The importance of catchment and lake processes in the phosphorus budget of a large lake.
Total phosphorus (P) river inputs and lake concentrations for the Neagh system in Northern Ireland are compared from the period 1974-1997. The main routes of P transfer between the lake water and the sediment are settlement of abiotic particles and planktonic diatoms, summer sediment release and re-sedimentation in the last months of the year. The annual river loading to the lake varied between 0.7 and 1.8 g P m(-2), and sediment release can be as much as 1.4 g P m(-2). A simple model evaluated the effect of sediment-water exchanges on the phosphorus available for spring phytoplankton growth. It showed that re-sedimentation of released P and washout over the winter greatly mitigated its effect. Correlation analysis demonstrated that the very large summer releases of sediment P were not related directly to the spring inputs from diatom settlement. No long-term trends in P release were seen.
Department of Agricultural and Environmental Science, The Queen's University of Belfast, UK. chris.gibson@dardni.gov.uk
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Wang
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Foy
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Lennox
D005618:Fresh Water / Q000737:chemistry; D019015:Geologic Sediments; D009660:Northern Ireland; D010758:Phosphorus / Q000032:analysis; D012621:Seasons
D010758:Phosphorus