Sediment Soot Radiocarbon Indicates that Recent Pollution Controls Slowed Fossil Fuel Emissions in Southeastern China

Abstract

Fossil fuel (FF) combustion emissions account for a large, but uncertain, amount of the soot in the atmosphere, play an important role in climate change, and adversely affect human health. However, historical estimates of FF contributions to air pollution are limited by uncertainties in fuel usage and emission factors. Here, we constrained FF soot emissions from southeastern China over the past 110 years, based on a novel radiocarbon method applied to sedimentary soot. The reconstructed soot accumulations reflect the integrated effects of increased FF use caused by economic development and reductions in emissions due to pollution controls. A sharp increase in FF soot started in 1950 as southeastern China industrialized and developed economically, but decreased FF soot fluxes in recent years suggest that pollution controls reduced soot emissions. We compare FF soot history to changes in CO 2 emissions, industrial and economic activities, and pollution controls and show that FF soot fluxes are more readily controlled than atmospheric CO 2 . Our independent FF soot record provides insights into the effects of economic development and controls on air pollution and the environmental impacts from the changes in soot emissions.

The Sihailongwan Maar Lake, northeastern China as a candidate Global boundary Stratotype Section and Point for the Anthropocene series

“…In China, the highest soot concentrations in SHLWML sediments occurred around 2000 CE and then decreased. This pattern is seen in the FF soot fraction in both SHLWML (Figure 4d) and Huguangyan Maar Lake (southern China, over 2000 km distant) (Han et al, 2022). Both show an increasing FF soot fraction trend followed by more recent decreases in this century (Figure S6).…”

“…These two events were used as independent ages to calibrate the 210 Pb ages. A piecewise-constant rate 210 Pb supply model (CRS-pw) (Han et al, 2022; Tylmann et al, 2014) was used for radiometric chronological reconstructions. The two independent 137 Cs ages matched the varve counting ages (at 77 and 88 mm).…”

“…The FF soot fraction increased following reforms that began in the late-1970s, with the opening of China, and peaked at 33 mm depth (2000 CE). The FF soot fractions then decreased, likely related to the desulphurisation of industrial facilities in China that began in 2004 CE (Han et al, 2022; Zhang et al, 2019b).…”

“…Soot 14 C. Soot is an air pollutant that originates from the burning of fossil fuels and biomass and influences climate though its effects on the earth's radiative budget. Measured soot F 14 C (fraction modern) values and calculated fossil fuel (FF) soot fractions (SI and (Han et al, 2022)) showed opposite patterns (Figure 4d). That is, high soot F 14 C values were found to correspond to low FF soot factions and vice versa.…”

A processing paradigm for loose varved sediments in Anthropocene strata research: An example from the Sihailongwan maar Lake

“…3B). The pw-CRS (Han et al 2022) was used to calculate the 210 Pb age, and the results showed that the top 13 cm of the core represented the past 150 years of deposition (Fig. 3C).…”