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Seasonal ^7Be and ^1^3^7Cs activities in surface air before and after the Chernobyl event [An article from: Journal of Environmental Radioactivity]
Book Details
Author(s)A. Kulan
PublisherElsevier
ISBN / ASINB000P6XLPA
ISBN-13978B000P6XLP6
AvailabilityAvailable for download now
MarketplaceUnited States 🇺🇸
Description
This digital document is a journal article from Journal of Environmental Radioactivity, published by Elsevier in 2006. The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser.
Description:
Seasonal fluctuations of cosmogenic ^7Be (T"1"/"2=53.4 days) and anthropogenic ^1^3^7Cs (T"1"/"2=30 years) activities in surface air (aerosols) have been extracted from a long data record (1972-2000) at high latitude (56^oN-68^oN, Sweden). Normalization to weekly average values was used to control long-term trends so that cyclical trends could be investigated. Enhanced ^7Be activity was observed in spring and summer seasons and likely relates to the seasonal thinning of the tropopause. Variations in the ^1^3^7Cs activity record seem to reflect how the isotope was injected in the atmosphere (stratospheric from bomb tests and tropospheric from the Chernobyl accident) and subsequent transport mechanisms. Accordingly, until 1986, the surface air ^1^3^7Cs activity was strongly related to nuclear weapons test fallout and exhibits temporal fluctuations resembling the ^7Be. Conversely, since 1986 the Chernobyl-produced ^1^3^7Cs dominates the long-term record that shows annual cycles that are strongly controlled by atmospheric boundary layer conditions. Additionally, short-term data within the post-Chernobyl period suggest subtle intrusion of air masses rich in ^1^3^7Cs that may occur throughout the year, and differences resulting from spatial occurrence at these latitudes. This is an important observation that may have to do with year-to-year variation and calls for caution when interpreting short-term data records.
Description:
Seasonal fluctuations of cosmogenic ^7Be (T"1"/"2=53.4 days) and anthropogenic ^1^3^7Cs (T"1"/"2=30 years) activities in surface air (aerosols) have been extracted from a long data record (1972-2000) at high latitude (56^oN-68^oN, Sweden). Normalization to weekly average values was used to control long-term trends so that cyclical trends could be investigated. Enhanced ^7Be activity was observed in spring and summer seasons and likely relates to the seasonal thinning of the tropopause. Variations in the ^1^3^7Cs activity record seem to reflect how the isotope was injected in the atmosphere (stratospheric from bomb tests and tropospheric from the Chernobyl accident) and subsequent transport mechanisms. Accordingly, until 1986, the surface air ^1^3^7Cs activity was strongly related to nuclear weapons test fallout and exhibits temporal fluctuations resembling the ^7Be. Conversely, since 1986 the Chernobyl-produced ^1^3^7Cs dominates the long-term record that shows annual cycles that are strongly controlled by atmospheric boundary layer conditions. Additionally, short-term data within the post-Chernobyl period suggest subtle intrusion of air masses rich in ^1^3^7Cs that may occur throughout the year, and differences resulting from spatial occurrence at these latitudes. This is an important observation that may have to do with year-to-year variation and calls for caution when interpreting short-term data records.
