A Method for the Identification of Asian Dust-Storm Particles Mixed Internally with Sea Salt

Continuous measurements of size‐resolved particle chemistry during INDOEX‐Intensive Field Phase 99

“…These particular combinations indicate agglomeration processes occurred. Dust particles associated with sea salt have been observed previously in Beijing (China) and Nagasaki (Japan) [Niimura et al, 1994[Niimura et al, , 1998], as well as over remote oceans [e.g., Andreae et al, 1986]. Positive and negative ion mass spectra of a particle classified as dust with elemental carbon and sulfates are presented in Figure 9.…”

Formation of Asian Dust-Storm Particles Mixed Internally with Sea Salt in the Atmosphere

“…In this study, Asian dust-storm particles mixed internally with sea salt were identified by the following criteria: 1) the particle contained both Na and Cl or 2) the particle had Na/Si weight ratio larger than 0.25, even if Cl was not detected (Niimura et al, 1994). In addition, the dialysis (extraction) of water-soluble material (Mossop, 1963;Tanaka, 1980;Okada, 1983) was applied to the samples collected on 1 and 10 May in Nagasaki.…”

“…Particles after dialysis treatment were also analyzed quantitatively by using the EDX spectrometry mentioned above. Since the dust-storm particles often contain mineral sodium (e. g., Nishikawa et al, 1991), which might be regarded as an insoluble material, sea-salt sodium was evaluated by using the results of the EDX analyses before and after the dialysis (Niimura et al, 1994) and was used for the calculation of the relative weight ratios of Na, S and Cl for sea salt on dust particles.…”

“…2d). On the basis of the criterion reported by Niimura et al (1994), the original particle is determined to be a mineral particle mixed internally with sea salt. Some results of the elemental composition of the dust particles collected in Beijing and Nagasaki in 1991 were also Fig.…”

“…Parungo et al (1986) collected some Saharan dust particles over the Atlantic Ocean containing a sea-salt component. Asian dust-storm particles with sea salt were also collected in the air over Japan (Sakurai, 1989;Niimura et al, 1994;Zhou et al, 1996), the North Pacific Ocean (Okada et al, 1990) and over the western Pacific Ocean (Zhou et al, 1992). However, the detailed information, such as the abundance of the mixed particles and their mixed properties, has not been obtained.…”