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Shipping is the cornerstone of international trade and thus a critical economic sector. However, ships predominantly use fossil fuels for propulsion and electricity generation, which emit greenhouse gases such as carbon dioxide and methane, and air pollutants such as particulate matter, sulfur oxides, nitrogen oxides, and volatile organic compounds. The availability of Automatic Information System (AIS) data has helped to improve the emission inventories of air pollutants from ship stacks. Recent laboratory, shipborne, satellite and modeling studies provided convincing evidence that ship-emitted air pollutants have significant impacts on atmospheric chemistry, clouds, and ocean biogeochemistry. The need to improve air quality to protect human health and to mitigate climate change has driven a series of regulations at international, national, and local levels, leading to rapid energy and technology transitions. This resulted in major changes in air emissions from shipping with implications on their environmental impacts, but observational studies remain limited. Growth in shipping in polar areas is expected to have distinct impacts on these pristine and sensitive environments. The transition to more sustainable shipping is also expected to cause further changes in fuels and technologies, and thus in air emissions. However, major uncertainties remain on how future shipping emissions may affect atmospheric composition, clouds, climate, and ocean biogeochemistry, under the rapidly changing policy (e.g., targeting decarbonization), socioeconomic, and climate contexts. 

Abstract. Isoprene-derived secondary organic aerosol (iSOA) is a significantcontributor to organic carbon (OC) in some forested regions, such astropical rainforests and the Southeastern US. However, its contribution toorganic aerosol in urban areas that have high levels of anthropogenicpollutants is poorly understood. In this study, we examined the formation ofanthropogenically influenced iSOA during summer in Beijing, China. Localisoprene emissions and high levels of anthropogenic pollutants, inparticular NOx and particulate SO42-, led to the formation ofiSOA under both high- and low-NO oxidation conditions, with significantheterogeneous transformations of isoprene-derived oxidation products toparticulate organosulfates (OSs) and nitrooxy-organosulfates (NOSs).Ultra-high-performance liquid chromatography coupled to high-resolution massspectrometry was combined with a rapid automated data processing techniqueto quantify 31 proposed iSOA tracers in offline PM2.5 filterextracts. The co-elution of the inorganic ions in the extracts caused matrixeffects that impacted two authentic standards differently. The averageconcentration of iSOA OSs and NOSs was 82.5 ng m−3, which was around 3 timeshigher than the observed concentrations of their oxygenated precursors(2-methyltetrols and 2-methylglyceric acid). OS formation was dependant onboth photochemistry and the sulfate available for reactive uptake, as shown by astrong correlation with the product of ozone (O3) and particulatesulfate (SO42-). A greater proportion of high-NO OS products wereobserved in Beijing compared with previous studies in less pollutedenvironments. The iSOA-derived OSs and NOSs represented 0.62 %of the oxidized organic aerosol measured by aerosol mass spectrometry on average, butthis increased to ∼3 % on certain days. These resultsindicate for the first time that iSOA formation in urban Beijing is stronglycontrolled by anthropogenic emissions and results in extensive conversion toOS products from heterogenous reactions.