Macroscopic and molecularscale assessment of soil

Authors: Yuji Arai Allison R Rick Tessa Saylor Emily Faas Ryan Tappero Antonio Lanzirotti

Publish Date: 2011/05/24

Volume: 11, Issue: 6, Pages: 968-979

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Abstract

Environmental contamination of lead Pb in soils and sediments poses serious threats to human and ecological health The objective of this study is to investigate the effect of seasonal dove sports hunting activities on Pb contamination in acid forest soilsA grid sampling method was used to investigate the spatial distribution of Pb contamination in surface soils Soils were analyzed for total metalloid concentration and characterized for physicochemical properties and mineralogy Adsorption isotherm experiments were also conducted to understand the reactivity and retention capacity of PbII in soils Finally synchrotronbased Xray microprobe and Xray absorption spectroscopy were used to understand the chemical speciation of Pb that controls the retention/release mechanisms of Pb in soilsThere was no excessive accumulation of Pb at the site However the concentration of Pb in surface soils was greater than the background level 16 mg kg−1 The contamination level of Pb was as high as 67 mg kg−1 near a patch of corn field where lime was frequently applied A microfocused Xray microprobe analysis showed the presence of Pb pellet fragments that predominantly contain oxidized PbII suggesting that oxidative dissolution was occurring in soils Dissolved PbII can be readily retained in soils up to ~3600 mg kg−1 via innersphere and outersphere surface complexation on carbon and aluminol functional groups of soil components suggesting that partitioning reactions control the concentration of Pb in soil solutionThe fate of Pb is likely to be controlled by 1 oxidative dissolution process of Pb0 pellets and 2 the release of outersphere and/or innersphere Pb surface complexes in humic substances and aluminosilicate/Al oxyhydroxides Although no remedial actions are immediately required the longterm accumulation of Pb in soils should be carefully monitored in protecting ecosystem and water quality at the dove hunting fieldThis research was supported in part by the Clemson University Undergraduate Creative Inquiry research funds The authors thank the undergraduate students from the Department of Biosystems Engineering for assisting the sieving and drying processes of soils Portions of this research were performed at BL X27A NSLS Brookhaven National Laboratory The BL X27A is supported in part by the US Department of Energy DOE geosciences DEFG0292ER14244 to the University of Chicago—CARS and Brookhaven National Laboratory Department of Environmental Sciences The use of the NSLS was supported by the US DOE Office of Science Office of Basic Energy Sciences under contract no DEAC0298CH10886

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