Monitoring redox sensitive conditions at the groundwater interface using electrical resistivity and self-potential.

摘要: Assessing redox conditions in soil and groundwater is challenging because reactions are oxygen sensitive, hence, destructive sampling methods may provide contact with air influence the state. Furthermore, commonly used potential sensors only point measurements prone to error. This paper assesses whether combining electrical resistivity (ER) self-potential (SP) can allow mapping of zones affected by anaerobic degradation. We use ER imaging degradation release iron manganese ions, which decreases pore water resistivity, produces gas, increases resistivity. Also, electrochemical differences between aerobic create an electron flow, forming a anomaly. In this laboratory study, four sand tanks constant table heights, time-lapse SP mapped changes electrical/electron flow properties due organic contaminant (propylene glycol) Sampled chemistry. When oxides were available, reduced cation water. unavailable, increased, plausibly from methane production, saturation. To bypass producing metallic cations, metal pipe was installed zones. The creates surplus at site. allowed site oxygen-rich near surface. current sent through formed anomaly observable on surface tank. Time-lapse demonstrates for under conditions. conductor bridges zone surface, causes However, alone produced no signal. Despite their limitations, promising tools monitoring sensitive unsaturated sandy soils but should not be isolation.