Increasing soil salinization and microplastics (MPs) pollution of farmland have become global agricultural issues that have to be faced, destabilizing plant-soil systems and bringing threats to ecosystems. Few studies have focused on the effects of MPs on saline soil water evaporation and desiccation crack formation, and the underlying influencing mechanisms of MPs and salts in soils. A mechanism test was conducted to explore the effects of MPs concentrations (0.5 %, 1 %, 3 %, w/w) on the simultaneous changes of water evaporation and cracking patterns of saline soils with different salinities (0, 0.1 %, 0.3 %, 0.5 %, w/w). Quantitative findings showed that (1) the MPs significantly reduced saturated conductivity by 14.9–46.8 % and 4.6–54.5 % in non-saline soil and lightly saline soil, respectively, which showed a decreasing trend with increasing MPs concentration; besides, soil salts also significantly reduced saturated conductivity, but the inhibition weakened with increasing soil salinity. (2) The MPs significantly reduced total porosity by 2.2–7.9 % and 1.8–6.6 % in non-saline and saline soils, respectively, which exhibited a slight decreasing trend with increasing MPs concentration. (3) The MPs reduced total evaporation by 0.4–6.1 % and 0.9–6.5 % in non-saline and saline soils, respectively. As the MPs concentration increased, the total evaporation of non-saline soil decreased, and the total evaporation of saline soils firstly decreased and then increased. After evaporation, both soil salt and MPs inhibited cracking. Correlations indicated that the presence of soil salt and MPs and their interactions explained more than half of the variability of soil and water characteristics and crack parameters. Mechanism exploration suggested that the MPs affect the evaporation process and crack behavior by changing soil pore size distribution, damaging soil structure, and the water repellency of the MPs particles; besides, the salts inhibit the soil water evaporation and surface cracking through increasing osmotic suction, blocking soil macropores, and promoting inter-microaggregate cementation. Our findings provide evidences for MPs influences on saline soil physical properties, water evaporation, and crack development, deserving attentions to the regulations and developments of soil-crop systems that facing salinization and plastic pollution.

中文翻译：

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含微塑料盐渍土水分蒸发和干燥裂缝形成同时变化的见解


日益严重的土壤盐碱化和农田微塑料污染已成为必须面对的全球农业问题，破坏植物-土壤系统的稳定，给生态系统带来威胁。很少有研究关注MPs对盐渍土水分蒸发和干燥裂缝形成的影响，以及MPs和土壤盐分的潜在影响机制。通过机理试验探讨MPs浓度(0.5 %、1 %、3 %、w/w)对不同盐度(0、0.1 %、0.3 %)盐渍土水分蒸发和开裂模式同时变化的影响。 ，0.5%，w/w)。定量结果表明：（1）MPs使非盐渍土和轻盐渍土的饱和电导率分别显着降低14.9%~46.8%和4.6%~54.5%，且随MPs浓度的增加呈降低趋势；此外，土壤盐分也会显着降低饱和电导率，但这种抑制作用随着土壤盐分的增加而减弱。 (2) MPs在非盐渍土和盐渍土中分别显着降低了总孔隙度2.2%~7.9%和1.8%~6.6%,且随MPs浓度的增加呈现轻微降低趋势。 (3) MPs在非盐渍土和盐渍土中分别减少了0.4-6.1%和0.9-6.5%的总蒸发量。随着MPs浓度的增加，非盐渍土总蒸发量减少，盐渍土总蒸发量先减少后增加。蒸发后，土壤盐分和 MPs 均抑制开裂。相关性表明，土壤盐和 MP 的存在及其相互作用解释了一半以上的土壤和水特征以及裂缝参数的变化。 机理探索表明MPs通过改变土壤孔径分布、破坏土壤结构以及MPs颗粒的憎水性来影响蒸发过程和裂缝行为；此外，盐类通过增加渗透吸力、堵塞土壤大孔隙、促进微团聚体间的胶结作用，抑制土壤水分蒸发和表面开裂。我们的研究结果为MPs对盐渍土物理性质、水分蒸发和裂缝发育的影响提供了证据，值得关注面临盐碱化和塑料污染的土壤-作物系统的调控和发展。