『Abstract
　Previous attempts to evaluate ocean P mass balance and residence time have utilized sequential extraction techniques to isolate and analyze P associated with Fe and Mn oxides and oxyhydroxides, authigenic minerals, detrital, and organic phases. However, in many oceanographic settings, diatoms are the primary producers, and the traditional sequential extraction protocol does not result in complete dissolution of diatom frustules and may not liberate all of the opal intrinsic P associated with the frustules themselves. By adding an opal dissolution step to the end of the extraction protocol, additional P was liberated from the sediments, suggesting that there is an opal-associated P fraction that likely contributes to total reactive P concentrations. In opal-rich sediments, the opal-associated P fraction averages as much as 50-60％ of extractable P, and total reactive P concentrations are often more than double when the opal-associated P fraction is included. The presence of opal-intrinsic P potentially has significant implications for ocean P mass balance and residence time of P in the oceans. For example, P burial has possibly been underestimated in settings dominated by diatoms. Additionally, consideration of a significant sedimentary opal-P component suggests that the residence time of P in the oceans may be even shorter than currently suspected.』

1. Introduction
2. Study sites
3. Methods
4. Results and discussion
5. Phosphorus accumulation rates and opal-associated P
6. Implications
7. Conclusions
Acknowledgments
References

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表2　抽出ステップ（Mortlock and Froelich, 1989とRuttenberg, 1992とAnderson and Delaney, 2000から）

ステップ	試薬	分離されたリン成分
酸化物に伴った	10mL CDB溶液（6時間）（0.22Mクエン酸ナトリウム、1M炭酸水素ナトリウム、0.13M亜ジチオン酸ナトリウム）、 10mL 1M塩化マグネシウム（2時間）、 10mL水（2時間）	吸着したおよび還元可能なあるいは反応しやすい鉄結合P（Adsorbed and reducible or reactive Fe-bound P）
自生	酢酸でpH 4に緩衝した10mL 1M酢酸ナトリウム、 10mL １M塩化マグネシウム（2時間）−2回、 10mL水（2時間）	炭酸フッ素燐灰石（Carbonate fluorapatite、CFA）、 生物起源水酸化燐灰石（biogenic hydroxy apatite）、 CaCO3結合P
砕屑性	10mL １M塩酸（16時間）	砕屑性P（Detrital P）
有機	1mL 50％（w/v）硝酸マグネシウム、 オーブンで低温乾燥、 550℃で灰化（2時間）、 10mL １M塩酸	有機P（Organic P）
オパールに伴った	10mL 1.5M水酸化ナトリウム（85℃、2時間）、 または、 10mL 1.5M水酸化ナトリウム（85℃、2時間）の後に10mL 2M炭酸ナトリウム（85℃、5時間）	オパールに伴ったP（Opal-associated P）
残渣（Residual）	5mL硝酸、4mLフッ化水素酸、1mL塩酸	続く抽出ステップで残留するP（P remaining following extraction steps）