Chemical form of arsenic compounds and distribution of their concentrations in the atmosphere

In order to understand the chemical form of arsenic compounds and their distribution in unpoluted areas, concentrations of arsenic compounds in the marine atmosphere were measured in several islands in several oceans. Furthermore, concentration of arsenic compounds were also measured between Tokyo and the Syowa station during a cruise by the Antarctic observation boat Shirase. Aerosols in the marine atmosphere were collected by a high‐volume air sampler with a quartz fiber filter. After extracting a sample, an analysis of arsenic compounds in the sample solution was carried out by hydride generation atomic absorption spectrophotometry combined with a cold trap of liquid nitrogen. This technique has a high analytical sensivity, so that it is suitable to determine arsenic compounds at trace level. The atmospheric concentrations of arsenic compounds were at the same level over the Pacific Ocean and the Atlantic Ocean. The concentration range of arsenic compounds over these oceans was 100–200 pg m⁻³ for inorganic arsenic, 10–20 pg m⁻³ for inorganic arsenic. It is considered that these values are the background concentrations in the northern hemisphere. On the other hand, over he Antarctic Ocean in the southern hemisphere, the atmospheric concentrations of inorganic arsenic were very low, and organic arsenics were little found. This fact indicates that arsenic in the atmosphere is strongly influenced by anthropogenic sources.