skip to main content
US FlagAn official website of the United States government
dot gov icon
Official websites use .gov
A .gov website belongs to an official government organization in the United States.
https lock icon
Secure .gov websites use HTTPS
A lock ( lock ) or https:// means you've safely connected to the .gov website. Share sensitive information only on official, secure websites.

Explore Research Products in the PAR
It may take a few hours for recently added research products to appear in PAR search results.


  • NSF Public Access
  • Search Results
  • Mapping the distribution of geogenic contaminants in bedrock from Colorado Plateau cores using continuous X-ray fluorescence spectroscopy
Title: Mapping the distribution of geogenic contaminants in bedrock from Colorado Plateau cores using continuous X-ray fluorescence spectroscopy
The Navajo Nation is the largest Native American reservation in the United States and is located on the Colorado Plateau. Uranium (U) and Arsenic (As) are two predominantly geogenic contaminants found on the Colorado Plateau. These contaminants leech into groundwater aquifers through anthropogenic activities, but little information is known about the natural distribution of these contaminants. Heavy uranium and coal mining have caused elevated levels of U and As to infiltrate groundwater, however there is little research on the natural distribution of these elements in the regional bedrock and the extent to which they exist as exposure pathways in water, air, and soil. We used a robotic X-ray Fluorescence (XRF) machine, Minalyzer CS, to scan over 850 meters of cores that were collected in Petrified Forest National Park (PFNP) and generated a whole-rock geochemical profile with respect to depth and show the areas in the cores that have elevated levels of Uranium and Arsenic. We also sampled for Inductively Coupled Plasma Mass Spectrometry (ICPMS) to calibrate the concentrations of elements from our XRF scans. In conjunction with X-ray Diffraction (XRD) analysis to quantify mineralogy and Computed Tomography (CT) to quantify porosity/permeability, we are in the process of developing models for the integrated geologic history of the region and the processes responsible for the concentration and mobilization of these elements in bedrock. An understanding of these processes is essential for differentiating the exposure risk between geogenic and anthropogenic sources of U and As.  more » « less
Award ID(s):
2050923
PAR ID:
10514679
Author(s) / Creator(s):
; ; ; ; ;
Editor(s):
OIsen, P
Publisher / Repository:
Navajo Technical University
Date Published:
Journal Name:
Proceedings American Geophysical Union
Edition / Version:
Final
Volume:
1
Issue:
1
Page Range / eLocation ID:
H53N-1504
Subject(s) / Keyword(s):
Pollution Arsenic Uranium Navajo
Format(s):
Medium: X Size: 2 MB Other: pdfA
Size(s):
2 MB
Location:
San Francisco, CA
Sponsoring Org:
National Science Foundation
More Like this
  1. ; ; ; ; ; ; ; ; ; (, Minerals)
    null (Ed.)
    Pumping groundwater from arsenic (As)-contaminated aquifers exposes millions of people, especially those in developing countries, to high doses of the toxic contaminant. Previous studies have investigated cost-effective techniques to remove groundwater arsenic by stimulating sulfate-reducing bacteria (SRB) to form biogenic arsenian pyrite. This study intends to improve upon these past methods to demonstrate the effectiveness of SRB arsenic remediation at an industrial site in Florida. This study developed a ferrous sulfate and molasses mixture to sequester groundwater arsenic in arsenian pyrite over nine months. The optimal dosage of the remediating mixture consisted of 5 kg of ferrous sulfate, ~27 kg (60 lbs) of molasses, and ~1 kg (2 lbs) of fertilizer per 3785.4 L (1000 gallons) of water. The remediating mixture was injected into 11 wells hydrologically upgradient of the arsenic plume in an attempt to obtain full-scale remediation. Groundwater samples and precipitated biominerals were collected from June 2018 to March 2019. X-ray diffraction (XRD), X-ray fluorescence (XRF), electron microprobe (EMP), and scanning electron microscope (SEM) analyses determined that As has been sequestered mainly in the form of arsenian pyrite, which rapidly precipitated as euhedral crystals and spherical aggregates (framboids) 1–30 μm in diameter within two weeks of the injection. The analyses confirmed that the remediating mixture and injection scheme reduced As concentrations to near or below the site’s clean-up standard of 0.05 mg/L over the nine months. Moreover, the arsenian pyrite contained 0.03–0.89 weight percentage (wt%) of sequestered arsenic, with >80% of groundwater arsenic removed by SRB biomineralization. Considering these promising findings, the study is close to optimizing an affordable procedure for sequestrating dissolved As in industry settings. 
