That composting pile of leaves in your yard might just hold the key to saving the San Francisco bay.
Researcher Allison Luengen at the University of San Francisco has discovered that decaying organic matter can halt the absorption of mercury by tiny plankton. That's a significant finding, since plankton are consumed by fish, which are in turn consumed by larger animals like birds, sea lions, and humans.
Unfortunately, that still leaves us with a lot of mercury in bay water, even if it's not being taken up by microorganisms. Removing the element is extremely difficult, especially in such a large and complex environment, featuring many different types of ecosystems. A 2006 plan to dredge and monitor the bay was the region's first attempt to deal with the contamination.
The bay's mercury pollution dates back to the gold rush, when it was used by prospectors. Despite contemporary efforts at envrionmental remediation, mercury levels have not changed in the bay since the 1970s. The long-term plan for the bay is simply to wait for the mercury to disperse -- with emphasis on the "long term" aspect. At the current rate, it could take over a century for the levels to decrease.
In the mean time, Luengren's discovery could help preserve the region's threatened wildlife. Mammals such as otters have experienced catastrophic population declines in recent years, with many scientists blaming human-derived water pollution.