Us city slickers have fouled the sandboxes we play in. Find an open field in a big city like Los Angeles or New York and the odds are that it’s a former toxic waste dump. Here in our neighborhood we’ve got a lot of lead and zinc–lead from paint and gasoline and zinc from brake linings.
These heavy metals don’t magically go away. They are elements, and short of an alchemical transformation you have to physically remove them, cover them up, or apply phosphate so that plants don’t take them up as readily.
One promising strategy is phytoremediation, the use of plants to uptake heavy metals.
City Atlas youarethecity, in New York, is experimenting with Indian mustard, mugwort, basket willow and sunflowers to remediate a contaminated garden. The results are promising with some metals down 50% in a year. Mugwort (Artimesia vulgaris) did an especially good job with a wide range of contaminants.
I should note that Garm Wallace, who runs Wallace Labs, a soil testing service, says that phytoremediation can take many years to get heavy metals down to a safe level. That being said, breeding plants specifically for heavy metal hyperaccumulation is a technology that could make up for our past transgressions.
Thanks to Michael Tortorello for the tip.