Limestone Bedrock as a Barrier to Uranium Migration, Sierra Peña Blanca, Chihuahua, Mexico

1981 ◽  
Author(s):  
Bruce Stege ◽  
Nicholas E. Pingitore ◽  
Philip C. Goodell ◽  
David V. LeMone
Keyword(s):  
Limestone Bedrock ◽  
Uranium Migration

Uranium migration through intact sandstone: effect of pollutant concentration and the reversibility of uptake

1996 ◽  
Vol 21 (1-4) ◽  
pp. 215-228 ◽  
Author(s):  
R. Sims ◽  
T.A. Lawless ◽  
J.L. Alexander ◽  
D.G. Bennett ◽  
D. Read
Keyword(s):  
Pollutant Concentration ◽  
Uranium Migration

scholarly journals Saltwater intrusion as potential driver of phosphorus release from limestone bedrock in a coastal aquifer

2017 ◽  
Vol 184 ◽  
pp. 166-176 ◽  
Author(s):  
Hilary Flower ◽  
Mark Rains ◽  
David Lewis ◽  
Jia-Zhong Zhang ◽  
René Price
Keyword(s):  
Coastal Aquifer ◽  
Saltwater Intrusion ◽  
Phosphorus Release ◽  
Limestone Bedrock

Phosphate biogeochemical barrier for uranium in situ immobilization in an aquifer nearby sludge repository

2021 ◽  
Author(s):  
Grigory Artemiev ◽  
Alexey Safonov ◽  
Nadezhda Popova
Keyword(s):  
Essential Elements ◽  
Ion Concentration ◽  
Soluble Form ◽  
High Concentration ◽  
Rapid Reduction ◽  
Near Surface ◽  
Nitrate Ions ◽  
Uranium Migration ◽  
Storage Facilities

<p>Uranium migration in the oxidized environment of near-surface groundwater is a typical problem of many radiochemical, ore mining and ore processing enterprises that have sludge storage facilities on their territory. Uranium migration, as a rule, occurs against a high salt background due to the composition of the sludge: primarily, nitrate and sulfate anions and calcium cations. One of the ways to prevent the uranium pollution is geochemical or engineering barriers. For uranium immobilization, it is necessary to create conditions for its reduction to a slightly soluble form of uraninite and further mineralization, for example, in the phosphate form. An important factor contributing to the rapid reduction of uranium is a in the redox potential decreasing and the removal of nitrate ions, which can be achieved through the activation of microflora. It should be added that phosphate itself is one of the essential elements for the development of microflora. This work was carried out in relation to the upper aquifer (7-12 m) near the sludge storage facilities of ChMZ, which is engaged in uranium processing and enrichment. One of the problems of this aquifer, in addition to the high concentration of nitrate ions (up to 15 g / l), is the high velocity of formation waters.<br>In laboratory conditions, the compositions of injection solutions were selected containing sources of organic matter to stimulate the microbiota development and phosphates for uranium mineralization. When developing the injection composition, special attention was paid to assessing the formation of calcite deposits in aquifer conditions to partially reduce the filtration parameters of the horizon and reduce the rate of movement of formation waters. This must be achieved to ensure the possibility of long-term deposition of uranium and removal of nitrate. The composition of the optimal solution was selected and in a series of model experiments the mineral phases containing the lowest hydrated form of the uranium-containing phosphate mineral meta-otenite were obtained.<br>In situ mineral phosphate barrier Formation field tests were carried out in water horizon conditions in a volume of 100m3 by injection of an organic and phosphates mixture. As a result, at the first stage of field work, a significant decreasing nitrate ion concentration, and reducing conditions formation coupled with the dissolved uranium concentration of decreasing were noted.</p>

scholarly journals Reconstructing the Gorte and Spiaz de Navesele Landslides, NE of Lake Garda, Trentino Dolomites (Italy)

Geosciences ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 404
Author(s):  
Giacomo Ruggia ◽  
Susan Ivy-Ochs ◽  
Jordan Aaron ◽  
Olivia Steinemann ◽  
Silvana Martin ◽  
...  
Keyword(s):  
Rock Avalanche ◽  
Source Area ◽  
Heavy Precipitation ◽  
First Order ◽  
Fault Systems ◽  
Lake Garda ◽  
Limestone Bedrock ◽  
Multi Method Approach ◽  
Method Approach

We applied a multi-method approach to reconstruct the Gorte rock avalanche (85–95 Mm3) located at the northeastern end of Lake Garda. The combination of field mapping, characterization of bedrock discontinuities, Dan3D-Flex runout modeling and dating of boulders with cosmogenic 36Cl supports the conclusion that the deposits stem from a single rock avalanche at 6.1 ± 0.8 ka. The Gorte event may have triggered the Spiaz de Navesele–Salto della Capra landslide (3.2 Mm3), whose deposits cover the southern end of the Gorte deposits. First-order controls on detachment were the NNE–SSW- and WNW–ESE-oriented fractures in the limestone bedrock, related to the Giudicarie and Schio-Vicenza fault systems, respectively. Dan3D-Flex runout modeling sufficiently reproduced the Gorte rock avalanche, which involved detachment and sliding of a quasi-intact block, likely along marly interbeds, followed by rapid disintegration. The frictional rheology in the source area and the turbulent frictional rheology (Voellmy) in the remaining part best replicate the observed deposit extent and thickness. Heavy precipitation that occurred at that time may have contributed to failure at Gorte. Nonetheless, its timing overlaps with the nearby (<15 km) Dosso Gardene (6630–6290 cal BP) and Marocca Principale (5.3 ± 0.9 ka) landslides, making a seismic trigger plausible.

