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1. Reversing Freshwater Salinization: A Holistic Approach

   Grant, S.B. (January 2021, Advances in water research)

   Inland freshwater salinity is rising globally, a trend that threatens water and food supplies, civil infrastructure, and freshwater ecosystems. 

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2. Impact of salinization on lake stratification and spring mixing

   https://doi.org/10.1002/lol2.10215  

   Ladwig, Robert; Rock, Linnea A.; Dugan, Hilary A. (October 2021, Limnology and Oceanography Letters)

   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. 

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3. The slow and steady salinization of Sparkling Lake, Wisconsin

   https://doi.org/10.1002/lol2.10191  

   Dugan, Hilary A.; Rock, Linnea A. (April 2021, Limnology and Oceanography Letters)

   The concentrations of conservative solutes in seepage lakes are determined by the relative inputs of precipitation vs. groundwater. In areas of road salt application, seepage lakes may be at high risk of salinization depending on groundwater flow. Here, we revisit a 1992 analysis on the salinization of Sparkling Lake, a deep seepage lake in Northern Wisconsin. The original analysis predicted a rapid increase in chloride concentrations before reaching a steady steady of 8 mg L⁻¹by 2020. Forty years of monitoring Sparkling Lake show that rather than reaching a dynamic equilibrium, chloride concentrations have steadily increased. We update the original box model approach by adding a soil reservoir component that shows the slow steady rise in chloride is the result of terrestrial retention. For freshwater rivers and lakes, chloride retention on the landscape will both delay chloride impairment and prolong recovery and must be considered when modeling future chloride contamination risk. 

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4. Effects of Freshwater Salinization and Biotic Stressors on Amphibian Morphology

   https://doi.org/10.1643/h2020070  

   Lewis, Jacquelyn L.; Borrelli, Jonathan J.; Jones, Devin K.; Relyea, Rick A. (March 2021, Ichthyology & Herpetology)

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5. The tradeoff between water savings and salinization prevention in dryland irrigation

   https://doi.org/10.1016/j.advwatres.2023.104604  

   Karimzadeh, Saeed; Hartman, Sarah; Chiarelli, Davide Danilo; Rulli, Maria Cristina; D'Odorico, Paolo (January 2024, Advances in Water Resources)

   Soil salinization is a global phenomenon that affects large tracts of arid farmland worldwide. It contributes to the loss of soil fertility, declining yields, and – in the most severe cases – land unsuitability for cultivation. Irrigation water applications are both the main cause of and the solution to, anthropogenic (or ‘secondary’) salinization because salt typically enters the soil column as dissolved in irrigation water and leaves it through excess water applications (e.g., leaching). Excess leaching, which places additional water costs in areas affected by water scarcity, can be achieved with different irrigation techniques and practices. Here, by complementing a process-based crop water model with a salt balance of the shallow soil, we investigate the tradeoff between root zone salinization and water conservation to limit withdrawals from the water source. We evaluate how such a tradeoff is achieved under different irrigation technology and excess leaching practices. Considering as a case study the cultivation of tomatoes in Egypt, we find that drip and furrow irrigation allows for better control of salt accumulation, thus preventing crop exposure to salt stress. Drip irrigation achieves this goal with minimal water applications because it maintains the soil wetter. Thus, the (rare) rainfall events find more suitable conditions to drain the excess moisture. Conversely, by using more irrigation water (and ‘less efficiently’), furrow irrigation allows for higher rates of soil drainage and salt leaching. The irrigation schedule typically adopted with sprinkler irrigation allows for soil drying, thus limiting the ability of rainfall events to drain the soil and leach its salts. Collectively, these results highlight the key role of irrigation technology and practices in the management of secondary salinity in dryland agriculture. Specifically, there is a tradeoff between minimizing water use and preventing salt accumulation in the root zone. Drip irrigation exhibits the co-benefit of achieving both goals, while furrow irrigation limits soil salinity at the cost of requiring greater volumes of applied irrigation water. 

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