The aim of this research was to evaluate the variability of Pb bioaccessibility in urban garden soils and how it is affected by phosphate, organic content, soil pH and soil mineral species. The bioaccessibility of Pb in 49 soil samples was assessed using the U.S. EPA method 1340 (extraction with a simulated gastric acid at pH 1.5) and a modified protocol (same solution, but at pH 2.5). Overall, bioaccessibility values were highly variable (14%–86% at pH 1.5 and 14%–73% at pH 2.5), reflecting the heterogeneous nature of urban soils and the influence of soil mineralogy and other factors on the stability and leachability of Pb. There was a negative relationship between phosphate and Pb bioaccessibility, but this was only observed when the modified protocol was used. Organic content also had a negative relationship with Pb bioaccessibility. Principal component analysis based on leaching solution chemistry (proxy to mineral speciation) suggested that carbonate and Fe/Mn hydroxide effects on Pb bioaccessibility are not as significant as phosphate and organic matter. These findings not only confirm the value of applying phosphorus and organic amendments to reduce Pb bioaccessibility in urban garden soils, but also highlight the complexity of the factors controlling health risks to gardeners.
Guest Editor: Richard K. Shaw.
1PhD Program in Earth and Environmental Sciences, Graduate Center of The City University of New York, New York, USA.
2Brooklyn College of The City University of New York, Department of Earth and Environmental Sciences, 2900 Bedford Avenue, Brooklyn, New York, USA.
3RUDN University, Agrarian-Technological Institute, Moscow, Russia.
4New York City Urban Soils Institute, Brooklyn, New York, USA.
5Advanced Science Research Center at the Graduate Center of The City University of New York, New York, New York, USA.
6US EPA Region 2, New York, New York, USA.
Address for correspondence: Ms. Anna Paltseva, Graduate Center of The City University of New York, 365 5th Avenue, New York, NY 10016. E-mail: firstname.lastname@example.org
Financial Disclosures/Conflicts of Interest: The project was supported by the RUDN University project 5-100.
Received March 18, 2018.
Accepted for publication September 28, 2018.