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Visualizing Preferential Flow Paths using Ammonium Carbonate and a pH Indicator
Author(s) -
Wang Zhi,
Lu Jianhang,
Wu Laosheng,
Harter Thomas,
Jury William A.
Publication year - 2002
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj2002.3470
Subject(s) - carbonate , tracer , ammonium , ammonium carbonate , soil water , geology , infiltration (hvac) , soil science , chemistry , mineralogy , materials science , inorganic chemistry , composite material , physics , organic chemistry , nuclear physics
Despite their negative charge, anionic dyes are less‐than‐ideal tracers of water flow in soil. A new method is presented here for detecting flow patterns faithfully representing the movement of water flow paths in structured and nonstructured soils. The method is based on application of ammonium carbonate during infiltration, which displays a unique color signature when sprayed with a pH indicator after excavation and exposure of the soil profile along a trench face. We compare its performance with that of the popular Brilliant Blue in a laboratory study, and show that it is a more conservative tracer of the water front. We also illustrate its use in a field experiment to detect preferential flow. In contrast to other methods, ammonium carbonate is inexpensive, nontoxic, and leaves negligible residue.