The Dirt, the blog of the American Society of Landscape Architects, reports on how urban brownfields in New York City are being cleaned up using phytoremediation. ASLA quotes urban designer Kaja Kuhl, Adjunct Associate Professor at Columbia University, who found that more than 11 percent of New York City is abandoned lots:
"If glued together, these disparate, small-scale lots would be the size of Manhattan. Also, most of the sites are small: 50 percent of all vacant lots of less than 2,500 square feet and 80 percent are less than 5,000 square feet. If applied across these small sites, low-cost and highly-effective phytoremediation techniques could have a powerful impact and help ensure future urban development is really just redevelopment."
Here's a video from ASLA that illustrates how phytoremediation works: