Characteristic of trace elements record in sediment from Dali Lake and climate change since 2100 cal a BP, North China

Abstract In order to better known the characteristic of salinity and redox occurred in Dali Lake since late Holocene, two sediment cores were obtained from Dali Lake in the north China, and trace elements, including Al, Mn, Zn, Mo, Pb, Fe, Sr and Ba, are analyzed. Accelerator mass spectrometry (AMS) 14C combining with the constant rate of supply (CRS) model and 137Cs produced about 2100 cal a BP records. From ∼2100 to 1650 cal a BP (stage Ⅰ), Mn-MAR and Fe-MAR do not show any correlation with Mo-MAR indicating anaerobic environment limited the adsorption of Mo on the Mn–Fe oxides. In the period of ∼1650-1050 cal a BP (stage Ⅱ; DACP), the decreased organic matter (OM), nutrients, Fe-MAR and Zn-MAR constrict the Mo to deposit suggest a weakened aerobic environment. Salinity (Sr/Ba) does not show any effects on the trace elements, OM and nutrients through the stage Ⅰ and Ⅱ. In the stage Ⅲ (∼1050 and 650 cal a BP; MWP), it may be an oxygen enrichment in Dali Lake sediment because of the favorable environment. Low salinity will partly facilitate the Al-MAR, Mn-MAR and Pb-MAR deposit. In the period between ∼650 and 30cal a BP (stage Ⅳ; LIA), Mn-MAR, Zn-MAR and Fe-MAR do not show any correlation with Mo-MAR illuminating an anaerobic environment. It can be observed that high salinity and OM improves the trace elements to deposit. And, decreased nutrients also enhanced the trace elements to save except for Mo-MAR. In recent 95 years, the redox in the lake sediment was generally difficult to justify due to human activity. However, high salinity level facilitated the adsorption of Al-MAR, Mn-MAR, Zn-MAR and Fe-MAR. The wavelet power spectrum of Mo-MAR and Sr/Ba indicate that the EASM, which may be controlled by solar insolation in the Dali Lake basin, is gradually decreasing.