HR: 0800h
AN: NS51A-01    [Abstracts]
TI: Geophysical Monitoring of Microbial Activity within a Wetland Soil
AU: * O'Brien, M
EM: mikeob2@pegasus.rutgers.edu
AF: Rutgers University - Newark, 101 Warren Street, Newark, NJ 07102, United States
AU: Zhang, C
EM: chizhang@pegasus.rutgers.edu
AF: Rutgers University - Newark, 101 Warren Street, Newark, NJ 07102, United States
AU: Ntarlagiannis, D
EM: dimntar@pegasus.rutgers.edu
AF: Rutgers University - Newark, 101 Warren Street, Newark, NJ 07102, United States
AU: Slater, L
EM: lslater@andromeda.rutgers.edu
AF: Rutgers University - Newark, 101 Warren Street, Newark, NJ 07102, United States
AU: Yee, N
EM: nyee@envsci.rutgers.edu
AF: Rutgers University - New Brunswick, 14 College Farm Road, New Brunswick, NJ 08901, United States
AB: We performed Induced Polarization (IP) and Self Potential (SP) measurements to record the geoelectrical signatures of microbial activity within a wetland soil. The experiment was conducted in laboratory, utilizing an open flow column set up. Soil samples from Kearny Marsh (KM), a shallow water wetland, were collected and stored at 4o Celsius prior to the start of the experiment. Two columns were dry packed with a mix of KM soil and sterile Ottawa sand (50% by weight). One column was sterilized and used as a control while the other column retained the biologically active soil sample. Both columns were saturated with a minimal salts medium capable of supporting microbial life; after saturation, a steady flow rate of one pore volume per day was maintained throughout the experiment. Ambient temperature and pressure changes (at the inflow and outflow of each column) were continuously monitored throughout the experiment. Common geochemical parameters, such as Eh, pH, and fluid conductivity were measured at the inflow and outflow of each column at regular intervals. IP and SP responses were continuously recorded on both columns utilizing a series of electrodes along the column length; additionally for the SP measurements we used a reference electrode at the inflow tube. Strong SP anomalies were observed for all the locations along the active column. Black visible mineral precipitant also formed in the active column. The observed precipitation coincided with the times that SP anomalies developed at each electrode position. These responses are associated with microbial induced sulfide mineralization. We interpret the SP signal as the result of redox processes associated with this mineralization driven by gradients in ionic concentration and mobility within the column, similar to a galvanic cell mechanism. IP measurements show no correlation with these visual and SP responses. Destructive analysis of the samples followed the termination of the experiment. Scanning electron microscopy (SEM) and Energy Dispersive Spectrometry (EDS) were used to identify and quantify the presence and composition of the mineral precipitation in the control and active columns. Further geochemical measurements are currently being performed in order to confirm and more accurately quantify the mineralization and associated processes.
DE: 0416 Biogeophysics
DE: 0419 Biomineralization
DE: 0488 Sulfur cycling
DE: 0497 Wetlands (1890)
DE: 1890 Wetlands (0497)
SC: Near-Surface Geophysics [NS]
MN: 2007 Joint Assembly