Sometimes we discover things that we don’t yet understand. We like to share those findings with you, even before we make sense of them. Here is one.


This map shows the concentrations of lead in the soil at about 60 sampling sites across Manhattan, including the medians of Broadway and Central Park. Our team, led by Amy Savage and Elsa Youngsteadt, took soil cores and worked with microbial ecologist Krista McGuire at Barnard College to analyze the soils’ nutrients and contaminants. Here we’re highlighting the lead results.

At first glance, it looks like lead concentrations may be higher in the city’s forests. Why is there so much lead in some soils and not others? We don’t know yet. Perhaps there is a simple answer. Perhaps not. Perhaps, even, you can help.

For reference, according to the US CDC, uncontaminated soils contain concentrations of lead less than 50 ppm; levels below 100 ppm concentration are considered safe for gardening without any special precautions.

Many thanks to Lauren Nichols for her mad mapping skills. New York City Parks data layer courtesy NYC Open Data.