『(Abstract)
Phosphorus (P) accumulation and the risk of P release were studied
in the estuarine sediments of the Chaohu Lake Valley in Eastern
China. Rapid agricultural intensification has occurred in this
area since the 1980s, resulting in the extensive use of phosphate
fertilizers. This extensive use of phosphate has affected P processes
throughout the valley and resulted in the total phosphorus (TP)
contents in the substrates and surface sediments increasing from
374 to 537 mg/kg, on average. Of all the forms of P evaluated
in this study, residual P (Res-P) was present at the highest levels
and accounted for 19.8 - 74.0％ of the TP. Conversely, the lowest
contents were observed for KCl-extracted P (KCl-P), which accounted
for only 0.602％ of the TP. Additionally, aluminum/iron-bound P
(NaOH-Pi), which accounted for 16.0 - 53.1％ of the TP, was an
important factor that caused the TP to increase due to long-term
P fertilization. However, calcium-bound P (Ca-P) was maintained
at a relatively stable level. Furthermore, the degree of P saturation
(DPS) and the P-induced lake eutrophication risk index (ERI) were
investigated to determine the risk of release of P from the sediments.
The average DPS and ERI values were found to range from 3.92 -
21.4％ and from 12.6 - 33.6％, respectively. These results suggest
that almost half of the estuarine sediments posed a potential
risk of eutrophication. Moreover, these findings indicate that
estuarine sediments that have been enriched with P are likely
the sources of P that lead to the formation of algal blooms in
Chaohu Lake.
Keywords: Agricultural intensification; Chaohu Lake; Estuarine
sediments; Risk』
Abbreviations
1. Introduction
2. Materials and methods
2.1. Study area
2.2. Sample collection
2.3. Analytical methods
2.4. Statistical analysis
3. Results
3.1. Spatial-vertical distribution of TP and P fractions
in the estuarine sediments
3.2. Relationship between P and OM
3.3. Risk of P release from estuarine sediments
4. Discussion
4.1. P buildup in response to agricultural intensification
4.2. The risk of P release from estuarine sediments
5. Conclusions
Acknowledgements
References
※リンの分別法は、van Eckによる方法をMoore and Reddy（1994）が修正したものを用いている。