AAAR 32nd Annual Conference
September 30 - October 4, 2013
Oregon Convention Center
Portland, Oregon, USA
Abstract View
Precipitation Scavenging of Aerosols in the Niigata Plain, Japan, during the Winter Season
SHIN OHARA, Shin-ichi Fujita, Naoto Kihara, Soichiro Sugimoto, Akira Takahashi, Central Research Institute of Electric Power Industry
Abstract Number: 158 Working Group: Remote and Regional Atmospheric Aerosols
Abstract In a coastal area of the Sea of Japan, it has been reported that the concentrations of Na$^+ and non-sea-salt SO$_4$^(2-) (nss-SO$_4$^(2-)) in precipitation tend to increase during winter. Northwesterly winter winds off the Asian continent bring sea-salt aerosols emitted from the Sea of Japan as well as long-range transported air pollutants to this area. The seasonally high concentrations of Na$^+ and nss-SO$_4$^(2-) in precipitation would be attributed to scavenged sea-salt aerosols and particulate nss-SO$_4$^(2-). However, the processes of precipitation scavenging of these aerosols are poorly understood.
In this work, we studied the precipitation scavenging of aerosols in the Niigata Plain, located along the Sea of Japan, during winter. For this purpose, the field sampling of precipitation and ambient aerosols was conducted at three sites in the Niigata Plain, during winters from 2008 to 2011. The distances from the coast to these sites were approximately 1 km, 17 km and 29 km. At each site, a wet-only sampler was installed for the collection of precipitation samples. Aerosol samples were collected on a 47 mm Teflon filter by using a ten-line low-volume sampler. These samples were collected every 6 hours between December and March during the winters of 2008 - 2011. Samples of the precipitation and the filter extract were analyzed for the species: NH$_4$^+, Na$^+, K$^+, Mg$^(2+), Ca$^(2+), Cl$^-, NO$_3$^- and SO$_4$^(2-). The electrical conductivity and pH of the precipitation samples were also determined.
In this presentation, we will discuss some of the analysis of the set data of ionic concentrations in the precipitation and the aerosol samples by using the scavenging ratio as well as some preliminary analysis of the relationship between the concentrations and the distance from the coast, focusing on differences in the precipitation scavenging of aerosols between coastal and inland areas.