Environmental changes during early-middle Holocene from the sediment record of the Chaohu Lake, Anhui Province.

A typical lake sediment core is obtained from the Chaohu Lake in the lower reaches of the Yangtze River, Anhui Province, China. The timing scale is constrained by AMS ¹⁴C dating method. Climate proxies such as pollen and grain size in the core are analyzed to reconstruct the environment changes at this site approximately between 9870 and 2170 cal. a BR The results indicate that at the research area, the climate in the early-middle Holocene had evolved through 3 stages. From 9870 to 6040 cal. a BP, proxy records show a warm and dry climate with low water levels after the late-glacial period. During this stage, cool and dry events occurred at about 8910 and 6060-6030 cal. a BP. Then, between 6040 and 4860 cal. a BP, the climate was humid and vegetation was more flourishing in the Chaohu Lake Valley. The Holocene Optimum occurred at 5840-5500 cal. a BP in the Chaohu Lake, showing the best condition of water and heat. Elm Decline occurred at the period of 5380-4930 cal. a BP. Since 4860 cal. a BP, the climate was warm and dry through 2170 cal. a BP as shown in both pollen spectrum and grain-size histories. Two obvious dry events occurred in 3760 and 2170 cal. a BP, respectively. At 2170 cal. a BP, the water level of the Chaohu Lake reached the lowest as the lakebed possibly exposed. Such lake sediment observations are consistent with the historical records in this area. [ABSTRACT FROM AUTHOR]