| 概要 |
観測地点の立地条件による大気沈着量の違いを評価するために，北海道足寄町内の市街域とその付近に位置する九州大学北海道演習林内の森林域でバルク降水を2016 年５月から12 月にかけて月２回ごとに採取し，降水量，イオン成分（Cl^-, NO_3^-, SO_4^2-, H^+, Na^+, NH_4^+, K^+, Mg^2+, Ca^2+）濃度，沈着量を比較した。観測期間中の総降水量は森林域で1,2...36mm，市街域で1,121mm となり，森林域で10% 程度多かったが，過去９年間の年間降水量では必ずしも森林域で多くはなかった。バルク降水のイオン成分濃度は森林域でK^+ とMg^2+ が市街域よりもそれぞれ10%，20% 程度高かったが，それ以外のイオン成分濃度は同程度だった。総降水量とイオン成分濃度を乗じて計算した総沈着量は，総降水量が森林域で10%程度多いために森林域で増加した。このことから，市街域の規模が小さい場合，主に人為起源と考えられているバルク降水中のNO_3^- やSO_4^2- の濃度に立地条件が与える影響は小さい．そのため，沈着量は観測地点における降水量によって違いが生じ得る可能性が考えられた。
To evaluate the effect of observation location on atmospheric deposition, bulk precipitation was collected twice a month at two places in Ashoro town: a city area and a nearby-forested area situated in Ashoro Research Forest, Kyushu University Forest. Amount and ion concentrations (Cl^-, NO_3^-, SO_4^2-, H^+, Na^+, NH_4^+, K^+, Mg^2+, Ca^2+) of bulk precipitation were determined during the period from May to December 2016. Total precipitation volume during the observation period at the nearby-forested area (1,236 mm) was higher than at the city area (1,121 mm). However, annual precipitation volume at the nearby-forested area was not always higher than at the city area over the past 10 years. Concentrations in bulk precipitation were almost the same for ions between the two sites except for K^+ and Mg^2+ that was 10% and 20% higher at the nearby-forested area, respectively. Total depositions of ions calculated from total precipitation volume and concentrations were higher at the nearby-forested area, corresponding to higher precipitation amount. In conclusion, the concentrations of anthropogenic-derived ions including NO_3^- and SO_4^2- in bulk precipitation are not affected by the observation location in a small city, while the depositions can be affected by precipitation amount at the observation location.続きを見る
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Mendeley出力
