Ionic Contribution to the Self-potential Signals Associated With

8/2/2019 Ionic Contribution to the Self-potential Signals Associated With

1/18

Ionic contribution to the self-

potential signals associatedwith a redox front

A. Revil , F. Trolard , G. Bourri , J. Castermant

, A. Jardani , C.A. Mendona

Presented by:

Fathiya Al-Hadhrami


2/18

Agenda

Why they did the research ?(objective)

What did they do?(method)

What did they find?(observations)

What dose it mean?(discussion of results)

Who cares?(significant)

Final message to take home(conclusion)


3/18

we consider the case of a sharp redox potential distribution

generated in a water-saturated porous medium with no

electron conductor present to bridge electron donors and

acceptors in the system.

These experiments demonstrate that despite the absence of

electron conductors, self-potential anomalies can be

observed.

However, their magnitudes are much weaker than in the

case of the geobattery associated with an abiotic electronic

conductor.

Objective


4/18

Experimental setup

Sketch of the experimental setups, Experiment 1. In Phase 1,2(A. Revil et al., 2009)


5/18

Experimental setup

Sketch of the experimental setups, Experiment 2. In Phase 1,2(A. Revil et al., 2009)


6/18

Distribution of the self-potential at the top surface of the tank for Experiment 1 (Phase 2). (A. Revilet al., 2009)

Observations


7/18

Distribution of the corrected redox potential inside the tank, at a depth of 3 cm, 3 h after theDC power supply was shut down (left) Distribution of the corrected redox potential across a

profile in the tank (along y at x=25 cm)(right)(A. Revil et al., 2009)

Observations


8/18

Variation of the self-potential signals with depth and time with respect to the reference

electrode. a. Self-potential signals versus depth 3 h after the DC power supply was shut

down. These profiles are shown at 5 distinct locations in the tank. b. Self-potential signals

versus time at 1 cm from the working and auxiliary electrodes(A. Revil et al., 2009)

Observations


9/18

Distribution of the

redox potential,

self-potential,

and pH along two

profiles

in Experiment 2.

(A. Revil et al.,

2009)

Observations


10/18

Map of the self-potential (SP) at different time intervals during Phase 1,2 experiment 2

(A. Revil et al., 2009)

Observations


11/18

Map of the self-potential (SP) at different time intervals during Phase 1(A. Revil et al.,

2009)

Observations


12/18

Map of the self-potential (SP) at different time intervals during Phase 1(A. Revil et al.,

2009)

Observations


13/18

Discussion of the observations

Description of phase 1:


14/18


There were 3 transport processes:


Operation Equations Comments

Electro-migration (OH)=20.6108 m2 s1 V1, e1.6 h.


15/18

Evolution of the pH and the

redox potential at the cathode

and at the

anode as a function of

time(Experiment 2, Phase 1,

total duration of Phase 1:6

days). 1(A. Revil et al., 2009)

Observations


16/18




17/18

Tomography of the self-potential signals 3 h after the DC power supply was shut down.

Created by Jardani et al. (2007, 2008) (A. Revil et al., 2009)



18/18

in the presence of a sharp redox potential gradient only

modest self-potential signals are generated in a porous

material in the absence of an electronic conductor.

despite their small magnitudes, the diffusion potentials

observed in the experiments were measurable and can be

easily observed .

An assumption that a possibly biotic electronic

conductor should be presented to explain the high values

of SP anomalies in contaminated landfill was presented.

Conclusion

Ionic Contribution to the Self-potential Signals Associated With

Documents

Transcript of Ionic Contribution to the Self-potential Signals Associated With