![]() Despite joints being over 60 years old, galvanic zones in Pattern 3 were active and possibly posed an important source of lead to drinking water. Geochemical modeling confirmed the required pH drop from the bulk water level to at least pH 3.0-4.0 (Pattern 2) and pH < 5.5 (Pattern 3) in order to form these minerals. The identification of copper-sulfate minerals (Pattern 2), and lead-sulfate and lead-chloride minerals (Pattern 3) in galvanic zones illustrated the migration of chloride and sulfate toward the anode. ![]() Pattern 2 is consistent with galvanic battery reversion. ![]() Pattern 3 is consistent with empirical galvanic series (lead → brass → copper in order of increasing nobility) and poses the greatest risk of Pb exposure. water utilities, provided the first direct view of three distinct galvanic corrosion patterns in practice: (1) no evidence of galvanic corrosion (2) galvanic corrosion with lead cathode (3) galvanic corrosion with lead anode. Visual and mineralogical analysis of 28 lead pipe joints, excavated after 60+ years from eight U.S. Galvanic corrosion as a mechanism of toxic lead release into drinking water has been under scientific debate in the U.S.
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