八方尾根および長野市における浮遊粒子状物質と酸性降下物の特性  [in Japanese] Chemical Components of Airborne Particulate Matter and Acid Deposition in Happoone and Nagano City.  [in Japanese]

Access this Article

Author(s)

Abstract

山岳地域における環境大気中の浮遊粒子状物質 (SPM) と大気降下物の特徴を把握するため, 唐松岳入方尾根および長野市においてSPMを1ヵ月毎に採取し, 化学成分濃度を測定し, 各種発生源寄与率の推定を行った。また, 大気降下物を1ヵ月毎に測定し, 酸性物質降下量を調査して, 渓流水への影響について検討した。<BR>八方尾根におけるSPM中のSO<SUB>4</SUB><SUP>2-</SUP>濃度は春季~ 夏季に高くなる変化を示した。春季 (3~4月) には黄砂の影響が見られ, 黄砂粒子の濃度は約4μg/m3と推定された。調査地点近傍の土壌粒子の寄与は少なかった。大気降下物のpHは平均5.1であり, 長野市 (平均5.3) よりもわずかに低く, 春季に高くなる傾向があった。nss-SO<SUB>4</SUB><SUP>2-</SUP>の降下量は長野市の約2倍あり, またNO<SUB>3</SUB><SUP>-</SUP>の降下量も多く, 清浄地域と考えられる山岳地域にも多量の酸性物質の降下が認められた。<BR>八方尾根付近の渓流である平川の水質は, pH7.6, アルカリ度0.48meq/<I>l</I>と十分な中和能があったが, 梅雨期には希釈効果により一時的にアルカリ度の低下が認められた。NO<SUB>3</SUB><SUP>-</SUP>濃度は融雪期 (3~4月) に上昇したが, pHの低下は見られなかった。

The chemical components of airborne suspended particulate matter (SPM) and deposition were measured in samples collected at monthly intervals both at Happoone in the Karamatsu Mountains of the Japan Alps and in Nagano City. The contributions of several sources to SPM were estimated via the chemical mass balance (CMB) method. The amount of deposition at Happoone was compared with that in Nagano City, and its effects on stream water components was observed.<BR>At Happoone, SO<SUB>4</SUB><SUP>2-</SUP>concentration in the SPM increased from spring to summer. In spring, Kosa aerosol was detected in the SPM and its concentration was estimatedto be 4 μg/m<SUP>3</SUP>. Few soil particles generated from the neighboring area were detected in the SPM. The mean pH of deposition at Happoone was 5.1, slightly lower than that (5.3) in Nagano City, and the Happoone value increased during spring. The deposition rates of nss-SO<SUB>4</SUB><SUP>2-</SUP> and NO<SUB>3</SUB><SUP>-</SUP>at Happoone were 1.5 times greater than those in Nagano City. These results suggest that greater amounts of acidic substances fell on this mountain region, which had seemed to be a clean area.<BR>The Hira River, a mountain stream near Happoone, had sufficient capacity to neutralize the acid deposition with pH remaining at 7.6 and alkalinity at 0.48 meq/l. However the alkalinity decreased temporarily due to dilution with rainfall during the rainy season. During the snow melt season, the concentration of NO<SUB>3</SUB><SUP>-</SUP>increased, although pH decline was not observed.

Journal

  • Journal of Japan Society for Atmospheric Environment / Taiki Kankyo Gakkaishi

    Journal of Japan Society for Atmospheric Environment / Taiki Kankyo Gakkaishi 31(6), 282-291, 1996

    Japan Society for Atmospheric Environment

Codes

Page Top