Partitioning of 127I and 129I in an unconfined glaciofluvial aquifer on the Canadian shield

2002 ◽  
Vol 90 (8) ◽  
Author(s):  
N. G. Alvarado-Quiroz ◽  
T. G. Kotzer ◽  
G. M. Milton ◽  
I. D. Clark ◽  
D. Bottomley
Keyword(s):  
Iodine Concentration ◽  
Canadian Shield ◽  
Medical Applications ◽  
Total Iodine ◽  
Aquifer System ◽  
Fine Grained ◽  
Crystalline Bedrock ◽  
Sandy Aquifer ◽  
Glacial Tills ◽  
Analytical Program

SummaryAt AECL – Chalk River Laboratories, Ontario, Canada solid, low-level radioactive wastes from industrial, academic and medical applications have been stored in trenches above unconsolidated sandy glacial tills and permeable very-fine to fine-grained sands overlying crystalline bedrock. The sandy aquifer system drains into a swamp comprised of approximately 3 m of sphagnum peat. A comprehensive field and analytical program, involving measurements of total iodine,The maximum iodine concentration and

Microbial Activities in a Coastal, Sandy Aquifer System (Doñana Natural Protected Area, SW Spain)

2010 ◽  
Vol 27 (5) ◽  
pp. 409-423 ◽  
Author(s):  
Sergio Velasco Ayuso ◽  
Ana Isabel López-Archilla ◽  
Carlos Montes ◽  
María del Carmen Guerrero
Keyword(s):  
Protected Area ◽  
Microbial Activities ◽  
Aquifer System ◽  
Sw Spain ◽  
Sandy Aquifer

scholarly journals Влияние условий осаждения из паров металлоорганических соединений на получение эпитаксиальных слоев n-CdTe с использованием изопропилиодида

2022 ◽  
Vol 56 (3) ◽  
pp. 350
Author(s):  
А.Н. Моисеев ◽  
В.С. Евстигнеев ◽  
А.В. Чилясов ◽  
М.В. Костюнин
Keyword(s):  
Secondary Ion Mass Spectrometry ◽  
Organometallic Compounds ◽  
Hall Effect Measurement ◽  
Iodine Concentration ◽  
Total Iodine ◽  
Hydrogen Flow ◽  
Active Concentration ◽  
Activation Efficiency ◽  
Wall Zone ◽  
Secondary Ion

The dependence of iodine incorporation in CdTe layers on the deposition conditions during metalorganic vapor phase epitaxy is investigated. The growth of the layers was carried out from dimethylcadmium and diethyltellurium in the hydrogen flow in a vertical reactor with a hot wall condition at a total pressure of 20 kPa. The total iodine concentration was determined by secondary ion mass spectrometry, the electrically active concentration was determined from the Hall effect measurement. The iodine incorporation depends on the crystallographic orientation of the substrate (were studied (100), (310), (111)A, (111)B, (211)A and (211)B), the concentration of the doping precursor (flux range 5·10–8–3·10–6 mol/min), the mole ratio of organometallic compounds (DMCd/DETe=0.25–4), growth temperature (335–390°C) and the walls of the reactor above the pedestal (hot wall zone 290–320°C). The total iodine concentration reached 5·1018 cm–3 and the activation efficiency was ~4 %. After thermal annealing in cadmium vapor at 500°C the activation efficiency was ~100 %.

A detailed 40Ar/39Ar age study of an Abitibi dike from the Canadian Superior Province

1979 ◽  
Vol 16 (5) ◽  
pp. 1060-1070 ◽  
Author(s):  
J. A. Hanes ◽  
Derek York
Keyword(s):  
Canadian Shield ◽  
Superior Province ◽  
Low Grade ◽  
Polar Wander ◽  
Mafic Mineral ◽  
Fine Grained ◽  
Apparent Polar Wander Path ◽  
Step Heating ◽  
Apparent Age ◽  
Hydrothermal Event

