ON INDUCED ELECTRICAL POLARIZATION AND GROUNDWATER

Clay horizons and other clay‐bearing unconsolidated sediments are potential sources of induced‐polarization anomalies. If such anomalies may be detected above system noise, the induced‐polarization method may be of value for in‐situ classification of unconsolidated sediments encountered in hydrological projects. One such project exists in Santa Clara County where near‐surface unconsolidated sediments are frequently considered as potential recharge areas. Of four areas surveyed with induced‐polarization apparatus in Santa Clara County, only two yielded significant frequency‐effect anomalies, and in each of these two the frequency effects were of the order of 3 percent. These anomalous frequency effects may be related to clayey gravels. The dipole‐dipole array, with spreads of 10 ft and 20 ft, was typically used in the study.

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An overview of the spectral induced polarization method for near-surface applications

Near Surface Geophysics ◽

10.3997/1873-0604.2012027 ◽

2012 ◽

Vol 10 (6) ◽

pp. 453-468 ◽

Cited By ~ 134

Author(s):

Andreas Kemna ◽

Andrew Binley ◽

Giorgio Cassiani ◽

Ernst Niederleithinger ◽

André Revil ◽

...

Keyword(s):

Induced Polarization ◽

Polarization Method ◽

Near Surface ◽

Spectral Induced Polarization

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A COMPARISON OF THE VARIOUS PARAMETERS EMPLOYED IN THE VARIABLE‐FREQUENCY INDUCED‐POLARIZATION METHOD

Geophysics ◽

10.1190/1.1439376 ◽

1964 ◽

Vol 29 (3) ◽

pp. 425-433 ◽

Cited By ~ 18

Author(s):

Philip G. Hallof

Keyword(s):

Induced Polarization ◽

Frequency Effect ◽

Variable Frequency ◽

Transient Method ◽

Polarization Method ◽

Applied Current ◽

Frequency Method ◽

Pulse Transient Method ◽

Factor Data ◽

The Time Domain

The increased use of the induced‐polarization method in recent years has resulted in two methods of measurement. The measurements in the frequency domain (variable‐frequency method) rely on changes in the apparent resistivities measured as the frequency of the applied current is varied. The measurement in the time domain (pulse‐transient method) detects transients in the measured potentials when the applied current is interrupted. The “chargeability” is the parameter used in the pulse‐transient method, while both the “frequency effect” and the normalized parameter “metal factor” are used in the variable‐frequency method. The most useful parameter would be the one which best indicates the amount of metallic mineralization present. Eight sets of field results from variable‐frequency field surveys are shown. The cases are shown in pairs; in each pair, the geometry of the source is much the same. By comparing the resistivity, the frequency effect (chargeability), and metal‐factor data with the amount of mineralization indicated by the drilling results, the usefulness of these parameters can be evaluated.

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DEPENDENCE OF IN‐SITU COMPRESSIONAL‐WAVE VELOCITY ON POROSITY IN UNSATURATED ROCKS

Geophysics ◽

10.1190/1.1440249 ◽

1972 ◽

Vol 37 (1) ◽

pp. 29-35 ◽

Cited By ~ 29

Author(s):

Joel S. Watkins ◽

Lawrence A. Walters ◽

Richard H. Godson

Keyword(s):

Wave Velocity ◽

Seismic Refraction ◽

Compressional Wave ◽

Unconsolidated Sediments ◽

Compressional Wave Velocity ◽

Near Surface ◽

Least Squares Fit ◽

Water Saturated ◽

Porosity Range

The relation of in‐situ compressional‐wave velocities to porosities, determined by seismic refraction for unsaturated near‐surface rocks from different areas in Arizona, New Mexico, and California, is grossly similar to relations determined by other investigators for water‐saturated rock and unconsolidated sediments. The principal difference is that in the porosity range 0.0–0.2, compressional waves travel somewhat more slowly in unsaturated rocks than in water‐saturated rocks, and much more slowly, in the porosity range 0.2–0.8. The function, ϕ=−0.175 ln (α)+1.56, where ϕ is the fractional porosity and α is the compressional‐wave velocity, was obtained as a least squares fit to the experimental data. Bulk densities are reported for all samples; moisture contents are reported in some instances.

