Chemical Characteristics of Aerosol Composition over the Yellow Sea and the East China Sea in Autumn*

Abstract

The total suspended particulate (TSP) samples over the Yellow Sea and the East China Sea were collected to determine the major compositions of water-soluble ionic species during two cruises in autumn 2007. The aerosol compositions exhibited an obvious regional variation between the two cruises, with higher concentrations (except Na 1 and Mg 21 ) over the northern Yellow Sea during the first cruise. The concentrations of the secondary ions [non-sea salt sulfate (nss-SO 4 22 ), NO 3 2 , and NH 4 1 ] were 11 6 4.9, 3.1 6 2.1, and 3.7 6 2.6 mg m 23 , respectively, which together contributed over 72% of the total determined ion concentrations. Significant correlations between these secondary ions were found within each sampling period, while nss-K 1 and nss-Ca 21 showed strong correlation with each other. The calculated results of equivalent concentrations of anions (nss-SO 4 22 and NO 3 2 ) and cations (NH 4 1 and Ca 21 ) showed that the acidic species were mostly neutralized with the alkaline species over the study areas. The mass ratio of nss-SO 4 22 /NO 3 2 was 1.4 during the investigation period. In addition, the concentrations of MSA were 0.011 6 0.044 and 0.0081 6 0.0047 mg m 23 during the two cruises, respectively. Based on the measured MSA, nss-SO 4 22, and their ratios, the relative biogenic sulfur contribution to the total nss-SO 4 22 was estimated to be only 2.0% during the two cruises, further suggesting the major contribution of anthropogenic source to sulfur budget over the marginal seas of China.

Water-Soluble Ionic Characteristics of Aerosols in the Marine Boundary Layer over the Yellow Sea during the KORUS-AQ Campaign

“…Thus, most of the MSA was in PM 2.5 ; the MSA mass concentration in PM 10 and PM 2.5 ranged from 0.096 to 0.61 μg m −3 and from 0.082 to 0.48 μg m −3 , respectively. In conjunction with the previous measurements (Zhang et al 2013(Zhang et al , 2015Cha et al 2016), this study shows an increasing trend of the MSA mass concentration over the Yellow Sea in recent years and the MSA concentration in the central Yellow Sea is larger than that in other regions (see Fig. 2 and Table 1).…”

“…These two groups are strongly correlated, with a slope of 1.2 for PM 10 and 1.1 for PM 2.5 . This finding is similar to that of Zhang et al (2013) over the Yellow Sea. This implies that most of the acidic ionic species were neutralized by the alkaline species over the Yellow Sea.…”

“…The nss-K + mass concentration over the Yellow Sea in this study is decreased than that in previous studies (e.g. Zhang et al 2013;Zhang et al 2015). The nss-Ca 2+ from soil (Kang et al 2003) clearly shows a decreasing trend from land to ocean (Fig.…”

“…This implies that most of the acidic ionic species were neutralized by the alkaline species over the Yellow Sea. Thus, nss-SO 4 2− and NO 3 − from anthropogenic SO 2 and NO x are adsorbed onto wet sand aerosol particles, and are then combined with Ca 2+ by replacing CO 3 2− in CaCO 3 from crustal sources during the longrange transport (Zhang et al 2013). In this study, nss-Ca 2+ showed a good correlation with NO 3 − (Tables 5 and 6).…”

“…Arimoto et al (1996) reported that marine biogenic sources accounted for 3.6% and 10.9% at the eastern and western sides of Jeju Island around the Yellow Sea, respectively. Zhang et al (2013) also estimated the contribution of biogenic nss-SO 4 2− to be 12% over the North Yellow Sea in the spring season (April 23-May 5, 2007). The differences between this study and previous ones may be explained by the differences in the sampling periods and locations as well as the seasonal variation in MSA concentration, at least partially.…”