Wildfires can pollute rivers and streams for nearly a decade after they burn, a new study has found, raising fresh concerns about the long-term impacts on drinking water and ecosystem health.
Researchers analysed more than 100,000 water samples from both burned and unburned river basins in the US, revealing that contaminants such as nitrogen, phosphorus, sediment and organic carbon remained elevated for years after a fire – far longer than previously assumed.
"It can take two years, up to eight years, for the effect to be fully felt," said Ben Livneh, Associate Professor at the University of Colorado Boulder and a co-author of the study.
The team found that while some pollutants peaked in the first one to five years, others lingered for much longer. Nitrogen and sediment remained significantly elevated up to eight years after a blaze, especially in forested regions.
Researchers also discovered substantial variation in how watersheds responded. Some experienced negligible change, but others saw up to 2,000 times more sediment than normal.
"There's a huge amount of variability in sedimentation rates," said Ms Brucker. "Some streams are completely clear of sediment after wildfires, and some have 2,000 times the amount of sediment."
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