報告書番号

484016

タイトル（和文）

日本の河川湖沼の水質現況ならびに火山性無機酸性湖研究の概要－酸性降下物影響と関連して

タイトル（英文）

OVERVIEW OF RIVER/LAKE WATER QUALITY AND LIMNOLOGICAL STUDIES ON VOLCANIC INORGANIC ACID LAKES IN JAPAN -IN RELATION TO THE EFFECTS OF ACID DEPOSITION-

概要 （図表や脚注は「報告書全文」に掲載しております）

既存の文献・データを基に，（１）水塊の感受性等陸水酸性化に関する知見の概要，（２）日本の河川湖沼水質の現況，（３）火山性無機酸性湖研究の概要を紹介した。これらは大気経由の酸性降下物によるわが国河川湖沼水の酸性化顕在化の有無およびその影響を考える際の基礎資料となる。わが国においてはこれまでのところ火山活動または鉱山排水の影響を受けている水域を除き炭酸平衡値（ｐＨ５．５～５．６）未満のｐＨ値は観測されていない。現在先ず検討すべき課題は，将来の酸性化顕在化の有無の評価，即ち，酸性降下物量の定量的評価ならびに酸性降下物に対し最も大きな中和能を有すと云われる土壌・基盤岩の中和能力評価にある。

概要 （英文）

IN THIS PAPER THE PRESENT CONDITIONS OF WATER QUALITY PARAMETERS,SUCH AS PH,ALKALINITY,OF SOME MAJOR RIVERS AND LAKES IN JAPAN,AND A REVIEW OF LIMNOLOGICAL STUDIES ON VOLCANIC INORGANIC ACID LAKES ARE DESCRIBED.THESE INFORMATIONS WILL BE EMPLOYED AS BASIC DATA WHEN WE CONSIDER THE FUTURE POSSIBILITY OF FRESHWATER ACIDIFICATIONDUE TO ACID DEPOSITION AND ITS EFFECTS IN JAPAN.THE TENTATIVE CONCLUSIONS ARE: 1)VALUES OF PH LESS THAN 5.6 HAVE NOT BEEN OBSERVED SO FAR IN MAJOR RIVERS AND LAKES IN JAPAN,EXCEPT FOR THOSE AFFECTED BY VOLCANIC ACTIVITIES. 2)TENDENCIES OF PH VALUE DECREASE OVER LONG TERM IN MAJOR RIVERS AND LAKES IN JAPAN ALSO HAVE NOT BEEN OBSERVED SO FAR,EXCEPT FOR THOSE AFFECTED BY VOLCANIC ACTIVITIES.SOME RIVERS AND LAKES IN POPULATEDAREAS SEEM TO HAVE TENDENCIES OF ALKALIZATION,REFLECTING THE INCREASE OF ALGAL PHOTOSYNTHETIC ACTIVITIES. 3)FEW DATA ARE AVAILABLE TO EVALUATE THE ACIDIFICATION IN SMALLER RIVERS/LAKES OR THAT DURING VERY SHORT TERM. 4)ALSO FEW DATA ARE AVAILABLE TO PREDICT THE FUTURE POSSIBILITY OFSURFACE WATER ACIDIFICATION OCCURENCE IN JAPAN.THEREFORE,STUDIES WITH THE FIRST PRIORTY ON THE AQUATIC ENVIRONMENT AND ACID DEPOSITION SHOULDBE ON COLLECTION OF DATA AND DEVELOPMENT OF TECHNOLOGY AVAILABLE TO ESTIMATE THE FUTURE POSSIBILITY OF ACIDIFICATION OCCURENCE IN JAPAN. 5)THERE ARE SEVERAL INORGANIC ACID RIVERS AND LAKES DUE TO VOLCANIC ACTIVITIES IN JAPAN.THEY SHOULD BE DISTINGUISHED AND THEIR DISTRIBUTION SHOULDBE DEFINED WHEN ACIDIFICATION DUE TO ACID DEPOSITION IS SURVEYED.

報告者

キーワード