2015 GSA Annual Meeting in Baltimore, Maryland, USA (1-4 November 2015)

Paper No. 84-3
Presentation Time: 8:35 AM


SHARP, Rosalie M.1, FITZSTEVENS, Maia G.1 and BRABANDER, Daniel J.2, (1)Environmental Studies, Wellesley College, 106 Central Street, Wellesley, MA 02481, (2)Geosciences, Wellesley College, 106 Central Street, Wellesley, MA 02481, rsharp@wellesley.edu

Community driven urban agriculture is an empowering source of affordable, fresh, healthy, and culturally appropriate food in urban neighborhoods. However, in many cities urban soil lead contamination correlates with elevated blood lead levels in children and thus threatens the potential social and environmental rewards of urban agriculture. Lead exposure causes significant neurological damage, especially in children, negatively impacting individuals and society. Compost application is a promising tool for soil lead remediation since low lead compost can dilute and bind lead in highly contaminated soils. This project evaluates the key biogeochemical characteristics of growing matrices in order to gain a comprehensive understanding of the ability of municipally sourced compost as a growth media to support urban agriculture and remediate lead contaminated urban soil. Samples of compost, garden soil, and unamended soil were collected in Roxbury, MA, in partnership with The Food Project, an organization that promotes urban farming for youth and community empowerment. Geochemical fingerprinting coupled with textural characterization using SEM images (JEOL VP-SEM0-EDS) confirms that compost and urban soil are geochemically distinct and constitute end members of the urban growing matrix spectrum examined in this study. Using an Energy Dispersive X-ray fluorescence instrument (SPECTRO-XEPOS), a CHNS Element Analyzer (Elementar Vario MICRO Cube), and performing the EPA in-vitro Bioaccessibility Assay, we examine major physical and chemical properties of bulk, sieved, and density separated samples in relation to Pb concentrations and bioaccessibility. Compared to unamended soils, compost has lower total Pb, a higher fraction of non-transportable grains (>150 µm), higher pH, and higher % organic carbon, all of which are associated with reduced Pb geomobility and bioaccessibility. This research will improve risk assessment of gardening in contaminated soils and shape effective and sustainable remediation recommendations for urban agriculture. This work contributes to a broader goal of optimizing urban carbon cycling to support social, cultural, and environmental sustainability in the urban ecosystem.