Hydrogen sulfide, the pungent stuff often referred to as
sewer gas, is a deadly substance implicated in several mass extinctions,
including one at the end of the Permian period 251 million years ago that wiped
out more than three-quarters of all species on Earth.
But in low doses, hydrogen sulfide could greatly enhance
plant growth, leading to a sharp increase in global food supplies and plentiful
stock for biofuel production, new University of Washington research shows.