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Title: Multiple tracers of shallow ground-water flow and recharge in hilly loess

Abstract

Vertical profiles of tritium and nitrate pore-water concentrations were determined to {approximately}8 m depth across two loess hillslopes. Mean recharge fluxes, estimated from chloride mass balance, are 5--10 times larger at the mid- and toe-slope positions than at the top-slope; the magnitudes of the values compare reasonably with results from other methods. The tritium and nitrate profiles exhibit multiple peaks which indicate that piston flow is not the sole flow process in this system. Results of a simple 1-D mixing model suggest that infiltration-exfiltration cycles in zones of plant root activity explain the shallow tritium peaks. Deeper peaks result from preferential vertical and/or lateral flow. The importance of these dispersive processes is underlined by great dilution of observed tritium concentrations, relative to expected concentrations assuming piston flow. In this setting, chloride is useful as a recharge estimator while tritium and nitrate serve as tracers of landscape-scale water movement.

Authors:
 [1]; ;  [2]
  1. Oak Ridge National Lab., TN (United States). Environmental Sciences Div.
  2. Washington State Univ., Pullman, WA (United States)
Publication Date:
Sponsoring Org.:
USDOE
OSTI Identifier:
260482
Resource Type:
Journal Article
Journal Name:
Ground Water
Additional Journal Information:
Journal Volume: 34; Journal Issue: 4; Other Information: PBD: Jul-Aug 1996
Country of Publication:
United States
Language:
English
Subject:
05 NUCLEAR FUELS; GROUND WATER; FLUID FLOW; TRACER TECHNIQUES; INTERSTITIAL WATER; MATHEMATICAL MODELS; CHLORIDES; NITRATES; TRITIUM; PERFORMANCE

Citation Formats

O`Brien, R., Keller, C.K., and Smith, J.L. Multiple tracers of shallow ground-water flow and recharge in hilly loess. United States: N. p., 1996. Web. doi:10.1111/j.1745-6584.1996.tb02055.x.
O`Brien, R., Keller, C.K., & Smith, J.L. Multiple tracers of shallow ground-water flow and recharge in hilly loess. United States. doi:10.1111/j.1745-6584.1996.tb02055.x.
O`Brien, R., Keller, C.K., and Smith, J.L. Mon . "Multiple tracers of shallow ground-water flow and recharge in hilly loess". United States. doi:10.1111/j.1745-6584.1996.tb02055.x.
@article{osti_260482,
title = {Multiple tracers of shallow ground-water flow and recharge in hilly loess},
author = {O`Brien, R. and Keller, C.K. and Smith, J.L.},
abstractNote = {Vertical profiles of tritium and nitrate pore-water concentrations were determined to {approximately}8 m depth across two loess hillslopes. Mean recharge fluxes, estimated from chloride mass balance, are 5--10 times larger at the mid- and toe-slope positions than at the top-slope; the magnitudes of the values compare reasonably with results from other methods. The tritium and nitrate profiles exhibit multiple peaks which indicate that piston flow is not the sole flow process in this system. Results of a simple 1-D mixing model suggest that infiltration-exfiltration cycles in zones of plant root activity explain the shallow tritium peaks. Deeper peaks result from preferential vertical and/or lateral flow. The importance of these dispersive processes is underlined by great dilution of observed tritium concentrations, relative to expected concentrations assuming piston flow. In this setting, chloride is useful as a recharge estimator while tritium and nitrate serve as tracers of landscape-scale water movement.},
doi = {10.1111/j.1745-6584.1996.tb02055.x},
journal = {Ground Water},
number = 4,
volume = 34,
place = {United States},
year = {1996},
month = {7}
}