新加坡六合彩开奖直播

The silica leakage hypothesis is one mechanism put forth to explain lower atmospheric C02 levels during glacial times. Measuring the percent opal from sediment cores recovered in the Eastern and Western Equatorial Pacific (EEP and WEP) and plotting it against time tests the validity of the opal leakage hypothesis. During glacial times a build up of silicic acid occurs in the Southern Ocean (SO) due to low diatom productivity. The excess silicic acid is transported to low latitude waters in the Pacific Ocean via Antarctic Intermediate Water. The silica rich water is upwelled at the Equator where the silicic acid is taken up by diatoms. The opaline frustules become incorporated into the sedimentary record when the diatom dies. The percent opal of sediment samples can be determined from recovered cores. Cores TR163-22 and ME 24 from the EEP show a strong increase in the percent opal 40-60 ka however the cores from the WEP, MD98-2181 and MD06-3067 do not have this signal. There is no increase in any core during the Last Glacial Maximum (LGM). Therefore contribution by the .silica leakage hypothesis in reducing C02 during glacial times is believed to be small.

Keywords: silica leakage hypothesis, silicic acid, C02, Eastern and Western Equatorial Pacific
Pages: 43
Supervisor: 听