底泥盐分释放对北大港水库分库蓄水后水质的影响

Influence of Salt Release from Sediment on Water Quality of Beidagang Reservoir after Divided Storage

北大港水库作为引黄济津工程的调节水库,蓄水时存在水质咸化现象,影响其发挥饮用水水源地的作用。为揭示北大港水库分库开挖后底泥盐分的释放强度,于2011年10～11月取原装土样进行室内试验,研究不同含盐量、静置与扰动、不同上覆水水深等条件下底泥盐分释放规律,探讨底泥盐分释放对水库水质的影响。结果表明,底泥盐分含量越大,Cl-单位面积释放量越大且与底泥盐分含量呈线性关系;相比于静置条件,扰动条件下底泥中的盐分更易释放到水体中,且释放量大;上覆水水深越深,对底泥产生的压力越大,越不利于底泥盐分的释放。通过分析计算可知,底泥盐分的释放对水库水质产生较大的影响,是水质咸化的重要因素。

As the regulating reservoir of the Proiect of the Yellow River water transfer for Tianiin, Beidagang Reservoir has a problem of water saliaization during the storage period, which afffects its function as the drinking water reservoir. In order to reveal the law of salt release from sediment after excavation, laboratory experiments have been done with the original soil samples which were taken during October to November in 2011. Under conditions of different salt content, rest, disturbance and different overlying water depth, the experiments are conducted to discuss the impact of release of sediment salinity on reservoir water quality. The results show that more salinity the sediments have, more Cl^- will be released per unit area and there is a linear relationship between them; compared with the state of rest, the salt in the sedi ment is easier released into the water column under the disturbance condition; the deeper the depth of overlying water is, the greater the pressure on the sediment is produced, the less the salinity will be released into the water. The calculation demonstrates that the release of sediment has great impact on the water quality of reservoir, and it is an important factor for water salinization.