『Abstract
　The influence of reagent concentration, extraction time, and lithological composition of sediment samples on the concentration and composition of the extracted phosphorus fractions was examined. Good reproducibility was achieved for dry samples. The proportions of P fractions were found to depend on the texture of lake sediments, which speaks about an essential role of cohesivity of sediments and sorption of phosphorus in the sediment flocs. The NaOH-P concentration was higher in the samples with a high silt content. Extraction duration did not influence the concentration of metal oxide bound P extraction with a low (0.1 M) NaOH concentration. The total P concentration showed a significant positive correlation with silt (r = 0.897), organic matter (r = 0.564), and carbonate content (r = 0.546). Sedimentary inorganic P in the studied sediments consisted mainly of HCl-P, while NaOH-P and NH4Cl-P constituted only a minor part.

Key words: lake sediments; phosphorus fractions; lithological composition.』

Introduction
Methods
　Samples
　Analyses
Results
Discussion
Conclusions
Acknowledgements
References

図1．リン分別法：副試料についての全P（P-tot）とアパタイトP（HCｌ−P）とゆるく結合したP（NH4Cl-P）と金属酸化物結合P（NaOH-P）の4種類の浸出法（Hieltjes and Lijklema,1980を修正）．（元は図）

試料 （４種類）	方法	画分
0.1 g	加熱（burning）550℃で3時間、 残渣：5 mLの0.5M HCｌ（塩酸）を加え、室温で48時間、 抽出⇒	P-tot （全P）
0.1 g	5 mLの0.5M HCｌ（塩酸）を加え、室温で24時間、 抽出⇒	HCl-P （アパタイトP）
1 g	10 mLの1M NH4Cｌ（塩化アンモニウム）を加え、室温で2時間振とう、 抽出⇒ 残渣：10 mLの1M NH4Cｌ（塩化アンモニウム）を加え、室温で2時間振とう、 抽出⇒	NH4Cｌ-P （ゆるく結合したP）
1 g	10 mLの0.1M NaOH（水酸化ナトリウム）を加え、室温で17時間振とう、必要ならH2SO4（硫酸）でフミン酸（humic acid）を抽出、 抽出⇒	NaOH-P （金属酸化物結合P）