4段濾紙法による奈良市と大台ケ原におけるガス成分およびエアロゾルの水溶性イオン成分の挙動

抄録

Aerosols and gaseous samples were collected weekly by a four stage filter pack method in Nara City, a small inland city, during the period from July 1993 to June 1996, and at Mt. Ohdaigahara, a clean mountainous area during the summers and autumns from June 1995 to October 1996; the concentrations of soluble ionic components (SO₄^2-, NO₃^-, Cl^-, Na⁺, NH₄⁺, K⁺, Ca²⁺ and Mg²⁺) of aerosols and gases (SO₂, HNO₃, HCl and NH₃) were derived. The concentrations of aerosols and gases varied seasonally in Nara City; specifically, the SO₂ concentration was high in winter and low in summer and the SO₄^2- concentration of aerosols was high in summer and low in winter. HNO₃, HCl and NH₃ concentrations were high in summer and low in winter. On the other hand, NO₃^-, Cl^- and NH₄⁺ concentrations of aerosols were high in winter and low in summer. The ratio of concentrations of fine particle components such as SO₄^2- and NH₄⁺ at Mt. Ohdaigahara to those Nara City were not much lower than those of gases and the ratio was about 40% suggesting the long range transport of SO₄^2- and NH₄⁺. Average amount of dry deposition of SO₄^2- and NO₃^- calculated by inferential method in Nara City were 0.80 and 1.6 mmol/m²/mo on bare ground, 0.96 and 1.7 mmol/m²/mo on agricultural land, 0.73 and 2.1 mmol/m²/mo on deciduous trees and 1.1 and 2.7 mmol/m²/mo on coniferous trees, respectively. Average SO₄^2- and NO₃^- amount of deposition calculated by inferential method at Mt. Ohdaigahara were 0.10 and 0.41 mmol/m²/mo on bare ground, 0.15 and 0.42 mmol/m²/mo on agricultural land, 0.18 and 0.55 mmol/m²/mo on deciduous trees and 0.27 and 0.64 mmol/m²/mo on coniferous trees, respectively.