A 1,400-year eolian dust activity record from Lake Erhai in the northeastern Tibetan Plateau

Abstract

Dust raised from Arid Central Asia (ACA) affects the global climate, global biogeochemical cycles, and human health. Studies on the ACA dust activities thus are crucial for understanding dust forcing mechanisms and the mitigation of hazardous storms. Located at the downwind margin of the ACA, the Lake Qinghai basin is an ideal trap for dust activities documentation. However, isolating eolian dust signals from Lake Qinghai sediments is difficult as the dust signals are well-mixed with riverine input signals. As a satellite of Lake Qinghai, Lake Erhai is much smaller and has only one inflow river. Lake Erhai, therefore, is much less sensitive to riverine input and its sediments theoretically contain more explicit dust signals. In this study, a 111.5-cm core was taken from Lake Erhai in 2016. The sediments’ grain size distribution (GSD) of this core was analyzed, and end-member (EM) analyses were applied to the GSDs to detect dust signals. Sediment carbonate content and carbonate oxygen isotopes (δ18Ocarb) were also measured to provide independent climate background information. Our results showed that the first EM is attributed to lake level dynamics due to its resemblances with carbonate content and δ18Ocarb records; the third EM, which peaked in the coarser grain size, is attributed to the riverine input; the remaining second EM likely captures the changes of regional dust activity and suggests that the Lake Qinghai basin has experienced multiple intense eolian dust activity intervals, i.e., 1000–1110, 1180–1290, and 1450–1560 AD over the past 1400 years. A further comparison of EMs with well-established climatic records in the northeastern Tibetan Plateau suggests that the rise and fall of regional dust activities are likely mainly controlled by wetness conditions and are secondarily affected by human activities.