Scientists Explore Impact of Los Angeles Wildfires on Ocean Health

LOS ANGELES—On a recent Sunday, Tracy Quinn drove along the Pacific Coast Highway to evaluate the damage inflicted on the coastline by the Palisades Fire.

The water’s surface was tainted by ash. Charred remnants of washing machines, dryers, and metal appliances were scattered along the shore. A sludge layer covered the water’s edge. During high tide, waves crashed against burnt homes, dragging debris and potentially toxic ash into the ocean as they receded.

“It was just heartbreaking,” said Quinn, president and CEO of the environmental organization Heal the Bay, whose team has reported findings of ash and debris as far as 25 miles south of the Palisades fire area west of Los Angeles.

As teams work to remove potentially hundreds of thousands of tons of hazardous waste resulting from the Los Angeles wildfires, researchers and officials are striving to comprehend how the fires on land have affected the marine environment. The Palisades and Eaton fires scorched thousands of homes, businesses, vehicles, and electronics, transforming everyday items into toxic ash containing pesticides, asbestos, plastics, lead, heavy metals, and more.

There are growing concerns and many unknowns regarding how this pollution could impact marine life since much of the debris may find its way into the Pacific Ocean.

“We haven’t previously witnessed such a concentration of burned homes and structures so close to the ocean,” Quinn noted.

Fire debris and hazardous ash can render the water unsafe for surfers and swimmers, particularly after rainfall that can wash chemicals, trash, and other risks into the ocean. Over the long term, scientists are concerned about the implications of charred urban contaminants on our food supply.

The atmospheric river and mudslides that battered the Los Angeles area the previous week heightened some of these concerns.

When the fires initiated in January, one of Mara Dias’ primary worries was the contamination of ocean water. Strong winds carried smoke and ash far beyond the fires before settling in the water, reported the water quality manager for the Surfrider Foundation, an environmental nonprofit.

Researchers aboard a research vessel during the wildfires confirmed the presence of ash and waste up to 100 miles offshore, noted marine ecologist Julie Dinasquet from the University of California, San Diego’s Scripps Institution of Oceanography. She recalled the overwhelming smell of burning electronics, an odor “not reminiscent of a pleasant campfire.”

Runoff following rains also poses a significant and immediate risk. Rainwater is capable of picking up contaminants and trash while flowing towards the ocean through drains and rivers. This runoff may carry “a substantial amount of nutrients, nitrogen, and phosphate that can originate from the ash of burnt materials,” said Dias, in addition to “heavy metals, and substances called PAHs, which are emitted when various fuels are burned.”

Mudslides and debris flows in the Palisades Fire burn area are also capable of introducing more hazardous waste into the ocean. Following wildfires, the soil in burn scars becomes less adept at absorbing rainfall and may form a barrier that repels water due to remnants of burnt organic material. This scenario increases the likelihood of mudslides and debris flows because there is less organic material to stabilize the soil.

Los Angeles County officials, in collaboration with other agencies, have installed thousands of feet of concrete barriers, sandbags, silt socks, and more to prevent debris from contaminating beaches. Additionally, the L.A. County Board of Supervisors recently enacted a motion seeking state and federal assistance to enhance beach clean-up efforts, prepare for storm runoff, and test ocean water for potential toxins and chemicals, among other measures.

In addition to routine samples, state water officials and others are investigating total and dissolved metals such as arsenic, lead, and aluminum, along with volatile organic compounds.

They are also analyzing microplastics, polycyclic aromatic hydrocarbons (PAHs), which are harmful to both human and aquatic life, and polychlorinated biphenyls (PCBs)—man-made chemicals linked to cancer in animals and serious health issues—once used in products such as pigments, paints, and electrical equipment but now banned from production.

County public health officials indicated that chemical tests of water samples last month did not raise health alarms, leading them to downgrade one beach closure to an ocean water advisory. Despite this, beachgoers are still advised to refrain from swimming.

Dinasquet and her colleagues are investigating how far potentially toxic ash and debris have spread across the ocean, how deep they have sunk, and ultimately where they may end up over time.

While forest fires can introduce essential nutrients like iron and nitrogen into the ocean ecosystem, promoting the growth of phytoplankton and creating a beneficial ripple effect throughout the ecosystem, the hazardous ash from urban coastal fires could lead to catastrophic outcomes, Dinasquet noted.

“Reports are already indicating significant amounts of lead and asbestos in the ash,” she added. “This poses severe risks for people and is likely detrimental to marine organisms as well.”

A significant concern remains whether toxic substances from the fire will infiltrate the food chain. Researchers intend to collect tissue samples from fish to detect the presence of heavy metals and contaminants. However, they acknowledge that it will take time to comprehend how a massive urban fire may influence the broader ecosystem and food supply.

Dias observed that while the ocean has historically absorbed pollution from land, the compounded effects of fires and other disasters have made the situation increasingly critical.

By Dorany Pineda