A new study by the U.C. San Diego Scripps Institution of Oceonography confirmed coastal water pollution transfers to the atmosphere in sea spray aerosol.
Researchers reported their findings on March 2 in the Journal of Environmental Science & Technology, showing that the chronic sewage-polluted coastal waters transfer to the atmosphere in a sea spray aerosol formed by breaking waves and bursting bubbles. The Sea Spray aerosol contains bacteria, viruses, and chemical compounds from the seawater, according to research.
The recent rainfall in the U.S. Mexico-Border region has caused wastewater treatment complications, resulting in sewage bacteria being diverted to the Tijuana River and flowing into the ocean in South Imperial beach.
“We’ve shown that up to three-quarters of the bacteria that you breathe in at Imperial Beach are coming from aerosolization of raw sewage in the surf zone,” said Prather. “Coastal water pollution has been traditionally considered just a waterborne problem. People worry about swimming and surfing in it but not about breathing it in, even though the aerosols can travel long distances and expose many more people than those just at the beach or in the water.”
According to lead researcher Kim Prather, a Distinguished Chair in Atmospheric Chemistry, and Distinguished Professor at Scripps Oceanography and UC San Diego’s Department of Chemistry and Biochemistry, an estimated 13 billion gallons of polluted waters entered the ocean through the Tijuana River since Dec.28, 20222.
The sample coastal aerosols were collected at Imperial Beach and water from the Tijuana River Between January and May 2019. Researchers used DNA sequencing and mass spectrometry to link bacteria and chemical compounds in coastal aerosol back to the sewage-polluted Tijuana River flowing into coastal waters.
The researchers are now conducting follow-up research to detect viruses and other airborne pathogens. Researchers say most bacteria and viruses are harmless and the presence of bacteria in sea spray aerosol does not automatically mean that microbes become airborne.
“This research demonstrates that coastal communities are exposed to coastal water pollution even without entering polluted waters,” said lead author Matthew Pendergraft, a recent graduate from Scripps Oceanography who obtained his Ph.D. under the guidance of Prather. “More research is necessary to determine the level of risk posed to the public by aerosolized coastal water pollution. These findings provide further justification for prioritizing cleaning up coastal waters.”
The research is led by Pather, in collaboration with UC San Diego School of Medicine and Jacobs School of Engineering researcher Rob Knight, and Pieter Dorrestein of the UC San Diego Skaggs School of Pharmacy and Pharmaceutical Science, both affiliated with the Department of Pediatrics – to study the potential links between bacteria and chemicals in sea spray aerosol with sewage in the Tijuana River.
