Biomass and fossil-fuel combustion history in the Osaka Plain, based on charcoal and spheroidal carbonaceous particles(SCPs) records of the latest Pleistocene and Holocene sediments

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Natural and anthropogenic combustion processes mobilize a large variety of materials about the environment. In this study, macroscopic and microscopic charcoal particles, and spheroidal carbonaceous particles (SCPs) in the latest Pleistocene and Holocene sediments of the Osaka Plain, central Japan, were studied. Charcoal particles are generated through biomass burning. SCPs are formed from incomplete high temperature combustion of fossil fuels.Based on the charcoal stratigraphy of the latest Pleistocene and Holocene sediments, the last 12ka is divided into three periods : 12 ka to 9 ka, 9 ka to 2 ka and since 2 ka. Charcoal abundance increased from about 12 ka, and the highest abundance of charcoal between 11 ka and 9 ka was associated with the ancient human activities. After 9ka, charcoal abundance decreased and increased gradually from 2 ka to present. Conquently, charcoal abundance evidence in the sediments suggests that variation of biomass fire frequency in the Osaka Plain was affected by ancient human activities.SCPs concentration in the latest Holocene sediments increased in the early 1930s. After that SCPs concentration increased rapidly in 1950s and decreased from 1970s to present. These trends can ascribed to the growth of industial activities and the regulation of atomospheric pollutant emission, respectively.