Alteration of natural ³⁷Ar activity concentration in the subsurface by gas transport and water infiltration

High ³⁷Ar activity concentration in soil gas is proposed as a key evidence for the detection of underground nuclear explosion by the Comprehensive Nuclear Test-Ban Treaty. However, such a detection is challenged by the natural background of ³⁷Ar in the subsurface, mainly due to Ca activation by cosmic rays. A better understanding and improved capability to predict ³⁷Ar activity concentration in the subsurface and its spatial and temporal variability is thus required. A numerical model integrating ³⁷Ar production and transport in the subsurface is developed, including variable soil water content and water infiltration at the surface. A parameterized equation for ³⁷Ar production in the first 15 m below the surface is studied, taking into account the major production reactions and the moderation effect of soil water content. Using sensitivity analysis and uncertainty quantification, a realistic and comprehensive probability distribution of natural ³⁷Ar activity concentrations in soil gas is proposed, including the effects of water infiltration. Site location and soil composition are identified as the parameters allowing for a most effective reduction of the possible range of ³⁷Ar activity concentrations. The influence of soil water content on ³⁷Ar production is shown to be negligible to first order, while ³⁷Ar activity concentration in soil gas and its temporal variability appear to be strongly influenced by transient water infiltration events. These results will be used as a basis for practical CTBTO concepts of operation during an OSI.

Occupational employment survey booklet of definitions : rubber and selected plastics products.

"BLS-2877 230."

Annual of the Boston Society of natural history, 1868-69.

Contains act of incorporation, constitution, sketch of the history of the society, list of members, list of publications, etc., etc.

Catalog of the types of recent mollusca of the Academy of Natural Sciences of Philadelphia /

Cover title.

Medicinal chemistry : chemistry, biochemistry, therapeutic and pharmacological action of natural and synthetic drugs.

Errata slip inserted in v. 1.

Institutes of natural philosophy, theoretical and practical. With some corrections; change in the order of the branches; and the addition of an appendix to the astronomical part, selected from Mr. Ewing's Practical astronomy.

"Appendix to the astronomy. Containing solar and lunar tables, with their explanation and use, and the projection of eclipses, selected from 'Ewing's Practical astronomy'": [233]-297.

Quantitative radiochemical methods for the determination of the sources of natural radioactivity.

"April 1956."

The journal of the Cincinnati Society of Natural History.

Vols. 3-4 include four reports on archaeological explorations near Madisonville, O., conducted under the direction of the Literary and Scientific Society of Madisonville. (Also issued separately).

Remote sensing of natural resources.

Mode of access: Internet.

Darwinism; an exposition of the theory of natural selection, with some of its applications,

Mode of access: Internet.

A compendium of natural philosophy: adapted to the use of the general reader, and of schools and academies.

Mode of access: Internet.

Analysis of cross-shore movement of natural longshore bars and material placed to create longshore bars /

At head of title: "Dredging Research Program."

Guide to the manuscript collections in the Academy of Natural Sciences of Philadelphia.

Mode of access: Internet.

Biennial report on the Illinois State Museum of Natural History at Springfield, Illinois.

Mode of access: Internet.

The physical and economic foundation of natural resources.

A collection of papers by eminent authorities, prepared for the Committee on Interior and Insular Affairs.