The Earth is becoming 'saltier'

Human activities have accelerated the natural salt cycle, causing the concentration of salt ions in rivers and streams to increase significantly over the past 50 years.

Salt sprinkled on the roads during the cold season is one of the main causes. Photo: Tricky Shark — Salt sprinkled on the roads during the cold season is one of the main causes. Photo: *Tricky Shark*

The world is getting saltier, and human activity is causing this, according to a new study in the journal Nature Reviews Earth & Environment , IFL Science reported on November 29. The change in salinity is causing major changes in the chemistry of rivers, affecting water quality and human health.

The Earth has a natural salt cycle, in which geological and hydrological processes, such as the weathering of rocks and minerals, bring salts to the Earth's surface over long periods of time. But in recent decades, humans have significantly accelerated this cycle through mining and land development, bringing salts to the surface faster than natural processes. The concentration of salt ions in rivers and streams has increased significantly in the past 50 years. Human-caused salinization affects about 1 billion hectares of land worldwide.

Salt here is not just sodium chloride—the white stuff sprinkled on food. In the terminology of chemists and geologists, salt is any chemical compound made up of a combination of cations (positively charged ions) and anions (negatively charged ions).

"When people think of salt, they often think of sodium chloride, but our work over the years has shown that humans have disturbed other salts, including those associated with limestone, gypsum, and calcium sulfate," said Sujay Kaushal, lead author of the study and professor at the University of Maryland.

Increased salt levels can have a range of negative impacts on the environment and human health. One of the main concerns is water quality. Salt ions can bind with contaminants in soil and sediment, forming a “chemical cocktail” that circulates through the environment and enters water sources.

The air is also not safe from rapid salinization. When lakes dry up, a phenomenon that is becoming more common due to climate change, plumes of salt can be released into the atmosphere. This can have negative effects on human health, the researchers say.

One of the major causes of salt contamination is the application of salt to roads during cold weather to prevent ice buildup. In the United States, this salt accounts for 44% of all salt consumed and accounts for nearly 14% of the dissolved solids that flow into rivers. Reducing the amount of salt applied to roads may be one solution, but it could also increase the number of road accidents.

Thu Thao (According to IFL Science )

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