Vadose Zone Transport of Tritium and Nitrate under Ponded Water Conditions
Vadose zone transport of tritium and nitrate can be important considerations at radioactive waste sites, landfills, or areas with industrial impacts. These contaminants are of particular concern because they typically have a relatively higher mobility in the subsurface compared to other compounds. H...
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MDPI AG
2022-07-01
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| Series: | Geosciences |
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| Online Access: | https://www.mdpi.com/2076-3263/12/8/294 |
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| author | Philip H. Stauffer Brent D. Newman Kay H. Birdsell Marvin O. Gard Jeffrey M. Heikoop Emily C. Kluk Terry A. Miller |
| author_facet | Philip H. Stauffer Brent D. Newman Kay H. Birdsell Marvin O. Gard Jeffrey M. Heikoop Emily C. Kluk Terry A. Miller |
| author_sort | Philip H. Stauffer |
| collection | DOAJ |
| description | Vadose zone transport of tritium and nitrate can be important considerations at radioactive waste sites, landfills, or areas with industrial impacts. These contaminants are of particular concern because they typically have a relatively higher mobility in the subsurface compared to other compounds. Here, we describe a semiarid site with tritium and nitrate contamination involving a manmade ponded water source above a thick unsaturated zone at Los Alamos National Laboratory in New Mexico, USA. This study demonstrates the value of vadose zone flow and transport modeling for the development of field investigation plans (i.e., identifying optimal borehole locations and depths for contaminant characterization), and how a combination of modeling with isotope and geochemical measurements can provide insight into how tritium and nitrate transport in the vadose zone in semiarid environments. Modeling results suggest that at this location, tritium transport is well predicted by classical multiphase theory. Our work expands the demonstrated usefulness of a standard tritium conceptual model to sites with ponded surface conditions and agrees with previous results where a standard model was able to explain the evolution of a tritium plume at an arid waste disposal site. In addition, depth-based analyses of δ<sup>18</sup>O and δ<sup>2</sup>H of pore waters helped confirm the extent of pond infiltration into the vadose zone, and the δ<sup>15</sup>N of nitrate showed that the contaminant release history of the site was different than originally assumed. |
| first_indexed | 2024-03-09T13:22:16Z |
| format | Article |
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| institution | Directory Open Access Journal |
| issn | 2076-3263 |
| language | English |
| last_indexed | 2024-03-09T13:22:16Z |
| publishDate | 2022-07-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Geosciences |
| spelling | doaj.art-5a4b5797a8444213a308a02456f50e082023-11-30T21:28:39ZengMDPI AGGeosciences2076-32632022-07-0112829410.3390/geosciences12080294Vadose Zone Transport of Tritium and Nitrate under Ponded Water ConditionsPhilip H. Stauffer0Brent D. Newman1Kay H. Birdsell2Marvin O. Gard3Jeffrey M. Heikoop4Emily C. Kluk5Terry A. Miller6Earth and Environmental Science Division, Los Alamos National Laboratory, Los Alamos, NM 87545, USAEarth and Environmental Science Division, Los Alamos National Laboratory, Los Alamos, NM 87545, USAEarth and Environmental Science Division, Los Alamos National Laboratory, Los Alamos, NM 87545, USAEarth and Environmental Science Division, Los Alamos National Laboratory, Los Alamos, NM 87545, USAEarth and Environmental Science Division, Los Alamos National Laboratory, Los Alamos, NM 87545, USAEarth and Environmental Science Division, Los Alamos National Laboratory, Los Alamos, NM 87545, USAEarth and Environmental Science Division, Los Alamos National Laboratory, Los Alamos, NM 87545, USAVadose zone transport of tritium and nitrate can be important considerations at radioactive waste sites, landfills, or areas with industrial impacts. These contaminants are of particular concern because they typically have a relatively higher mobility in the subsurface compared to other compounds. Here, we describe a semiarid site with tritium and nitrate contamination involving a manmade ponded water source above a thick unsaturated zone at Los Alamos National Laboratory in New Mexico, USA. This study demonstrates the value of vadose zone flow and transport modeling for the development of field investigation plans (i.e., identifying optimal borehole locations and depths for contaminant characterization), and how a combination of modeling with isotope and geochemical measurements can provide insight into how tritium and nitrate transport in the vadose zone in semiarid environments. Modeling results suggest that at this location, tritium transport is well predicted by classical multiphase theory. Our work expands the demonstrated usefulness of a standard tritium conceptual model to sites with ponded surface conditions and agrees with previous results where a standard model was able to explain the evolution of a tritium plume at an arid waste disposal site. In addition, depth-based analyses of δ<sup>18</sup>O and δ<sup>2</sup>H of pore waters helped confirm the extent of pond infiltration into the vadose zone, and the δ<sup>15</sup>N of nitrate showed that the contaminant release history of the site was different than originally assumed.https://www.mdpi.com/2076-3263/12/8/294vadose zonestable isotopetritiumcontaminant transport |
| spellingShingle | Philip H. Stauffer Brent D. Newman Kay H. Birdsell Marvin O. Gard Jeffrey M. Heikoop Emily C. Kluk Terry A. Miller Vadose Zone Transport of Tritium and Nitrate under Ponded Water Conditions Geosciences vadose zone stable isotope tritium contaminant transport |
| title | Vadose Zone Transport of Tritium and Nitrate under Ponded Water Conditions |
| title_full | Vadose Zone Transport of Tritium and Nitrate under Ponded Water Conditions |
| title_fullStr | Vadose Zone Transport of Tritium and Nitrate under Ponded Water Conditions |
| title_full_unstemmed | Vadose Zone Transport of Tritium and Nitrate under Ponded Water Conditions |
| title_short | Vadose Zone Transport of Tritium and Nitrate under Ponded Water Conditions |
| title_sort | vadose zone transport of tritium and nitrate under ponded water conditions |
| topic | vadose zone stable isotope tritium contaminant transport |
| url | https://www.mdpi.com/2076-3263/12/8/294 |
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