『Abstract
Spatial variation of phosphorus fractions in bottom sediment,
pore water and overlying water in three shallow eutrophic lakes,
Nishiura, Kitaura and Sotonasakaura, Japan, and the contributions
of the fractional P to mobilization of phosphorus from sediment
were examined in this study. The vertical distributions of dissolved
inorganic phosphorus (DIP) concentrations in overlying and pore
water differed with lake and sampling site. In particular, DIP
was high in pore water in the surface layer of the sediment for
the middle to downlake areas of Lake Kitaura. DIP release flux
calculated from a gradient of the concentrations at the sediment
- water interface was high compared with other sites. The distribution
of fractional P content in sediments was highly variable. The
citrate - dithionite - bicarbonate - non-reactive phosphorus (CDB-NRP)
fraction, in particular, differed greatly among the three lakes.
According to correlation in the ratios between CDB-NRP and loss
on ignition, sediments of these lakes were classified in three
clusters. The CDB-NRF fraction was suggested to play a role in
DIP release from sediment. The possibility of nitrate concentration
playing a role in the control of DIP release was considered.
Keywords: Phosphorus; P fractions; Sediment; P release rate; Lake
eutrophication』
Introduction
Materials and methods
Study site
Sediment and overlying water sampling and analysis
Sediment core sampling
Overlying water analysis
Phosphorus fractionation in sediment
Statistical analysis
Results and discussion
Basic properties of bottom sediments
Vertical distributions of phosphorus concentrations in overlying
and pore water
Distribution of fractional phosphorus content in bottom sediment
Fractional phosphorus content and release potential
Conclusions
Acknowledgments
References
| 堆積物コア試料と水試料 | |||
| 水試料 |
計量 濾過（0.45μm） |
DTP & DIP | |
| 堆積物コア試料 |
薄切り（スライス） 計量 |
||
| 薄切りした堆積物 |
計量 遠心分離〔3000rpm（1430G）、20分間〕 |
||
| 孔隙水 | DTP & DIP | ||
| 残った堆積物 |
計量 乾燥（105℃、2時間） 計量（含水率） |
||
| 乾燥堆積物 |
粒径測定 強熱（550℃、2時間） 計量（強熱減量） |
||
| リンの分別 |
0.22M Na3C6H5O7・H2O（クエン酸ナトリウム） 0.11M NaHCO3（炭酸水素ナトリウム） Na2S2O4（亜ジチオン酸ナトリウム） （抽出：85℃、30分間） |
||
| 抽出試料 |
CDB-RP（Fe-P） CDB-NRP（Org.-P） |
||
| 残渣 |
1M NaOH （抽出：振とう、25℃、16時間） |
||
| 残渣 | |||
| 抽出試料 |
NaOH-RP（Al-P） NaOH-NRP（Org.-P） |
||
| 残渣 |
2M HCｌ （抽出：100℃、30分間） |
||
| 残渣 | |||
| 抽出試料 |
HCｌ−RP（Ca-P） HCｌ−NRP（Org.-P） |
||
| 残渣画分 | |||
※リンの抽出分析法は、主にWilliams et al.（1971；1976；1980）による。