The nature and extent of bomb tritium remaining in deep vadose zones: A synthesis and prognosis
Data files
Dec 14, 2023 version files 55.45 KB
Abstract
Tritium present in deep vadose zones is a useful tracer for estimating groundwater recharge, but its full utility is constrained by not knowing where and for how long the tritium tracing method remains applicable. We obtained 44 tritium profiles from 17 globally distributed sites with vadose zone thicknesses of 13−624 m and used transport models to estimate the number of years that tritium may still be useful. Results show that the method may still be usable for 26 of 44 soil profiles surveyed, mainly in China, Australia, USA, South Africa, and Senegal, with a remaining useful period of between 6 and 83 years. We also developed a statistical model that uses outputs from a hydrological model to predict the applicability of the tritium tracing method. Global implementation of the statistical model showed that the method remains usable at 20% of Earth’s land mass (excluding Antarctica and Greenland) over the next few decades.
README
The dataset -- soil water tritium profiles (n = 40) -- was compiled from the peer-reviewed literature (see Text S2 in manuscript). This was supplemented with 4 profiles from study sites in Changwu, Shaanxi Province, China.
The dataset was compiled by co-authors Yanan Huang (huangynbox@nwafu.edu.cn) and Zhi Li (lizhibox@nwafu.edu.cn) of Northwest A&F University.
For any questions regarding the dataset, please send an email to Yanan Huang (huangynbox@nwafu.edu.cn) and Zhi Li (lizhibox@nwafu.edu.cn).
Filename: tritium_profile_all_data.csv
- SiteID - refers to the assigned site identifier as also referenced to in tritium_sourcepapers.csv
- depth (m) - depth of sampling in meters
- 3H - tritium concentration in T.U. or tritium units
- sampling year - year of sampling
Filename: tritium_sourcepapers.csv
- No - numeric identifier assigned to each unique soil tritium profile
- Country - country where the sample was collected
- SiteID - refers to the assigned site identifier as also referenced to in tritium_profile_all_data.csv
- Source paper - Author-year of the source paper from where the data was retrieved
- Title - title of the published paper
Filename: GeospatialModel_20230722.csv
- No - numeric identifier assigned to each unique soil tritium profile
- Country - country where the sample was collected
- SiteID - refers to the assigned site identifier as also referenced in tritium_profile_all_data.csv. This ID is unique to the soil profile at a given site (n = 44)
- SiteUniID - refers to the unique site identifier for each site (n = 17)
- aet_p - actual evapotranspiration divided by mean annual precipitation
- pet_p - potential evapotranspiration divided by mean annual precipitation
- dwt - depth to water table in m (vadose zone thickness)
- peak_v - porewater velocity in m y-1 calculated using the Lorentzian growth peak model (Equation S9)
- cxtfit_v - porewater velocity in m y-1 estimated from CXTFIT-STANMOD
- cxtfit_D - dispersion coefficient in m2 y-1 estimated from CXTFIT-STANMOD
- cxtfit_R2 - CXTFIT model R-squared
- Applicability tau - the number of years, before or after the year 2022, that the tritium method may still be applicable. The threshold of peak concentration here is set at 0.3 TU
Filename: parameters.csv
- No - numeric identifier assigned to each unique soil tritium profile
- Country - country where the sample was collected
- SiteID - refers to the assigned site identifier as also referenced in tritium_profile_all_data.csv. This ID is unique to the soil profile at a given site (n = 44)
- year - time elapsed in years between 1963 and sampling year
- Input_V -porewater velocity in m y-1
- Input_D - dispersion coefficient in m2 y-1
- Input_MU - decay constant of tritium times time elapsed in years
- Input_MASS - tritium input concentration in T.U. or tritium units
- Initial conc. -tritium initial concentration
Filename: soil_type_land_use.csv
- No - numeric identifier assigned to each unique soil tritium profile
- Location - site name and country
- SiteID - refers to the assigned site identifier as also referenced in tritium_profile_all_data.csv. This ID is unique to the soil profile at a given site (n = 44)
- Land use - land use type from the literature where explicitly mentioned
- Soil type - based on HWSD (Harmonized World Soil Database)
- Sand - % sand
- Silt - % silt
- Clay - % clay
Methods
The dataset – soil water tritium profiles (n = 40) – was compiled from the peer-reviewed literature (see Text S2 in manuscript). This was supplemented with 4 profiles from study sites in Changwu, Shaanxi Province, China.
The dataset was compiled by co-authors Yanan Huang (huangynbox@nwafu.edu.cn) and Zhi Li (lizhibox@nwafu.edu.cn) of Northwest A&F University.