Shigekatsu Sakai

Snowcover Components in Northern Japan

Snowcover surveys were carried out in Hokkaido, northern Japan. Snowpack samples were collected using a steel pipe at 80 sites in 1988, 69 sites in 1992, and 66 sites in 1996 and 2000 during the time when the water equivalents of the snowcover are the greatest. Spatial distribution maps of water equivalents and of the concentrations and the accumulated amounts of hydrogen, non-sea-salt sulfate and non-sea-salt calcium ion of the snowcover drawn by Kriging method are discussed.The distribution maps show that water equivalents and the accumulated amounts of hydrogen and non-sea-salt sulfate in all the sample years were largest in the Japan Sea region, as were the ion concentrations of hydrogen and non-sea-salt sulfate. It was estimated this was caused by air pollutants transported from a great distance. The ratio of areas below pH 5.0 increased temporally from 1988 (20%) to 1992, 1996 and 2000 (66–80%). This trend was estimated to be affected by a decline of non-sea-salt calcium concentrations derived from alkaline road dust. In addition, the effect of snowcover components was assessed by comparison between the acid loads of the snowcover and the acid neutralizing capacity of lake water. We found that lakes in the middle of the Japan Sea coast have the potential to be acidified by snowmelt.

Long term trends in atmospheric concentrations of polycyclic aromatic hydrocarbons and nitropolycyclic aromatic hydrocarbons: A study of Japanese cities from 1997 to 2014

Total suspended particulate matter (TSP) was collected during the summer and winter in five Japanese cities spanning Hokkaido to Kyushu (Sapporo, Kanazawa, Tokyo, Sagamihara and Kitakyushu) from 1997 to 2014. Nine polycyclic aromatic hydrocarbons (PAHs) with four to six rings, including pyrene (Pyr) and benzo[a]pyrene (BaP), were identified using high-performance liquid chromatography (HPLC) with fluorescence detection. Two nitropolycyclic aromatic hydrocarbons (NPAHs), 1-nitropyrene (1-NP) and 6-nitrobenzo[a]pyrene (6-NBaP), were identified by HPLC with chemiluminescence detection. A comparison of PAH and NPAH concentrations and [NPAH]/[PAH] ratios such as [1-NP]/[Pyr] and [6-NBaP]/[BaP] revealed the following characteristics in the five cities: (1) In Sapporo, Kanazawa, Tokyo and Sagamihara, the concentrations of PAHs and NPAHs were high at the beginning of the sampling period and then steadily decreased, with NPAHs decreasing faster than PAHs. The large initial [1-NP]/[Pyr] ratios suggest that the major contributor was automobiles but subsequent decreases in this ratio suggest decreased automobile contributions. (2) By contrast, PAH concentrations in Kitakyushu did not decrease during the sampling period, though concentrations of NPAHs decreased. The consistently smaller [1-NP]/[Pyr] ratio and larger [6-NBaP]/[BaP] ratio in Kitakyushu suggests that the major contributor of PAHs was not automobiles but iron manufacturing which uses a large amount of coal. The sudden increase in atmospheric PAH concentrations in the winter of 2014 may also be due to iron manufacturing.