40Ar/39Ar step-heating analyses were performed on 11 felsic and mafic mineral separates from a 90 m wide Precambrian diabase dike of the Abitibi swarm in the Superior Province of the Canadian Shield. Deuterically altered minerals from the dike interior define a primary age of 2150 ± 25 Ma. Updated ages, obtained from felsic separates within 30, and mafic within 1.5 m of the dike border, are evidence of a previously undetected 'Hudsonian' (1.7–1.8 Ga) hydrothermal event in the area. It is possible to distinguish the deuteric from the later hydrothermal alteration by both dating and petrographic methods. The data from this study demonstrate the successful application of 40Ar/39Ar dating to early Proterozoic dikes which have suffered low grade metamorphism. The ages support a north to south sense of motion of the Track 5 apparent polar wander path (APWP). A monotonic decrease in apparent age of felsic spectra indicates reactor induced recoil effects which are correlated with the fine-grained saussurite in the feldspar.

scholarly journals Geological framework of the Laurentian trough aquifer system, southern Ontario

2018 ◽  
Vol 55 (7) ◽  
pp. 677-708 ◽  
Author(s):  
David R. Sharpe ◽  
André J.-M. Pugin ◽  
Hazen A.J. Russell
Keyword(s):  
Lake Ontario ◽  
Water Levels ◽  
Coarse Grained ◽  
Oak Ridges Moraine ◽  
Aquifer System ◽  
Fine Grained ◽  
Niagara Escarpment ◽  
Base Level ◽  
Glacial Periods ◽  
East West

The Laurentian trough (LT), a depression >100 km long, >3000 km2 in area, and 100 m deep at the base of the Niagara Escarpment, extends from within Georgian Bay to Lake Ontario. It has a complex erosional history and is filled and buried by up to 200 m of interglacial and glacial sediment. The primary depression fronts a cuesta landscape and is attributed to differential erosion by fluvial, glacial, and glaciofluvial processes, exposing Ordovician rocks along the Canadian Shield margin. The fill succession includes sediments from the last two glacial periods (Illinoian, Wisconsinan) and the intervening interglacial time (Sangamonian), a poorly dated succession with at least three regional unconformities. A subaerial (interglacial, Don Formation) unconformity relates to low base level mainly preserved in lows of the LT, succeeded by a long period of rising water levels and glaciolacustrine conditions as ice advanced into the Lake Ontario basin. A second unconformity, within the Thorncliffe Formation, is the result of rapid channel erosion to bedrock, forming an ∼north–south network filled with coarse-grained glaciofluvial, transitional to fine-grained glaciolacustrine subaqueous fan sediment. The overlying drumlinized Newmarket Till, up to 50 m thick, is a distinct regional unit with a planar to undulating base. A third unconformity event eroded Newmarket Till, locally truncating it and underlying sediment to bedrock. Three younger sediment packages, Oak Ridges Moraine (channel and ridge sediment), Halton, and glaciolacustrine overlie this erosion surface. Significant regional aquifers are hosted within the LT. Upper Thorncliffe Formation sediments, north–south glaciofluvial channel–fan aquifers, are protected by overlying mud and Newmarket Till aquitards. Similarly, Oak Ridges Moraine sediments comprise a north–south array of glaciofluvial channel–fans and east–west fan aquifers, locally covered by silt–clay rhythmite and till aquitards.

Mass transport and scale-dependent hydraulic tests in a heterogeneous glacial till–sandy aquifer system

2001 ◽  
Vol 243 (3-4) ◽  
pp. 162-179 ◽  
Author(s):  
B Nilsson ◽  
R.C Sidle ◽  
K.E Klint ◽  
C.E Bøggild ◽  
K Broholm
Keyword(s):  
Mass Transport ◽  
Glacial Till ◽  
Aquifer System ◽  
Sandy Aquifer

Evolution of coastal sandy aquifer system in Kalpitiya peninsula, Sri Lanka: sedimentological and geochemical approach

2013 ◽  
Vol 71 (11) ◽  
pp. 4925-4937 ◽  
Author(s):  
Pathmakumara Jayasingha ◽  
A. Pitawala ◽  
H. A. Dharmagunawardhane
Keyword(s):  
Sri Lanka ◽  
Aquifer System ◽  
Sandy Aquifer ◽  
Geochemical Approach

scholarly journals Development and validation of an iodine-specific FFQ to estimate iodine intake in Australian pregnant women

