Vertical profile of organic and elemental carbon in sediments of Songkhla Lake, Thailand

In this study, a historical record of atmospheric deposition in the sediment cores from Songkhla Lake, the second largest lake in Southeast Asia, located in the southern part of Thailand is reported. It is well known that lake sediments, including spheroidal carbonaceous particles generated by both anthropogenic and natural emissions, contain records of lake, catchment, and atmospheric deposition histories. Vertical profiles of these carbonaceous particles can be used to investigate enormously influential disturbances, particularly those triggered by extreme paleo events, over large spatial areas. In this study, organic carbon/elemental carbon (OC/EC) ratios displayed unusually high values of 3.07 and 4.02 for depths 240 and 340 mm, respectively. Previous studies have attributed remarkably high values of OC/EC ratios to both biomass burnings and volcanic eruptions. Although anthropogenic emissions (e.g. fossil fuel combustions) can be responsible for relatively high levels of contamination, as expected, the existence of relatively low OC/EC ratios (i.e. 1.43 ± 0.30) for all sediment samples (except those collected at 240 and 340 mm depths) suggests a tropical background of these particles.