Migrating ducks and stray tumbleweed bushes have been contaminated with radioactivity after landing briefly in waste water ponds at the Idaho National Engineering and Environmental Laboratory (INEEL).
In the mid 1990s, staff at INEEL realised that tumbleweeds were able to: “Blow into waste water ponds, wash up on shore, and blow out again,” said Ronald Warren, an expert contracted to scrutinise radioactivity at INEEL. “The tumbleweeds blew against a 2m high fence where they built up, forming a ramp other weeds could climb over.” In a two-year study, Warren measured how much radiation the tumbleweeds took with them from two waste ponds near a US Navy test reactor. The team found that the tumbleweeds carried a total of 66MBq and spread it over 32 hectares.
“The activity from those tumbleweeds made a relatively small, around 15%, increase to the activity due to global fallout in that area,” he says. The risk of affecting the public is slight, as the nearest house is 42km away and the tumbleweed travels less than 1km.
Nonetheless, INEEL has taken action. It has made the fence higher, and collects the tumbleweeds and buries them. Growing shrubs near the ponds has also hampered the tumbleweed.
However, birdlife is harder to cope with. Warren has found 21 species of migratory duck that fly over INEEL, and some stop in the waste ponds.