Saltwater intrusion (SWI) on low-lying coastal farms causes soil salinization, which may gradually render the land unsuitable for cultivation. Many studies on SWI focus on groundwater flow and salt transport, where the temporal dynamic of consequent soil salinization is understudied. To understand the effects of SWI on soil salinity, we gathered multi-scale field datasets on water level and salinity during an aquaculture impoundment, which resulted in both vertical and lateral groundwater salinization. By comparing continuous field data before and after impoundment, we captured lateral SWI and vertical SWI processes and the resulting soil salinity variation. In the vertical SWI process, soils from the surface to 0.2 m-deep were salinized immediately after saltwater irrigation due to the downward hydraulic gradient. A relatively slow salinization was formed at a depth below 0.3 m. In the lateral SWI process, the hydraulic conductivity of the sediments was doubled, which resulted in a more significant variability of salinity. Our findings illustrate that the temporal agricultural water management associated with transforming cropland into aquaculture ponds can alter soil physical characteristics and hydrological conditions at different locations. The resulting soil salinization showed multi-scale variability, which was much more complex than groundwater salinization. Therefore, studying the complete transformation process of coastal land use can contribute to an improved understanding of soil and groundwater salinization due to agricultural activities, which is essential to protecting and managing coastal soils and the associated agroecosystem services.

中文翻译：

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陆上水产养殖场垂直和横向盐水入侵导致土壤盐碱化的时间动态


盐水入侵 （SWI） 对低洼沿海农场会导致土壤盐碱化，这可能会逐渐使土地不适合耕种。许多关于 SWI 的研究都集中在地下水流和盐分输送上，其中对随之而来的土壤盐碱化的时间动态研究不足。为了了解 SWI 对土壤盐度的影响，我们收集了水产养殖蓄水期间水位和盐度的多尺度野外数据集，这导致了垂直和横向地下水盐碱化。通过比较蓄水前后的连续现场数据，我们捕获了横向 SWI 和垂直 SWI 过程以及由此产生的土壤盐度变化。在垂直 SWI 过程中，由于向下的水力梯度，从地表到 0.2 m 深的土壤在盐水灌溉后立即盐碱化。在 0.3 m 以下的深度形成相对缓慢的盐碱化。在横向 SWI 过程中，沉积物的水力传导率增加了一倍，这导致盐度的变化更加显着。我们的研究结果表明，与将农田转变为水产养殖池塘相关的时间农业用水管理可以改变不同位置的土壤物理特性和水文条件。由此产生的土壤盐碱化显示出多尺度变化，这比地下水盐碱化复杂得多。因此，研究沿海土地利用的完整转变过程有助于更好地了解农业活动引起的土壤和地下水盐碱化，这对于保护和管理沿海土壤和相关农业生态系统服务至关重要。