Oct 30, 2017

California wildfires leave behind toxic ash

A woman finds her wedding ring in the debris of her burned home. Photo: Jeff Chiu / AP

As the last flames from the deadly California wildfires are extinguished, the state faces another hurdle in the form of ash — possibly toxic — left behind, WIRED's Adam Rogers reports.

Why it matters: The environmental impacts of large volumes of ash range from contaminated soil to algal blooms. "We're anywhere from five years to 100 years in terms of the longevity of effects," Oregon State University researcher Kevin Bladon told WIRED. "That really depends on the severity of the fire and our ability to get some vegetation re-established on site."

Ash created in low temperature fires, under 840 degrees Fahrenheit, is grey or black and mostly organic carbon whereas ash created in hotter fires is white because most of the carbon has burned away, leaving calcium and magnesium. Depending on the chemical composition of the ash, it will be hydrophobic or hydrophilic. Rainfall will mix with more hydrophilic ash and could enter streams. If the ash is hydrophobic, it will repel the water and may then run off quickly, washing soil away in the process.

  • If the ash runs off into streams, it could eventually reach the San Francisco Bay and stimulate algal blooms. With the volume of ash created in the recent fires, these potentially large blooms could "eat all the dissolved oxygen out of a waterway, making it unlivable for everything else," per WIRED.
  • If it stays on land, a mixture of calcium oxide in certain types of ash and rain could create a layer of cement-like limestone on forest floors. "Basically, the ash can pave a forest," Rogers writes.

The big question: Scientists have experience with ash from burned vegetation but the recent California fires burned both forests and cities. So the resulting ash will "be full of heavy metals and toxins — no one knows exactly how much, and it depends on what burned and at what temperature."

The bottom line from Rogers: "All of which means the real trick in Northern California will be debris cleanup."

Go deeper

Fed temporarily lifts Wells Fargo's growth restrictions

Photo: Streeter Lecka/Getty Images

The Federal Reserve said Wednesday it will temporarily lift Wells Fargo’s growth restrictions, which were put in place following the bank’s customer abuse scandals.

Why it matters: The Fed’s only reason for lifting the cap is so Wells Fargo can dole out more loans to struggling small businesses as part of the government’s coronavirus aid package. Earlier this week, the bank said it could only lend a total of $10 billion, thanks to Fed restrictions that it can’t grow its assets beyond $1.95 trillion.

Coronavirus dashboard

Illustration: Sarah Grillo/Axios

  1. Global: Total confirmed cases as of 12 p.m. ET: 1,450,343 — Total deaths: 83,568 — Total recoveries: 308,617Map.
  2. U.S.: Total confirmed cases as of 12 p.m. ET: 399,979 — Total deaths: 12,912 — Total recoveries: 22,539Map.
  3. Business updates: Roughly one-third of U.S. apartment renters didn't make April payments.
  4. Federal government latest: The U.S. has begun to see "glimmers of hope" despite its highest recorded number of deaths in 24 hours, Anthony Fauci said.
  5. Public health latest: Surgeon General Jerome Adams highlighted the disproportionate impact the illness is having on African-American communities.
  6. World latest: Indians look to Taiwan amid China's coronavirus missteps
  7. 🚌 Public transit: Systems across the country are experiencing ridership collapse, squeezed funding streams and slow recovery from the pandemic.
  8. What should I do? Pets, moving and personal healthAnswers about the virus from Axios expertsWhat to know about social distancingQ&A: Minimizing your coronavirus risk.
  9. Other resources: CDC on how to avoid the virus, what to do if you get it.

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Bernie Sanders suspends presidential campaign

Photo: ANDEL NGAN/AFP via Getty Images

Sen. Bernie Sanders announced Wednesday that he is suspending his presidential campaign.

The big picture: It's an end to the campaign of the leading progressive in the race — and the candidate who seemed to be the clear front-runner for the Democratic nomination just a few months ago. It also makes Biden the presumptive Democratic nominee four months before the party's convention in Milwaukee.