Fluctuations of eolian flux and ocean productivity in the mid-latitude north Pacific during the last 200 kyr

Abstract

In order to understand fluctuations in terrestrial and marine environments, a sedimentary core H3571 was investigated from the Hess Rise located in the mid-latitude North Pacific under the north westerly wind system. The δ 18 O , grain size and grain shape of type 1 quartz suggest that this quartz is of aerosol origin. Good correlation between Al and aerosol quartz in content and mass accumulation rate (MAR) indicates that the alumino silicate minerals in the sediments are mainly transported by wind. MAR of mineral aerosol (MAR Aerosol) varies from 156 to 732 mg cm −2 kyr −1 during the last 200 kyr. The MAR Aerosol maxima occur in oxygen isotope stage (OIS) 4 to latest OIS 5, middle OIS 6, moderate maxima occur in early OIS 1–2, late OIS 3 and middle OIS 3. These maxima are ascribed to reduced precipitation during the summer monsoon and to strengthened wind speed during the winter monsoon. The mean organic carbon/total nitrogen atomic ratio is 7.2, suggesting that the organic matter in the core H3571 is also mainly of marine origin. The MAR of organic carbon (MAR Organic) exhibits two prominent maxima in OIS 2 and 4 and relatively high values in middle and late OIS 6. Enhanced primary productivity is most likely to be responsible for the high burial rate of organic carbon in the sediments. Carbonate and phosphorus inputs with aerosol into sea surface have played a minor role through dissolution in diminishing PCO 2 in surface water during glacial times. On the other hand, the aerosol silica supply to the ocean may have some potential to affect the burial of biogenic silica into sediments. The effect of mineral aerosol on the ocean carbon cycle would be greater in the coastal and hemipelagic regions of the Western Pacific and Equatorial Atlantic, as compared with that in the Hess Rise regime.