Shawnee A



H. Pang and T.C. Zhang, Department of Civil Engineering, University of Nebraska-Lincoln at Omaha Campus, Omaha, NE 68182-0178 The feasibility of using microelectrodes to measure microscale pH spatial distribution in the soils samples for remediation of TNT were investigated. The tested soil was aged soil contaminated with TNT, sampled from the Nebraska Ordnance Plant. pH-sensitive ion-selective microelectrodes were used to measure the pH distribution of the samples.

The measurement system consisted of a test column, a light source, a working microelectrode and a Ag/AgCI reference electrode [tip diameter (I.D.) = lmm], and a stereomicroscope situated on a vibration isolation table with a Faraday cage. Outside of the Faraday cage, a 3-D motorized micromanipulator was used to position the tip of the microelectrode. The signals were measured with a chemical microsensor. The spatial variability of soil pH was examined based on the signal recorded with a Fisher Recordall.

The tip diameter of the pH-sensitive microelectrode was preferable to be 50 ~ 100 (m. With a smaller tip size, the tip of a microelectrode would be broken easily by the coarse particles in the soil as the microelectrode penetrated the soil sample. If the tip diameter of a microelectrode is larger than 200 (m, the electrode would damage the structure of the tested samples.

The pH of the tested soil ranged from 3.7 to 9, depending on the concentration of TNT within the soil samples and the location of the measuring point. The pH decreased and variability increased with depth. In all cases, pH spatial variances in the vertical were larger than in the horizontal. This study illustrated that pH of a soil sample can be successfully measured using a microelectrode and the soil heterogeneity and spatial dependence of pH in microscale existed.

Key words: microelectrode, pH, remediation, microscale environment

Top of Page

Return to Main Table of Contents
(to see full list of programs and abstracts)

Sub-Menu of Event Programs
(to see specific list of abstracts)

Tuesday, May 20, 1997

Metals Kansa A

Remediation of Munitions Compounds Kansa B

Analytical Methods Kansa C/D

General Topics Kansa B

Wednesday, May 21, 1997

Metals Kansa A

Zero-Valent Metals Kansa A

Remediation Kansa A

Vegetation-based Remediation Kansa B

Partnerships & Innovative Technologies Kansa C/D

Nonaqueous Phase Liquids Kansa C/D

Thursday, May 22, 1997

Biofilms & Barriers Kansa A

Bioremediation Kansa B

Partnerships & Technology Innovations Kansa C/D

Remediation Kansa C/D


Return to Publications Menu


Send comments on the Great Plains/Rocky Mountain HSRC web pages to:;
comments or questions about this WWW server, to: