结果表明，光照组的水温、电导率均值比避光组分别高约0-3℃和20μs，光照组和避光组的pH值无显著差别。此外无论光照与否，电导率均随疏浚深度的增加逐渐降低，pH值变化与疏浚深度关系不大。

Effect of Dredging Depth and Light on Nitrogen and Phosphorus Release from the Surface Sediment of Haihe River

Fully mixed Haihe surface sediments and tap water were used to conduct the indoor static nutrient（mainly ammonia and total phosphorus） release experiment, and to evaluate the effect of dredging depth and light on the release process. During the whole running period （from July 20th 2007 to January 8th 2008）, regardless of the light or dark conditions, completely dredging of sediment could significantly reduce the average water column total phosphorus concentration from 0.27-0.41mg·L^-1 to 0.02-0.03 mg·L^-1 when compare to that without dredging （P〈0.05）. However, insignificant effect of dredging depth on ammonia was observed. Moreover, light resulted in 0.05 mg·L^-1 and 0.26 mg·L^-1 decrease of average phosphorus concentrations in the partly and completely dredging rigs while negligible impact of light on am- monia release was noticed. In addition to above nutrient variables, results of other water quality parameters such as pH, electronic conductivity（EC ） and water temperature measurements indicated that water temperature and EC were 0.3 % and 20μS higher in the experimental rigs under light conditions than those under dark conditions, but no obvious effect of light on pH values was recorded. In despite of light or dark, EC was increased with decreasing dredging depth while pH values was weak linked with the sediment dredging depth.