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Monitoring of In Situ Remediation with the Direct Current Time-Domain Induced Polarization Method

24th European Meeting of Environmental and Engineering Geophysics ◽

10.3997/2214-4609.201802498 ◽

2018 ◽

Author(s):

A. Nivorlis ◽

T. Dahlin ◽

M. Rossi ◽

H. Wei

Keyword(s):

Direct Current ◽

Time Domain ◽

Induced Polarization ◽

In Situ Remediation ◽

Polarization Method ◽

Current Time

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On the determination of the apparent frequency-effect in the frequency-domain induced polarization method

Geoexploration ◽

10.1016/0016-7142(76)90002-8 ◽

1976 ◽

Vol 14 (2) ◽

pp. 81-91 ◽

Cited By ~ 3

Author(s):

D. Patella ◽

D. Schiavone

Keyword(s):

Frequency Domain ◽

Induced Polarization ◽

Frequency Effect ◽

Polarization Method

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The Precipitation Imaging Package: Phase Partitioning Capabilities

Remote Sensing ◽

10.3390/rs13112183 ◽

2021 ◽

Vol 13 (11) ◽

pp. 2183

Author(s):

Claire Pettersen ◽

Larry F. Bliven ◽

Mark S. Kulie ◽

Norman B. Wood ◽

Julia A. Shates ◽

...

Keyword(s):

Phase Transition ◽

Phase Identification ◽

Near Surface ◽

Surface Precipitation ◽

Phase Partitioning ◽

Thermodynamic Conditions ◽

Lapse Rates ◽

Precipitation Phase

Surface precipitation phase is a fundamental meteorological property with immense importance. Accurate classification of phase from satellite remotely sensed observations is difficult. This study demonstrates the ability of the Precipitation Imaging Package (PIP), a ground-based, in situ precipitation imager, to distinguish precipitation phase. The PIP precipitation phase identification capabilities are compared to observer records from the National Weather Service (NWS) office in Marquette, Michigan, as well as co-located observations from profiling and scanning radars, disdrometer data, and surface meteorological measurements. Examined are 13 events with at least one precipitation phase transition. The PIP-determined onsets and endings of the respective precipitation phase periods agree to within 15 min of NWS observer records for the vast majority of the events. Additionally, the PIP and NWS liquid water equivalent accumulations for 12 of the 13 events were within 10%. Co-located observations from scanning and profiling radars, as well as reanalysis-derived synoptic and thermodynamic conditions, support the accuracy of the precipitation phases identified by the PIP. PIP observations for the phase transition events are compared to output from a parameterization based on wet bulb and near-surface lapse rates to produce a probability of solid precipitation. The PIP phase identification and the parameterization output are consistent. This work highlights the ability of the PIP to properly characterize hydrometeor phase and provide dependable precipitation accumulations under complicated mixed-phase and rain and snow (or vice versa) transition events.

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North polar trough formation due to in-situ erosion as a source of young ice in mid-latitudinal mantles on Mars

Scientific Reports ◽

10.1038/s41598-021-83329-3 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

J. Alexis P. Rodriguez ◽

Kenneth L. Tanaka ◽

Ali M. Bramson ◽

Gregory J. Leonard ◽

Victor R. Baker ◽

...

