饱和土壤与河流底泥水动力弥散研究

目的]研究溴化钾在土壤与河道底泥中水动力弥散系数,为构建污染物在土壤中的迁移数值模型提供数据参考。方法]通过高80 cm的土壤箱体和高60 cm的柱体进行模拟试验,研究南京化工园土壤与河道底泥的水动力弥散系数。结果]南京化工园四柳河沿岸土壤KBr穿透时间比较长,为22.83 d,流出液中KBr的浓度变化比较平缓,液体流速为0.35 ml/min,弥散系数为0.001 638 m2/d;河道底泥KBr穿透时间短,为3.33 d,液体流速为8.83 ml/min,弥散系数为0.004 094 m2/d。土壤中KBr流出速度慢,在9.083 d时还未见KBr物质,在9.38 d才测出KBr浓度为0.03 mg/L;而河道底泥中KBr流出速度非常快,在0.49 d时测出KBr浓度达到3.70 mg/L,之后从3.70～4.10 mg/L间的浓度变化比较平稳,用了2.84 d的时间。结论]污染物KBr在土壤中的穿透时间长,弥散系数值小,而在河道底泥中穿透的时间短,弥散系数值相对较高。

Experiment in the Saturated Soil and the Hydrodynamic Dispersion of the Mud in River Bottom

Objective]The reference data in the construction of the numerical model of the contaminant's migration in the soil was provided through the research on the hydrodynamic dispersion coefficient of the bromide in the soil and the sediment of river bottom.Method]The hydrodynamic dispersion coefficient of the soil and the river sediment in the Nanjing Chemical Industrial Park was studied through the simulation experiment in the soil box with the height of 80 cm and the soil column with the height of 60 cm.Results]The passing time of the soil KBr along the Siliuhe River in the Nanjing Chemical Industrial Park was longer,with 22.83 days.The variation of the concentration of KBr in the effluent was relatively flat,the flow rate of liquid was 0.35 ml/min and the diffusion coefficient was 0.001 638 m2/d.The transmission time of river sediment KBr was short,with 3.33 days,the flow rate of liquid was 8.83 ml/min and the diffusion coefficient was 0.004 094 m2/d.The outflow speed of soil KBr was slow,the KBr substance did not appear in the 9.083 days and in the 9.38 days the KBr substance appeared,which concentration was 0.03 mg/L,while the outflow speed of river sediment KBr was very fast,the concentration of KBr was up to 3.70 mg/L in the 0.49 days,then it was relatively stable with the variation in the concentration from 3.70-4.10 mg/L within the time of 2.84 days.Conclusion] The transmission time of the contaminant KBr in the soil was long with small diffusion coefficient and the transmission time of the KBr in river sediment was short with the relatively high diffusion coefficient.