摘要:

This is a summary ofSEAN Bulletin, 13(4), April 30, 1988, a publication of the Smithsonian Institution's Scientific Event Alert Network. The complete bulletin is available in the microfiche edition ofEosas a microfiche supplement or as a paper reprint. For the microfiche, order document E88‐003 at $2.50 (U.S.) by writing to AGU Orders , 2000 Florida Avenue, N.W., Washington, DC 20009 or by calling toll free on 800‐424‐2488. For the paper reprint, orderSEAN Bulletin(giving volume and issue numbers and issue date) through the same address; the price is $3.50 for one copy of each issue number for those who do not have a deposit account, $2 for those who do; additional copies of each issue number are $1. Subscriptions toSEAN Bulletinare also available from AGU‐Orders; the price is $18 for 12 monthly issues mailed to a U.S. address, $28 if mailed elsewhere, and must be

ISSN:0002-8606    

DOI:10.1029/EO069i022p00625-02

年代:1988

数据来源: WILEY

摘要:

The U.S. National Committee for the International Association of Hydrogeologists is asking for applications from U.S. scientists for service as a U.S. representative on the International Association of Hydrogeologists Commission on Mineral and Thermal Waters. Any interested person should contact Dr. E. S. Simpson, Secretary‐Treasurer, IAH U.S. National Committee, Department of Hydrology and Water Resources, University of Arizona, Tucson, AZ 85721 (telephone: 602‐621‐1855 or

ISSN:0002-8606    

DOI:10.1029/EO069i022p00626-01

年代:1988

数据来源: WILEY

ISSN:0002-8606    

DOI:10.1029/EO069i022p00627-01

年代:1988

数据来源: WILEY

摘要:

“Mg May Protect Waste Under Glass,” a news item in the January 26, 1988, issue ofEos(p. 49), summarized the work of John O'Keefe (National Aeronautics and Space Administration/ Goddard Space Flight Center, Greenbelt, Md.), B. P. Glass (University of Delaware, Newark), and Aaron Barkatt (Catholic University of America, Washington, D.C.). We can only agree with Barkatt's final word of caution about O'Keefe's (overall conclusion) suggestion that “Mg added to the backfill surrounding glass‐filled cannisters…would react with infiltrating fresh water to seal off the glass from dissolution that would release radioactive material.” It is indeed an oversimplified interpretation, since several environmental parameters (and not onlypH nor Mg++activity) simultaneously control glass dissolution.From the start, two main dissolution mechanisms of a silicated glass have to be distinguished: congruent dissolution (all of the glass constituents dissolves simultaneously) and selective dissolution (the modifier elements of the glass network, e.g., alkali and alkaline earths, are exchanged). In the first case, the glass dissolution rate is controlled by the rate of Si‐O‐Si bond breakdown, which depends on temperature,pH, and solution silica activity. In the second case, the glass corrosion rate depends on the diffusion rate of the various species into a residual hydrate

ISSN:0002-8606    

DOI:10.1029/EO069i022p00628-02

年代:1988

数据来源: WILEY