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Abstract
Cd and Zn concentrations in vegetables raised in a community garden on a low‐pH, urban soil (Udorthent) with no history of dumping or other contamination were higher than those from another community garden located on a reclaimed landfill where digested sewage sludge had been applied, and where total soil Cd, Cu, Pb, Zn, and soil pH were higher. Vegetables from the latter site in turn had higher levels of Cd and Zn than those raised on a low‐metal, neutral‐pH, urban garden site. Split plots with and without added lime were established on the low‐pH site. Beet (Beta vulgaris, L.), lettuce (Lactuca sativa, L.), radish (Raphanus sativus, L.), and Swiss chard (Beta vulgaris, L., var. cicla) had lower Cd and Zn concentrations in limed than unlimed plots, while vegetable Cu and Pb concentrations were not affected by liming. After four years of liming, Cd and Zn in vegetables reached background levels, and there was no observable difference between limed and unlimed plots. Cd and Zn in Swiss chard, lettuce, and beet leaves showed highly significant inverse correlations with soil pH (.64** < r2 < .96**) in limed and unlimed plots. These results indicate that total soil Cd and Zn may be less important than soil pH in determining vegetable metal availability. Beet and radish root had lower concentrations of Cd, Cu, and Zn than did leaves of the same species, while beet roots had higher Pb levels than beet leaves. Among the four metals studied, only Cd and Zn in vegetables correlated closely (r2 = .85**), indicating a common mode of uptake.