2015 ◽  
Vol 113 (6) ◽  
pp. 944-952 ◽  
Author(s):  
Dominique Condo ◽  
Maria Makrides ◽  
Sheila Skeaff ◽  
Shao J. Zhou
Keyword(s):  
Pregnant Women ◽  
Urinary Iodine ◽  
Optimal Growth ◽  
Iodine Concentration ◽  
Iodine Intake ◽  
Urinary Iodine Excretion ◽  
Urinary Iodine Concentration ◽  
Food Record ◽  
Total Iodine ◽  
Supplement Use

Adequate iodine is important during pregnancy to ensure optimal growth and development of the offspring. We validated an iodine-specific FFQ (I-FFQ) for use in Australian pregnant women. A forty-four-item I-FFQ was developed to assess iodine intake from food and was administered to 122 pregnant women at 28 weeks gestation. Iodine supplement use was captured separately at 28 weeks gestation. Correlation between iodine intake from food estimated using the I-FFQ and a 4 d weighed food record as well as correlation between total iodine intake and 24 h urinary iodine excretion (UIE), 24 h urinary iodine concentration (UIC), spot UIC and thyroid function were assessed at 28 weeks gestation. A moderate correlation between the two dietary methods was shown (r0·349,P< 0·001), and it was strengthened with the addition of iodine supplements (r0·876,P< 0·001). There was a fair agreement (k= 0·28,P< 0·001) between the two dietary measures in the classification of women as receiving adequate ( ≥ 160 μg/d) or inadequate ( < 160 μg/d) iodine intake from food, but the limits of agreement from the Bland–Altman plot were large. Total iodine intake was associated with 24 h UIE (β = 0·488,P< 0·001) but not with spot UIC. Iodine intake from food using the I-FFQ was assessed at study entry ( < 20 weeks gestation) in addition to 28 weeks gestation, and there was a strong correlation in iodine intake at the two time points (r0·622,P< 0·001), which indicated good reproducibility. In conclusion, the I-FFQ provides a valid tool for estimating iodine intake in pregnant women and can be used to screen women who are at risk of inadequate intake.

Quantification of groundwater–seawater interaction in a coastal sandy aquifer system: a study from Panama, Sri Lanka

2013 ◽  
Author(s):  
Rohana Chandrajith ◽  
Dinusha Chaturangani ◽  
Sumith Abeykoon ◽  
Johannes A. C. Barth ◽  
Robert van Geldern ◽  
...  
Keyword(s):  
Sri Lanka ◽  
Aquifer System ◽  
System A ◽  
Sandy Aquifer

scholarly journals Investigation of alternative mechanisms of aquifer-system compaction and land subsidence in Shanghai

2015 ◽  
Vol 372 ◽  
pp. 13-15 ◽  
Author(s):  
Y. Yuan ◽  
Y.-S. Xu ◽  
S.-L. Shen ◽  
N. Zhang
Keyword(s):  
Load Transfer ◽  
Internal Erosion ◽  
Coarse Grained ◽  
Traditional Theory ◽  
Groundwater Extraction ◽  
Surface Loading ◽  
Aquifer System ◽  
Fine Grained ◽  
Hydraulic Gradients ◽  
Initial Results

Abstract. Alternative subsidence mechanisms related to groundwater extration and surface loading of built infrastructure in Shanghai have been evaluated to explain continued subsidence despite the controlled reduction of groundwater extraction. The traditional theory of aquifer-system compaction embodied in the aquitard drainage model cannot fully explain this phenomenon. Two possible alternative mechanisms were studied previously: (i) surface loading attributed to urban construction; (ii) creep occuring in sandy deposits of aquifers. These mechanisms could not fully explain the observed subsidence. Two additional alternative mechanistic models are proposed that involve principles of load transfer considering the temporally and spatially redistributed stresses associated with groundwater extraction: (i) the Cosserat continuum mechanism, considering shear force on the permeable coarse-grained matrial in the aquifer due to hydraulic gradients in the aquifer; and (ii) internal erosion of fine-grained (clay and silt) particles within the aquifer. Initial results based on simulations incorporating Cosserat mechanics look promising.

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