过去6.0～2.0Ma大气铁载荷及其指示的北半球大冰期发生的可能原因（英文）

Atmospheric iron loading in Asia during 6.0~2.0 Ma and implications for the onset of Northern Hemisphere Glaciation

基于中国中部的一个沉积序列的铝浓度重建了过去6.0~2.0 Ma的大气铁载荷与粉尘通量变化。铁载荷从6.0 Ma的~0.3μg·m^(-3)开始增加,到3.0 Ma左右达到最高值约1.2μg·m^(-3),然后开始迅速下降。黄土高原的大气铁载荷和粉尘通量变化型式与ODP 885/886孔的粉尘通量,以及ODP 882孔的生物蛋白石海洋沉积速率的变化型式一致,都显示了从6.0 Ma到2.7 Ma的增加趋势。这表明粉尘的海气交换最可能通过铁肥机制影响海洋生产力。从3.6 Ma至2.7 Ma,铁载荷与北太平洋古海洋生产力及全球大气CO_2的变化存在高度一致性,指示了粉尘/铁通量的增加及其导致的各种反馈作用很可能加速北半球大冰期的发生。

Atmospheric iron loadings and dust fluxes for the last 6.0 to 2.0 Ma before the present were reconstructed from Al concentrations in a sediment profile from central China. Iron loadings increased from -0.3 μg·m^-3 at 6.0 Ma and peaked at -1.2 μg·m^-3 around 3.0 Ma then decreased sharply. The patterns of atmospheric Fe loadings and dust fluxes to the loess plateau, the dust fluxes at ODP site 885/886, and the marine accumulation rate of biogenie opal at the ODP site 882 all show similar increasing trends from 6.0 to 2.7 Ma. This suggests that the air/sea exchange of dust influenced marine productivity, most likely through an iron-fertilization mechanism. A strong coherence between the evolution of iron loadings with the variations of paleoproductivity in North Pacific and global atmospheric CO2 was found from 3.6 to 2.7 Ma, this implies that increased dust/iron fluxes and associated feedbacks may have accelerated the onset of glaciation in the Northern Hemisphere.