Ocean spray formation
When wind, whitecaps, and breaking waves mix air into the sea surface, the air regroups to form bubbles, floats to the surface, and bursts at the air-sea interface.
When they burst, they release up to a thousand particles of sea spray,which range in size from nanometers to micrometers and can be expelled up to 20 cm from the sea surface.
Ocean spray aerosol, which can affect everyone than simply beachgoers, surfers, and swimmers, is a known carrier of coastal water pollution, according to new research led by Scripps Institution of Oceanography at UC San Diego.
Rainfall in the area of the US-Mexico border complicates the treatment of wastewater, which leads to untreated sewage being redirected into the Tijuana River and spilling into the ocean at south Imperial Beach. For many years, Imperial Beach’s coastline waters have been chronically polluted by this input of toxic water.
Ocean spray as a sewage vehicle
According to recent studies, ocean spray aerosol produced by breaking waves and bursting bubbles is a transport vehicle for sewage-polluted coastal waters into the atmosphere. Aerosolized saltwater contains chemical substances, viruses, and microorganisms.
The study’s results are published in the journal Environmental Science & Technology on March 2.
Kim Prather, the study’s lead author and Distinguished Chair in Atmospheric Chemistry at Scripps Oceanography and UC San Diego’s Department of Chemistry and Biochemistry, claims that since December 28, 2022, an estimated 13 billion gallons of sewage-polluted waters have entered the ocean via the Tijuana River.
She is also the NSF Center for Aerosol Effects on Chemistry of the Environment’s founding director (CAICE).
“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.”
Presence of Tijuana River bacteria in oceanic aerosols
Between January and May 2019, the team collected samples of water from the Tijuana River and coastal aerosols at Imperial Beach. After that, they connected the bacteria and chemical elements in coastal aerosol to the Tijuana River’s sewage pollution as it entered coastal waters using DNA sequencing and mass spectrometry.
It was discovered that bacteria and pollutants from the Tijuana River were present in oceanic aerosols. The team is currently carrying out follow-up research to look for viruses and other airborne diseases.
Prather and colleagues warn that the research does not prove that sewage in ocean spray aerosol is making people sick.
The majority of bacteria and viruses are non-lethal, and just because bacteria are present in ocean spray aerosol does not necessarily mean that pathogenic or other germs go airborne.
More research is required, according to the authors, into risk factors such as infectiousness, exposure levels, and other variables.
To investigate possible connections between bacteria and chemicals in ocean spray aerosol and sewage in the Tijuana River, three different research groups worked together, led by Prather in collaboration with Rob Knight of the UC San Diego Jacobs School of Engineering and School of Medicine, and Pieter Dorrestein of the UC San Diego Skaggs School of Pharmacy and Pharmaceutical Science, both affiliated with the Department of Pediatrics.
“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 PhD 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.”
Source:UC San Diego
