Ocean pollutants that get trapped in the surf zone can become aerosolized and transported through the air to inland locations. We are working to better understand the ocean and atmospheric conditions leading to the ocean-to-atmosphere transfer of bacteria, viruses, pollutants, and toxins in waterborne coastal pollution in the San Diego, California, coastal region. The results will have significant implications for public health.

Why We Care
Coastal waters along Tijuana, Mexico, and Imperial Beach, California, are frequently polluted by millions to billions of gallons of untreated and partially treated sewage, as well as stormwater runoff. More than 100 million global annual illnesses occur in individuals who have direct physical contact with polluted coastal water. However, coastal water pollution may cause additional illnesses in people on land when waterborne pollutants are transferred into the air in sea spray aerosol generated by bursting bubbles in breaking waves. Sewage-associated bacteria in the polluted Tijuana River flowing into coastal waters can become aerosolized and transported along the coast, as well as inland, in sea spray aerosol. Further, coastal water pollution can be selectively transferred in sea spray aerosol, which can expose many more people to disease and illness than just those entering the water.

What We Are Doing
We are working to understand the factors leading to the aerosolization of waterborne pollutants in coastal regions. Specifically, the project seeks to address the following questions:

• • Which pathogens, toxins, and pollutants are most efficiently aerosolized from polluted estuaries, rivers, and the ocean? How do these change seasonally as ocean circulation changes? In particular, how do the ocean emissions change during wet vs. dry seasons?
  • What are the ocean and atmosphere conditions that lead to the most efficient aerosolization of pollutants and pathogens?
  • How are less frequent but more intense storms impacting the release of pollutants into the ocean and ultimately the atmosphere?
  • How will a warmer coastal ocean influence phytoplankton blooms that produce toxins that get released into the air?
  • Which pathogens, bacteria, volatile organic carbons, personal care products, drugs, and pharmaceuticals released in wastewater outputs become airborne?
  • How are changes in infrastructure affecting the levels and types of airborne pollutants?
  • What changes in processing can be added to reduce waterborne and airborne pollution sources and decrease exposure risk?
  • Which bloom toxins are transferred to the air? How far do these waterborne-derived pollutants travel in the atmosphere? How many more citizens are exposed via the airborne pathway? What are the long-term health implications to chronic and short-term exposure to this mixture of airborne pollutants?
  • How can the results from this study focusing on the San Diego coastal region at Imperial Beach near the Tijuana River Estuary be used to inform and expand studies on potential pollutants and pathogens in other coastal regions of the state and country?

Laboratory and field measurements will be conducted around the Imperial Beach, California, area. Work will be conducted in collaboration with students from the local high school to prioritize understanding the impact of aerosolized pollutants in spaces where youth spend most of their time.

Benefits of Our Work
This project will help us better understand the ocean and atmosphere conditions that lead to aerosolization of coastal water pollution. With this information, models can be developed to predict when aerosolization of coastal water pollution will be high and how it can be minimized, which can inform warning systems and improve public health.

This Community Directed Spending project is led by Dr. Kimberly Prather at the University of California San Diego.