Role of organic phosphorus in sediment in a shallow eutrophic lake

Shinohara, Ryuichiro; Hiroki, Mikiya; Kohzu, Ayato; Imai, Akio; Inoue, Takanobu; Furusato, Eiichi; Komatsu, Kazuhiro; Satou, Takayuki; Tomioka, Noriko; Shimotori, Koichi; Miura, Shingo

doi:10.1002/2017wr020486

Cited by 21 publications

(5 citation statements)

References 58 publications

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“…An alternative explanation is that oxic conditions caused by the water level drawdown may have allowed adsorption of PO 4 3− onto the sediment solids, even if organic P had been mineralized. This explanation is consistent with the results of previous work, which have shown that mineralization of organic matter in the sediment plays a role in determining nutrient dynamics in the pore water where we collected the sediments in Lake Kasumigaura (Shinohara et al, 2017). However, the release of nutrients from sediments involves very complex processes that can result from a number of physical and biogeochemical mechanisms (Orihel et al, 2017).…”

Section: Discussionsupporting

confidence: 94%

Water‐level drawdowns can improve surface water quality and alleviate bottom hypoxia in shallow, eutrophic water bodies

et al. 2022

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Water‐level drawdowns are a management option for improving water quality in shallow, eutrophic lakes, but how much water levels should be reduced and what abiotic and biotic mechanisms can be expected to reduce the adverse effects of eutrophication are unclear. We conducted a study with two experimental pools (10 m wide, 30 m long, and approx. 2.5 m water depth) in a before‐after‐control‐impact design to examine whether water‐level drawdowns could influence surface water quality and bottom‐water conditions, as well as how physicochemical and biological variables contributed to improvements. In the experiment, we fertilised the pools to increase productivity and induce hypoxia, and then reduced water levels four times in increments of 0.5 m. Our experiment using high‐frequency sensors showed that water‐level drawdowns could decrease cyanobacterial blooms and alleviate hypoxia relatively quickly by changing physicochemical conditions. Water‐level reductions quickly increased bottom light illuminance, increased bottom‐water temperatures, and weakened stratification. The result was a dramatic increase in bottom‐water dissolved oxygen concentrations. Water‐level drawdowns also decreased the relative fluorescence of chlorophyll and phycocyanin, probably because of a decrease of internal nutrient loadings from sediment. Total nitrogen and NH4‐N concentrations in the water column decreased after water‐level reductions, and NH4‐N and PO4‐P concentrations in sediment pore waters were reduced in the water‐level treatment. Periphyton biomass did not change after the water‐level drawdowns. Water‐level manipulations increased the abundance of cyclopoids and calanoids but not large cladocerans. These biological processes responded slowly to water‐level drawdowns and are unlikely to have contributed to water quality improvement. Overall, the size of the water‐level reduction required to start changing water quality was 0.5–1.0 m. Our results suggested that a temporary reduction in water‐level of 20%–40% of the depth might help to suppress cyanobacterial blooms and hypoxia in shallow lakes, reservoirs, and agricultural ponds. Such water‐level management may help resolve conflicting demands for water and may be incorporated into management plans for flood control.

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Section: Discussionsupporting

confidence: 94%

Water‐level drawdowns can improve surface water quality and alleviate bottom hypoxia in shallow, eutrophic water bodies

et al. 2022

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“…It is also interesting to stress that as P I increased with reservoir age, P o decreased (Table 4). This trend is supported by the study of Shinohara et al (2017), in which the concentration of inorganic P in the sediment of a shallow eutrophic lake in Japan increased over time whereas the concentration of organic P decreased. Such a result suggests that organic P is converted into inorganic P, as bacteria in the sediment can decompose the organic matter, consuming oxygen and releasing inorganic P.…”

Section: Sediment Phosphorus Analysismentioning

confidence: 63%

Modeling phosphorus exchange between bottom sediment and water in tropical semiarid reservoirs

et al. 2020

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This study investigated phosphorus (P) dynamics in the sediment-water interface of three distinct reservoirs located in a tropical semiarid region. Sequential chemical fractioning of the P content in the sediment and controlled experiments of the sedimentwater interface were performed to understand and model the effect of the different P fractions on the exchange dynamics under anoxic and oxic scenarios. The results revealed that the older the reservoir, the higher the amount of iron and aluminum-bound P in the sediment, and that this fraction was responsible for a 10-fold increase in P concentration in the water during anoxic conditions. After aeration, P in water decreased but did not return to its initial concentration. The most recently constructed reservoir showed the lowest P concentration in the sediment and dominance of the unavailable P fraction, resulting in no potential impact on water quality. Phosphorus release and precipitation rates were well described by zero-and first-order models, respectively.Reservoirs with high P availability in the sediment, not only released more phosphorus but also presented a lower precipitation rate, resulting in higher potential damage to water quality and making some in-lake treatment techniques ineffective.

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“…where R G is the heat flux through the bottom sediment (W m À2 ), K sed is the thermal conductivity of sediment (¼0.25 W m À1 K À1 ), T w is the surface water temperature (K), T sed is the sediment temperature (K), and δz is the thickness of the sediment (m). Our observations involved monitoring water and sediment temperature monthly (Shinohara et al 2017). Based on the temperatures of the water and sediment at 0.0 m and 1.5 cm, we estimated the heat flux between the water and bottom sediment to be in the range of À4.0 to 8.0 W m À2 .…”

Section: Heat Fluxes Other Than Fluxes Through the Lake Surface: Uncertainties And Limitationsmentioning

confidence: 99%

Relative impacts of increases of solar radiation and air temperature on the temperature of surface water in a shallow, eutrophic lake

et al. 2021

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We monitored lake surface water temperatures from 1992 to 2019 in Lake Kasumigaura, a shallow lake in Japan. We hypothesized that increases of shortwave radiation had increased surface water temperatures and heat fluxes more than had the increases of air temperature. We used the heat flux analyses and the sensitivity analyses to test the hypothesis. The fluxes of solar radiation gradually increased during the study period in a manner consistent with the phenomenon of global brightening. The increase was especially apparent in the spring. The rate of increase of surface water temperature was especially significant in May. Air temperature did not significantly increase in May, but it increased significantly in June (0.40 °C decade−1). A sensitivity analysis of the heat fluxes at the lake surface (shortwave radiation, longwave radiation, latent heat flux, and sensible heat flux) revealed that surface water temperature was more sensitive to changes of shortwave radiation than to air temperature during the spring. Although other factors such as inflows of groundwater and river water may also have impacted surface water temperatures, the increase of solar radiation appeared to be the major factor responsible for the increase of surface water temperature during the spring in Lake Kasumigaura.

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Role of organic phosphorus in sediment in a shallow eutrophic lake

Cited by 21 publications

References 58 publications

Water‐level drawdowns can improve surface water quality and alleviate bottom hypoxia in shallow, eutrophic water bodies

Water‐level drawdowns can improve surface water quality and alleviate bottom hypoxia in shallow, eutrophic water bodies

Modeling phosphorus exchange between bottom sediment and water in tropical semiarid reservoirs

Relative impacts of increases of solar radiation and air temperature on the temperature of surface water in a shallow, eutrophic lake

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