Anthropogenic freshwater salinization affects thousands of lakes worldwide, and yet little is known about how salt loading may shift timing of lake stratification and spring mixing in dimictic lakes. Here, we investigate the impact of salinization on mixing in Lakes Mendota and Monona, Wisconsin, by deploying under-ice buoys to record salinity gradients, using an analytical approach to quantify salinity thresholds that prevent spring mixing, and running an ensemble of vertical one-dimensional hydrodynamic lake models (GLM, GOTM, and Simstrat) to investigate the long-term impact of winter salt loading on mixing and stratification. We found that spring salinity gradients between surface and bottom waters persist up to a month after ice-off, and that theory predicts a salinity gradient of 1.3–1.4 g kg⁻¹ would prevent spring mixing. Numerical models project that salt loading delays spring mixing and increases water column stability, with ramifications for oxygenation of bottom waters, biogeochemistry, and lake habitability.

中文翻译：

---

盐渍化对湖泊分层和泉水混合的影响

人为淡水盐碱化影响了全世界数以千计的湖泊，但人们对盐负荷如何改变湖泊分层和二分湖春季混合的时间知之甚少。在这里，我们调查了盐化对威斯康星州门多塔湖和莫诺纳湖混合的影响，方法是部署冰下浮标记录盐度梯度，使用分析方法量化防止春季混合的盐度阈值，并运行垂直单维水动力湖泊模型（GLM、GOTM 和 Simstrat）研究冬季盐负荷对混合和分层的长期影响。我们发现春季地表水和底层水之间的盐度梯度在结冰后持续长达一个月，该理论预测盐度梯度为 1.3–1.4 g kg ⁻¹会阻止弹簧混合。数值模型预测，含盐量会延迟泉水混合并增加水柱稳定性，并对底层水的氧化作用、生物地球化学和湖泊宜居性产生影响。