Short-term variation in benthic phosphorus transfer due to discontinuous aeration/oxygenation operation

Abstract

The short-term dynamics of soluble reactive phosphorus (SRP) transport across the sediment surface in a brackish lake due to discontinuous aeration and oxygenation operations were investigated using laboratory and field experimental and analytical procedures. According to a laboratory incubation experiment using intact sediment cores, SRP release from the sediment was clearly suppressed by aeration, and substantial negative SRP transfer was observed during oxygenation treatment, while a positive value was observed for N 2 bubbled cores. A remarkable but impermanent increase in SRP release rate was observed within 1 or 2 days of discontinuing the aeration and oxygenation, respectively, and the release rate rapidly deceased to a quasi-steady value under N 2 bubbling conditions. An analytical model could quantitatively reproduce these laboratory experimental results for anoxic and aerated conditions, showing that this impermanent increase was attributable to the rapid release of accumulated SRP in the oxic surface layer of the sediment. Field experiments using an in situ oxygenator showed the same tendency as the laboratory experiments, but with much larger values of the benthic SRP transfer rate. Overall, the short-term dynamics of benthic SRP transport caused by discontinuous aeration and oxygenation are considered to be an important process for the phosphorus cycle in the field.

Effects of three iron material treatments on hydrogen sulfide release from anoxic sediments

“…The water samples, which were collected from the sampling site, were treated to minimize the effects of biochemical reactions during the incubation experiments. The water was first filtered using cellulose acetate membrane filters (0.45 μm pore size, 293 mm diameter, C045A293C, Advantec Co., Ltd, Tokyo, Japan), bubbled with N 2 gas to minimize the oxygen concentration, and carefully poured into the core to avoid sediment suspension (Inoue et al 2017). Thereafter, the iron materials were added to the cores in varying amounts (Table 1), and the cores were sealed to make them air-tight.…”

Thin-layer fine-sand capping of polluted sediments decreases nutrients in overlying water of Wuhan Donghu Lake in China

“…This process can continue for several decades, even after inputs of external nutrients from industrial and domestic wastewater discharge and agricultural runoff have stopped (Søndergaard et al 2003;Lukkari et al 2009). In contrast, when surface sediments are in an aerobic state, their increased potential to bind compounds may increase the flux of nutrients from the water column to sediments (Ekeroth et al 2016;Inoue et al 2017). To mitigate eutrophication of water bodies, many efforts have attempted to increase the potential of sediments to bind nutrients or to impede fluxes of nutrients from contaminated sediments to the water column (Jacobs and Förstner 1999;Zou et al 2017; Ehsani and Hayes 2018;Peng et al 2018).…”

Estimation of Changes in the Nutrient Release Rate from Sediments after a Tsunami by an Incubation Experiment

“…V is the volume of the overlying water, calculated by measuring the height of the overlying water of each core (Core 1: 19.4 cm, Core 2: 20.2 cm, Core 3: 19.4 cm, Core 4: 19.4 cm, Core 5: 18.5 cm, Core 6: 18.5 cm). Release rates were estimated by the sediment core incubation method [19] and the mathematical modeling method [16]. The core incubation method considers that the release from sediment leads to a change in concentration in the overlying water.…”

“…It is possible that PO 4 -P adsorbed on this ferric hydroxide and reduced the release rate [24]. As oxygen consumption advances in the sediment and becomes reductive, ferric hydroxide is reduced, the film dissipates and then desorption and release of the adsorbed PO 4 -P begins [17,19]. The precipitous increase in the release rate of PO 4 -P in the latter half of the experiment may have been caused by this phenomenon.…”