『Abstract
　The amounts and forms of potentially mobile P in surface sediments from two lakes, Volvi and Koronia, located in Northern Greece were evaluated using a sequential chemical extraction. Five sedimentary P reservoirs were separately quantified: loosely sorbed P (NH4Cl-P); iron associated P (BD-P); calcium bound P (HCl-P); metal oxide bound P (NaOH-P) and residual P (organic and refractory P). Samples were taken in two seasons and the average concentration of the fractions of phosphorus were calculated. The results indicated that the TP content and chemically extractable phosphorus in the sediments of Koronia Lake were higher than those of Volvi Lake. Sediment TP was also strongly and positively correlated with sediment Fe. Fine-sized sediments exhibited significantly higher concentrations for both lakes than the sand fraction. The P in the surface sediment mainly consisted of HCl-P and Res-P, while NH4Cl-P and BD-P only constituted a minor part. The rank order of the different P extracts was the same for the two lakes and was Residual-P＞HCl-P＞NaOH-P＞BD-P＞NH4Cl-P.

Keywords: lake sediment; phosphorus; sequential fractionation』

1. Introduction
2. Materials and methods
　2.1. Site description
　2.2. Sediment samples and procedure
3. Results and discussion
4. Conclusions
References

図１．　本研究で用いた連続抽出法．（元は図）
Psenner et al.(1984)による連続抽出法を主とし、Hupfter et al.(1995)による方法を一部加えたもの

連続抽出の流れ	抽出剤など	分画リン
堆積物試料（各画分の残渣が次へ）
画分１：中性でのNH4Cl抽出リン	25 mlの1M NH4Cl、 pH 7で2時間	NH4Cｌ−P	ゆるく吸着したP
画分２：バッファーした亜ジチオン酸（dithionite）抽出リン（25℃）	0.11M Na2S2O4/NaHCO3、 1時間	BD-P	Fe-P
画分３：NaOH抽出リン	0.1M NaOH、 16時間	NaOH−ｒP	“Al-P”
画分４：HCｌ抽出リン	0.5M HCｌ、 16時間	HCｌ−P	Ca-P
画分５：残渣リン		Residual-P	（計算された）“Res-P”