Spatial and temporal variations in the intensity of subsurface denitrification in the water-column of the eastem Arabian Sea have been investigated using chemical and isotopic proxies. The data show a steady increase in the denitrification intensity from ∼10 ka to ∼2 ka BP, probably caused by changes in surface productivity fuelled by strengthening of upwelling (monsoonal intensity). In addition, changes in redox conditions and detrital material input are assessed using abundances of a suite of major and trace elements. The temporal variations in some of the monsoonal proxies are characterized by periodicities of ∼1400 and ∼700 years, similar to those reported in the South Asian (Chinese) monsoon and high-latitude climate (north Atlantic region).
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