Kodesová Radka, Vignozzi Nadia, Rohosková Marcela, Hájková Tereza, Kocárek Martin, Pagliai Marcello, Kozák Josef, Simůnek Jirka
Dept. of Soil Science and Soil Protection, Czech University of Life Sciences Prague, Kamýcká 129, 16521 Prague 6, Czech Republic.
J Contam Hydrol. 2009 Feb 16;104(1-4):107-25. doi: 10.1016/j.jconhyd.2008.10.008. Epub 2008 Oct 31.
When soil structure varies in different soil types and the horizons of these soil types, it has a significant impact on water flow and contaminant transport in soils. This paper focuses on the effect of soil structure variations on the transport of pesticides in the soil above the water table. Transport of a pesticide (chlorotoluron) initially applied on soil columns taken from various horizons of three different soil types (Haplic Luvisol, Greyic Phaeozem and Haplic Cambisol) was studied using two scenarios of ponding infiltration. The highest infiltration rate and pesticide mobility were observed for the Bt(1) horizon of Haplic Luvisol that exhibited a well-developed prismatic structure. The lowest infiltration rate was measured for the Bw horizon of Haplic Cambisol, which had a poorly developed soil structure and a low fraction of large capillary pores and gravitational pores. Water infiltration rates were reduced during the experiments by a soil structure breakdown, swelling of clay and/or air entrapped in soil samples. The largest soil structure breakdown and infiltration decrease was observed for the Ap horizon of Haplic Luvisol due to the low aggregate stability of the initially well-aggregated soil. Single-porosity and dual-permeability (with matrix and macropore domains) flow models in HYDRUS-1D were used to estimate soil hydraulic parameters via numerical inversion using data from the first infiltration experiment. A fraction of the macropore domain in the dual-permeability model was estimated using the micro-morphological images. Final soil hydraulic parameters determined using the single-porosity and dual-permeability models were subsequently used to optimize solute transport parameters. To improve numerical inversion results, the two-site sorption model was also applied. Although structural changes observed during the experiment affected water flow and solute transport, the dual-permeability model together with the two-site sorption model proved to be able to approximate experimental data.
当土壤结构在不同土壤类型及其土层中存在差异时，会对土壤中的水流和污染物运移产生重大影响。本文聚焦于土壤结构变化对潜水位以上土壤中农药运移的影响。使用两种积水入渗情景，研究了最初施用于取自三种不同土壤类型（简育淋溶土、灰化黑土和简育始成土）各土层的土柱上的一种农药（绿麦隆）的运移情况。观察到简育淋溶土的Bt(1)土层具有发育良好的棱柱体结构，其入渗率和农药迁移率最高。简育始成土的Bw土层土壤结构发育不良，大孔隙和重力孔隙比例较低，测得其入渗率最低。在实验过程中，由于土壤结构破坏、黏土膨胀和/或土壤样品中截留空气，水的入渗率降低。由于最初团聚良好的土壤团聚体稳定性较低，简育淋溶土的Ap土层土壤结构破坏最大，入渗减少最多。利用HYDRUS-1D中的单孔隙度和双渗透率（具有基质和大孔隙域）流模型，通过数值反演，利用第一次入渗实验的数据估算土壤水力参数。利用微观形态图像估算双渗透率模型中大孔隙域的比例。随后，使用单孔隙度和双渗透率模型确定的最终土壤水力参数来优化溶质运移参数。为了改善数值反演结果，还应用了两点吸附模型。尽管实验过程中观察到的结构变化影响了水流和溶质运移，但双渗透率模型与两点吸附模型一起被证明能够近似实验数据。
