title: Factors influencing release of phosphorus from sediments in a high productive polymictic lake system.
abstract: Phosphorus (P) release rates from bottom sediments are high (20.6 mg/m(2)/day) in Dal Lake (India), a polymictic hyper-eutrophic lake. These gross release rates occur over a period of 72 days during summer only. Likewise, a net internal load of 11.3 tons was obtained from mass balance estimates. Significant proportion i.e. approximately 80% of 287.3 tons/yr of nitrate nitrogen (NO(3)-N) load is either eliminated by denitrification or gets entrapped for a short period in high macrophyte biomass of 3.2 kg/m(2) f.w., which eventually get decomposed and nitrogen (N) is released back. These processes result in low lake water NO(3)-N concentrations which potentially influence sediment phosphorus (P) release. Especially, nitrate nitrogen (NO(3)-N) <500 microg/L in the lake waters were associated with high P concentrations. Phosphorus was also observed to increase significantly in relation to temperature and pH, and it seems likely that release of phosphorus and ammonical nitrogen (NH(4)-N) depend on decomposition of rich reserves of organic matter (893 tons d.w. in superficial 10-cm bottom sediment layer). Lake P concentrations were significantly predicted by a multivariate regression model developed for the lake. This study describes significance of various lake water variables in relation to P-release from bottom sediments.
authors.affiliation: Research and Monitoring Division, Lakes and Waterways Development Authority, Nishat, Srinagar Jammu and Kashmir, India. solim_saba@yahoo.co.in
authors.forename: S U
authors.initials: SU
authors.lastname: Solim
authors.forename: A
authors.initials: A
authors.lastname: Wanganeo
mesh_terms: D005068:Eutrophication; D005618:Fresh Water / Q000737:chemistry*; D005843:Geography; D019015:Geologic Sediments / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D007194:India; D008903:Minerals; D009566:Nitrates / Q000032:analysis; D009584:Nitrogen / Q000032:analysis; D009930:Organic Chemicals / Q000032:analysis; D010758:Phosphorus / Q000032:analysis*; D000644:Quaternary Ammonium Compounds / Q000032:analysis; D013696:Temperature; D013997:Time Factors
chemical_list: D008903:Minerals; D009566:Nitrates; D009930:Organic Chemicals; D000644:Quaternary Ammonium Compounds; D010758:Phosphorus; D009584:Nitrogen