『Abstract
A sequential extraction method (SEDEX) has been developed to
separately quantify five sedimentary P reservoirs: loosely sorbed
P; ferric iron-bound P; authigenic carbonate fluorapatite + biogenic
apatite + CaCO3-associated P; detrital apatite
P; and organic P. The SEDEX method successfully separates two
of the main categories of authigenic phosphate phases called upon
most often as sedimentary sinks for diagenetically mobilized P:
ferric oxyhydroxide-associated P and authigenic carbonate fluorapatite
(CFAP). It offers a means for separating authigenic CFAP from
detrital apatite of igneous or metamorphic origin. The importance
of this distinction is that CFAP represents an oceanic sink for
reactive P, whereas detrital apatite does not. In addition, a
means for reversing secondary adsorption of P onto residual solid
surfaces during extraction has been developed.
Extensive standardization of the SEDEX method for application
to marine sediments has been performed with analogs for naturally
occurring phosphatic phases.』
(Introduction)
Acknowledgments
Development and evaluation of the SEDEX method
General strategy
Standardization experiments: Design and procedure
Reproducibility of the SEDEX method
Comparison of SEDEX to other methods for determining solid-phase
P concentration
Analysis of supernatant solutions
Results and discussion
Standardization experiments
Reproducibility of the SEDEX method
Comparison of SEDEX to other methods for determining solid-phase
P concentration
Conclusions
References
ステップ | 抽出剤 | 抽出相 | 反応* |
T |
1モルMgCl2(塩化マグネシウム) (pH 8) |
交換性またはゆるく吸着したP | MgPO4-錯体の生成および(または)Cl-による質量作用置換 |
U |
0.30モルNa3-citrate(クエン酸ナトリウム) 1.0モルNaHCO3(炭酸水素ナトリウム) (pH 7.6) citrate bicarbonate solution〔クエン酸塩炭酸水素塩(重炭酸塩)溶液〕45ミリリットル中にNa-dithionite(亜ジチオン酸ナトリウム)1.125グラム |
易還元性または反応性第二鉄-結合〔鉄結合P〕 | 亜ジオン酸によるFe3+の還元およびクエン酸による続いてのキレート化 |
V | acetic acid(酢酸)でpH 4に緩衝した1モルNa-acetate(酢酸ナトリウム) | CFAP+生物起源hydroxyapatite(ハイドロキシアパタイト)+CaCO3-結合〔自生アパタイト+生物起源アパタイト+CaCO3-結合P〕 | 適度に低いpHでの酸溶解および(または)酢酸によるCa2+のキレート化 |
W | 1モルHCl(塩酸) | FAP〔砕屑アパタイト+その他の無機P〕 | 酸溶解 |
X |
550℃で灰化 1モルHCl(塩酸) |
有機P |
550℃での乾燥酸化 灰化した残渣の1モル塩酸抽出 |
* 続くステップUとVのMgCl2洗浄に対する反応メカニズムはステップTに対して説明されているとおりである。;続くステップT〜VのH2O洗浄によって、次の主要な抽出剤が加えられる前に残留溶液はすべて置換される。 |