Sources and dry deposition of carbonaceous aerosols over the coastal East China Sea: Implications for anthropogenic pollutant pathways and deposition

Abstract

While many studies have been conducted on carbonaceous aerosols in urban areas worldwide, investigations of carbonaceous components in marine atmospheres are rather limited. In this study, 75 paired total suspended particle (TSP) and PM2.5 samples were collected over four seasons on Huaniao Island (HNI), an island that lies downwind of continental pollutants emitted from mainland China moving towards the East China Sea (ECS). These samples were analyzed for organic carbon (OC) and elemental carbon (EC), with a special focus on char-EC (char) and soot-EC (soot), to understand their sources, and the scale and extent of pollution and dry deposition over the coastal ECS. 2 The results showed that char concentrations in PM2.5 and TSP averaged from 0.13-1.01 and 0.31-1.44 µg/m 3 ; while for soot, they were from 0.03-0.21 and 0.16-0.56 µg/m 3 , respectively. 69.0% of the char and 36.4% of the soot were present in the PM2.5 fraction. The char showed apparent seasonal variations, with highest concentrations in winter and lowest in summer; while soot displayed relatively small seasonal variations, with maximum concentrations in the fall and minimum concentrations in summer. The char/soot ratios in PM2.5 averaged from 3.29-17.22; while for TSP, they were from 1.20-7.07. Both of the ratios in PM2.5 and TSP were highest in winter and lowest in fall. Comparisons of seasonal variations in OC/EC and char/soot ratios confirmed that char/soot may be a more effective indicator of carbonaceous aerosol source identification than OC/EC. Annual average atmospheric dry deposition fluxes of OC and EC into ECS were estimated to be 229 and 107 µg/m 2 /d, respectively, and their deposition fluxes significantly increased during episodes in fall, winter and spring. It was estimated that the loadings of OC+EC and EC accounted for 1.3% and 4.1% of the total organic carbon and EC in ECS surface sediments, respectively, implying a relatively small contribution of OC and EC dry deposition to organic carbon burial. This finding also indicates a possibly more important contribution of wet deposition to organic carbon burial in sediments of ECS, and this factor should be considered for future study.

Existence and Formation Pathways of High- and Low-Maturity Elemental Carbon from Solid Fuel Combustion by a Time-Resolved Study

“…Half of the low-temperature combustion-generated ECs were Char-EC. This finding is concordant with previous research results. ,, It can be seen in Figure S3 that the R S/C varied markedly from 0.15 to 23.8 in particle samples from different sources or from different ambient samples. − Generally, the fuel types can significantly affect the value of R S/C in carbonaceous particles; vapor-phase carbon black has the highest value of R S/C followed by diesel vehicle emission and residential coal combustion has the lowest value of R S/C . However, the value of R S/C from the same fuel types still can be different due to the difference in the operation method (e.g., R S/C of diesel soot higher than that from diesel vehicle emission for 1 order of magnitude).…”

Spatial‐temporal distribution, photoreactivity and environmental control of dissolved organic matter in the sea-surface microlayer of the eastern marginal seas of China

“…5b)), probably due to the input from atmospheric deposition during winter, and the relatively low CDOM concentrations in bulk water. Atmospheric deposition of organic carbon and nutrients were found a peak in winter over the coastal ECS (Wang et al, 2019). We suggested that the EFs of CDOM The SML is an aggregate-enriched biofilm environment with distinct microbial communities,…”

Occurrence, sources and seasonal variation of PM2.5 carbonaceous aerosols in a water level fluctuation zone in the Three Gorges Reservoir, China

“…When the OC/EC ratios exceed 2.0, the relationship of OC and EC can be used to estimate the SOC as (Turpin et al, 1995 (Chow et al, 1996;Castro et al, 1999;Cao et al, 2005;Feng et al, 2009). However, the ratio of char to soot (char/soot) may also be a valuable indicator to imply source variations since there are distinct changes between different emission sources (Han et al, 2010;Wang et al, 2019). for SOC and 33.0% for SOC/EC, respectively.…”