Compaction effects on evaporation and salt precipitation in drying porous media

[摘要] Compaction and salinization of soils reduce croplands fertility, affectnatural ecosystems, and are major concerns worldwide. Soil compaction alterssoil structure and affects the soil's hydraulic properties, and it thereforemay have a significant impact on evaporation and solute transport processesin the soil. In this work, we investigated the combined processes of soilcompaction, bare soil evaporation, and salt precipitation. X-ray computedmicrotomography techniques were used to study the geometrical soil pore andgrain parameters influenced by compaction. The impact of compaction onevaporation and salt precipitation was studied using column experiments. Wefound that compaction reduced the average grain size and increased thenumber of grains, due to the crushing of the grains and their translocationwithin the compacted soil profile. Changes in pore and grain geometry andsize were heterogeneously distributed throughout the soil profile, withchanges most apparent near the source of compaction, in our case, at thesoil surface. The column experiments showed that the presence of small poresin the upper layer of the compacted soil profile leads to higher evaporationloss and salt precipitation rates, due to the increase of hydraulicconnectivity to the soil surface and the prolongation of the first stage ofevaporation.

[学科分类] 妇产科学