Mariner 10 Magnetometer (MAG) averaged M1 SUMMARY data at Mercury.

not applicable

The Sacramento / San Joaquin River Delta (SSJRD) is contaminated with legacy mercury (Hg) from historical mining and mineral processing activities throughout the watershed, as well as from contemporary atmospheric and industrial inputs. The current project was designed for the purpose of developing high-resolution spatial and temporal models for estimating concentrations of mercury species in surface waters of the SSJRD. The field component of the project brings together three high-resolution platforms for collecting water-quality data (fixed continuous monitoring stations (CMS) outfitted with in-situ sensors, spatial mapping using boat-mounted flow-through sensors, and satellite-based remote sensing) coupled with a discrete sample collection program for mercury species and ancillary water-quality metrics. The four mercury species targeted in the study include both particulate and filter-passing fractions of total mercury and methylmercury. Field data were collected during the period July 2019 through July 2021. Sampling at the four primary CMS sites included discrete sample collections during all station operations and maintenance visits (approximately every six weeks) and during four 13-hour to 15-hour tidal sampling events, during which samples were collected every 2 hours (approximately) over a full tidal cycle. This tidal sampling occurred once per season (winter, spring, summer, and fall) at each of the four CMS locations. Likewise, four seasonal boat-mapping sampling events were conducted, each over a 3-day period and coincident with Landsat 8 satellite overpasses on the 2nd day of sampling and within 2 days of a Sentinel 2 A/B satellite overpass. Each boat-mapping event included collection of discrete water samples for mercury species and other water-quality metrics at 33 sites over a three-day period, covering approximately 210 kilometers through the SSJRD. The models constructed to estimate concentrations of mercury species are organized into four types (Tiers), which are based on which high-resolution water-quality data platform is being emphasized, as follow: Tier 1 Models – those based only on in-situ sensor derived turbidity and dissolved organic matter fluorescence, which are the two metrics most relevant to the satellite-based data collection platforms; Tier 2 Models – those based only on CMS in situ sensor data; Tier 3 Models – those based only on data from boat-mounted flow-through sensors, including spectrophotometric measurements, associated with the spatial mapping events; and Tier 4 models – based on sensor data from both the CMS sites and boat-mapping events, but limited to sensor data common to both. The information presented herein falls under six categories, which are associated with the following six Child pages: a) Discrete Sample Data – represents laboratory analytical results and field measurements associated with discrete surface-water samples collected from both the CMS and boat-mapping sampling events; b) Optical Spectral Data – represents excitation-emissions matrix spectra (EEMs) and absorption data associated with discrete surface-water samples collected from both the CMS and boat mapping sampling events; c) High-resolution (15 minute) Temporal Data from CMS Locations – includes time series in-situ sensor data collected from the four primary fixed CMS sampling locations; d) High-Resolution Boat Mapping Data – data collected with boat mounted flow-through sensor arrays during the four mapping events; e) Remote Sensing Data – GeoTIFF image files of turbidity and dissolved organic matter (DOM) products derived from Sentinel 2 A/B imagery of the SSJRD from June 2019 – May 2021; and f) Model Archive Summaries – documentation of the 16 top global models (four model types x four mercury species) in terms of modeling approach, model statistics, validation, and final equations. In addition, a geospatial file (SSJRD_Sites.kmz) is provided on this Parent page, which identifies all of the study fixed

The movement of mercury (Hg) from the atmosphere to the biosphere occurs by both wet and dry deposition to solid surfaces, water, and vegetation. Most of the annual dry atmospheric Hg deposition in deciduous forests is believed to originate from litterfall which consists mainly of dead leaves that fall to the earth’s surface, primarily during the autumn and winter seasons. Atmospheric Hg reaches an annual maximum concentration in leaves at the time of leaf fall. Analysis of litterfall samples helps to quantify total annual atmospheric Hg deposition to forests when combined with precipitation Hg data. This data set is derived from litterfall samples collected during 2017-18 and 2018-19 at 27 selected National Atmospheric Deposition Program (NADP) sites in 12 states located across the eastern half of the United States. Through the Litterfall Mercury Monitoring Initiative (LMMI), operated by the U.S. Geological Survey (USGS), litterfall sample collectors were distributed to the selected NADP sites where site operators retrieved multiple 4-week-long samples during the leaf fall period. These samples were collected and shipped to the USGS Mercury Research Laboratory where they were analyzed for concentrations of total Hg and methylmercury (MeHg), and litterfall dry mass was also determined. The samples for total Hg and MeHg analysis represent composites from 4 collectors across all sample collections at each site during the litterfall season. Litterfall dry mass was determined from all 8 sample collectors across all sample collections.

Legacy product - no abstract available