Surface-Water Nitrate Exposure to World Populations Has Expanded and Intensified during 1970–2010

Wang, Junjie; Liu, Xiaochen; Beusen, Arthur H. W.; Middelburg, Jack J.

doi:10.1021/acs.est.3c06150

Cited by 11 publications

(1 citation statement)

References 76 publications

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“…The recent documentation of an EPA Lead and Copper Rule (LCR) Action level exceedance at least partly due to high nitrate poses a serious concern because nitrate maximum contaminant level violations are common and the treatment options for its removal are costly. Global surface water nitrate levels have increased over the last 50 years, and despite efforts to improve water quality in the U.S., many areas of the country still have high source water nitrate levels. − At the same time, more utilities are diversifying their source water portfolios to meet sustainability targets, which can include the use of recycled waters that will sometimes have higher nitrate . The inability to control elevated lead due to nitrate with 90 or 100% orthophosphate underscores the need for an improved understanding of lead solder corrosion control.…”

Section: Introductionmentioning

confidence: 99%

Zinc Orthophosphate Can Reduce Nitrate-Induced Corrosion of Lead Solder

Lopez,

Xiao,

Crockett

et al. 2024

ACS EST Water

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Nitrate-induced spallation of lead-bearing solder particles into drinking water is not sufficiently controlled by phosphate-based inhibitors, although adding zinc can improve their performance. Studies using copper coupons coated with new lead− tin solder in water with up to 12 mg/L nitrate demonstrated that zinc orthophosphate reduced lead release by more than 90% and outperformed orthophosphate alone. Lead release and spallation from harvested pipes with decades-old lead−tin solder in a high nitrate water were improved but not eliminated with zinc orthophosphate over a period of months. When applied at a water utility with high source water nitrate, monthly in-home field sampling showed that 90th percentile lead levels dropped below the action level after dosing zinc orthophosphate at full scale for 6 months. Scanning electron microscopy (SEM) analysis of pipe scales revealed that zinc and orthophosphate codeposit at the copper−solder interface and may act as a mixed inhibitor, with zinc inhibiting the cathodic reaction on the copper pipe, phosphate limiting the anodic reaction, and an added benefit of zinc orthophosphate preferentially precipitating at the galvanic interface between the anode and the cathode. Updates to corrosion control guidance for waters with higher nitrate due to seasonal runoff or source water changes are needed.

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