The dynamic links between Central Asian dust emission,Tibetan cryosphere,Pacific productivity and global climate changes
The dust cycle plays a critical role in the interactions between the lithosphere,hydrosphere,cryosphere,atmosphere and biosphere at the surface of the Earth systems.Intensive surface weathering and glacial abrasion of bedrocks of the lithosphere have produced a large amount of nutrient-rich silt.These clastic materials were transported by rivers to inland basins and subsequently available for atmospheric dust under the influence of arid climates and wind,profoundly impacting marine biogeochemical processes and global climate through the dust transport processes from land to ocean.At the global scale,dust emitted from Asian arid and semi-arid regions is transported over long distances in the upper atmosphere,and it is an important source of atmospheric mineral dust in the Northern Hemisphere.To date,however,there is a lack of clear and distinct understanding about the temporal variations in dust activities and dust nutrients of Central Asia as well as their relationships with tectonic activities,global cooling and atmospheric circulation system since the late Cenozoic.Moreover,little information is known about the potential link between the nutrient supply of Central Asian dust and changes in primary productivity of the North Pacific in the geological past.Consequently,large uncertainties exist about the critical role of Asian dust emission in modulating marine biogeochemical cycles and global climate.Eolian loess-paleosol sequences are widely distributed on the downwind geomorphic surfaces of mountain slopes and river terraces in Central Asia.Several independent lines of evidence suggest that the major expansion of eolian loess deposits in Central Asia occurred since the late Pliocene.These loess deposit thus archive the continuous histories of dust activities and the drying of the Asian interior,and temporal variations in nutrient compositions of Central Asian dust.In light of these issues,this paper systematically sorts out the distribution,age and production processes of loess dust over Central Asia.Temporal variations in dust activities and nutrient availability of Central Asian dust as well as their driving mechanisms over the geological timescales were also summarized.The existing results suggest that increasing nutrient supply of Central Asian dust associated with intensified Tibetan glacial erosion played a critical role in modulating primary productivity in the North Pacific and global carbon cycles.Fresh rock debris eroded from the Tianshan and West Kunlun Mountains in the northern Tibetan Plateau is the major source of dust materials over Central Asia.The production of Central Asian dust is closely linked with the cyclical pulses of increased glacial erosion and frost weathering processes in the mountainous regions of the Tibetan Plateau.Overall,a dynamic linkage exists between Central Asian dust emission,Tibetan cryosphere,and global climate changes.Finally,it is proposed that future research needs to focus more attention on the dynamic links between silt production of Central Asian dust,nutrient release and glacial processes in the Tibetan Plateau.Additional studies over a wider geographic range should be conducted to elucidate the temporal variations in nutrient compositions and concentrations of Central Asian dust prior to the Icehouse climate state as well as their influences on oceanic ecosystems.Combined with further analysis of climate modelling,the roles of increasing nutrient supply of Central Asian dust in the evolution of global carbon cycles and climate changes need to be further examined.
Central Asialoess and dustIron Fertilization HypothesisPacific Oceancarbon cycles
万方数据
维普
