June 20, 2024

Humans Disrupting Global Salt Cycle, Posiing ‘Existential Threat,’ Warns New Study

The influx of salt in streams and rivers due to human activities is becoming an ‘existential threat,’ warns a research group led by University of Maryland Geology Professor Sujay Kaushal. The study, published in the journal Nature Reviews Earth & Environment, reveals that human activities are increasing the saltiness of Earth’s air, soil, and freshwater, which could have severe consequences if current trends continue.

While natural geologic and hydrologic processes bring salts to the surface over time, human activities such as mining and land development are rapidly accelerating the natural ‘salt cycle.’ Agriculture, construction, water and road treatment, and other industrial activities also contribute to salinization, which harms biodiversity and can render drinking water unsafe.

The researchers describe these disturbances as an ‘anthropogenic salt cycle,’ highlighting that humans are affecting the concentration and cycling of salt on a global scale. Previous studies were limited to case studies of specific areas, but this research establishes the global interconnectedness of salt disruption.

The study examines various salt ions found underground and in surface water, not just the commonly known sodium chloride. It demonstrates that human-caused salinization has affected approximately 2.5 billion acres of soil globally, an area equivalent to the size of the United States. The concentration of salt ions has also increased in streams and rivers over the last 50 years, coinciding with a rise in global salt use and production.

The impact of salinization extends to the atmosphere and ecosystems. In some regions, drying lakes release saline dust into the air. Road salts used for snow treatment can also become aerosolized, generating sodium and chloride particles. Salinization has cascading effects, accelerating snow melting and potentially damaging communities reliant on snow for water supply. Salt ions can also bind to contaminants, forming harmful ‘chemical cocktails’ that circulate in the environment.

Road salts have a significant impact in the US, with approximately 44 billion pounds of deicing agent used annually. They account for 44% of US salt consumption and 13.9% of total dissolved solids in streams. To prevent excessive salt in waterways, the study recommends policies that restrict road salt use or promote alternatives. Several US cities, including Washington, D.C., have begun using beet juice as a less salty alternative for treating icy roads.

The study’s authors call for the establishment of a planetary boundary to regulate safe and sustainable salt use, similar to how carbon dioxide levels are managed to mitigate climate change. However, regulating salt comes with unique challenges, as it is not considered a primary drinking water contaminant in the US. Despite the complexity, the increasing levels of salt in the environment pose a significant risk that needs to be addressed. Finding the right balance between public safety and water quality is crucial.


  1. Source: Coherent Market Insights, Public sources, Desk research
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