Tong Juxiu, Yang Jinzhong, Hu Bill X, Sun Huaiwei
Key Laboratory of Groundwater Cycle and Environment Evolution (China University of Geosciences), Ministry of Education, Beijing, 100083, People's Republic of China.
School of Water Resources and Environment, China University of Geosciences, Beijing, 100083, People's Republic of China.
Environ Sci Pollut Res Int. 2016 Oct;23(20):20378-20387. doi: 10.1007/s11356-016-7248-2. Epub 2016 Jul 25.
Prevention of chemical transfer from soil to surface runoff, under condition of irrigation and subsurface drainage, would improve surface water quality. In this paper, a series of laboratory experiments were conducted to assess the effects of various soil and hydraulic factors on chemical transfer from soil to surface runoff. The factors include maximum depth of ponding water on soil surface, initial volumetric water content of soil, depth of soil with low porosity, type or texture of soil and condition of drainage. In the experiments, two soils, sand and loam, mixed with different quantities of soluble KCl were filled in the sandboxes and prepared under different initial saturated conditions. Simulated rainfall induced surface runoff are operated in the soils, and various ponding water depths on soil surface are simulated. Flow rates and KCl concentration of surface runoff are measured during the experiments. The following conclusions are made from the study results: (1) KCl concentration in surface runoff water would decrease with the increase of the maximum depth of ponding water on soil surface; (2) KCl concentration in surface runoff water would increase with the increase of initial volumetric water content in the soil; (3) smaller depth of soil with less porosity or deeper depth of soil with larger porosity leads to less KCl transfer to surface runoff; (4) the soil with finer texture, such as loam, could keep more fertilizer in soil, which will result in more KCl concentration in surface runoff; and (5) good subsurface drainage condition will increase the infiltration and drainage rates during rainfall event and will decrease KCl concentration in surface runoff. Therefore, it is necessary to reuse drained fertile water effectively during rainfall, without polluting groundwater. These study results should be considered in agriculture management to reduce soluble chemical transfer from soil to surface runoff for reducing non-point sources pollution.
在灌溉和地下排水条件下，防止化学物质从土壤转移到地表径流中，将改善地表水水质。本文进行了一系列实验室实验，以评估各种土壤和水力因素对化学物质从土壤转移到地表径流的影响。这些因素包括土壤表面积水的最大深度、土壤的初始体积含水量、低孔隙度土壤的深度、土壤类型或质地以及排水条件。在实验中，将两种土壤（沙子和壤土）与不同数量的可溶性氯化钾混合，装入沙箱，并在不同的初始饱和条件下制备。在土壤中进行模拟降雨诱导的地表径流实验，并模拟土壤表面不同的积水深度。在实验过程中测量地表径流的流速和氯化钾浓度。根据研究结果得出以下结论：（1）地表径流水中氯化钾浓度会随着土壤表面积水最大深度的增加而降低；（2）地表径流水中氯化钾浓度会随着土壤初始体积含水量的增加而增加；（3）孔隙度较小的土壤层较薄或孔隙度较大的土壤层较厚，会导致较少的氯化钾转移到地表径流中；（4）质地较细的土壤，如壤土，能在土壤中保留更多肥料，这将导致地表径流中氯化钾浓度更高；（5）良好的地下排水条件会增加降雨期间的入渗和排水速率，并降低地表径流中氯化钾的浓度。因此，有必要在降雨期间有效回用排出的肥沃水，同时不污染地下水。在农业管理中应考虑这些研究结果，以减少可溶性化学物质从土壤转移到地表径流中，从而减少面源污染。
