College of Resources and Environment, Shanxi Agricultural University, Taigu, 030801, Shanxi, China.
College of Resources and Environment, National Experimental Teaching Demonstration Center, Shanxi Agricultural University, Taigu, 030801, Shanxi, China.
Sci Rep. 2021 Mar 18;11(1):6252. doi: 10.1038/s41598-021-85338-8.
Iron tailings have few macropores which severely inhibit infiltration and transport of soil water. Polyacrylamide (PAM) can regulate soil water, but it is rarely used when remediating tailings matrix. In this research, PAM of four molecular weights of 300w, 600w, 800w, and 1000w were selected as amendments, and were each applied at five mass concentrations of 0% (CK), 0.01%, 0.04%, 0.08%, and 0.16% to observe their effects on water transport in iron tailings using column simulations in the laboratory. After adding PAM, the water retention and saturated water content of iron tailings increased significantly (P < 0.05). With increases in PAM molecular weight and mass concentration, the saturated hydraulic conductivity showed a downward trend, but the saturated hydraulic conductivity increased after a dry-wet cycle. With the increase of PAM mass concentration, adding PAM of 1000w molecular weight to iron tailing decreased infiltration capacity, but treatments of other molecular weights all initially increased then decreased infiltration capacity. The greatest improvement on infiltration capacity of iron tailings was observed with the addition of PAM of 300w molecular weight and 0.01% mass concentration. Adding PAM increased the vertical depth of the saturation zone of iron tailings (P < 0.05) with a maximum depth of 20.83 cm. The Kostiakov model more accurately simulated water infiltration of iron tailings compared with the Horton and Philip models. On the whole, when PAM of low molecular weight and concentration was added to iron tailings, PAM increased stable infiltration, saturated water content, and water retention. It also inhibited saturated hydraulic conductivity of iron tailings. Therefore, in practice, it is necessary to select the appropriate molecular weight and mass concentration of PAM according to the dominant limiting factors and remediation needs of the matrix.
铁尾矿的大孔很少，严重抑制了土壤水的入渗和传输。聚丙烯酰胺（PAM）可以调节土壤水分，但在修复尾矿基质时很少使用。本研究选择了 300w、600w、800w 和 1000w 四种分子量的 PAM 作为改良剂，分别在 0%（CK）、0.01%、0.04%、0.08%和 0.16%五个质量浓度下添加，观察其对实验室柱模拟铁尾矿中水传输的影响。添加 PAM 后，铁尾矿的水分保持和饱和含水量显著增加（P<0.05）。随着 PAM 分子量和质量浓度的增加，饱和导水率呈下降趋势，但干湿循环后饱和导水率增加。随着 PAM 质量浓度的增加，向铁尾矿中添加 1000w 分子量的 PAM 会降低入渗能力，但其他分子量的处理均先增加后减少入渗能力。向铁尾矿中添加 300w 分子量和 0.01%质量浓度的 PAM 可最大程度地提高铁尾矿的入渗能力。添加 PAM 增加了铁尾矿饱和带的垂直深度（P<0.05），最大深度为 20.83cm。与 Horton 和 Philip 模型相比，Kostiakov 模型更准确地模拟了铁尾矿的水分入渗。总的来说，当低分子量和低浓度的 PAM 添加到铁尾矿中时，PAM 会增加稳定的入渗、饱和含水量和水分保持。它还抑制了铁尾矿的饱和导水率。因此，在实践中，根据基质的主要限制因素和修复需求，有必要选择合适的 PAM 分子量和质量浓度。
