Geology topics

Joseph P. Levitt

Publications and source records attributed to Joseph P. Levitt.

4 recordsLinked to original sources

USGS2024

A brief note on substantial sub-daily arsenic variability in pumping drinking-water wells in New Hampshire

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 concentrations equivalent to 16 % – 36 % 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 exposures in near-real-time.

Science of the Total Environment↗

USGS2020

Groundwater chloride concentrations in domestic wells and proximity to roadways in Vermont, 2011–2018

The Vermont Department of Health and the U.S. Geological Survey analyzed the concentrations of chloride in groundwater samples collected from 4,319 domestic wells across Vermont between 2011 and 2018. Ninety of these wells were sampled twice and the remaining 4,229 were sampled once. This sample size represents approximately 4 percent of all wells in the State of Vermont. More than half of the wells sampled statewide had groundwater chloride concentrations less than 5 milligrams per liter, whereas more than 1 percent had groundwater concentrations greater than 250 milligrams per liter. Statistical analysis of this dataset revealed distinct patterns in the distribution of chloride in domestic wells. Wells closer (less than 100 meters) to a paved road had significantly higher concentrations of chloride than wells farther ( more than 100 meters) away. Also, wells in urban and in high population density areas, particularly Chittenden and Grand Isle Counties, had significantly higher concentrations of chloride and exhibited greater change in concentrations of chloride over time than wells in less populated areas. This evaluation addresses the distribution of chloride concentrations across the State, which may have adverse health impacts from water infrastructure corrosion and implications for deicing salt application at the State and local levels.

Vermont↗

USGS2020

Time scales of arsenic variability and the role of high-frequency monitoring at three water-supply wells in New Hampshire, USA

Groundwater geochemistry, redox process classification, high-frequency physicochemical and hydrologic measurements, and climate data were analyzed to identify controls on arsenic (As) concentration changes. Groundwater was monitored in two public-supply wells (one glacial aquifer and one bedrock aquifer), and one bedrock-aquifer domestic well in New Hampshire, USA, from 2014 to 2018 to identify time scales of and controls on As concentration changes. Concentrations of As and other geochemical constituents were measured bimonthly. Specific conductance (SC), pH, dissolved oxygen, and pumping rate/water level were measured at high frequency (every 5 to 15 min). Median (and 95% confidence interval) As concentrations at the three wells were 4.1 (3.7–4.6), 18.9 (17.2–23.6), and 37.5 (30.4–42.9) μg/L. Arsenic variability in each of the three wells, in relative standard deviation, ranged from 9 to 12%. Median quarterly As concentrations were highest in all wells in the spring. The bedrock-aquifer public-supply well As concentration increased over the period of study while pumping rate decreased. In the public-supply wells, As variability was correlated with SC and pH, and As species were related to SC, pH, pumping, precipitation, and changes in redox process. Specific conductance also had a seasonal pattern in the two public-supply wells and was correlated with Na and Cl. Excess Na in water samples suggests possible ion exchange with dissolved Ca, creating more capacity to dissolve CaCO 3 from calcareous rocks, which can increase pH and in turn, As concentrations in wells. High-frequency monitoring data are cost effective to collect, which could be advantageous in other parts of the United States and in the many parts of the world where glacial aquifers are in direct contact with other water supply aquifers or where water from different aquifers have potential to mix.

New Hampshire↗

USGS2017

Trends in methyl tert-butyl ether concentrations in private wells in southeast New Hampshire: 2005 to 2015

In southeast New Hampshire, where reformulated gasoline was used from the 1990s to 2007, methyl tert- butyl ether (MtBE) concentrations ≥0.2 μg/L were found in water from 26.7% of 195 domestic wells sampled in 2005. Ten years later in 2015, and eight years after MtBE was banned, 10.3% continue to have MtBE. Most wells (140 of 195) had no MtBE detections (concentrations <0.2 μg/L) in 2005 and 2015. Of the remaining wells, MtBE concentrations increased in 4 wells, decreased in 47 wells, and did not change in 4 wells. On average, MtBE concentrations decreased 65% among 47 wells whereas MtBE concentrations increased 17% among 4 wells between 2005 and 2015. The percent change in detection frequency from 2005 to 2015 (the decontamination rate) was lowest (45.5%) in high-population-density areas and in wells completed in the Berwick Formation geologic units. The decontamination rate was the highest (78.6%) where population densities were low and wells were completed in bedrock composed of granite, metamorphic, and mafic rocks. Wells in the Berwick Formation are characteristically deeper and have lower yields than wells in other rock types and have shallower overburden cover, which may allow for more rapid transport of MtBE from land-surface releases. Low-yielding, deep bedrock wells may require large contributing areas to achieve adequate well yield, and thus have a greater chance of intercepting MtBE, in addition to diluting contaminants at a slower rate and thus requiring more time to decontaminate.

New Hampshire↗