Phosphite in Sedimentary Interstitial Water of Lake Taihu, a Large Eutrophic Shallow Lake in China

Abstract

The seasonal occurrence and distribution of phosphite (HPO3(2-), P) in sedimentary interstitial water from Lake Taihu was monitored from 2011 to 2012 to better understand its possible link to P cycle in the eutrophic shallow lake. Phosphite concentrations ranged from < MDL to 14.32 ± 0.19 μg P/kg with a mean concentration of 1.58 ± 0.33 μg P/kg, which accounts for 5.51% total soluble P (TSP(s)) in surficial sediments (0-20 cm). Spatially, the concentrations of sedimentary phosphite in the lake's northern areas were relatively higher than those in the southern areas. Higher phosphite concentrations were always observed in seriously polluted sites. Generally, phosphite in the deeper layers (20-40 cm and 40-60 cm) showed minor fluctuations compared to that in the surficial sediments, which may be associated with the frequent exchange at the sediment-water interface. Phosphite concentrations in surficial or core sediments decreased as spring > autumn > summer > winter. Higher phosphite levels occurred in the areas with lower redox (Eh), higher P contents, and particularly when metal bonded with P to form Al-P(s) and Ca-P(s). Phosphite may be an important media in the P biogeochemical cycle in Lake Taihu and contribute to its internal P transportation.

Redox chemistry in the phosphorus biogeochemical cycle

“…The oxidation-reduction potential (Eh) and the percentage of reduced P are negatively correlated (R = 0.24 for hypophosphite and 0.41 for phosphite), as are pH and reduced P (R = 0.51 for hypophosphite and 0.57 for phosphite). These correlations are consistent with studies of phosphite in Lake Taihu (11). These results suggest that reduced P compounds are common to many environments in the hydrosphere, although given the limited geographical scope of the present study, extending these results to estimate the global quantity of reduced P is unreasonable.…”

“…Email: mpasek@usf.edu. most reduced P, although this is not universally true (11). The oxidation-reduction potential (Eh) and the percentage of reduced P are negatively correlated (R = 0.24 for hypophosphite and 0.41 for phosphite), as are pH and reduced P (R = 0.51 for hypophosphite and 0.57 for phosphite).…”

“…However, the reduced P compounds phosphite, hypophosphite, and phosphine are known to occur in nature (Fig. 1), and have origins that range from nonbiological (8,9) to biological (10,11). Phosphite and hypophosphite can be used by many microorganisms as sole P sources, suggesting there must be an environmental source of these compounds (12).…”

Do NH 3 and chemical oxygen demand induce continuous release of phosphorus from sediment in heavily polluted rivers?

“…The Chinese government is very concerned about controlling pollution inputs, and so regulations and projects have been implemented, such as the Chinese National Water Pollution Control and Technology Management Project. Despite recent sustained efforts to improve water quality, eutrophication still persists in rivers in semi-arid regions, and the water quality has deteriorated to such a degree that it is not suitable for any use (Han et al, 2013). Although external P inputs to rivers have been decreasing, internal release of P from sediment provides sufficient reactive P to sustain harmful algal blooms (Read et al, 2014).…”

Phosphorus speciation of sediments from lakes of different tropic status in Eastern China

“…The Chinese government is also very concerned about controlling pollution inputs, and so regulations and projects have been implemented, such as the Chinese National Water Pollution Control and Technology Management project. Despite recent sustained efforts to improve water quality, eutrophication still persists in some lakes, and the water quality has deteriorated to such a degree that it is not suitable for use (Han et al 2013). Although external P inputs to lakes have been decreasing, internal release of P from sediment provides sufficient reactive P to sustain the harmful algal blooms (Read et al 2014).…”