Late Quaternary water depth changes in Hala Lake, northeastern Tibetan Plateau, derived from ostracod assemblages and sediment properties in multiple sediment records

Trace GC with PTV inlet in splitless mode, 30m DB-5 capillary column (J&W Scientific) with 0.25mm i.d. and 0.25 lm film, and was operated at a constant helium flow rate of 1 ml/min. The oven temperature pro- gram differed for each lipid class. For hydrocarbons, the starting temperature was 90 °C, rising to 230 °C at 13 °C/min, then to 325 °C at 5.5 °C/min, followed by 13 min at 325 °C. Effluent from the GC entered the GC-C III interface, a graphite-lined ceramic tube at 1400 °C, where quantitative pyrolysis to graphite, hydrogen gas and carbon monoxide occurred (Bur- goyne and Hayes, 1998). The hydrogen gas stream was introduced to the Finnigan Deltaplus XP mass spectrometer via an open split, where a flow of helium carried the H2 gas into the mass spectrometer.

El Junco Lake is presumed to have remained fresh and therefore its lake-water dD value is dictated solely by the isotopic composition of precipitation, and the relative rates of evaporation and precipitation. More negative lake-water dD values reflect a greater rate of rainfall relative to evaporation during wet periods. Conclusions of the paper are about moisture balance (P-E) in the tropical Pacific.

It is expected that dD values of botryococcene will decline when precipitation rates increase, possibly providing a metric for the severity of extreme rainfall events that are associated with El Nino events. (All botryococcene dD values were highly correlated with water dD values (R2>0.99). And, Zhang and Sachs 2007, Organic Geochemistry), 38: 582-608.

Zhang, Zhaohui , Leduc, Guillaume , Sachs, Julian P.

El Niño evolution during the Holocene revealed by a biomarker rain gauge in the Galápagos Islands

Zhang, Z., Leduc, G. and Sachs, J. P.: El Nino evolution during the Holocene revealed by a biomarker rain gauge in the Galapagos Islands, Earth and Planetary Science Letters, 404, 420–434, doi:10.1016/j.epsl.2014.07.013, 2014.