低温科学 = Low Temperature Science;第80巻

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尾瀬ヶ原上田代池溏群の底質に対する洪水の影響

福原, 晴夫;永坂, 正夫;高野, 典礼;村田, 智吉;千賀, 有希子;藤原, 英史;野原, 精一

Permalink : http://hdl.handle.net/2115/85016
JaLCDOI : 10.14943/lowtemsci.80.25
KEYWORDS : 高層湿原;池溏堆積物;灰分;泥炭;気候変動;mire;pool sediment;ash;peat;climatic changes

Abstract

尾瀬ヶ原上田代の39池溏,中田代5池溏より堆積物コアを採取し,目視により4層に分け,タイプ分けを行った.最表層のSsはFe含量が比較的高く,Bsは最も灰分量が高く,Fe含量も高く,Dsはこれらの中間的な灰分量,Fe含量を示した. Psは有機物を多量に含み,灰分量,Fe含量共に最も低かった.Bsは洪水による河川運搬物を含む層と推定した.コアは8タイプに分けられ,タイプSDPが最も多く(36%),次いでタイプSP(20%)であった.表層10cm の全灰分量は11.54-154.43(mg cm-3)を示した.全灰分量の高い池溏はFe含量も高く,池溏水のpHも高かった.全灰分量,63μm未満灰分量,Fe含量,池溏水のpHは,洪水影響大と推定した池溏で高かった.尾瀬ヶ原上田代のいくつかの池溏底質には洪水の影響が及んでいることが示唆された.
Sediment cores were sampled at 39 pools in the Kamitashiro and 5 pools in the Nakatashiro at the Ozegahara mire. Four layers were identified in the sediments by visual observation, Ss; at the outermost layer with high Fe contents, Bs; brown sediments with the highest ash content containing sand and silt, Ds; dark reddish-brown sediments with an intermediate range of ash and Fe contents, Ps; peat sediments. Cores were classified to eight types by the order of layers. Total ash contents of 0-10 cm cores ranged from 11.54 to 154.43 (mg cm-3), correlating positively with Fe contents and pool water pH. The sediments of FFPools (frequently flooded pool) indicated higher contents of total ash, below 63 μm ash and Fe than those of OFPools (occasionally flooded pool), showing the effect of floods on pool substrates. The higher pH values of pool water were also observed in the FFPool. Some pools at the Kamitashiro in the Ozegahara mire have been influenced by floods.

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