HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Ahuja, L. R. Articles by Heathman, G. C. Search for Related Content PubMed Articles by Ahuja, L. R. Articles by Heathman, G. C. Agricola Articles by Ahuja, L. R. Articles by Heathman, G. C.

Macropore Transport of a Surface-Applied Bromide Tracer: Model Evaluation and Refinement

Great Plains Systems Research, Fort Collins, CO 80522

G. C. Heathman

USDA-ARS, National Agricultural Water Quality Lab., Durant, OK 74702

*Corresponding author (ahuja{at}gpsrvl.gpsr.colostate.edu).

ABSTRACT

Rapid transport of surface-applied agrichemicals to groundwater through macropores is a major problem that requires a better understanding and quantification. A simple model of macropore flow and transport of a surface-applied Br^– tracer under rainfall was evaluated and refined by testing against soil-column data reported earlier. The experiments consisted of eight treatment combinations, each in duplicate, of the following conditions: soil initially air dry vs. soil initially wetted by rainfall; a 10-mm layer of dry aggregates on the surface vs. no aggregates; and a 3-mm artificial macropore made along the column's vertical axis vs. no macropore. A solution of SrBr₂ was atomized over the surface, followed by application of simulated rainfall. Evaluation of the model indicated that: (i) once the Green-Ampt infiltration parameters were calibrated on control columns, water flow into other columns was simulated correctly; however, in order to match the macropore bottom outflow, the lateral absorption of water from macropore to soil matrix had to be adjusted for compaction of the macropore wall and variable water pressure around the pore circumference under small macropore flow rates; (ii) for chemical mass in macropore outflow, better results were obtained if, in the wetted portion of the soil profile, the water flow down the macropore mixed with 0.5 mm of soil around the walls and its soil solution; (iii) microporosity of surface aggregates determined from control columns resulted in fairly good simulations of the increase of the chemical in macropore flow caused by aggregates.

Received for publication July 28, 1994.

This article has been cited by other articles:

				J. M. Kohne, B. P. Mohanty, and J. Simunek Inverse Dual-Permeability Modeling of Preferential Water Flow in a Soil Column and Implications for Field-Scale Solute Transport Vadose Zone J., December 16, 2005; 5(1): 59 - 76. [Abstract] [Full Text] [PDF]

				G. A. Fox, R. Malone, G. J. Sabbagh, and K. Rojas Interrelationship of Macropores and Subsurface Drainage for Conservative Tracer and Pesticide Transport J. Environ. Qual., November 1, 2004; 33(6): 2281 - 2289. [Abstract] [Full Text] [PDF]

				J. Perret, S.O. Prasher, A. Kantzas, and C. Langford Three-Dimensional Quantification of Macropore Networks in Undisturbed Soil Cores Soil Sci. Soc. Am. J., November 1, 1999; 63(6): 1530 - 1543. [Abstract] [Full Text] [PDF]