Biomass burning and cyanide production.
Aquatic ecological risks due to cyanide releases from biomass burning. Barber, Timothy, et al. Chemosphere, 50:343-348; 2003
As reported in The Human Ecologist:
"Burning of biomass such as wood, grass, and leaves can release dangerous amounts of cyanide, which can poison water supplies. A study of wildfire in North Carolina fount that nearby streams were contaminated with 49 parts per billion of cyanide, a level high enough to kill rainbow trout. Forest and brush fires may play a major role in fish kill."