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Impact of Solar Radiation on Perchlo...

Kunwar, Bishnu,

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Impact of Solar Radiation on Perchlorate Formation in the Atmosphere: Evidence from Ice Core Measurements /

紀錄類型:	書目-電子資源 : Monograph/item
正題名/作者:	Impact of Solar Radiation on Perchlorate Formation in the Atmosphere: Evidence from Ice Core Measurements // Bishnu Kunwar.
作者:	Kunwar, Bishnu,
面頁冊數:	1 electronic resource (110 pages)
附註:	Source: Dissertations Abstracts International, Volume: 85-07, Section: B.
Contained By:	Dissertations Abstracts International85-07B.
標題:	Chemistry. -
電子資源:	https://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=30988138
ISBN:	9798381305777

Impact of Solar Radiation on Perchlorate Formation in the Atmosphere: Evidence from Ice Core Measurements /
Kunwar, Bishnu,

Impact of Solar Radiation on Perchlorate Formation in the Atmosphere: Evidence from Ice Core Measurements /Bishnu Kunwar. - 1 electronic resource (110 pages)

Source: Dissertations Abstracts International, Volume: 85-07, Section: B.

Perchlorate, which derives from both anthropogenic and natural sources in the current environment, poses a substantial health hazard to humans as it competes with iodine uptake in the thyroid gland. Consequently, there has been considerable concern about minimizing human exposure to environmental perchlorate by restricting its release from man-made sources. However, the absence of a clear understanding regarding the respective contributions of man-made and natural sources has hindered widespread regulation efforts. A 300-year (1700-2007) Summit, Greenland ice core record from a previous study showed relatively stable perchlorate concentrations in Greenland snow prior to 1980, with some elevated perchlorate levels associated with large volcanic eruptions that inject a substantial amount of SO2 and HCl gases into the stratosphere. The present 400-year perchlorate record from Summit, Greenland ice cores shows that the 1601-1700 time period is an exception to the stable pre-industrial perchlorate level. The average perchlorate concentration (standard deviation) from 1601 to 1700 (2.1 ± 1.5 ng kg-1) is nearly twice (p-value <0.05) as high as that from 1700 to 1979 (1.2 ± 1.2 ng kg-1). A lack of significant increases in sulfate levels between 1601 and 1700 suggests that the effect of volcanic activities on the perchlorate level during this period could be insignificant. Sunlight is necessary to generate chlorine radicals in the atmosphere, which then interact with ozone in the stratosphere to produce perchlorate. The Maunder Minimum (1645-1715), a period of low solar activity (low sunspot number), is within the time period from 1601 to 1700 with high perchlorate levels. Variations in solar activity during the Maunder Minimum may have had some effect on the production of perchlorate in the atmosphere. As chlorine dioxide (ClO2) acts as a key intermediate species in perchlorate formation within the stratosphere, ClO2 results in significant levels of perchlorate production when subjected to low solar radiation, mainly through the process of UV-mediated photodecomposition.

English

ISBN: 9798381305777Subjects--Topical Terms:

516420
Chemistry.
Subjects--Index Terms:

Greenland ice core

Impact of Solar Radiation on Perchlorate Formation in the Atmosphere: Evidence from Ice Core Measurements /
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520 $a Perchlorate, which derives from both anthropogenic and natural sources in the current environment, poses a substantial health hazard to humans as it competes with iodine uptake in the thyroid gland. Consequently, there has been considerable concern about minimizing human exposure to environmental perchlorate by restricting its release from man-made sources. However, the absence of a clear understanding regarding the respective contributions of man-made and natural sources has hindered widespread regulation efforts. A 300-year (1700-2007) Summit, Greenland ice core record from a previous study showed relatively stable perchlorate concentrations in Greenland snow prior to 1980, with some elevated perchlorate levels associated with large volcanic eruptions that inject a substantial amount of SO2 and HCl gases into the stratosphere. The present 400-year perchlorate record from Summit, Greenland ice cores shows that the 1601-1700 time period is an exception to the stable pre-industrial perchlorate level. The average perchlorate concentration (standard deviation) from 1601 to 1700 (2.1 ± 1.5 ng kg-1) is nearly twice (p-value <0.05) as high as that from 1700 to 1979 (1.2 ± 1.2 ng kg-1). A lack of significant increases in sulfate levels between 1601 and 1700 suggests that the effect of volcanic activities on the perchlorate level during this period could be insignificant. Sunlight is necessary to generate chlorine radicals in the atmosphere, which then interact with ozone in the stratosphere to produce perchlorate. The Maunder Minimum (1645-1715), a period of low solar activity (low sunspot number), is within the time period from 1601 to 1700 with high perchlorate levels. Variations in solar activity during the Maunder Minimum may have had some effect on the production of perchlorate in the atmosphere. As chlorine dioxide (ClO2) acts as a key intermediate species in perchlorate formation within the stratosphere, ClO2 results in significant levels of perchlorate production when subjected to low solar radiation, mainly through the process of UV-mediated photodecomposition.
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