Characterization of transport pathways and depositional changes in Mercury(Hg)and their connection to climatic and environmental changes on various time scales are crucial for better understanding the anthropogenic impacts on the global Hg cycle in the Anthropocene epoch.In this study,we examined Hg variations recorded in a stalagmite from central China,covering the period from 25.5 to 10.9 thousand years ago.Our data show a marked increase in Hg concentrations during the late Last Glacial Maximum,which coincided with the period of highest dust deposition on the Chinese Loess Plateau.Hg concentrations were lower during Heinrich events 1 and 2 and the Younger Dryas but higher during the BùllingAllerùd and the early Holocene.We suggest that regional dust load,which enhances atmospheric dry deposition of Hg,is the primary factor influencing Hg deposition in central China on glacialinterglacial timescales.On millennial-to-centennial timescales,climate also plays a significant role.Warmer and wetter conditions increase vegetation,litterfall,and soil/rock weathering,which in turn boost mineral dissolution and soil erosion in the vadose zone.These processes collectively result in higher Hg concentrations in the stalagmite.
A long-standing question regarding the Holocene evolution of the East Asian Summer Monsoon(EASM)is whether it peaked during the early Holocene(EH)as inferred from rainfall-related proxy records[1,2],or during the mid-Holocene as inferred from ecoenvironmental records from northern China[3,4].Cheng et al.
