Contribution of alkaline phosphatase to phosphorus cycling in natural riparian zones in the Wangyu River running into Lake Taihu

Ding

et al. 2021

Preprint

Self Cite

Phosphorus (P) has an important role in eutrophication and it is essential to explore the processes and mechanisms of P mobility in natural waters. In this study, laboratory experiments were conducted to simulate the SW system (sediment and water) and SAW system (sediment, algae and water) under four hydrodynamic intensity conditions (static control, 50 rpm, 125 rpm and 200 rpm treatments), to investigate P mobility. Results in SW system showed that, sediment was an important source of P for overlying water, and the released total P (TP) increased with stronger hydrodynamic intensity, when P associated with metal pools (redox-sensitive P [BD-P] and meta-oxides bound P [NaOH-P]) were the most unstable and easier to migrate into the overlying water. Stronger hydrodynamic disturbances could enhance the processes including sediment resuspension, dissolution of particles, and release of P, when P mobility had a close relationship with redox conditions near sediment-water interface (SWI). Therefore, the release of TP, BD-P and NaOH-P from sediment increased and decreased in the control and 50-200 rpm treatments over time. In SAW system, the release of TP significantly increased from sediment comparing to SW system, and the growth of Microcystis aeruginosa could selectively enhance the release of BD-P, NaOH-P, and organic P (OP). Meanwhile, the released P from sediment was quickly accumulated by algal cells. The maximum accumulation ability of P by cells, the highest photosynthetic efficiency and the best growth of M. aeruginosa were observed in 125 rpm treatment. But with excessively strong hydrodynamic intensity (200 rpm treatment), the accumulation ability of P and alkaline phosphatase activity (APA) of M. aeruginosa was suppressed, which might hinder algal utilization of P and inhibit algal growth. Overall, our findings demonstrated the patterns of P mobility in natural ecosystems and could contribute to the understanding of P cycling.

Section: Analyses Of Sediment Samplesmentioning

confidence: 99%

Processes and Mechanisms of Phosphorus Mobility Among Sediment, Water and Cyanobacteria Under Hydrodynamic Conditions

Ding

et al. 2021

Preprint

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“…Then, DOM stock solution were added into half the petri dishes at a nal content of 5.0 mg TOC L − 1 , representing four experimental groups: without DOM in DOP-rich medium (NM-P group), with DOM in DOP-rich medium (M-P group), without DOM in DOP-free medium (NM-NP group), with DOM in DOP-free medium (M-NP group). The selected DOM availability in our experiment could re ect its ambient concentrations during the outbreak period of HABs (Ren et al 2015;Boyer et al 2006).…”

Section: Experimental Setup 221 Effects Of Irradiation On M Aeruginosamentioning

confidence: 99%

“…After regular collection of algal cultures or enzyme solutions, APA was estimated using pnitrophenylphosphate (pNPP) as the substrate (Ren et al 2015).…”

Section: Estimation Of Apa and Its Inactivation Ratesmentioning

confidence: 99%

“…Since M. aeruginosa could not eliminate UV-induced effects through above-mentioned adaptation processes or sustain its normal growth with stored P in DOP-free medium, F v /F m of UV-radiated algae did not recover to the initial value and the worst UV adaption capability was observed.4.3. Roles of DOM on APase InactivationAlthough many studies have examined the kinetic and fate of APase under varying conditions(Ren et al 2015;Ma et al 2019); limited information was provided on the effects and regulation of irradiation and DOM, despite the complex light conditions and widespread presence of DOM in natural waters.It was reported that APase was stable in water and could remain active for several days, but HA occupying the main part of DOM pool could directly associate with APase(Boavida et al 1998;Sun et al 2014). Our study supported previous data and HA might block the active sites of APase, leading to APA decrease in the dark.…”

mentioning

confidence: 99%

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Effects of Algal Utilization of Dissolved Organic Phosphorus by Microcystis Aeruginosa on its Adaptation Capability to Ambient Ultraviolet Radiation

