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Saharan dust: a rain of fertilizer

Dusty plumes are detrimental to health but crucial to earth’s biology and climate
Hazy skies are over the Brazos Valley this weekend as the latest cloud of Saharan dust arrives
Hazy skies are over the Brazos Valley this weekend as the latest cloud of Saharan dust arrives(KBTX)
Published: Jul. 24, 2021 at 12:04 PM CDT|Updated: Jul. 24, 2021 at 12:16 PM CDT
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BRYAN, Texas (KBTX) - The latest round of Saharan dust has created a dull, gray haze over the Brazos Valley’s sky once again. While this dust creates unique sunrise and sunsets to enjoy, it does have some harmful impacts to health for certain, sensitive respiratory groups. The TCEQ listed the air quality as “moderate” across much of Texas and all of the Brazos Valley Saturday.

Hazy skies are over the Brazos Valley this weekend as the latest cloud of Saharan dust arrives
Hazy skies are over the Brazos Valley this weekend as the latest cloud of Saharan dust arrives(KBTX)

According to a local allergist, when Saharan dust is in the atmosphere the “symptoms mimic allergy with exposure, but the exact mechanism is not the same. Instead of functioning as an allergen like dust mites or pollen, it functions as more of an irritant of the airway.” Those with sensitive respiratory concerns, CPOD, and severe asthma are encouraged to remain indoors as much as possible when a higher concentration of this dust is in place.

This dust does benefit the earth as it moves west each summer. NASA studies show that wind and weather pick up, on average, 182 million tons of dust each year and carry it past the western edge of the Saraha. As the dusty air moves 10,000 to 15,000 feet above the ground, bits of it fall in a steady “rain” of particles. The minerals that make up this dust plume are rich in iron and phosphorus, which both plants on land and phytoplankton in the sea need to grow. According to National Geographic, “more than 70% of the iron available to the ocean-bound photosynthesizers in the Atlantic comes from Saharan dust, per a 2014 study.”

Fine particles of this dust may have their greatest impact on the Amazon. These small flecks of iron and phosphorus act as a fertilizer for the rainforest, helping to replenish minerals washed away from the soil and into the Amazon River by heavy rain. This nutrient delivery from Africa is important for maintaining healthy vegetation for one of the world’s most important ecosystems.

Dust moving through the atmosphere above the Atlantic ocean also helps to suppress tropical development during hurricane season. Tropical cyclones feed off warm ocean water but also moisture in the air. This dry, dusty larger are often dry as a bone, which typically works against any tropical weather maker, stunting rain and thunderstorm development. Think of it like a flame being robbed of oxygen needed to keep burning.

As weather patterns change in a warming climate, NASA scientists predict a 30% reduction in Saharan dust activity, from current levels, over the next 20 to 50 years. As the plumes of dust decline, so will their impacts on vegetation, forests, and ocean life.

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