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北海道演習林拓北流域及び福岡演習林御手洗水流域において，2005年6月－2006年6月にかけて降水，渓流水を採取・分析し，各流域における大気質や基岩等の立地環境の違いが降水や渓流水の化学成分に及ぼす影響について検討した．拓北流域では，降水，バルク降水，渓流水を採取し，御手洗水流域では，バルク降水，渓流水を採取した．拓北流域では，バルク降水のpH値が降水と比べて高かった．水素イオン以外のイオン成分濃...度は，降水と比べてバルク降水で上昇しており，特にCa^(2+)，NH_4^+の上昇が顕著であった．このイオン成分濃度の上昇の原因は，無降雨期間におけるガス状，粒子状物質のロート上への乾性沈着によるものと思われた．pH上昇の原因として，乾性沈着によるアルカリ土類金属やアンモニアの溶解が考えられた．バルク降水のNH_4^+濃度やNH_4^+沈着量は御手洗水流域と比べて拓北流域で高く，NO_3^-，SO_4^(2-)沈着量は拓北流域と比べて御手洗水流域で高い結果となり，大気質による違いを反映していた．バルク降水のpHは，御手洗水流域で4.5，拓北流域で5.3であり，御手洗水流域において顕著に低かった．その原因として，御手洗水流域において大気汚染に由来するNO_3^-，SO_4^(2-)濃度が高まっていること，拓北流域ではバルク降水中のNH_4^+，K^+，Ca^(2+)濃度が御手洗水流域よりも高いためと考えられた．渓流水のNO_3^-，SO_4^(2-)濃度は，拓北流域と比べて御手洗水流域において顕著に高い値を示した．その原因として，御手洗水流域においてNO_3^-，SO_4^(2-)沈着量が拓北流域と比べて高いためと考えられた．また，拓北流域では，K^+濃度が高く，御手洗水流域では，pH及びMg^(2+)濃度が顕著に高かった．この違いは基岩の違いが反映していると考えられた．御手洗水流域における渓流水のpHとMg^(2+)濃度には有意な正の相関がみられた．
The effects of air quality and bedrock on the characteristics of precipitation and streamwater chemistry at the Takuhoku Experimental Watershed （TEW）, Ashoro Research Forest, and Ochozu Experimental Watershed （OEW）, Kasuya Research Forest were investigated from June 2005 to June 2006. Precipitation, bulk precipitation, and streamwater were collected at TEW and bulk precipitation and streamwater were collected at OEW. The results showed that the annual pH value of bulk precipitation was higher than that of the precipitation at TEW. Annual concentrations of major ions except for H+, especially Ca_2^+ and NH_4^+ , in bulk precipitation were higher than those of precipitation due to gaseous and particulate dry deposition during non-precipitation. This result implies that alkaline earth metals and atmospheric ammonia are the major cause of the increase in pH value in bulk precipitation at TEW. NH_4^+ concentration and deposition of bulk participation were higher at TEW than those at OEW, whereas NO_3^- and SO_4^(2-) deposition were higher at OEW than those at TEW, indicating the effect of air quality. The annual values of pH in bulk precipitation were 4.5 and 5.3 at OEW and TEW, respectively. The difference between the watersheds could be caused by the higher concentrations of atmosphericallyderived NO_3^- and SO_4^(2-) in bulk precipitation at OEW and the higher concentrations of NH_4^+, K^+, Ca^(2+) in bulk precipitation at TEW than those at OEW. Concentrations of NO_3^- and SO_4^(2-) in streamwater were considerably higher at OEW than those at TEW. This could be caused by the higher deposition of NO_3^- and SO_4^(2-) at OEW than those at TEW. As well, higher pH and Mg_2+ concentrations in streamwater were found at OEW than at TEW, whereas K+ concentration was higher at TEW than at OEW. This could be due to the different bedrock type between TEW and OEW. A significant positive relationship was found between pH and Mg^(2+) concentration in streamwater at OEW.続きを見る
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Mendeley出力
bkuf_088_033