Precipitation runoff from lead: Fid-Bau Portal

Precipitation runoff from lead

Matthes, S.A. / Cramer, S.D. / Covino, B.S. jun. / Bullard, S.J. / Holcomb, G.R.

Lead ions may be introduced into the environment by the flow of precipitation runoff from the surface of lead structures such as gutters, roofs, piping, siding, and sculpture. Precipitation runoff is water from rain, dew, or fog that drains from a surface and contains air or water-born deposited reactants and soluble ions from the metal surface. Analysis of precipitation runoff from sites in Newport (marine unpolluted) and Albany (rural unpolluted), Oregon, was used to characterize these sites. Typical lead concentrations found in the precipitation runoff were between 0.7 and 3.7 mg/L compared with the United States EPA lead drinking water standard of 0 mg/L (with an action level of 0.015 mg/L). Corrosion film studies indicate that lead in the runoff is primarily from the solubility of cerrusite (lead carbonate) and hydrocerrusite (lead hydroxy carbonate). After an initial induction period, the measured release rate of lead ions to the environment was a constant 0.010 millimoles Pb per liter of precipitation runoff flowing over one square meter of lead surface (2.1 mg Pb/L) at both Albany and Newport. Cumulative corrosion film dissolution rates were 14.3 and 19.6 mmol Pb/m²y for Albany and Newport, respectively. This corresponds to steady state lead corrosion rates of 0.26 and 0.36 my m/y respectively. Ionic species dry deposited onto the lead surface were determined from precipitation runoff data, giving valuable information concerning the impact of environmental constituents and pollution on lead corrosion.