Data for "Primary measurement of gaseous elemental mercury concentration with a dynamic range of six decades" article for submission

Data for mass concentration analysis and spectral analysis for the paper titled, "Comparison of primary laser spectroscopy and mass spectrometry methods for measuring mass concentration of gaseous elemental mercury"

Data for mass concentration analysis and spectral analysis for the paper titled, "Comparison of primary laser spectroscopy and mass spectrometry methods for measuring mass concentration of gaseous elemental mercury"

Data for "Tate, M. T., Janssen, S. E., Lepak, R. F., Flucke, L., & Krabbenhoft, D. P. (2023). National-scale assessment of total gaseous mercury isotopes across the United States. Journal of Geophysical Research: Atmospheres, 128, e2022JD038276. https://doi.org/10.1029/2022JD038276". This dataset is associated with the following publication: Tate, M., S. Janssen, R. Lepak, L. Fluke, and D. Krabbenhoft. Assessment and Application of an Active Total Gaseous Mercury Collector to Survey Mercury Sources Across the United States. Environmental Science & Technology Letters. American Chemical Society, Washington, DC, USA, 128(8): N/A, (2023).

EPA/NOAA Mauna Loa Observatory Daily Gaseous Elemental Mercury (GEM) data 2002-2010. This dataset is associated with the following publication: Feinberg, A., N. Selin, C. Braban, K. Chang, D. Cust�dio, D. Jaffe, K. Kyll�nen, M. Landis, S. Leeson, K. Molepo, M. Murovec, M. Nerentorp Mastromonaco, K. Aspmo Pfaffhuber, J. R�diger, G. Sheu, and V. St.Louis. Increasing anthropogenic emissions inconsistent with declining atmospheric mercury concentrations. PNAS (PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES). National Academy of Sciences, WASHINGTON, DC, USA, 0, (2024).

In 2021, the U.S. Geological Survey (USGS) Mercury Research Laboratory (MRL) conducted a large-scale assessment of mercury (Hg) concentrations and Hg stable isotope values in tributaries of Lake Superior in order to define the sources and amounts of Hg entering the lake. Water samples were collected monthly from 18 tributaries in the United States from April through October in 2021 and during 2022 spring melt (May 2022). As a complement, 10 tributaries on the Lake Superior Northshore were sampled three times a year (spring, summer, and fall) by Lakehead University and Lakehead Region Conservation Authority. Nine tributaries were also sampled twice per year (spring and summer) in Pukaskwa National Park by Parks Canada. Filtered total Hg (THg) concentrations from United States and Canadian Northshore ranged from 0.2 to 8.8 nanograms per liter (ng L-1), with a median value of 1.2 ng L-1. Unfiltered THg in Pukaskwa National Park ranged from 0.6 to 5.0 ng L-1 with a median of 3.2 ng L-1, but encompassed both the filtered and particulate bound Hg. Median methylmercury (MeHg) values were approximately 0.1 ng L-1 for both filtered and unfiltered waters, but could reach levels greater than 1 ng L-1 during higher flow events. THg and MeHg concentrations were positively correlated to dissolved organic carbon (DOC) concentrations for most tributaries. Hg loads to Lake Superior were calculated for U.S. tributaries using the R package loadflex ( http://dx.doi.org/10.1890/ES14-00517.1 ), median loads for THg were 18 grams per day, but could increase to 590 grams per day under high flow and snow melt conditions.

The dataset presented here represents the concentrations and stable isotopic composition of gaseous mercury (Hg) for 31 sites across the United States. This national-scale monitoring effort was performed by the National Atmospheric Deposition Program (NADP) and the USGS over a two-year period (March 2016 - May 2018). The network includes a highly diverse set of sites ranging from remote (e.g. Denali National Park, AK and Mauna Loa, HI) to highly urbanized (e.g. Bronx, NY and Boston, MA). Air samples were collected using a custom designed bulk air sampler, in which air was pumped at approximately 1 L/min through particulate and soda lime filters prior to passing through two quartz tubes containing gold coated glass beads where gaseous Hg was collected. Each sampling period was two weeks long. The Hg was thermally desorbed from the gold beads and collected in a liquid oxidizing trap. The total Hg concentration and isotopic composition was determined on this solution. The average total gaseous Hg concentration across sites was 1.23 ± 0.28 ng/m3, but higher concentrations were observed at sites closer to known Hg sources, such as Oak Ridge National Lab (6.53 ng/m3). For all sites, the average odd isotope mass independent fractionation (MIF, Δ199Hg), an indicator of photochemistry, was -0.20 ± 0.07‰ and had a range of -0.43 to 0.01 ‰. Mass dependent fractionation (MDF, δ202Hg), the commonly used isotope ratio for source tracking, was generally positive with a mean value of 0.45 ± 0.40‰, although intermittent negative MDF was also observed at some sites. Urban sites were consistently lighter in δ202Hg (0.34‰) compared to remote background sites (0.65‰), potentially indicating differences between emission sources. Though regional differences in odd MIF and MDF were small, we observed a trend showing enrichment of δ202Hg in the northeastern United States, from the Ohio River Valley to remote sites in northern Maine and Nova Scotia, suggesting a shift from localized emission sources to globally transported Hg across this region.