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Infra-Red Photography of Coal (1935)

WALKER, J. J. ; SLATER, L.

[s.l.] : Nature Publishing Group

Nature 135 (1935), S. 623-623

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ISSN: 1476-4687

Source: Nature Archives 1869 - 2009

Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics

Notes: [Auszug] IN a letter in NATURE of February 2 (p. 265) Prof. J. Walton has remarked that infra-red photography of thin sections of coal should give interesting results. We would like to direct attention to some results of work on this subject. We should mention first that there are already some ...

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1038/135623b0

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Electrochemical spectral induced polarization modeling of artificial sulfide-sand mixtures (2014)

Placencia-Gomez, E., Slater, L. D.

Society of Exploration Geophysicists (SEG)

In: Geophysics

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Publication Date: 2014-12-09

Description: We examined the sensitivity of the electrochemical spectral induced polarization (SIP) model developed by Wong to the oxidation extent of pyrite and pyrrhotite minerals disseminated in silica sand. The sensitivity of this model to the oxidation of sulfide minerals was mainly related to the model parameters defining the ratio of the active to the inactive passive ions $$({c}_{2}/{c}_{o})$$ dissolved in the pore water, and the variation of the current reaction parameters $$\alpha $$ and $$\beta $$ . The increase in these parameters as well as in the associated exchange current densities, $${i}_{o}(\alpha )$$ and $${i}_{o}(\beta )$$ was consistent with an increase in the activation of the charge transfer at the metal-electrolyte interface, resulting in the decrease in polarization of such an interface, which was reflected by a decrease in the SIP phase response as previously argued by Wong. Under this premise, the model described fairly well measurements below 500 Hz from a laboratory experiment, being consistent with the depletion of the SIP phase response associated with the oxidation degree promoted on the disseminate sulfides analyzed here. This suggested that electrochemical modeling of SIP measurements can provide information to assess the oxidation state of sulfides and also to infer the formation of passivating layers coating the metal minerals during oxidation-dissolution processes. Our results suggested a possible alternative for the monitoring of mine waste deposits producing acid mine drainage and the stability of sequestered harmful metals during remedial treatments by means of the SIP method.

Print ISSN: 0016-8033

Electronic ISSN: 1942-2156

Topics: Geosciences , Physics

Published by Society of Exploration Geophysicists (SEG)

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Advances in interpretation of subsurface processes with time-lapse electrical imaging (2014)

Singha, K. ; Day-Lewis, F. D. ; Johnson, T. ; [et al.]

Wiley

In: Hydrological Processes. 2015; 29(6): 1549-1576. Published 2014 Aug 08. doi: 10.1002/hyp.10280.

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Publication Date: 2014-08-08

Description: Electrical geophysical methods, including electrical resistivity, time-domain induced polarization, and complex resistivity, have become commonly used to image the near subsurface. Here, we outline their utility for time-lapse imaging of hydrological, geochemical, and biogeochemical processes, focusing on new instrumentation, processing, and analysis techniques specific to monitoring. We review data collection procedures, parameters measured, and petrophysical relationships and then outline the state of the science with respect to inversion methodologies, including coupled inversion. We conclude by highlighting recent research focused on innovative applications of time-lapse imaging in hydrology, biology, ecology, and geochemistry, among other areas of interest. © 2014 John Wiley & Sons, Ltd.

Print ISSN: 0885-6087

Electronic ISSN: 1099-1085

Topics: Architecture, Civil Engineering, Surveying , Geography

Published by Wiley

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Using hydrologic measurements to investigate free-phase gas ebullition in a Maine peatland, USA (2014)

Bon, C. E. ; Reeve, A. S. ; Slater, L. ; [et al.]

Copernicus

In: Hydrology and Earth System Sciences. 2014; 18(3): 953-965. Published 2014 Mar 10. doi: 10.5194/hess-18-953-2014.

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Publication Date: 2014-03-10

Description: Northern peatlands cover more than 350 million ha and are an important source of methane (CH4) and other biogenic gases contributing to climate change. Free-phase gas (FPG) accumulation and episodic release has recently been recognized as an important mechanism for biogenic gas flux from peatlands. It is likely that gas production and groundwater flow are interconnected in peatlands: groundwater flow influences gas production by regulating geochemical conditions and nutrient supply available for methanogenesis, while FPG influences groundwater flow through a reduction in peat permeability and by creating excess pore water pressures. Water samples collected from three well sites at Caribou Bog, Maine, show substantial dissolved CH4 (5–16 mg L−1) in peat waters below 2 m depth and an increase in concentrations with depth. This suggests production and storage of CH4 in deep peat that may be episodically released as FPG. Two min increment pressure transducer data reveal approximately 5 cm fluctuations in hydraulic head from both deep and shallow peat that are believed to be indicative of FPG release. FPG release persists up to 24 h during decreasing atmospheric pressure and a rising water table. Preferential flow is seen towards an area of relatively lower hydraulic head associated with the esker and pool system. Increased CH4 concentrations are also found at the depth of the esker crest, suggesting that the high permeability esker is acting as a conduit for groundwater flow, driving a downward transport of labile carbon, resulting in higher rates of CH4 production.

Print ISSN: 1027-5606

Electronic ISSN: 1607-7938

Topics: Geography , Geosciences