The effects of salt precipitation on water and heat transport in soil have garnered considerable attention. However, salt precipitation growth on the soil surface and its influence on soil evaporation and temperature under a fixed groundwater table are not well understood. Therefore, the objective of this study was to investigate the impact of the evolution of salt precipitation on evaporation and temperature in sandy soils with a fixed groundwater table depth (20 cm). The laboratory experiment consisted of two treatments for sand columns: one with fresh groundwater, and the other with saline groundwater. Regions with salt precipitates expanded laterally and vertically whereby a salt crust was formed that disconnected from the soil. The lateral growth of salt precipitation had a minor impact on evaporation as the soil remained wet, while mostly being covered by the salt crust. However, the elevated salt crust caused a sharp decrease (>60%) in the evaporation rate. Therefore, a new stage of saline soil evaporation was determined; the evaporation rate was further reduced by the elevated salt crust. Moreover, the soil profile temperature decreased when the soil was covered by the salt crust, which is likely attributable to the increased albedo and the formation of a layer of air owing to the elevated salt crust. Therefore, we suggest that the upward growth of salt precipitation should be comprehensively studied because it can cause significant reductions in evaporation rates and soil temperature.

中文翻译：

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变化的盐分降水对固定地下水位砂质土壤蒸发和温度的影响

盐分降水对土壤水热传递的影响已引起广泛关注。然而，在固定地下水位下，土壤表面的盐分降水增长及其对土壤蒸发和温度的影响尚不清楚。因此，本研究的目的是研究盐分降水演变对地下水位固定深度（20 cm）沙质土壤蒸发和温度的影响。实验室实验包括对沙柱的两种处理方法：一种使用淡水，另一种使用含盐地下水。有盐沉淀物的区域横向和纵向扩展，由此形成与土壤断开的盐壳。由于土壤保持湿润，盐分的横向增长对蒸发的影响很小，而大部分被盐壳覆盖。然而，升高的盐壳导致蒸发率急剧下降（> 60%）。因此，确定了盐渍土蒸发的新阶段；盐壳升高进一步降低了蒸发率。此外，当土壤被盐壳覆盖时，土壤剖面温度降低，这可能是由于盐壳升高导致反照率增加和空气层形成。因此，我们建议对盐分降水的向上增长进行综合研究，因为它会导致蒸发率和土壤温度的显着降低。确定了盐渍土蒸发的新阶段；盐壳升高进一步降低了蒸发率。此外，当土壤被盐壳覆盖时，土壤剖面温度降低，这可能是由于盐壳升高导致反照率增加和空气层形成。因此，我们建议对盐分降水的向上增长进行综合研究，因为它会导致蒸发率和土壤温度的显着降低。确定了盐渍土蒸发的新阶段；盐壳升高进一步降低了蒸发率。此外，当土壤被盐壳覆盖时，土壤剖面温度降低，这可能是由于盐壳升高导致反照率增加和空气层形成。因此，我们建议对盐分降水的向上增长进行综合研究，因为它会导致蒸发率和土壤温度的显着降低。