Photochemical degradation of dissolved organic matter reduces the availability of phosphorus for aquatic primary producers

0487076 - BC 2018 RIV GB eng J - Journal Article
Porcal, Petr - Kopáček, Jiří
Photochemical degradation of dissolved organic matter reduces the availability of phosphorus for aquatic primary producers.
Chemosphere. Roč. 193, FEB (2018), s. 1018-1026. ISSN 0045-6535. E-ISSN 1879-1298
R&D Projects: GA ČR GA15-09721S
Institutional support: RVO:60077344
Keywords : photochemistry * phosphorus * dissolved organic matter * aluminum * iron
OECD category: Environmental sciences (social aspects to be 5.7)
Impact factor: 5.108, year: 2018

In situ experiments were done to determine the effects of the photochemical degradation of dissolved organic matter (DOM) and subsequent formation of particulate matter on dissolved phosphorus (P) concentrations in surface waters. Filtered (1.2 or 0.4 mu m) headwaters (DOM of 8.1-26 mg L-1, P of 2243 mu g L-1) were exposed to solar radiation in quartz bottles located 5 cm below the water surface for 710 days. Dark controls were wrapped in aluminum foil. After incubation, particulate organic carbon (POC) and particulate phosphorus (PP) were determined in both the filtrate and newly formed particles. The results revealed increasing concentrations of PP and POC in exposed samples with increasing exposure time (cumulative irradiation energy). At the end of experiments, PP concentrations were from 5 to 20 mu g L-1 in the exposed samples. Based on an enumeration of bacteria in the samples, we estimated the contribution of biotic and abiotic processes to the PP production. The abiotic PP formation ranged from 56 to 83% and 50-95% of the total PP in the exposed and control samples, respectively. The remainder was assumed to be bacterial P uptake. Despite the overlapping intervals, biotic and abiotic PP productions were usually higher in exposed samples than in controls. The PP and POC production was affected by the properties of DOM, such as its humic content and freshness index. We hypothesize that the observed immobilization of dissolved P in bacteria and on photochemically-formed particles can contribute to a P limitation of primary production in headwater environments that receive waters rich in soil DOM.
Permanent Link: http://hdl.handle.net/11104/0281759