煤矸石基多孔材料对黄河流域矿区复垦土壤溶质运移的影响

Effect of coal gangue-based porous materials on solute transport of reclamation soil in mining areas in the Yellow River Basin

  • 摘要: 为解决单独利用煤矸石作为矿区复垦土壤存在的孔隙度低、保肥性差等问题,研究了煤矸石基多孔材料对煤矸石粉中Cl和K+运移的影响,揭示了多孔材料对煤矸石孔隙分布和溶质运移的影响规律,并使用对流-弥散方程(CDE)对K+和Cl的穿透曲线(BTCs)进行拟合,求其运移参数。向煤矸石粉中添加0%、10%、20%、25%、30% 5种不同含量的多孔材料,通过静态批试验和垂直土柱易混置换试验,获得Cl作为惰性非吸附示踪剂和K+作为吸附示踪剂的穿透曲线。静态批试验结果表明添加多孔材料使K+分配系数(Kd)提高19.40%~45.97%。通过垂直土柱易混置换试验可知,掺入10%~25%的多孔材料,可以通过降低饱和导水率(Ks)延缓Cl的运移速率,通过降低Ks、提高吸附能力延缓K+的穿透时间。施用25%多孔材料能够使出流液中的Cl浓度降低0.34%~47.64%、K+浓度降低11.86%~92.43%。CDE模型可以较好地描述Cl和K+的穿透曲线。煤矸石和多孔材料以7.5∶2.5(体积比)混合的复配模式,可以有效减少溶质运移。

     

    Abstract: In order to solve the problems of low porosity and poor fertility retention of using coal gangue alone as reclamation soil in mining areas, we investigated the influence of coal gangue-based porous materials on the transport of Cl and K+ in coal gangue powder, and elucidated the impact of porous materials on coal gangue pore distribution and solute transport. The convection-dispersion equation (CDE) was used to fit the breakthrough curves (BTCs) of K+ and Cl, determining their transport parameters. By adding five different contents (0%, 10%, 20%, 25%, 30%) of porous materials to coal gangue powder, static batch tests and vertical soil column displacement tests were conducted to obtain the breakthrough curves of Cl as an inert non-adsorbing tracer and K+ as an adsorbing tracer. Static batch test results indicated that the addition of porous materials increased K+ distribution coefficient (Kd) by 19.40%-45.97%. Vertical soil column displacement tests revealed that incorporating 10%-25% porous materials could delay the transport rate of Cl by reducing saturated hydraulic conductivity (Ks) and delay the breakthrough time of K+ by reducing Ks and enhancing soil adsorption capacity. The application of 25% porous material could reduce the Cl concentration in the effluent by 0.34%-47.64% and K+ concentration by 11.86%-92.43%. The CDE model could well describe the breakthrough curves of Cl and K+. A composite mode with a 7.5∶2.5 (v/v) ratio of coal gangue powder to porous materials could effectively reduce solute transport.

     

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