Temporal Variability of Carbon Burial and the Underlying Mechanisms in Bosten Lake Since 1950

The arid and semi-arid regions of northwest China have experienced significant climate changes and human activities since 1950, with implications for the carbon cycle. We collected two short sediment cores to investigate the anthropogenic and climate impacts on the carbon burial in Bosten Lake. Basic physical and chemical properties were measured, including total organic carbon (TOC) and total inorganic carbon (TIC), isotopic compositions of TOC (δ13Corg) and carbonate (δ13Ccarb and δ18Ocarb), grain size, and 137Cs and 210Pb. Our data showed carbon burials revealed a profound temporal variability with an overall increasing trend, and the TIC burial rate was proximately twice of the TOC since 1950. The remarked increasing trend in TOC burial rate since 1950 (TIC burial during 1950–2002) was a result of warming and/or increased human activities; the sharp decline in TIC during the recent decade (2002–2012) was associated with lower biological activity, reduced evaporation and a rapid decline in lake level. The role of carbon storage in lake sediments, especially in arid area, should deserve to be paid more attention to the terrestrial carbon cycle.