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

Han, Bing; Zhang, Songhe; Wang, Peifang; Wang, Chao

doi:10.1038/s41598-018-21080-y

Cited by 28 publications

(10 citation statements)

References 54 publications

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“…Greater strains in viscoelastic materials are expected because they exhibit time-dependent stress-strain behavior and potentially undergo permanent deformation under stress. Additionally, at higher flow rates protrusions appear in the viscoelastic biofilm that are absent in the elastic biofilm 62 .…”

Section: Resultsmentioning

confidence: 98%

Biofilm viscoelasticity and nutrient source location control biofilm growth rate, migration rate, and morphology in shear flow

Nguyen

Ybarra

Başağaoğlu³

et al. 2021

Sci Rep

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We present a numerical model to simulate the growth and deformation of a viscoelastic biofilm in shear flow under different nutrient conditions. The mechanical interaction between the biofilm and the fluid is computed using the Immersed Boundary Method with viscoelastic parameters determined a priori from measurements reported in the literature. Biofilm growth occurs at the biofilm-fluid interface by a stochastic rule that depends on the local nutrient concentration. We compare the growth, migration, and morphology of viscoelastic biofilms with a common relaxation time of 18 min over the range of elastic moduli 10–1000 Pa in different nearby nutrient source configurations. Simulations with shear flow and an upstream or a downstream nutrient source indicate that soft biofilms grow more if nutrients are downstream and stiff biofilms grow more if nutrients are upstream. Also, soft biofilms migrate faster than stiff biofilms toward a downstream nutrient source, and although stiff biofilms migrate toward an upstream nutrient source, soft biofilms do not. Simulations without nutrients show that on the time scale of several hours, soft biofilms develop irregular structures at the biofilm-fluid interface, but stiff biofilms deform little. Our results agree with the biophysical principle that biofilms can adapt to their mechanical and chemical environment by modulating their viscoelastic properties. We also compare the behavior of a purely elastic biofilm to a viscoelastic biofilm with the same elastic modulus of 50 Pa. We find that the elastic biofilm underestimates growth rates and downstream migration rates if the nutrient source is downstream, and it overestimates growth rates and upstream migration rates if the nutrient source is upstream. Future modeling can use our comparison to identify errors that can occur by simulating biofilms as purely elastic structures.

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Section: Resultsmentioning

confidence: 98%

Biofilm viscoelasticity and nutrient source location control biofilm growth rate, migration rate, and morphology in shear flow

Nguyen

Ybarra

Başağaoğlu³

et al. 2021

Sci Rep

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“…Emergent plants such as Phragmites communis and Typha orientalis were the main dominant species in shallow waters at low water levels. When water levels rose, the growth and diffusion of plant communities were inhibited in their original areas [41,42], and they moved upward along the water's shoreline to meet increasing demands for light and water depth. The reduction in biomass and density of Phragmites communis and other emergent plants under high water levels creates the primary conditions for germination of the submerged macrophyte seed bank [43], resulting in a significant increase in the species numbers of submerged macrophytes in shallow water.…”

Section: Discussionmentioning

confidence: 99%

Effects of Water Level Fluctuations on the Growth Characteristics and Community Succession of Submerged Macrophytes: A Case Study of Yilong Lake, China

Zhao

Fang

Zhao

et al. 2021

Water

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Water level fluctuation (WLF) has a significant effect on aquatic macrophytes, but few experimental studies have examined the effect of WLF on submerged community succession, especially from a large-scale perspective. In this study, field monitoring of WLF and submerged macrophytes was conducted in Yilong Lake (SE China) over two years, and the impacts of WLF on the growth characteristics and the community structure of submerged macrophytes were determined. The results show that the biomass of submerged macrophytes decreased significantly after the water level increased and submerged macrophytes could cope with the adverse environment by adjusting their growth posture, for example, increasing plant length and reducing branch number. However, different submerged plants have different regulatory abilities, which leads to a change in the community structure. Myriophyllum spicatum, Stuckenia pectinata, and Najas marina had better adaptation abilities to WLF than Najas minor and Utricularia vulgaris. Changes in water depth, dissolved oxygen, and transparency significantly contribute to the effect of WLF on submerged plant communities. Therefore, when determining the range of WLF, the above three critical factors and submerged plant species should be considered. WLF changed the spatial distribution of the aquatic plant community. When water levels rose, the density of the submerged macrophyte community in the original growth region reduced as the emergent plants migrated to shallower water, and the seed bank germination was aided by transparent water produced among emergent plants. This can be used as a pioneering measure to restore submerged plants in eutrophic lakes with low transparency. In addition, a suitable water depth created by WLF was conducive to activating the seed bank and improving the diversity of aquatic plants. Finally, a distribution map of aquatic plants in Yilong Lake is drawn.

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“…Greater strains in vicscoelastic materials are expected because they exhibit time-dependent stress-strain behavior and potentially undergo permanent deformation under stress. Additionally, at higher flow rates protrusions appear in the viscoelastic biofilm that are absent in the elastic biofilm 58 .…”

Section: Elastic Versus Viscoelastic Biofilmsmentioning

confidence: 98%

Nutrient Source Location and Biofilm Viscoelasticity Control Biofilm Growth Rate, Migration Rate, and Morphology in Shear Flow

Nguyen¹,

Ybarra²,

Başağaoğlu³

et al. 2021

Preprint

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We present a numerical model to simulate the growth and deformation of a viscoelastic biofilm in shear flow under different nutrient conditions. The mechanical interaction between the biofilm and the fluid is computed using the Immersed Boundary Method with viscoelastic parameters determined a priori from measurements reported in the literature. Biofilm growth occurs at the biofilm-fluid interface by a stochastic rule that depends on the local nutrient concentration. We compare the growth, migration, and morphology of viscoelastic biofilms with a common relaxation time of 18 minutes over the range of elastic moduli 10-1000 Pa in different nearby nutrient source configurations. Simulations with shear flow and an upstream or a downstream nutrient source indicate that soft biofilms grow more if nutrients are downstream and stiff biofilms grow more if nutrients are upstream. Also, soft biofilms migrate faster than stiff biofilms toward a downstream nutrient source, and although stiff biofilms migrate toward an upstream nutrient source, soft biofilms do not. Simulations without nutrients show that on the time scale of several hours, soft biofilms develop irregular structures at the biofilm-fluid interface, but stiff biofilms deform little. Our results agree with the biophysical principle that biofilms can adapt to their mechanical and chemical environment by modulating their viscoelastic properties. We also compare the behavior of a purely elastic biofilm to a viscoelastic biofilm with the same elastic modulus of 50 Pa. We find the elastic biofilm underestimates growth rates and downstream migration rates if the nutrient source is downstream, and it overestimates growth rates and upstream migration rates if the nutrient source is upstream. Future modeling can use our comparison to identify errors that can occur by simulating biofilms as purely elastic structures.

show abstract

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

Cited by 28 publications

References 54 publications

Biofilm viscoelasticity and nutrient source location control biofilm growth rate, migration rate, and morphology in shear flow

Biofilm viscoelasticity and nutrient source location control biofilm growth rate, migration rate, and morphology in shear flow

Effects of Water Level Fluctuations on the Growth Characteristics and Community Succession of Submerged Macrophytes: A Case Study of Yilong Lake, China

Nutrient Source Location and Biofilm Viscoelasticity Control Biofilm Growth Rate, Migration Rate, and Morphology in Shear Flow

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