Skip to main content
ARS Home » Research » Publications at this Location » Publication #95236
Title: QUANTIFYING THE WATER DYNAMICS OF PREFERENTIAL FLOW: I. SILT LOAM AT PURDUE SITE

Author
item KUNG, SAMUEL - UNIVERSITY OF WISCONSIN
item KLADIVKO, ELAINE - PURDUE UNIVERSITY
item GISH, TIMOTHY
item STEENHUIS, TAMMO - CORNELL UNIVERSITY
item BUBENZER, GARY - UNIVERSITY OF WISCON
item HELLING, CHARLES

Submitted to: Journal of Environmental Quality
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/1/1999
Publication Date: N/A
Citation: N/A

Interpretive Summary: Field experiments were conducted at the South East Purdue Agricultural Center in Butlerville, IN to quantify the impact of the preferential flow paths on contaminant transport. A tile drain monitoring facility was used to compare the transport characteristics of several mobile tracers. The conservative tracers were sequentially applied during a mild 3 mm per hour precipitation event which had a 10 hour duration. Bromide was surface-sprayed shortly before the irrigation started, while the three benzoic acid tracers (PFBA, o-TFMBA, and 2,6DFBA) were applied at +2, +4, and +6 hours after irrigation started, respectively. Using saturated hydraulic conductivity data from soil cores indicated that it would take 2 days for these tracers to reach the tile drains. However, bromide first appeared in the tile drain about 4 hours after application while PFBA, o-TFBA, and 2,6 DFBA, were detected in the tile drainage at 102 minutes, 42 minutes, and 18 minutes after their applications, respectively. Futhermore, the percentage of the applied tracers recovered from tile drainage that were associated with this preferentail flow event were: bromide (7.04%), PFBA (13.9%), o-TFMBA, (18.7%), and 2,6 DFBA (19.7%). As a result, both the scope and magnitude of preferential flow were dramatic on this field and suggest that a soil sampling protocol based on collecting soil cores at random locations once every several days is unsuitable for determining the deep leaching under field conditions.

Technical Abstract: Field experiments were conducted at the South East Purdue Agricultural Center in Butlerville, IN to quantify the impact of the preferential flow paths on contaminant transport. A tile drain monitoring facility was used to quantify the water dynamics of preferential flow by sequentially applying several mobile tracers (bromide, chloride, and three fluoro-benzoic acids, i.e., PFBA, o-TFMBA, and 2,6 DFBA). Bromide was sprayed shortly before the irrigation started, while PFBA, o-TFMBA, and 2,6DFBA were applied at +2, +4, and +6 hours after irrigation started, respectively. The irrigation intensity was 3 mm per hour and lasted for 10 hours. Results showed that the bromide first appeared in the tile drains about four hours after irrigation started while the three benzoic acids, PFBA, o-TFBA, and 2,6 DFBA, were detected in the tile drainage at 102, 42, and 18 minutes after their applications, respectively. The percentages of the applied tracers recovered from the tile drainage were as follows: bromide (7.04%), PFBA (13.9%), o-TFMBA, (18.7%), and 2,6 DFBA (19.7%). These fast arrival times confirmed that: (1) water dynamics of preferential flow dictates the deep leaching; and (2) water movement and contaminant transport would shift toward the larger end of the pore spectrum of the preferential flow paths when a soil surface became wetter during a precipitation event. As a result, a protocol based on collecting soil cores at random locations once every several days is unsuitable for determining the deep leaching under field conditions.