Degradation rates of organic phosphorus in lake sediment

Abstract

Phosphorus (P) binding groups were identified in phytoplankton, settling particles, and sediment profiles by 31 P NMR spectroscopy from the Swedish mesotrophic Lake Erken. The 31 P NMR analysis revealed that polyphosphates and pyrophosphates were abundant in the water column, but rapidly mineralized in the sediment. Orthophosphate monoesters and teichoic acids degraded more slowly than DNA-P, polyphosphates, and P lipids. Humic acids and organic acids from phytoplankton were precipitated from the NaOH extract by acidification and identified by 31 P NMR spectroscopy. The precipitated P was significantly more recalcitrant than the P compound groups remaining in solution, but does not constitute a major sink of P as it did not reach a stable concentration with depth, which indicates that it may eventually be degraded. Since P also precipitated from phytoplankton, the origin of humic-P can not be related solely to allochthonous P.

Characteristics of phosphorus components in the sediments of main rivers into the Bohai Sea

“…So in the five rivers, the Yongdingxin River and the Ziya River had the high risk of eutrophication. The pyro-P and polyphosphate were the other two IP compositions by 31 P NMR, and can be used directly by aquatic organisms, therefore they are potential risk sources of algal blooms (Hupfer et al, 2004;Reitzel et al, 2007). What's more, the pyro-P has also reflected the human impact.…”

Organic matter and pH affect the analysis efficiency of 31 P-NMR

“…Therefore, the organic matter most likely originates from the decomposition of aquatic plants when the TC/TN ratio is under 7. When the ratio of TC/TN is greater than 20, terrestrial input is the source of the organic matter in the freshwater sediment (Chen and Wan, 2000;Reitzel et al, 2007).…”

The Chemical Nature of Phosphorus in Subtropical Lake Sediments

“…Although organic P can constitute 30-80 % of the P in lake sediments (Williams and Mayer 1972;Boström et al 1982), it has been relatively under-studied compared to inorganic phosphate (Mitchell and Baldwin 2005). In particular, organic P occurs in a variety of forms that behave differently in the aquatic environment (McKelvie 2005), so information on the relative abundance of P compounds in sediments is of importance for understanding P dynamics in lakes (Reitzel et al 2007;Turner and Weckström 2009;Zhu et al 2013). However, organic P is conventionally determined by sequential fractionation and detection by molybdate colorimetry Condron and Newman 2011).…”

“…Recent studies have determined the chemical nature of sediment organic P by alkaline extraction and solution 31 P nuclear magnetic resonance (NMR) spectroscopy, which classifies organic P into a series of compounds and functional groups, including phosphomonoesters, phosphodiesters (e.g., DNA, lipids), and phosphonates (e.g., Carman et al 2002;Ahlgren et al 2005;Reitzel et al 2007;Zhu et al 2013). The technique also identifies inorganic phosphates, including orthophosphate, pyrophosphate, and polyphosphate (e.g., Hupfer et al 2004).…”

“…Moreover, the relative importance of the various P forms in sediments will depend on sediment composition, sedimentation rate, diagenesis, and physicochemical conditions (Lopez and Morgui 1993;Gonsiorczyk et al 1998). Of significance is the fact that differences in the abundance of P compounds with depth in lake sediments can provide information on mineralization rates and the contribution of the various compounds to the internal P load (Ahlgren et al 2005;Reitzel et al 2007).…”