A 1400 year environmental magnetic record from varved sediments of Lake Xiaolongwan (Northeast China) reflecting natural and anthropogenic soil erosion

Abstract

Lake sediments can provide high-quality information about human activities. In this study, we investigate a sediment core from Lake Xiaolongwan using magnetic and geochemical methods. The dominant magnetic minerals of this sediment core are stable single domain (SSD) and superparamagnetic (SP) magnetite particles. The increasing amount of SP particles reflected by the rise of magnetic susceptibility and frequency dependent magnetic susceptibility since AD 1500 can be attributed to an increasing influx in pedogenic soil, which is related to a regional-scale increase in the intensity of human activity in Northeastern China. This extends the timing of human activities, which is independent from climate changes and its effects on local ecosystems in Northeastern China significantly.

Multi—Proxy Reconstructions of Climate Change and Human Impacts Over the Past 7000 Years From an Archive of Continental Shelf Sediments off Eastern Hainan Island, China

“…In recent years, studies have suggested that human activities play an important role in controlling ecosystems and soil erosion in monsoonal China. Increases in χ lf and χ fd over the last 2000 years in sediments from the Yangtze delta in eastern China, Lake Xiaolongwan in northeast China, and lakes Erhai and Xingyun in southwest China reflect an increase in soil erosion attributed to enhanced human activity (Dearing et al, 2008;Wang et al, 2010;Su et al, 2015;Wu et al, 2015). Numerous studies likewise found that increasing contents of various metals, including Cu, Pb, and Zn, could be closely linked to mining and metalworking activities, reflecting a progressive intensification of human activities (Zong et al, 2010;Hu et al, 2013;Hillman et al, 2014;Wan et al, 2015;Xu et al, 2017;Huang et al, 2018).…”

“…It is therefore essential to understand climate and human activities, as well as their impacts upon terrestrial ecosystems on longer timescales, in order to reconstruct each of them accurately. However, previous studies to determine human-environment interactions were mainly dependent on sediment cores from lakes (Dearing et al, 2008;Hillman et al, 2014;Su et al, 2015) and river deltas (Wang et al, 2010;Zong et al, 2010;Strong et al, 2013). Highresolution records from continental shelves are relatively scarce.…”