Forms of Particulate Phosphorus and the Sediment Carbon/Nitrogen Ratio as Indicators of Phosphorus Origins in Aquatic Systems

Abstract

Abstract An evaluation has been carried out on the composition of sediment from a number of different environments in Lake Geneva basin (Switzerland) and compared to Lake Erie sediment, specifically on the forms of phosphorus and the C/N ratio. Compositional features and progressive spatial and temporal changes in composition have been used to define origins of phosphorus and organic matter and to elucidate both river and lake processes. Lake Geneva bottom sediment clearly represents a compositional continuum from the mixing of the mineralized product of primary production (C/N ratio 8–10) in the water column with allochthonous sediment derived predominantly from the upper Rhone River (C/N ratio 12–17). Analysis of the sediment in the effluent of a number of sewage treatment plants gave very high levels of phosphorus, particularly non-apatite inorganic phosphorus and C/N ratios from 6.7 to 9. Changes in composition in the sediments of storm driven rivers were related to the variable influences of point and diffuse sources as they respond to climatic variation and to land use and human population in the basins.