Scientists have known for years that together, bacteria and plants can remediate contaminated sites. Ramakrishna Wusirika, of Michigan Technological University, has determined that how you add bacteria to the mix can make a big difference.
He has also shed light on the biochemical pathways that allow plants and bacteria to clean up some of the worst soils on the planet while increasing their fertility.
Wusirika, an associate professor of biological sciences, first collected stamp sands near the village of Gay, in Michigan's Upper Peninsula. For decades, copper mining companies crushed copper ore and dumped the remnantsan estimated 500 million tons of stamp sandthroughout the region. Almost nothing grows on these manmade deserts, which are laced with high concentrations of copper, arsenic and other plant-unfriendly chemicals.
Then, Wusirika and his team planted maize in the stamp sand, incorporating bacteria in four different ways:
After 45 days, the team uprooted the plants and measured their dry weight. All maize grown with bacteria was significantly more vigorousfrom two to five times largerthan the maize grown in stamp sand alone. The biggest were those planted as seedlings or as germinated seeds.
However, when the researchers analyzed the dried maize, they made a surprising discovery: the seed-planted maize took up far more copper as a percentage of dry weight. In other words, the smaller plants pulled more copper, ounce per ounce, out of the stamp sands than the bigger ones.
That has implications for land managers trying to remediate contaminated sites, or even for fa
|Contact: Marcia Goodrich|
Michigan Technological University