Photochemical cleaving of allochthonous organic-metal complexes contributes to phosphorus immobilization in surface waters. (January 2017)

• Record Type: Journal Article
• Authors: Porcal, Petr; Frejlachová, Kristýna; Kopáček, Jiří; Nedoma, Jiří; Šavrdová, Tereza
• Is Part Of: Chemosphere. Volume 167(2017)
• Page Start: 374
• Page End: 381
• Publication Date: 2017-01
• Subjects: Photodegradation -- DOM -- Phosphorus -- Aluminum -- Iron; DOM dissolved organic matter -- DOC dissolved organic carbon -- POC particulate organic carbon -- Δ;33P measured decrease in 33P activity -- Δ;33PNET net 33P activity retention -- At modeled decrease in 33P activity -- Amax modeled maximum decrease in 33P activity -- Δ;Amax retained modeled 33P activity; Pollution -- Periodicals; Pollution -- Physiological effect -- Periodicals; Environmental sciences -- Periodicals; Atmospheric chemistry -- Periodicals; 551.511
• DOI: 10.1016/j.chemosphere.2016.10.022
• Languages: English
• ISSNs: 0045-6535

Abstract

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 with 33 P-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. Highlights: Photochemical degradation of dissolved organic matter affects metal complexation. Photochemically formed metal particles support phosphorus sorption. This process reduces the phosphate mobility and bio-availability in waters.