報告書番号

285049

タイトル（和文）

土壌へのヒ素とホウ素の吸着特性

タイトル（英文）

ADSORPTION CHARACTERISTICS OF ARSENIC AND BORON BY SOIL

概要 （図表や脚注は「報告書全文」に掲載しております）

石炭灰から溶出する微量元素のうち，環境保全上注目されているヒ素（三価）とホウ素について土壌への吸着特性を調べ，次の結果を得た。（１）ヒ素とホウ素の吸着量は，溶液のｐＨの影響を大きく受け，ヒ素では８付近，ホウ素では８～９において最大吸着量を示した。（２）ヒ素とホウ素の吸着等温線は，それぞれラングミュア型およびフロインリッヒ型の吸着等温式に適合した。また，溶液中のヒ素とホウ素が低濃度の場合には，いずれもヘンリー型の吸着等温式に適合した。（３）ヒ素とホウ素の吸着量は，それぞれは土壌に含まれるＦｅ酸化物や水和酸化物量およびアルミニウム水和酸化物やアロフェン量の違いにらよって変動した。（．）石炭灰埋立地を想定した鉛直一次元の非定常拡散移流モデルにより，土壌内での石炭灰溶出水の浸透過程におけるヒ素とほホウ素の吸着と移動について解析した。

概要 （英文）

IN ORDER TO OBTAIN BASELINE DATA CONCERNING THE SURFACE AND GROUND WATER POLLUTION CAUSED BY COAL ASH DISPOSAL, LABORATORY EXPERIMENTS WERE PERFORMED TO STUDY THE CHARACTERISTICS OF ADSORPTION BY SOIL OF ARSENIC AND FORM. THE MAIN RESULTS ARE AS FOLLOWS : (1)ARSENIO (3) AND BORON ADSORPTION OF SOIL WAS STRONGLY DEPENDENT ON PHWITH ADSORPTION MAXIMA AT PH 8 AND 8-9, RESPECTIVELY. (2)ARSENIC (3) AND BORON ADSORPTION OF SOIL OVER THE ENTIRE CONCENTRATION RANGES INVESTIGATED WAS DESCRIBED BY THE LANGMUIR ADSORPTION ISOTHERM AND THE FREUNDLICH ADSORPTION ISOTHERM, RESPECTIVELY. THE HENRY ADSORPTION ISOTHERM WAS ALSO APPLICABLE OVER THE LOWER CONCENTRATION RANGED OF ARSENIC (3) AND BORON. (3)ARSENIC (3) AND BORON ADSORPTION ON SOIL IS CONTROLLED MAINLY BY THE CONTENTS OF EXTRACTABLE FE OXIDES AND HYDROXIDES FOR ARSENIC(3) AND BY THE CONTENTS OF EXTRACTABLE AL HYDROXIDES AND ALLOPHANE (AMORPHOUS ALUMINUM SILICATES) FOR BORON. (4)ADSORPTION AND MOVEMENT OF ARSENIC (3) AND BORON DURING THE INFILTRATION OF COAL ASH LEACHATE IN SOIL LAYER WERE INVESTIGATED BY MEANS OF THE UNSTEADY-STATE, ONE-DIMENSIONAL CONVECTIVE-DIFFUSIVE MASS TRANSPORT MODEL. THIS MODEL IS VERY USEFULFOR EVALUATION AND PREDICTION OF THE CONTAMINATION OF GROUND WATER BY TRACE ELEMENTS SUCH AS ARSENIC (3) AND BORON LEACHED AT COAL ASH DISPOSAL SITES.

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