施用膨润土增强淤积泥沙持水能力及阻控硝态氮淋失试验研究

Experimental Research on Enhancing Water Holding Capacity and Controlling Nitrate Nitrogen Leaching of Silting Sediment by Applying Bentonite

为了研究施用膨润土对淤积泥沙持水能力及硝态氮淋失的影响,以黄河淤背区淤积泥沙为研究对象,通过室内一维积水入渗装置,在淤积泥沙表层设置掺入质量分数分别为10%、20%、25%、30%的膨润土保水层与不掺膨润土的淤积泥沙进行对比试验,分析入渗性能、持水能力及硝态氮淋失量的差异。结果表明:膨润土可有效改善淤积泥沙入渗性能,累积入渗量随膨润土掺量的增加而降低;与不掺膨润土的淤积泥沙相比,掺入膨润土保水层的淤积泥沙累积入渗量提高21.5%~84.2%,入渗速率降低34.0%~65.6%;淤积泥沙持水能力随膨润土掺量的增加而增强,在累积入渗量为900 mL时,湿润锋运移距离减小2.1~7.7 cm,保水层含水率提高15.3%~69.8%,30 d淤积泥沙累积蒸发量减少2.9%~11.4%;膨润土可有效降低淤积泥沙中硝态氮淋失量,有效改善了淤积泥沙中氮素的利用效果。

To research effects of bentonite application on water holding capacity and nitrate nitrogen leaching of silting sediment,taking silting sediment in silt-backed areas of the Yellow River as the research object,a comparison test was conducted on bentonite water retaining layers with mass fractions of 10%,20%,25%,30%and silting sediment without bentonite installed in the surface layer of silting sediment through an indoor one-dimensional water infiltration device.Differences of infiltration performance,water holding capacity,and nitrate nitrogen leaching were analyzed.The results show that the bentonite can effectively improve the infiltration performance of the silting sediment,the cumulative infiltration volume decreases with the increase of bentonite.Compared with the silting sediment without bentonite,the cumulative infiltration volume of silting sediment mixed with bentonite water retention layer increases by 21.5%to 84.2%,the infiltration rate decreases by 34.0%to 65.6%.The water holding capacity of silting sediment increases with the increase of bentonite,at the cumulative infiltration volume of 900 mL,the wetting front transport distance decreases by 2.1 cm to 7.7 cm,the water content of the water retention layer is increased by 15.3%to 69.8%,and the cumulative evaporation of 30 d silting sediment is reduced by 2.9%to 11.4%.Bentonite can effectively reduce nitrate nitrogen leaching from silting sediment,which effectively improves the utilization of nitrogen in silting sediment.