O2, pH, and Redox Potential Microprofiles around Potamogeton malaianus Measured Using Microsensors

Abstract

This study aimed to elucidate the effects of periphyton on the microprofiles of oxygen (O2), pH, and oxidation-reduction potential around the stems and leaves of a submerged macrophyte Potamogeton malaianus and on the plant growth in the eutrophic shallow Taihu Lake, China. The microprofiles were measured using a motorized microprofiling system equipped with microsensors. The leaf age of the macrophyte and periphyton exerted significant effects on the microprofiles of O2, pH, and oxidation-reduction potential. O2 concentration and pH increased whereas the oxidation-reduction potential decreased with decreasing distance to the stem/leaf surface. The fluctuation amplitudes of O2, pH, and oxidation-reduction potential were the largest in the microprofiles of mature leaves and the lowest in senescent leaves. The periphyton increased the thickness of the broad diffusive boundary layer and fluctuation amplitudes of O2, pH, and oxidation-reduction potential. When the periphyton was removed, the thickness of the broad diffusive boundary layer in the microprofiles of stems, senescent leaves, and mature leaves reduced by 29.0%, 49.72%, and 70.34%, and the O2, pH, and oxidation-reduction potential fluctuation amplitudes also declined accordingly. Our results suggest that a thick periphyton exerted negative effects on the growth of macrophytes by providing extensive shading and creating a barrier that hindered the transport of dissolved substances such as O2, and led to premature decline in macrophytes in the eutrophic Taihu Lake. The consequent implications can help to elucidate the control mechanism of the broad diffusive boundary layer around macrophytes on nutrient cycling in eutrophic waters and to better understand the role of this layer in the Taihu Lake and other similar eutrophic waters.

Effects of water flow on submerged macrophyte-biofilm systems in constructed wetlands

“…The sharper gradient of phyllosphere oxygen concentrations in the flowing water illustrated that water flow promoted the exchange of oxygen between leaf and water. Previous study 32 illustrated that biofilms contributed a lot to phyllosphere oxygen profiles of stems and senescent leaves of Potamogeton malaianus , but the rate of contribution was minor to young leaves due to the high oxygen release of young leaves and thin biofilms. In the present study, biofilms on young leaves were sampled to explore the effect of water flow to the biofilms.…”

“…Thus the biofilm on young leaves might have a small contribution to the oxygen profiles as reported by Dong et al . 32 .…”

Chemical Properties of Soil under Different Redox Potentials

“…Highly reduced soils were found to be less acidic and less alkaline than the moderately reduced and oxidized soils. In a report on O 2 , pH and Eh around pond weed by Dong et al (2014), it was observed that an increase in pH of acid soil arose from a decrease in redox potential. According to Walstra and Jenness (1984) working on the redox potential of milk as related to its pH also concluded that the pH of milk was raise with a decrease in redox potential.…”

Effects of Road Infrastructure on Plantain Production among Farmers in Ekiti Southwest Local Government Area of Ekiti State, Nigeria

“…Highly reduced soils were found to be less acidic and less alkaline than the moderately reduced and oxidized soils. In a report on O 2 , pH and Eh around pond weed by Dong et al (2014), it was observed that an increase in pH of acid soil arose from a decrease in redox potential. According to Walstra and Jenness (1984) working on the redox potential of milk as related to its pH also concluded that the pH of milk was raise with a decrease in redox potential.…”