HR: 10:20h
AN: H12C-01 INVITED [Abstracts]
TI: Development of a "smart" tracer: The resazurin-resorufin assay of biological activity
AU: * Haggerty, R
EM: haggertr@geo.oregonstate.edu
AF: Oregon State University, Dept. of Geosciences, 104 Wilkinson Hall, Corvallis, OR 97331-
5506, United States
AU: Argerich, A
EM: alba@ceab.csic.es
AF: Centre d'Estudis Avançats de Blanes, Accés a la Cala St. Francesc 14, Blanes, 17300,
Spain
AU: Martí, E
EM: eugenia@ceab.csic.es
AF: Centre d'Estudis Avançats de Blanes, Accés a la Cala St. Francesc 14, Blanes, 17300,
Spain
AB:
A smart tracer is a tracer that provides, directly or through measurement of its concentration or in combination
with another compound, at least 1 bit more information than a conservative tracer. In other words, the tracer
provides information about conditions in the hydrologic system in addition to arrival time such as chemical
conditions or biological activity. We have developed a smart tracer for quantifying biological activity along a flow
path.
We identified and characterized a suitable compound, resazurin (Raz), along with its reduction product resorufin
(Rru). Resazurin is a weakly fluorescent redox-sensitive phenoxazin dye that undergoes an irreversible reduction
to strongly fluorescent resorufin under mildly reducing conditions – most commonly in the presence of living
bacteria. The Raz-Rru system has been widely used to test for the presence and viability of bacteria and other
living cells. We characterized the decay, reaction, sorption and transport behavior of Raz and Rru in various
waters and sediments. The compounds are stable (decay and reaction timescales of 100s-1000s of h) in natural
water, except in the presence of strong light. Raz rapidly reacts to Rru in sediment (timescale of 1 h). The
compounds are affected by significant sorption, with a Kd of 6.63 mL/g in sediment with 2.19% organic
carbon. A set of mathematical models of the tracer concentrations were developed. Lastly, we conducted a
successful field test of the tracer in the Riera de Santa Fe at Montseny, Catalonia, Spain. Results of these tests
will be reported.
DE: 0420 Biomolecular and chemical tracers
DE: 0448 Geomicrobiology
DE: 0471 Oxidation/reduction reactions (4851)
DE: 1813 Eco-hydrology
DE: 1830 Groundwater/surface water interaction
SC: Hydrology [H]
MN: 2007 Fall Meeting