Response of geochemical records in lacustrine sediments to climate change and human impact during middle Holocene in Mengjin, Henan Province, China

In this paper, we examined the response of geochemical records in lacustrine sediments to climate and human activity in Mengjin, Henan Province of China during the middle Holocene. Indices used in this study include K, Na, Mn, Ba, Sr, Al, Ti, cation ratios, and Gramineae pollen in lacustrine sediments. Results indicate a drought event in this area around 5660 cal a BP, which weakened soil leaching and changed the element composition of surface soil runoff entering the paelo-lake and lacustrine sediments. Human activity appearing from 4695 cal a BP to 4000 cal a BP also affected the chemical composition of lake sediments. Human activities led to enhanced soil erosion and destroyed soil leaching horizons. Therefore, the substance of soil illuvial layer exposed to the surface and entering the paleo-lake were substantially altered by human activities.