Manganese Increases Lead Release to Drinking Water

Abstract

Lead and manganese are regulated in drinking water due to their neurotoxicity. These elements have been reported to co-occur in drinking water systems, in accordance with the metal-scavenging properties of MnO 2 . To the extent that manganese is a driver of lead release, controlling it during water treatment may reduce lead levels. We investigated transport of lead and manganese at the tap in a full-scale distribution system: consistent with a cotransport phenomenon, the two metals were detected in the same colloidal size fraction by size-exclusion chromatography with multielement detection. We also studied the effect of manganese on lead release using a model distribution system: increasing manganese from 4 to 215 μg L −1 nearly doubled lead release. This effect was attributed primarily to deposition corrosion of lead by oxidized phases of manganese, and we used 16S rRNA sequencing to identify bacteria that may be relevant to this process. We explored the deposition corrosion mechanism by coupling pure lead with either MnO 2 -coated lead or pure lead exposed to MnO 2 in suspension; we observed galvanic currents in both cases. We attributed these to reduction of Mn(IV) under anaerobic conditions, and we attributed the additional current under aerobic conditions to oxygen reduction catalyzed by MnO 2 .

Predicting manganese and iron precipitation in drinking water biofilters

“…Manganese (Mn) is a common metal in surface and groundwaters, with concentrations typically ranging from 0.001 to 0.2 mg/L, but sometimes exceeding 1 mg/L (World Health Organization, 2004). Its concentration should be limited because (a) Mn discolors water and causes a metallic taste, (b) residual Mn concentrations may be detrimental to children's health (Bouchard, Surette, Cormier, & Foucher, 2018;Dion et al, 2018;Rahman et al, 2015Rahman et al, , 2017, and (c) Mn may increase lead release in distribution systems (Schock, Cantor, Triantafyllidou, Desantis, & Scheckel, 2014;Trueman et al, 2019). In Canada, Mn concentrations are limited to a maximum acceptable concentration of 0.12 mg/L and an aesthetic objective of 0.02 mg/L (Health Canada, 2019).…”

Considerations for new manganese analytical techniques for drinking water quality management

“…Mn oxide deposits within distribution systems have also been found to accumulate or co‐release with other metals including: aluminum (Al) (Friedman et al, 2010; Gerke et al, 2016; Han et al, 2018; G. Li et al, 2018; Triantafyllidou et al, 2019), arsenic (As) (Friedman et al, 2010; Triantafyllidou et al, 2019), chromium (Cr) (Friedman et al, 2010; Gerke et al, 2016), iron (Fe) (Gerke et al, 2016; Han et al, 2018) and Pb (Friedman et al, 2010, 2016; Gerke et al, 2016; Locco et al, 2021). Mn deposits in the distribution system can increase Pb release, either by reduction of less soluble Pb(IV) species to highly soluble Pb(II), or accumulation onto Mn colloidal particles (Brandhuber et al, 2013, 2015; Schock et al, 2014; Trueman et al, 2019). Given recent epidemiologic evidence of synergistic neurodevelopmental effects, co‐occurrence of Mn and Pb release at consumers' taps has an increased public health risk potential.…”

Halifax Water's Lead Service Line Replacement Program Gets the Lead Out

“…This work showed that residual iron and aluminum from coagulation were important contributors to lead release and that natural organic matter also affected lead release. More recently, the CWRS has focused on the benefits of manganese reduction because of its influence on lead release as well as its status as a regulated contaminant (Trueman et al 2019). All of these findings have informed Halifax Water's current corrosion control program, as discussed subsequently.…”