『Abstract
　We evaluated the P sources (point, diffuse), through a nested watershed approach investigating the Blaise (607 km²), dominated by livestock farming, the Grand Morin (1202 km²), dominated by crop farming, and the Marne (12,762 km²), influenced by both agriculture and urbanization. Fertilizers account for the main P inputs (＞60％) to the soils. An agricultural P surplus (0.5-8 kg P ha^-1 year^-1) contributes to P enrichment of the soil. The downstream urbanized zone is dominated by point sources (60％, mainly in dissolved forms), whereas in the upstream basin diffuse sources dominate (60％, mostly particulate). Among the diffuse sources (losses by forests, drainage and runoff), losses by runoff clearly dominate (＞90％). P retention in the alluvial plain and the reservoir represents 15-30％ of the total P inputs. Dissolved and particulate P fluxes at the outlet of the Marne are similar (340 and 319 tons of P year^-1, respectively). The Blaise sub-basin receives P from point and diffuse sources in equal proportions, and retention is negligible. The Grand-Morin sub-basin, influenced by the urbanized zone receives, as does to the whole Marne basin, 60％ of P inputs as point sources. The total particulate phosphorus in suspended sediments averaged 1.28 g P kg^-1, of which about 60％ are inorganic and 40％ organic P. Particulate phosphorus exchangeable in 1 week and 1 year (³²P isotopic method) accounts for between almost 26％ and 54％ of the particulate inorganic phosphorus in the suspended sediment and might represent an important source of dissolved P, possibly directly assimilated by the vegetation.

Key words: Diffuse and point sources; Dissolved and particulate phosphorus; Eutrophication; Exchangeability』

Introduction
Materials and methods
　Site description and sampling
　Sample preparation and P analyses
　Determination of the amount of P ions exchanged between suspended sediment and solution
　Statistical analyses
　Phosphorus mass balance calculations at the outlets of the sub-basins
　Point sources in the Marne watershed
　Retention of phosphorus in the flood-plain
　Retention of phosphorus in the Marne reservoir
　Diffuse sources calculations
　Agricultural phosphorus budget
　Atmospheric depositions
　Total phosphorus stock in the soil
Results
　Agricultural phosphorous budget
　Total P stock in soils
　P budget: quantification of the proportion of diffuse sources vs. point sources
　Phosphorous content and exchangeability in re-suspended sediments
Discussion
　Agricultural phosphorous budget
　Specific phosphorus loss from runoff and leaching
　Phosphorous budget at hydrographic network scale
　Exchangeability of particulate P
Acknowledgements
References

Figure 6. Phosphorus budget (a) in the Marne basin (b) in the Grand-Morin sub-basin and (c) in the Blaise sub-basin (fluxes in tons P year-1). Percentages of P point sources vs. P diffuse sources, and of dissolved P vs. particulate P are indicated in the figure. The underlined results of runoff are calculated by difference (See Method section). Nemery（最初のeの頭に´） et al.(2005)によるPhosphorus budget in the Marne Watershed (France): urban vs. diffuse sources, dissolved vs. particulate formsから