Response of sensitive grain size components in the muddy area off the southern coast of Weihai city, China, to Holocene climate and environmental changes

Abstract

Studying marine sediment is crucial for understanding the processes and mechanisms of Holocene climate and environmental changes. In this study, we analyzed the grain size distribution of the sediments from WHZK01 Core (0–14.95 m) in the muddy area off the southern coast of Weihai city, and extracted the sensitive grain size (SGS) using the grain size-standard deviation method, to further analyse the sediment transport mechanism since the Holocene and its significance as an environmental indicator in the climate change. The results show that the sediments in WHZK01 Core is mainly composed of silt and clayey silt, with poor sorting and a positive skewness, and primarily transported by suspension and saltation. We identified three SGSs: SGS 1 (<15.63 μm), SGS 2 (15.63 μm–148.65 μm), and SGS 3 (>148.65 μm), corresponding to the fine, medium, and coarse components of the sediment, respectively. Among them, SGS 2 exhibits a strong correlation with events of intensified East Asian winter monsoon(EAWM). Based on the variations in this grain size fraction, eight prominent EAWM intensification events over the past ∼11,000 years (Holocene) were identified: 8100–7600 a BP, 6300–6000 a BP, 5500–5050 a BP, 4600–4200 a BP, 4100–3600 a BP, 2850–2400 a BP, 1900–1500 a BP and 700-175 a BP, which are good indicators of palaeoclimatic environmental changes.