Late Holocene (~ 2 ka) East Asian Monsoon variations inferred from river discharge and climate interrelationships in the Pearl River Estuary

Abstract

A sediment core from the Pearl River Estuary (PRE) was analyzed for grain size and organic geochemistry parameters (TOC and δ13C_org). The results showed that high mean grain-size value and increased sand content were correlated with the high TOC and negative δ13C_org. These results indicated high river runoff in the PRE area. Peak river discharge occurred during the periods 1900–1750, 1500–1600, 1400–1200, 1000–900 and 750–600 cal yr BP. The main changes recorded in grain-size distributions, TOC contents, and δ13C_org variations appear to be directly related to monsoon precipitation in the sediment source area. An increased East Asian summer monsoon rainfall (EASM) and/or an enhanced East Asian winter monsoon rainfall could result in the increasing of monsoon rainfall. Typhoon related rainfalls could act as positive influence on precipitation levels. The study of the correlations between the rainfall records and ENSO activities revealed a close relationship between the monsoon rainfall in the PRE and the tropical Pacific variations. The frequent occurrence of ENSO might result in the southern migration of the EASM rain belt and lead to more typhoon-derived rainfall in the PRD during the late Holocene