Lake surface fluctuations since the late glaciation at Lake Daihai, North central China: A direct indicator of hydrological process response to East Asian monsoon climate

Sediment retrieved by coring from the center of enclosed Lake Daihai in north central China, and lacustrine sediments obtained from lake terrace outcrops, were employed to reconstruct the lake surface fluctuations and the relationships with monsoon climate since the late glaciation based on accelerator mass spectrometry (AM S) radiocarbon chronology. Before ca. 13 ka BP, the surface of the lake was lower, indicating a deficiency of effective precipitation and dry climate, the result of relatively decreased monsoon precipitation. During ca. 13 11 ka BP the lake surface ascended to a relatively higher level, marking a significant increase of effective precipitation. The climate became humid, indicating strengthened monsoon rainfall. Then, the lake surface experienced a sharp decline ca. 11-10 ka BP, this could suggest a severe reduction of effective monsoon precipitation and drier climate. Ca. 10-9.0 ka BP, the lake surface area expanded temporarily as the level rose, denoting the amelioration of monsoon-related effective precipitation and a relatively humid climate. Subsequently, the lake surface declined at ca. 9.0-7.3 ka BP, reflecting the prevalence of dry climate and relatively decreased monsoon precipitation. Higher lake level and larger lake depth indicated large scale expansion of the lake surface at ca.7.3-3.2 kit BP, despite some secondary fluctuations, This implied plentiful monsoon-related effective precipitation and more humid climate in the lake basin. Since ca. 3.2 ka BP, the lake surface has experienced a severe fall, except for a minor rise around 2.0 ka BP, indicating dry climate as a whole from waning monsoon precipitation and relatively increased evaporation. The effective precipitation variations revealed by lake surface fluctuations in Lake Daihai since the late glaciation are not only related to forcing factors such as insolation and temperature-driven air masses from the continent and the ocean, but are also influenced by regional feedback from topography, vegetation coverage and hydrological status. (C) 2008 Elsevier Ltd and INQUA. All rights reserved.