Emily C. Hicks Joseph P. Levitt David C. Lloyd Mhairi M. McDonald Kristin M. Romanok Kelly Smalling Joseph D. Ayotte Paul M. Bradley 2024 <div id="ab0005" class="abstract author" lang="en"><div id="as0005"><p id="sp0030">Large variations in redox-related water parameters, like pH and dissolved oxygen (DO), have been documented in New Hampshire (United States) drinking-water wells over the course of a few hours under pumping conditions. These findings suggest that comparable sub-daily variability in dissolved concentrations of redox-reactive and toxic arsenic (As) also may occur, representing a potentially critical public-health data gap and a fundamental challenge for long-term As-trends monitoring. To test this hypothesis, discrete groundwater As samples were collected approximately hourly during one day in May and again in August 2019 from three New Hampshire drinking-water wells (2 public-supply, 1 private) under active pumping conditions. Collected samples were assessed by laboratory analysis (total As [As_Tot], As(III), As(V)) and by field analysis (As_Tot) using a novel integrated biosensor system. Laboratory analysis revealed sub-daily variability (range) in As_Tot<span>&nbsp;</span>concentrations equivalent to 16&nbsp;% – 36&nbsp;% of that observed in the antecedent 3-year bimonthly trend monitoring. Thus, the results indicated that, along with previously demonstrated seasonality effects, the timing and duration of pumping are important considerations when assessing trends in drinking-water As exposures and concomitant risks. Results also illustrated the utility of the field sensor for monitoring and management of As_Tot<span>&nbsp;</span>exposures in near-real-time.</p></div></div> application/pdf 10.1016/j.scitotenv.2024.170838 en Elsevier A brief note on substantial sub-daily arsenic variability in pumping drinking-water wells in New Hampshire article