Chie Nakagawa

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.

Acidity in winter time deposition on the Japan seaside of Japan

Abstract The extent to which weekly precipitation samples are representative of acidity in precipitation on the Japan Sea side of Japan was analyzed with respect to daily wet deposition samples. In comparison to weekly deposition samples, the pH of daily deposition samples is distributed in a narrow range between pH 4.2 and 5.0. Weekly samples of higher pH appeared to be inflated by excess Ca2+ which was emitted from road dust. The average annual pH remained nearly constant during the six winters of the study.

An estimation of the contribution of the sulfate ion to rainwater acidity

Abstract A new method to estimate the contribution of sulfate to acidity in rainwater is proposed. The application of the method was demonstrated using rainwater data collected at Kanazawa, an area of low industrial activity on the Japan Sea side of Japan. Contribution percentages of SO4 2− to acidity in rainwater of a pH between 4.0 to 4.6 were approximately 70% during non‐winter weather, and about 85% during winter. Results were also compared to estimates based on the wide‐spread method of using excess sulfate (non‐seasalt derived sulfate) for the estimation of acidity.

Leakage of mercury from chelate resin columns by chelate detaching

Abstract It is known from experience that mercury leaks from chelate resin columns which are used for mercury wastewater treatment. In this paper, one of the reasons for the mercury leakage phenomena is discussed. After shaking the synthetic mercury wastewater with chelate resin, the supernatant became turbid. Using a highly sensitive mercury analysis, it was found that the results at lower mercury concentrations deviated from the Freundlich relation. From the results, it was presumed that the chelate component was detached by friction in the process of packing chelate resin into the column, and this chelate component adsorbed mercury while passing through the column.