title: Photochemical cleaving of allochthonous organic-metal complexes contributes to phosphorus immobilization in surface waters.
abstract: The photochemical transformation of terrestrial dissolved organic carbon (DOC) in surface waters exposed to UV radiation causes the precipitation of metal (Al and Fe) bearing complexes with high phosphorus sorption capacities. To better elucidate this process, a series of laboratory experiments was performed with stream and river waters with pH range from 3.5 to 8.2 and concentrations of dissolved reactive phosphorus from 2 to 142 μg L-1. Samples were filtered (0.4 μm) and UV (350 nm) irradiated for 24 h at 68 W m-2, i.e. under conditions equivalent to ∼2 summer days of natural solar radiation. Irradiated samples and dark controls were then spiked with33P-phosphate and the kinetics of P adsorption on freshly formed particles was determined after separation by ultracentrifugation. Up to 68% of the added P was removed from the solution within 48 h of the spike. The P sorption was pH dependent, with the maximum sorption ability at pHs of 6-7. We hypothesize that this process can importantly contribute to the immobilization and lower bioavailability of P in the inlet areas of (especially circum-neutral) lakes due to the intensive photochemical degradation of allochthonous DOC-metal complexes.
authors.affiliation: Biology Centre of the Czech Academy of Sciences, v.v.i, Institute of Hydrobiology and Soil & Water Research Infrastructure, Na Sadkach 7, Ceske Budejovice, 370 05, Czech Republic; University of South Bohemia in Ceske Budejovice, Faculty of Science, Branisovska 1760, 370 05, Czech Republic. Electronic address: porcal@hbu.cas.cz.
authors.forename: Petr
authors.initials: P
authors.lastname: Porcal
authors.affiliation: University of South Bohemia in Ceske Budejovice, Faculty of Science, Branisovska 1760, 370 05, Czech Republic.
authors.forename: Kristýna
authors.initials: K
authors.lastname: Frejlachová
authors.affiliation: Biology Centre of the Czech Academy of Sciences, v.v.i, Institute of Hydrobiology and Soil & Water Research Infrastructure, Na Sadkach 7, Ceske Budejovice, 370 05, Czech Republic.
authors.forename: Jiří
authors.initials: J
authors.lastname: Kopáček
authors.affiliation: Biology Centre of the Czech Academy of Sciences, v.v.i, Institute of Hydrobiology and Soil & Water Research Infrastructure, Na Sadkach 7, Ceske Budejovice, 370 05, Czech Republic.
authors.forename: Jiří
authors.initials: J
authors.lastname: Nedoma
authors.affiliation: University of South Bohemia in Ceske Budejovice, Faculty of Science, Branisovska 1760, 370 05, Czech Republic.
authors.forename: Tereza
authors.initials: T
authors.lastname: Šavrdová
mesh_terms: D000327:Adsorption; D000535:Aluminum / Q000737:chemistry; D005618:Fresh Water / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D007501:Iron / Q000737:chemistry; D008670:Metals / Q000737:chemistry*; D010758:Phosphorus / Q000032:analysis / Q000737:chemistry*; D055668:Photochemical Processes; D045483:Rivers / Q000737:chemistry; D014867:Water / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000737:chemistry
chemical_list: D008670:Metals; D014874:Water Pollutants, Chemical; D014867:Water; D010758:Phosphorus; D000535:Aluminum; D007501:Iron
keywords: Aluminum; DOM; Iron; Phosphorus; Photodegradation