Effects of Soil Property and Soil Amendment on Wea

Authors: Lena Q Ma Donald W Hardison Willie G Harris Xinde Cao Qixing Zhou

Publish Date: 2006/07/26

Volume: 178, Issue: 1-4, Pages: 297-307

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Abstract

Weathering of abraded metallic Pb from bullets is a significant source of Pb contamination in shooting range soils Weathering studies were performed using metallic Pb powder to simulate the finesize fraction of metallic Pb found in shooting range soils The effects of soil properties moisture organic matterOM and pH on weathering of abraded metallic Pb were examined by incubating a typical Florida soil for 5 to 12 days at 100 or 80 field capacity FC after spiking with 5 metallic Pb after removal of soil OM at 100 FC and after adjusting the soil pH to 48 61 or 85 at 100 FC The weathering products were examined using Xray diffraction XRD Transformation of metallic Pb to secondary Pbminerals was more rapid at 100 FC in the presence of OM and at lower pH While little transformation of Pb occurred in the absence of soil OM and mostly litharge PbO was found at higher pH both hydrocerussite and litharge formed at lower pH A threestep weathering mechanisms of metallic Pb including oxidation carbonation and dissolution was proposed Addition of both calcium carbonate and phosphate rock was effective in reducing watersoluble Pb though the effect was minimal after 11 weeks of incubation attributing to the liming effect of metallic Pb added to the soil While reducing soil moisture and organic matter and increasing soil pH slowed weathering of metallic Pb in a soil the effect of calcium carbonate and phosphate rock on Pb solubility in soils highly contaminated with Pb was limited

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