不同浓度粉末活性炭及其施用方式对土壤入渗的影响

以喀斯特地区典型的石灰土为研究对象,采用室内一维定水头法土柱模拟试验手段,以4种活性炭浓度(0,0.005,0.01,0.02 g/g)及2种混合施用方式(0—10,10—20 cm)、3种成层施用方式(6—8,10—12,16—18 cm)为变量,观测土壤湿润锋推移及累积入渗量的动态变化过程,利用线性关系式和van Genuchten经验公式分别模拟湿润锋推移情况及水分特征曲线经验公式,测量不同土层的质量含水量来研究活性碳粉对土壤入渗过程的影响。结果表明:(1)相同入渗时间内,较高浓度(0.02 g/g)和较浅层的施用方式(0—10 cm混施和6—8 cm层施)对比其他试验组,在土柱湿润锋推移速度的减缓方面表现最优;(2)在前期(t=80 min),入渗受活性炭粉末抑制的程度与其浓度呈正相关,但高浓度的碳粉同时会减缓湿润锋推移速度,故最终入渗量(t=340 min)受其浓度影响较小,同时土壤入渗受活性炭粉末理化性质的影响,层状铺设入渗后期呈现斜率增大的趋势;(3)van Genuchten经验公式及RETC软件对土壤入渗过程的模拟皆表明活性炭粉末施入土壤后,其浓度与土壤吸收水分的能力呈正相关,与土壤释水能力呈负相关;(4)活性炭粉末使得土壤田间持水量与凋萎系数均有所提升,活性炭粉末施用浓度越高,田间持水量越大。(5)层施状态下的活性炭粉末能增加所在土层的质量含水量,为对于其他深度土层的含水量则影响不大。

Effects of Different Concentrations of Powdered Activated Carbon and Its Application Method on Soil Infiltration

Taking the typical lime soil in Karst area as the research object, the indoor one-dimensional fixed head method was used to simulate the soil column. Four activated carbon concentrations (0, 0.005, 0.01 and 0.02 g/g), two mixed application methods (0-10, 10-20 cm) and three layered application methods (6-8, 10-12 and 16-18 cm) were used as variables. To observe the dynamic process of soil wetting front movement and cumulative infiltration, the linear relationship and van Genuchten empirical formula were used to simulate the movement of wetting front and the empirical formula of water characteristic curve, respectively, and the mass water contents of different soil layers were measured to study the effect of activated carbon powder on soil infiltration process. The results showed that:(1) In the same infiltration time, compared with other experimental groups, the higher concentration (0.02 g/g) and the shallow application mode (0-10 and 6-8 cm) were better in slowing down the moving speed of soil column wetting front. (2) At the early stage (t<80 min), the inhibition degree of infiltration by activated carbon powder was positively correlated with its concentration, but the high concentration of carbon powder could slow down the movement rate of wetting front at the same time. Therefore, the final infiltration amount (t<340 min) was less affected by its concentration, and affected by the physical and chemical properties of activated carbon powder. The slope increased at the later stage of layered laying infiltration. (3) The simulation of soil infiltration parameters by van Genuchten empirical formula and RETC software showed that the concentration of activated carbon powder was positively correlated with the ability of soil to absorb water, and it was negatively correlated with soil water release capacity. (4) Activated carbon powder increased soil field water holding capacity and wilting coefficient, and the higher the concentration of activated carbon powder, the greater the field water holding capacity. (5) Under the condition of layer application, the activated carbon powder could increase the mass water content of the soil layer, but had little effect on the water content of other deep soil layers.