Huang

Zhu

et al. 2021

Preprint

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Phosphorus (P) plays an important role in eutrophication and algal adaptation to environmental stresses; therefore, a better understanding of the impact of P is essential to control cyanobacterial bloom. In this study, Microcystis aeruginosa was treated with 5-h of ambient irradiation in the culture medium with different availability of dissolved organic P (DOP) and dissolved organic matter (DOM), to explore algal responses. Compared to photosynthetically active radiation (PAR), ambient UV-A and UV-B radiation exerted oxidative stresses and had inhibitive effects on the growth and photosynthesis of M. aeruginosa in DOP-rich medium. However, M. aeruginosa had a strong adaptation capability and the negative effects of UV radiation were eliminated with DOM addition (5 mg L− 1 humic acid [HA]). Combining dissolved inorganic P (DIP) and DOP contents in the culture medium, adaptation of M. aeruginosa to UV radiation in the DOP-rich waters could be mainly achieved through the hydrolysis of DOP and metabolism of DIP, and the DOP utilization behaviors of M. aeruginosa greatly affected its UV adaptation capability. In DOP-rich medium without DOM, APase inactivation after UV radiation negatively affected DOP utilization by M. aeruginosa, and algal P demand for UV adaptation could not be fully met. DOM could act as an antioxidant and greatly decreased APase inactivation after UV radiation, when M. aeruginosa utilized DOP faster to produce more DIP and to increase algal carotenoid, phycocyanin production and its superoxide dismutase (SOD) activity in the DOP-rich medium, resulting in a strong UV adaptation capability. Consequently, M. aeruginosa showed the lowest adaptation capability to UV radiation in the DOP-free medium. Overall, our findings indicated the close relationship of algal DOP utilization and its adaptation to ambient UV radiation of typical cyanobacteria in DIP-limited and DOP-enriched natural waters.

“…After sampling overlying water, p-nitrophenylphosphate (pNPP) was also directly added for determining alkaline phosphatase activity (APA), which has been reported to be important for algal utilization of dissolved organic P (DOP) and its prosperity in the natural waters (Ren et al 2015). Moreover, uorescence-labeled enzyme activity (FLEA) technique was also used to illustrate APA of M. aeruginosa.…”

Section: Parameters Of M Aeruginosamentioning

confidence: 99%

Processes and mechanisms of phosphorus mobility among sediment, water, and cyanobacteria under hydrodynamic conditions

Ding

et al. 2021

Environ Sci Pollut Res

Self Cite

Phosphorus (P) has an important role in eutrophication and it is essential to explore the processes and mechanisms of P mobility in natural waters. In this study, laboratory experiments were conducted to simulate the SW system (sediment and water) and SAW system (sediment, algae and water) under four hydrodynamic intensity conditions (static control, 50 rpm, 125 rpm and 200 rpm treatments), to investigate P mobility. Results in SW system showed that, sediment was an important source of P for overlying water, and the released total P (TP) increased with stronger hydrodynamic intensity, when P associated with metal pools (redox-sensitive P [BD-P] and meta-oxides bound P [NaOH-P]) were the most unstable and easier to migrate into the overlying water. Stronger hydrodynamic disturbances could enhance the processes including sediment resuspension, dissolution of particles, and release of P, when P mobility had a close relationship with redox conditions near sediment-water interface (SWI). Therefore, the release of TP, BD-P and NaOH-P from sediment increased and decreased in the control and 50-200 rpm treatments over time. In SAW system, the release of TP signi cantly increased from sediment comparing to SW system, and the growth of Microcystis aeruginosa could selectively enhance the release of BD-P, NaOH-P, and organic P (OP). Meanwhile, the released P from sediment was quickly accumulated by algal cells. The maximum accumulation ability of P by cells, the highest photosynthetic e ciency and the best growth of M. aeruginosa were observed in 125 rpm treatment. But with excessively strong hydrodynamic intensity (200 rpm treatment), the accumulation ability of P and alkaline phosphatase activity (APA) of M. aeruginosa was suppressed, which might hinder algal utilization of P and inhibit algal growth. Overall, our ndings demonstrated the patterns of P mobility in natural ecosystems and could contribute to the understanding of P cycling.