scholarly journals BENTONITE-QUARTZ SAND AS THE BACKFILL MATERIALS ON THE RADIOACTIVE WASTE REPOSITORY

2010 ◽  
Vol 5 (2) ◽  
pp. 115-120
Author(s):  
Raharjo Raharjo
Keyword(s):  
Radioactive Waste ◽  
Quartz Sand ◽  
Nitrate Solution ◽  
Fixed Bed ◽  
Weight Percent ◽  
Retardation Factor ◽  
Backfill Materials ◽  
Uranium Migration ◽  
Water Saturated ◽  
Bentonite Particle

An investigation of the contribution of quartz sand in the bentonite mixture as the backfill materials on the shallow land burial of radioactive waste has been done. The experiment objective is to determine the effect of quartz sand in a bentonite mixture with bentonite particle sizes of -20+40, -40+60, and -60+80 mesh on the retardation factor and the uranium dispersion in the simulation of uranium migration in the backfill materials. The experiment was carried out by the fixed bed method in the column filled by the bentonite mixture with a bentonite-to-quartz sand weight percent ratio of 0/100, 25/75, 50/50, 75/25, and 100/0 on the water saturated condition flown by uranyl nitrate solution at concentration (Co) of 500 ppm. The concentration of uranium in the effluents in interval 15 minutes represented as Ct was analyzed by spectrophotometer, then using Co and Ct, retardation factor (R) and dispersivity () were determined. The experiment data showed that the bentonite of -60+80 mesh and the quartz sand of -20+40 mesh on bentonite-to-quartz sand with weight percent ratio of 50/50 gave the highest retardation factor and dispersivity of 18.37 and 0.0363 cm, respectively.   Keywords: bentonite, quartz sand, backfill materials, radioactive waste  

scholarly journals IDENTIFYING FAULT ACTIVITY IN THE CENTRAL EVOIKOS GULF (GREECE)

2018 ◽  
Vol 40 (1) ◽  
pp. 439 ◽  
Author(s):  
Th. Rondoyanni ◽  
D. Galanakis ◽  
Ch. Georgiou ◽  
I. Baskoutas
Keyword(s):  
Late Quaternary ◽  
Active Faults ◽  
Point Of View ◽  
Geological Mapping ◽  
Normal Faults ◽  
Geophysical Research ◽  
Alluvial Deposits ◽  
Moderate Seismicity ◽  
Limestone Bedrock ◽  
Topographic Relief

Geological mapping on a 1:5.000 scale and a tectonic analysis in the wider Chalkida region of the Island of Evia and the adjacent Drossia area of Central Greece, have allowed the identification of a number of active and potentially active normal faults. These faults have been formed or reactivated during the Late Quaternary, since they affect Pleistocene brackish and terrestrial deposits. Some of the faults affect the contact of the limestone bedrock with the Quaternary formations, presenting characteristic polished surfaces. The faults, in places covered by the alluvial deposits of the Chalkida plain, are also detected by geophysical research. Among the identified faults, the most important are considered the Aghios Minas- Chalkida, the Avlida and the Lefkadi active faults. The first one extends from Drossia to the Chalkida area, crossing the sea straights, and has an ENE-WSW direction and a south dip. The other two, are parallel antithetic faults oriented WNW-ESE, and bound the South Evoikos Gulf on the Greek mainland and the Evia Island respectively. The mapping and evaluation of active faults in this region of moderate seismicity, with low topographic relief and consequent absence of morphotectonic features, is especially important from a seismic hazard point of view.

scholarly journals A comparative study for structural bedrock delineation by using conventional geophysical methods

2001 ◽  
Vol 34 (4) ◽  
pp. 1301
Author(s):  
Τ. Δ. ΠΑΠΑΔΟΠΟΥΛΟΣ ◽  
I. A. ΑΛΕΞΟΠΟΥΛΟΣ ◽  
Π. Ι. ΚΑΜΠΟΥΡΗΣ
Keyword(s):  
Seismic Refraction ◽  
Geophysical Methods ◽  
Clear Distinction ◽  
The Past ◽  
Tectonic Processes ◽  
Refraction Method ◽  
Limestone Bedrock ◽  
Modern Analysis ◽  
Seismic Refraction Method ◽  
Effective Design

In this paper is examined the potential and effectiveness of two conventional geophysical methods in geotechnical research. The seismic refraction method that has been successfully used in the past for subsurface bedrock delineation in foundation projects, failed to indicate clear distinction between flysch and limestone bedrock material in the area under investigation. This failure is due to the macro-anisotropy structure of the limestone that resulted from joints, tectonic processes or/and karstic phenomena and later fillings of the voids with argillaceous material. The geoelectrical method of vertical sounding, on the other hand, although provided a clear distinction for the bedrock characterization, failed to distinguish the overburden cover from the underlain flysch formation. Finally, in this paper it is shown that for a successful application of geophysical work in  geotechnical research, it is required effective design, utilization of modern analysis methods and handling more than geophysical methods.

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