    more » « less
  2. ; ; ; ; ; ; ; ; ; ; et al (, Proceedings of the International Ocean Discovery Program Expedition reports)
    We report semiquantitative elemental data from X-ray fluorescence (XRF) scanning of Site U1558 sediment cores drilled during International Ocean Discovery Program Expeditions 390C and 393. These expeditions, together with Expeditions 395E and 390, form the South Atlantic Transect, which collected sediment and basement cores from the western flank of the southern Mid-Atlantic Ridge. XRF scanning of the continuous splice of Site U1558, using Holes U1558A and U1558F, was conducted at three acceleration voltages to capture a range of major, minor, and trace elements. At Site U1558, positive correlations exist between terrigenous-sourced elements (Al, Si, Ti, and Fe) and a negative correlation exists between the terrigenous-sourced elements and Ca. XRF geochemistry is correlated with lithologic changes, most notably at the boundary of Lithologic Units I and II, where Unit I is brown and reddish brown nannofossil-rich clay and Unit II is pink, pinkish white, pinkish gray, and light brown nannofossil ooze and chalk with varying amounts of clay and foraminifera. Peaks in XRF data align with the boundaries of Lithologic Subunits IIA and IIB and Subunits IIB and IIC. 
    more » « less
  3. ; ; ; ; ; ; ; ; ; (, Frontiers in Water)
    Glacial meltwater contributions to streams depend on watershed characteristics that impact water quantity and quality, with potential changes as glaciers continue to recede. The purpose of our study was to investigate the influence of glacier and bedrock controls on water chemistry in glacial streams, focusing on a range of small to large watersheds in Alaska. Southcentral Alaska provides an ideal study area due to diverse geologic characteristics and varying amounts of glacial coverage across watersheds. To investigate spatial and temporal variability due to glacial coverage and bedrock type, we analyzed water samples (n= 343) from seven watersheds over 2 years for major and trace element concentrations and water stable isotopes. We found variable water chemistry across the glacial rivers related to glacial coverage and the relative amount of metamorphic, sedimentary, and igneous bedrock. Some sites had elevated concentrations of harmful trace elements like As and U from glacier melt or groundwater. Longitudinal (upstream to downstream) variability was apparent within each river, with increasing inputs from tributaries, and groundwater altering the water chemistry relative to glacier meltwater contributions. The water chemistry and isotopic composition of river samples compared with endmember sources suggested a range from glacier-dominated to groundwater-dominated sites along stream transects. For example, water chemistry in the Knik and Matanuska rivers (with large contributing glaciers) was more influenced by glacier meltwater, while water chemistry in the Little Susitna River (with small glaciers) was more influenced by groundwater. Across all rivers, stream chemistry was controlled by glacier inputs near the headwaters and groundwater inputs downstream, with the water chemistry reflecting bedrock type. Our study provides a greater understanding of geochemical and hydrological processes controlling water resources in rapidly changing glacial watersheds. 
    more » « less
  4. ; ; ; ; ; (, Proceedings of the International Ocean Discovery Program Expedition reports)
    Semiquantitative elemental results from X-ray fluorescence (XRF) scanning of sediment cores from International Ocean Discovery Program (IODP) Site U1574 in the Vøring Plateau, Norwegian Margin, are presented in this report. XRF elemental data were collected every 1 cm from a stratigraphically complete and continuous cored section with 102% recovery from the sea bottom to ~170 meters below seafloor in Hole U1574C. We report raw element intensities (counts) for Al, Si, K, Ca, Ti, Fe, Br, Sr, and Zr and identify covariation patterns consistent with lithofacies variations. Our high-resolution XRF scanning was conducted to better characterize the sediment depositional history at Site U1574 and to aid interpretation of past environmental and oceanographic conditions in the Norwegian Margin, targeting the earliest incursion of deep water into the young North Atlantic Ocean during the Early to Middle Eocene. The high-resolution XRF data also may help improve the age-depth model for the sediment succession at Site U1574. 
    more » « less
  5. ; ; ; (, Journal of Testing and Evaluation)
    The rapid growth of the cannabis market in the United States has led to increasing focus on the consumer product safety of the myriad of new products entering commerce. The cannabis plant is widely accepted to be an efficient accumulator of potentially toxic elements, and its resinous nature makes it well suited to accumulate surface contaminants. Unfortunately, limited data are currently available on the occurrence of many elements in consumer cannabis, and even fewer studies have examined surface adhered particulate matter. As part of this study, 26 elements (silver, aluminum, arsenic, barium, beryllium, calcium, cadmium, cobalt, chromium, copper, iron, mercury, potassium, magnesium, manganese, molybdenum, sodium, nickel, lead, antimony, selenium, thorium, thallium, uranium, vanadium, and zinc) were quantified in hemp produced for cannabidiol and commercially available hemp marketed for smoking. Additionally, surface adhered particulate matter was examined as a potential contributor of elemental impurities, and various methodologies were compared. Results confirm that hemp entering commerce in the United States contains a variety of elemental impurities and frequently contains adhered particulate matter such as soil minerals, agricultural additives, microplastics/textile fibers, and materials from harvesting/processing equipment. Consumer exposure potential for some elements such as copper was found to be high enough to warrant additional investigation as to the possible health effects and may justify additional oversight from regulators, who should consider expanding testing panels to a larger suite of elements than arsenic, cesium, mercury, and lead. 
    more » « less
  • Citation Formats
  • MLA
  • APA
  • Chicago
  • BibTeX
  • Save / Share this Record
  • Send to Email