GEOGRAPHY

Sources of aerosol black carbon in the South China Sea and Northeast Indian Ocean and their effects revealed


Recently, Geng Xiaofei, a postdoctoral fellow at the Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, and researcher Zhang Gan, in collaboration with Michael Bird, a professor at James Cook University in Australia, used the analysis of double carbon isotope (δ13C-Δ14C) based on catalytic hydrogenation technology to quantitatively analyze the concentration of aerosol black carbon in the South China Sea and Northeast Indian Ocean and trace its source, and discussed the impact of atmospheric deposition of black carbon on the marine carbon cycle. The results were published in ES&T and were selected as a sub-cover story in the current issue.

The relevant research paper was selected as the current sub-cover article of ES&T. Photo courtesy of the research team

Aerosol black carbon is a short-lived climate pollutant that plays an important role in extreme weather events and the ocean carbon cycle. Quantitative analysis of black carbon sources from marine aerosols has long been a technical challenge.

The study found that both the concentration of aerosol black carbon and δ13C-Δ14C showed significant spatial heterogeneity. In the South China Sea and Northeast Indian Ocean, six dual-carbon isotope provinces where aerosol black carbon can be identified, namely “Near Chinese mainland South China Sea”, “Remote South China Sea”, “Southeast Asian Indian Ocean”, “Indian Ocean Remote Sea”, “Malacca Strait” and “Sunda Strait”.

Bicarbon isotopic characterization of aerosol black carbon in the South China Sea and Northeast Indian Ocean. Photo courtesy of the research team

Based on the isotope mass conservation model, the study found that fossil fuel combustion and biomass combustion contributed 50.3±12.3% (28-82%) and 49.7±12.3% (18-72%) to aerosol black carbon in the South China Sea and Northeast Indian Ocean, respectively. Combined with the comprehensive analysis of black carbon emission simulation, metal element tracing and air mass backward trajectory in the shipping industry, the sources of black carbon can be explored in more depth. The results showed that liquid fossil fuel combustion and C3 plant combustion were the main sources of aerosol black carbon in the study area.

Although the determination of δ13C-Δ14C of aerosol black carbon in this study is based on catalytic hydrogenation technology, and the determination of δ13C-Δ14C of dissolved black carbon is based on the benzopolycarboxylic acid method, the determination of δ13C-Δ14C by these two methods shows some comparability. On this basis, further cross-circular isotope fingerprint comparison showed that marine aerosol black carbon and seawater dissolved black carbon showed similar dual-carbon isotopic composition characteristics, suggesting that atmospheric deposition of black carbon may be an important source of marine dissolved black carbon. (Source: China Science News Zhu Hanbin)

Related paper information:https://doi.org/10.1021/acs.est.3c03481



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