Excel spreadsheet with the following columns of data: Date/Time (6/2016 to 10/2016) Total Gaseous Mercury Concentration (ng/m3) Sulfur dioxide concentration (ppb) Carbon monoxide concentration (ppm) Carbon dioxide concentration (ppm) Wind direction in degrees Wind speed in miles per hour Temperature in degrees celcius Percent relative humidity. This dataset is not publicly accessible because: The data used in this study were not generated or funded by the EPA. It can be accessed through the following means: The total-gaseous mercury (TGM) measurement data were collected by Dr. Lynne Gratz, Assistant Professor of Environmental Science, at Colorado College, 14 E. Cache La Poudre St. Colorado Springs, Colorado 80903 USA. This data is not available to EPA for public dissemination. Information on obtaining this data should be directed to Dr. Gratz at: lgratz@coloradocollege.edu or (719) 389-7465. The CO, SO2, temperature, wind speed, wind direction, and relative humidity were collected at the Colorado Department of Public Health & Environment (CDPHE) air monitoring location at Highway 24 in Colorado Springs. This data is already available in the public domain. Certified hourly data from this and other CDPHE air monitoring stations, including the Manitou Springs and Colorado College stations that were also mentioned in this manuscript, are available through the U.S. EPA Air Quality System (AQS) database (https://aqs.epa.gov/api) downloaded on September 1st 2017. Additional information can be obtained by emailing: cdphe.information@state.co.us303. Format: The data are in an Excel format. Citation information for this dataset can be found in the EDG's Metadata Reference Information section and Data.gov's References section.

Automated collectors at Elkmont passively accumulated litterfall for two consecutive 4-week periods each in 2008 and 2009. Samples were collected, and submitted for analysis of mercury by low-level, trace-metals methods. Species of leaf included poplar, maple, birch, pine, dogwood, hemlock. and magnolia. The average concentration of total mercury in the eight samples was 32.6 nanograms per gram. The estimated litterfall deposition for the eight samples was 12.4 nanograms per square meter.

Mercury (Hg) is a persistent environmental contaminant and can accumulate and concentrate in food webs as methylmercury (MeHg), presenting a health risk to humans and wildlife. Multiyear monitoring and modeling studies have shown that atmospheric Hg in litterfall is an important form of Hg deposition to forests. Annual litterfall consists primarily of leaves with some amounts of needles, twigs, bark, flowers, seeds, fruits, and nuts. Atmospheric Hg accumulates in leaves and reaches an annual maximum concentration at autumn leaf drop. This data set is derived from autumn litterfall collected at 30 selected National Atmospheric Deposition Program (NADP) Mercury Deposition Network (MDN) sites in deciduous and mixed deciduous-coniferous forests from 16 states in the eastern United States during 2007-2009 and 2012-2015. The NADP administered litterfall collection at the MDN sites. The U.S. Geological Survey (USGS) distributed sets of passive litterfall sample collectors to MDN site operators for systematic retrieval of samples during the 8 to 16 weeks of autumn leaf drop each year at each site. Samples were processed and analyzed at the USGS Mercury Research Laboratory where concentrations of Hg and MeHg and litterfall dry mass and sample moisture were determined. All sites did not have data for all years. Most sites had four Hg concentrations per year and a few sites had less than or more than four Hg concentrations in specific years. MeHg concentrations were determined in one composite sample per site in 2007 and 2012-2015. Litterfall mass was determined from 4 to 8 samples per site per year. Seven annual groups of data were compiled into this dataset. More information is available from the NADP at http://nadp.sws.uiuc.edu/

Mercury (Hg) is a persistent environmental contaminant and can accumulate and concentrate in food webs as methylmercury (MeHg), presenting a health risk to humans and wildlife. Multiyear monitoring and modeling studies have shown that atmospheric Hg in litterfall is an important form of Hg deposition to forests. Annual litterfall consists primarily of leaves with some amounts of needles, twigs, bark, flowers, seeds, fruits, and nuts. Atmospheric Hg accumulates in leaves and reaches an annual maximum concentration at autumn leaf drop. This data set is derived from ambient autumn litterfall samples collected at 23 selected National Atmospheric Deposition Program (NADP) Litterfall Mercury Monitoring Initiative (LMMI) sites located near NADP Mercury Deposition Network sites in deciduous and mixed deciduous-coniferous forests in 11 states in the eastern United States during 2016. The NADP administered litterfall collection at the LMMI sites. The U.S. Geological Survey (USGS) distributed sets of passive litterfall sample collectors to LMMI site operators for systematic retrieval of samples during the 4 to 24 weeks of autumn leaf drop at each site. Samples were processed and analyzed at the USGS Mercury Research Laboratory where concentrations of Hg and MeHg and litterfall dry mass and sample moisture were determined. Hg concentrations were measured in 4 samples collected from each site and MeHg concentrations were measured in one composite sample per site. Litterfall mass and sample moisture were determined for 8 samples per site. Duplicate sets of these sample data were determined for 3 sites in 2016.

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).