Stan E. Beaubien

Chromium speciation and distribution in the great lakes.

A technique is described for selectively measuring the forms of chromium in freshwater samples, with detection limits of 21 ng L -1 for Cr(III), 4 ng L -1 for Cr(VI), and 8 ng L -1 for colloidal/organic Cr. Recovery of the Cr(VI) and Cr(III) spikes were consistently >90%, but only about 70% for the added organic Cr. When the method was applied to samples from Lake Ontario, it was found that Cr(VI) made up 75-85% of the dissolved Cr and that Cr-(III) was consistently below the analytical detection limit. About 10% of the dissolved Cr was in the colloidal/organic form. Average concentrations of total dissolved Cr in the epilimnetic waters were found to be 69 ng L -1 in Lake Superior, 136 ng L -1 in Lake Erie, and 351 ng L -1 in Lake Ontario

Characterization of a CO2 gas vent using various geophysical and geochemical methods

An understanding of gas migration along faults is important in many geologic research fields, such as geothermal exploration, risk assessment, and, more recently, the geologic storage of man-made carbon dioxide (C O2 ) . If these gases reach the surface, they typically are discharged to the atmosphere from small areas known as gas vents. In a study of an individual gas vent located in the extinct Latera caldera, central Italy, near-surface geochemical and geophysical surveys were conducted to define the spatial distribution of gas-induced effects in the first few meters of the soil and, by inference, the 3D structure and geometry of the associated gas-permeable fault. Grid surveys and detailed profiles were performed across this vent using time-domain reflectometry (TDR), ground-penetrating radar (GPR), frequency-domain electromagnetics (FDEM), electrical resistivity tomography (ERT), and gas geochemistry measurements. Detailed profilesurveys indicate that the leaking C O2 has changed the physical, chemic...

GPR, TDR, and geochemistry measurements above an active gas vent to study near-surface gas-migration pathways

The migration of deep gas to the atmosphere along faults and associated structures is important in many fields, from studying the natural contribution of atmospheric greenhouse gases leaking from geothermal areas to ensuring the safety of man-made natural gas and carbon dioxide (C O2 ) geologic-storage sites. Near-surface geophysical and geochemical techniques were applied to a naturally occurring gas vent located along a deep terrestrial fault to better understand the structure and geophysical response of this gas-migration pathway. A number of ground-penetrating radar (GPR) profiles were first conducted across the vent. Spot samples were then measured along one of these profiles for in situ apparent permittivity (using time-domain reflectometry — TDR), complex permittivity on dried samples (using a capacitivecell), soil-gas composition, and clay and bulk mineralogy. Results show how the migrating gas induces secondary effects that modify the signature of the vent as seen in the GPR profiles. In particul...

Spatial and Temporal pCO2 Marine Monitoring Near Panarea Island (Italy) Using Multiple Low-Cost GasPro Sensors

The present paper describes the GasPro probe, a small, low-cost unit for in situ, continuous pCO2 monitoring. Laboratory tests defining its performance characteristics are reported, as are the results from a 60 h water-column deployment of 20 such units near a natural CO2 seep site off the coast of Panarea Island (Italy). The spatial-temporal evolution of dissolved CO2 movement is presented and possible origins and controlling mechanisms discussed. Results highlight the potential for this technology to be used for better understanding various dynamic physical and biochemical processes in marine environments, and for marine environmental monitoring of off-shore industrial sites. These experiments have allowed us to assess the advantages and disadvantages of the present GasPro prototype and to define areas for ongoing improvement.

GPR, TDR, and geochemistry measurements above an active gas vent to study near-surface gas-migration pathwaysGPR, TDR, and geochemistry above a gas vent

The migration of deep gas to the atmosphere along faults and associated structures is important in many fields, from studying the natural contribution of atmospheric greenhouse gases leaking from geothermal areas to ensuring the safety of man-made natural gas and carbon dioxide (C O2 ) geologic-storage sites. Near-surface geophysical and geochemical techniques were applied to a naturally occurring gas vent located along a deep terrestrial fault to better understand the structure and geophysical response of this gas-migration pathway. A number of ground-penetrating radar (GPR) profiles were first conducted across the vent. Spot samples were then measured along one of these profiles for in situ apparent permittivity (using time-domain reflectometry — TDR), complex permittivity on dried samples (using a capacitivecell), soil-gas composition, and clay and bulk mineralogy. Results show how the migrating gas induces secondary effects that modify the signature of the vent as seen in the GPR profiles. In particul...