Keyword(s):

Katabatic Wind ◽

Spiral Pattern ◽

Near Surface ◽

Valuable Source ◽

History Of ◽

North Polar ◽

Human Exploration ◽

Erosional Event

AbstractThe clockwise spiral of troughs marking the Martian north polar plateau forms one of the planet’s youngest megastructures. One popular hypothesis posits that the spiral pattern resulted as troughs underwent poleward migration. Here, we show that the troughs are extensively segmented into enclosed depressions (or cells). Many cell interiors display concentric layers that connect pole- and equator-facing slopes, demonstrating in-situ trough erosion. The segmentation patterns indicate a history of gradual trough growth transversely to katabatic wind directions, whereby increases in trough intersections generated their spiral arrangement. The erosional event recorded in the truncated strata and trough segmentation may have supplied up to ~25% of the volume of the mid-latitude icy mantles. Topographically subtle undulations transition into troughs and have distributions that mimic and extend the troughs’ spiraling pattern, indicating that they probably represent buried trough sections. The retention of the spiral pattern in surface and subsurface troughs is consistent with the megastructure’s stabilization before its partial burial. A previously suggested warm paleoclimatic spike indicates that the erosion could have occurred as recently as ~50 Ka. Hence, if the removed ice was redeposited to form the mid-latitude mantles, they could provide a valuable source of near-surface, clean ice for future human exploration.

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Strategies of In Situ Generated Magnesium Catalysis in Asymmetric Reactions

Synlett ◽

10.1055/a-1409-2734 ◽

2021 ◽

Author(s):

Dongxu Yang ◽

Linqing Wang

Keyword(s):

Asymmetric Synthesis ◽

Alkaline Earth ◽

Earth Metal ◽

Asymmetric Reactions ◽

Chiral Ligands ◽

Alkaline Earth Metal ◽

Enantioselective Reactions ◽

Earth's Crust

AbstractMagnesium (Mg) is a cheap, non-toxic, and recyclable alkaline earth metal that constitutes about 2% weight in the Earth’s crust. The use of magnesium catalysts to forge chiral moieties in molecules is highly attractive. Based on our work in recent years, we describe the current progress in the development of in situ generated magnesium catalysts and their application in asymmetric synthesis. In this perspective, a critically concise classification of in situ generated magnesium catalytic modes, with relevant examples, is presented, and representative mechanisms of each category are discussed. Building on the established diverse strategies, one can foresee that more innovative and structurally creative magnesium catalysts that are generated in situ will be developed to overcome more formidable challenges of catalytic enantioselective reactions.1 Introduction2 Magnesium Catalysts Generated in Situ from Chiral Ligands Containing Dual Reactive Hydrogens3 Magnesium Catalysts Generated in Situ from Monoanionic Chiral Ligands4 Bimetallic and Polymetallic Magnesium Catalysts Assembled in Situ5 Summary and Outlook

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Underwater Holographic Sensor for Plankton Studies In Situ Including Accompanying Measurements

Sensors ◽

10.3390/s21144863 ◽

2021 ◽

Vol 21 (14) ◽

pp. 4863

Author(s):

Victor Dyomin ◽

Alexandra Davydova ◽

Igor Polovtsev ◽

Alexey Olshukov ◽

Nikolay Kirillov ◽

...

Keyword(s):

World Ocean ◽

Field Tests ◽

Field Measurements ◽

Measuring Systems ◽

Water Turbidity ◽

Background Data ◽

Average Size ◽

Size Dispersion

The paper presents an underwater holographic sensor to study marine particles—a miniDHC digital holographic camera, which may be used as part of a hydrobiological probe for accompanying (background) measurements. The results of field measurements of plankton are given and interpreted, their verification is performed. Errors of measurements and classification of plankton particles are estimated. MiniDHC allows measurement of the following set of background data, which is confirmed by field tests: plankton concentration, average size and size dispersion of individuals, particle size distribution, including on major taxa, as well as water turbidity and suspension statistics. Version of constructing measuring systems based on modern carriers of operational oceanography for the purpose of ecological diagnostics of the world ocean using autochthonous plankton are discussed. The results of field measurements of plankton using miniDHC as part of a hydrobiological probe are presented and interpreted, and their verification is carried out. The results of comparing the data on the concentration of individual taxa obtained using miniDHC with the data obtained by the traditional method using plankton catching with a net showed a difference of no more than 23%. The article also contains recommendations for expanding the potential of miniDHC, its purpose indicators, and improving metrological characteristics.

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