Characteristics and sources of aerosol aminiums over the eastern coast of China: insights from the integrated observations in a coastal city, adjacent island and surrounding marginal seas

Abstract

Abstract. An integrated observation of aerosol aminiums was conducted in a coastal city (Shanghai) in eastern China, a nearby island (Huaniao Island), and over the Yellow Sea and East China Sea (YECS). Triethylaminium (TEAH+) was abundant over Shanghai but not detected over the island and the open seas, suggesting its predominantly terrestrial origin. By contrast, relatively high concentrations of dimethylaminium (DMAH+) and trimethylaminium + diethylaminium (TMDEAH+) were measured over the ocean sites, indicating the significant marine source contribution. Environmental factors, including boundary layer height (BLH), temperature, atmospheric oxidizing capacity and relative humidity, were found to be related to aminium concentrations. All the detected aminiums demonstrated the highest levels in winter in Shanghai, consistent with the lowest BLH and temperature in this season. Aminiums mainly existed in fine particles and showed a bimodal distribution, with two peaks at 0.18–0.32 µm and 0.56–1.0 µm, indicating that condensation and cloud processing were the main formation pathways for aminiums in analogy with NH4+ and non-sea-salt SO42- (nss-SO42-). Nonetheless, a unimodal distribution for aerosol aminiums was usually measured over the YECS or over Huaniao Island when influenced mainly by the marine air mass, which suggested that aminiums in marine aerosols may undergo different formation pathways from those on the land. Terrestrial anthropogenic sources and marine biogenic sources were both important contributors for DMAH+ and TMDEAH+, and the latter exhibited a significantly higher TMDEAH+ to DMAH+ ratio. By using the mass ratio of methanesulfonate (MSA) to nss-SO42- as an indicator of marine biogenic source, we estimated that marine biogenic source contributed to 26 %–31 % and 53 %–78 % of aerosol aminiums over Huaniao Island in the autumn of 2016 and summer of 2017, respectively. Due to the important role of atmospheric amines in new particle formation, the estimation results highlighted the importance of marine biogenic emission of amines on the eastern coast of China, especially in summer.

Size‐Resolved Mixing States and Sources of Amine‐Containing Particles in the East China Sea

“…The higher DEA‐containing particle counts in the East China Sea detected in this study are consistent with the results of previous studies. Zhou et al (2019) reported relatively high concentrations of DEA‐containing particles in the East China Sea compared to the adjacent city, indicating the significant contribution of marine sources to the DEA‐containing particle counts. As shown in Figure 1, higher DEA‐containing particle counts were observed in case 1.…”

“…MMA‐containing particles are the dominant amine‐containing particles in urban areas (Ho et al, 2015; Liu et al, 2017). High concentrations of TMA‐containing particles have also been detected in urban (Zhang et al, 2012) and marine areas (Zhou et al, 2019). DEA‐containing particles are the dominant amine‐containing particles in marine areas (Fierz‐Schmidhauser et al, 2010; Xie et al, 2018; Zhou et al, 2019).…”

“…However, few studies have reported the contribution of ships to amine-containing particles. Zhou et al (2019) reported that DEA-containing particles are the main amine-containing particles in the East China Sea.…”

“…Gaston et al (2013a) reported that port and urban emissions are the dominant sources of the amines in Southern California. In autumn of 2016, the contributions of terrestrial sources to the amines over Huaniao Island in the East China Sea were estimated to be more than 60% (Zhou et al, 2019). Marine emissions are likely to affect the concentrations of particulate amines in coastal sites.…”

“…Huang et al (2018) found that monomethylamine (MMA) is the dominant particulate amine in the East China Sea, ranging from 0.27 to 7.04 ng m −3 with an average of 4.76 ng m −3 . High concentrations of particulate DMA and particulate TMA + DEA were found in the East China Sea, ranging from 30.2 to 32.2 and 11.8 to 27.5 ng m −3 , respectively (Xie et al, 2018; Zhou et al, 2019). On the adjacent continents, C1, C2, and C4 gaseous amines are the dominant species with average concentrations of 15.7, 40.0, and 15.4 ppt, respectively (Yao et al, 2016).…”