Dissertations, Theses, and Capstone Projects

Date of Degree

9-2019

Document Type

Dissertation

Degree Name

Ph.D.

Program

Earth & Environmental Sciences

Advisor

Zhongqi Cheng

Committee Members

Peter Groffman

Murray McBride

Alexander Van Geen

Pengfei Zhang

Subject Categories

Soil Science

Keywords

trace metals, urban soil, vegetables, bioaccessibility, phosphates, XRF, gardens, urban agriculture

Abstract

This dissertation examined total and bioaccessible soil lead (Pb) and arsenic (As) concentrations and their accumulation in commonly grown garden vegetables in New York City (NYC) metropolitan area. Direct oral ingestion of contaminated soil and consumption of plants that have accumulated Pb or As from underlying soil are known human exposure pathways in urban garden soils that often contain elevated levels of contaminants. The research had four components: (1) assessment of the variability of bioaccessible Pb in NYC urban soils; (2) field experiments to evaluate Pb stabilization and As mobilization by phosphate and alternative amendments; (3) development of a new screening method for rapidly assessing bioaccessible Pb using an X-ray fluorescence (XRF) Analyzer and (4) a case study of a highly contaminated urban garden. The research involved a mixture of field experiments in urban and suburban locations and detailed laboratory measurements of Pb and As in soil and plant tissue samples. The results highlight the potential risks of Pb and As in both urban and suburban garden soils to humans. The results should be of use to policy makers, soil managers, and gardeners interested in reducing these risks and developing best practices to minimize gardener exposure to contaminants.

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