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New Study Traces Airborne Dust Back To Shrinking Salton Sea

A bird skirts the Salton Sea's receding shoreline, April 10, 2015.

Photo by Nicholas McVicker

Above: A bird skirts the Salton Sea's receding shoreline, April 10, 2015.

New Study Traces Airborne Dust Back To Shrinking Salton Sea

GUEST:

David Wagner, science and technology reporter, KPBS

Transcript

A new UC Riverside study provides some answers to the question of whether the shrinking Salton Sea is worsening air quality and hurting the health of nearby residents.

As the Salton Sea shrinks — exposing land that was once underwater to desert winds — one concern has been that increased dust emissions will make already poor air quality worse for nearby residents. A recently published study out of UC Riverside confirms this is already starting to happen.

"With drying up of the lake and exposing of the shoreline, we get an additional source of airborne dust," said UC Riverside associate professor of atmospheric science Roya Bahreini, who led the study. "And exposure to these particles can have health impacts for humans."

The researchers wanted to know how much of the airborne dust around the Salton Sea is actually coming from newly exposed lakebed, known as "playa." So they sampled airbone particulate matter at Bombay Beach and Salton City in August 2015 and again in February 2016.

They found that nearly 10 percent of the kind of particulate matter known to raise the risk of heart and lung disease came from playa. Forty-five percent came from desert sources. Man-made pollution also contributed to the particulates in the air the researchers sampled.

Though the contribution from playa emissions may seem relatively low now, Bahreini said it could increase sharply in the near future. Under a water transfer agreement, the Salton Sea is scheduled to stop receiving inflows of "mitigation" water from the Imperial Irrigation District at the end of 2017. That means the sea is likely to shrink more quickly.

"Contribution of the playa to airborne dust is going to increase because the water inputs are going to decrease significantly by the end of the year," Bahreini said.

The researchers also looked at the chemical composition of the airborne playa dust. They wanted to understand if pesticides that flowed into the Salton Sea for decades could make airborne playa dust more hazardous to human health, as some have feared.

But they found that while airborne playa dust was saltier and higher in some trace elements like calcium and selenium, it was not especially toxic compared to desert soils. The concentrations of toxic elements remained far below thresholds set by the California EPA. The only exception was the element nickel, which did exceed the agency's reference exposure levels during three of the 25 sampling periods.

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