Historical and contemporary use of lead (Pb) has led to elevated concentrations in urban soils. Many residential soils contain concentrations of Pb below typical remediation or cleanup thresholds (e.g. 400 mg/kg); yet they still present a risk to human health, with disproportionate impacts on urban children. Because of the diffuse nature of contamination, the typical remediation strategy – removal of Pb laden soil and replacement with clean topsoil – is logistically and economically infeasible. Therefore, to reduce risk, many researchers have explored <i>in situ</i> remediation aimed at reducing Pb bioavailability. The addition of phosphate amendments has received the most attention. In this study we explore a randomized-control study of 142 residential parcels located in Detroit, Michigan treated with phosphate amendments to decrease the availability of soil Pb. First, we evaluate how commonly measured soil parameters (e.g. organic matter (OM), soil pH) impact Pb bioaccessibility. Based on a multiple regression model, we find when the OM content of urban soils increases from 5% (mean observed) to 6%, Pb <i>in vitro</i> bioaccesible (IVBA) Pb decreases by 6.1%. When the soil pH decreases from 7.8 (mean observed) to 7.7, Pb IVBA decreaseds by 2.3%. The proximity of soil sampling locations to former smelter locations were also found to influence Pb bioaccessibility. Second, we find the addition of a phosphorus containing bone meal amendment reduces Pb IVBA 9.8%. Finally, we explore how this remediation strategy impacts soils in the front, middle and rear of residential lots to determine if there is a significant difference in the changes in bioaccessibility and/or results in other undesirable outcomes, enhanced leaching of arsenic or phosphorus.

Altering lead bioaccessibility: A randomized-control trial of bone meal amendment remediation in Detroit, Michigan

ACS Spring 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.