Izumi Noguchi

Annual and seasonal trends in chemical composition of precipitation in Japan during 1989–1998

Abstract Annual and seasonal trends were discussed for precipitation chemistry in Japan on the basis of a nationwide monitoring network by Japan Environment Agency. For this analysis, 17 sites, selected from the 23 network sites after evaluation of data completeness for the present purpose, were grouped into four areas in terms of the sea which could characterize each area: the Pacific Ocean, the Japan Sea, the Seto Inland Sea and the East China Sea areas. Major ion concentrations at each site were subjected to least-squares multiple regression analysis, and discussion was principally focused on the area-groups. Each area showed significant (p

Peat-fire-related air pollution in Central Kalimantan, Indonesia

The past decade marked record high air pollution episodes in Indonesia. In this study, we specifically focus on vegetation fires in Palangkaraya located near a Mega Rice Project area in Indonesia. We analyzed various gaseous air pollution data such as particulate matter (PM10), SO2, CO, O3, and NO2 study region. We also conducted elemental analysis at two different sites. Results from 2001 to 2010 suggested the longest hazardous air pollution episode during 2002 lasting about 80 days from mid-August to late-October. Maximum peak concentrations of PM10, SO2, CO, and O3 were also observed during 2002 and their values reached 1905, 85.8, 38.3, and 1003×10(-6) gm(-3) respectively. Elemental analysis showed significant increase in concentrations during 2011 and 2010. Satellite retrieved fires and weather data could explain most of the temporal variations. Our results highlight peat fires as a major contributor of photochemical smog and air pollution in the region.

The effect of alkaline dust decline on the precipitation chemistry in Northern Japan

The precipitation chemistry in northern Japan, especially Hokkaido, has been investigated since 1982. This area has often been found to have high concentrations of alkaline road dust (asphalt dust) in the air, caused by the use of studded tires during the winter. It is well known that the composition of precipitation in these areas is often dominated by asphalt dust including calcium bicarbonate. However, recently the concentration of asphalt dust in the air has decreased owing to a ban on the use of studded tires. Simultaneously, in precipitation, the lowering of pH values and the increase of hydrogen ion depositions have been occurring owing to the decrease of non-sea-salt calcium ions (nss-Ca2+) concentrations and depositions derived from asphalt dust. In addition, we found that a decrease of nss-Ca2+ firstly leads to a decrease of bicarbonate ions (HCO3−), the counter ion to nss-Ca2+ in asphalt dust. Therefore, the increase of H+ concentrations and depositions was great in comparison with the decrease of nss-Ca2+ concentrations and depositions in areas where the HCO3−concentrations, varied by pH, and depositions had been low. Furthermore, this variation was mainly observed in the ionic composition of snow cover and snowfall at sites along the Japan Sea in northern Japan during winter. In this area, the Acid Shock effect may become a serious problem from the decline of pH values in melting snow. Moreover, we found that ammonium ions and non-sea-salt sulfate ions depositions have also been decreasing in response to a decrease of nss-Ca2+ depositions, derived from asphalt dust. It seems that this phenomenon is caused by the decrease of asphalt dust concentrations in the air.

Influence of the growth mechanism of snow particles on their chemical composition

Abstract Case studies of chemical analysis of solid precipitation were made at sites on the outskirts and central part of Sapporo City, Japan to investigate the difference in precipitation chemistry owing to the mechanism by which snow particles grow, i.e. by vapor deposition or by riming. Even in vapor depositional growth, the samples were found to be acidic. NO 3 − and nss-Cl − contributed to the acidification. In the samples of riming growth, the nss-SO 4 2− concentration was considerably high. Snow samples from the site in the central city area were less acidic due to the higher concentration of nss-Ca 2+ in the early period of snowfalls.

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.

Aquatic Chemistry of a Reservoir during the Thaw Season

The aquatic chemistry of a reservoir in a snowy area on the Japan Sea side of Hokkaido Prefecture in northern Japan was investigated during the 1999 thaw season.We observed slight and brief acidification, during which period the dissolved aluminum increased. The variation in its concentration was similar to that in dissolved organic carbon.

Tree Decline at the Somma of Lake Mashu in Northern Japan

Decline of the mountain birch (Betula ermanii) has been observed at the somma of Lake Mashu in northern Japan. To clarify its causes, ozone (O3) and fog chemistry were evaluated. O3 concentration was lower in summer, but higher in spring, with a monthly mean of 50–60 ppbv. The results of on-site open-top-chamber (OTC ) experiments using birch seedlings suggested the possibility that O3 decreased the leaf photosynthetic capacity and shifted biomass allocation to the roots. The results of fog measurements showed that the fog acidity was not serious; however, nitrogen input via fog deposition was estimated to be 30 meq m-2 in the plant-growing season, and this could be the main nitrogen source for trees in this area. These results indicated that anthropogenic air pollutants have influenced plant growth in this area. However, there is still great uncertainty about O3 effects on the mountain birch, such as its effects causing stomatal sluggishness, water stresses, and these effects combined with nitrogen input. Further evaluation of these factors is necessary to assess the tree decline.

Automatically Determined pH of Precipitation Samples, Collected by an Automatic Rain-Sensing Sampler and Its Spatial Distribution

Precipitation pH was automatically measured on site for each 0.5 mm-rainfall sample at 29 nationwide stations in Japan in Phase-II of Acid Deposition Survey from 1989 FY to 1992 FY by Japan Environment Agency. The mean pH of all of the stations over the entire survey period was pH 4.6. There was no pH record less than pH 3.0 which was supposed to affect plant growth. In western Japan and in remote islands in the Sea of Japan, lower pH was observed than in the other regions. Regarding seasonal variations, pH was rather lower in winter and spring. The mean pH of initial 0.5 mm-rainfall was lower than that of the whole rainfall at many stations, although it was higher at 8 stations. The monthly means of pH based on the automatic measurements of 0.5 mm-rainfall samples were compared with those from the manual measurements of biweekly samples, showing that the automatically determined pH was lower than the manually determined one by 0.3 pH unit on average. One of the possible causes of this pH difference is solution of alkali particles in the stored samples.