David Ams is an environmental hydro-geochemist at ARCADIS-US. He is based out of the company’s Newtown, Pennsylvania office. He received his Ph.D. from the University of Notre Dame in geochemistry, where his research focused on metal cation, mineral, and bacterial surface interactions. He has also performed research focused on the ability of bacteria to catalyze the transformation of labile lead phases to insoluble minerals. Currently, he is involved in large scale groundwater remediation projects where in situ precipitation of dissolved metals is the key technology being implemented.
Presentation Description Bacterial Alkaline Phosphatase Induces Lead Mineral Transformation: A Novel
Mechanism for the Reduction of Aqueous Lead Concentrations
This study evaluates the ability of a bacterially produced alkaline phosphatase (APase) to
transform the lead carbonate mineral cerussite to the less soluble lead phosphate mineral
pyromorphite. APase is a phosphoenzyme that catalyzes the hydrolysis of less bioavailable
organo-phosphates and polyphosphates to form bioavailable orthophosphate. While
orthophosphate released by APase is available for incorporation by bacteria and other
microorganisms it is also available to bind with Pb ions and precipitate Pb-phosphate minerals.
In this study, cerussite was initially reacted with polyphosphate in batch reactors resulting in the
complete transformation of solid phase Pb to a soluble polyphosphate-Pb complex. The
subsequent addition of APase to the polyphosphate-Pb system resulted in the complete
transformation of the soluble polyphosphate-Pb complex to the insoluble Pb-phosphate mineral
pyromorphite, effectively reducing the solubility of Pb by approximately 60 orders of magnitude
relative to cerussite. These results highlight the potential role of naturally occurring
phosphoenzymes in the sequestration of Pb in the form of highly insoluble mineral phases and
reducing dissolved lead concentrations in aqueous systems.
