HR: 0800h
AN: H41F-0466    [Abstracts]
TI: Electrical Properties of Reacted Iron Cores Extracted From a Permeable Reactive Barrier Installation
AU: * Wu, Y
EM: yuxinwu@pegasus.rutgers.edu
AF: Rutgers University, Room 136, 101 Warren Street, Newark, NJ 07102 United States
AU: Slater, L
EM: lslater@andromeda.rutgers.edu
AF: Rutgers University, Room 136, 101 Warren Street, Newark, NJ 07102 United States
AU: Korte, N
EM: nkorte1@hotmail.com
AF: Honeywell FM&T, 1946 Clover Court, Grand Junction, CO 81506 United States
AB: We conducted experiments to investigate the application of non-invasive electrical method for monitoring iron corrosion and mineral precipitation processes on angle cores recovered from the Kansas City Plant reactive iron barrier. Electrical measurements showed continuous changes from the soil/iron interface into the barrier for all three cores. Scanning electron microscopy (SEM) identified iron surface alteration with thickest corrosion rind, indicating most severe corrosion, occurred close to upgradient soil/iron interface relative to locations further into the cores. Nitrogen adsorption measurements showed decreases in specific surface area of iron minerals from upgradient soil/iron interface into the barrier. X-ray diffractometry (XRD) identified precipitation of iron oxide/hydroxide, carbonate minerals, iron sulfide as well as green rusts in all three cores, and magnetite was identified as the dominant phase. Electrical measurements correlated well with solid phase analysis and illustrated the sensitivity of low frequency electrical method to iron corrosion and mineral precipitation processes. Electrical signature changes are attributed to (1) higher complex interfacial conductivity due to increased surface area and mineralogical alteration, and (2) increased electronic conduction due to enhanced electron transfer across the iron-fluid interface facilitated by mineralogical alternation and increased specific surface area during iron corrosion and mineral precipitation. Electrical measurements along with solid phase analysis also revealed more severe corrosion occurred at north end relative to south end of the barrier correlated with more groundwater flow through north end of the barrier. Our results on field cores are consistent with laboratory studies on synthetic iron columns presented previously and demonstrate that electrical measurements are a proxy indicator of Fe0 surface alteration and could be implemented for field barrier corrosion process monitoring.
DE: 1829 Groundwater hydrology
DE: 1835 Hydrogeophysics
DE: 1859 Rocks: physical properties
SC: Hydrology [H]
MN: Fall Meeting 2005