Getting the Dirt on Clean Soil in New York City

October 9, 2018

Urban gardening in New York City can be difficult thanks to lead contamination, but researchers have found a way to promote safe crop growth by using discarded clean soil from construction sites.

community garden in new york city neighborhood

Thanks to decades of gasoline emissions and paint dust, the soil in many parts of New York City shows lead contamination, thereby making urban gardening a difficult undertaking. At the same time, construction projects often pay high prices to get rid of clean glacial sediment, which lies below the contaminated surface layer of soil in Brooklyn and Queens. Now researchers at Brooklyn College have found a way to use that discarded sediment to produce clean soil, which backyard gardeners can in turn use to grow safe crops. 

NYC Clean Soil Bank matches up construction projects that need to get rid of sediment with construction projects that can use it. Providing that sediment to gardeners as well would be a huge boon to community garden initiatives. “This project kills three birds with one stone,” said Zhongqi “Joshua” Cheng, a professor at Brooklyn College, The Graduate Center, CUNY, and Macaulay Honors College. According to the research team’s findings, using clean sediment helps solve soil contamination problems, reduces solid waste from construction sites, and facilitates urban agriculture. “All of these contribute to the sustainability of cities,” he explained.

The research was published in Landscape and Urban Planning and the Journal of Environmental Management, and showed that even when the clean soil mixture was surrounded by contaminated soil, lead levels in fruits and leafy greens were “well below” limits set by the European Union. Creating clean soil from waste-stream materials will “maximize the many benefits of urban green spaces and agriculture,” including “food justice, STEM education, and the expansion of green jobs,” said Sara Perl Egendorf, a Ph.D. student at The Graduate Center, and lead author of one of the studies.

The researchers will continue to monitor lead levels at their urban test sites. “We are also looking more extensively into compost quality and the potential of making soils by mixing clean sediments with biosolids,” Cheng said.

Co-authors from the Environmental Sciences Initiative at The Graduate Center’s Advanced Science Research Center (ASRC) include postdoctoral research assistant Maha Deeb; Ph.D. student Anna Paltseva; Professor Peter Groffman, who is also on the Brooklyn College faculty, and undergraduate Victor Flores. Also involved in the study were Columbia University, the New York City Mayor’s Office of Environmental Remediation, Tulane University School of Medicine, and the New York City Urban Soils Institute.

Brooklyn College will host “Legacy Lead Town Hall” on Oct. 19. Attendees are encouraged to bring soil samples in ziplock bags for free testing.