Sustainable Solutions for Environmental Pollution, Volume 2. Группа авторов

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Sustainable Solutions for Environmental Pollution, Volume 2 - Группа авторов

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Pézan CW in winter and summer 2020. The dash area corresponds to the CW.

Schematic illustration of monitoring of vegetation on the St Just–St Nazaire de Pézan CW using Sentinel-2 satellite images. Snapshot of Sentinel-2 satellite view of the Tres Rios. Schematic illustration of monitoring of Tres Rios fringing marshes using satellite images.
= NDVI, black continuous line = maximal temperature, gray continuous line = minimal temperature (US National Centers for Environmental Information).

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      There are two levels of modeling: modeling of specific processes, such as plant development or pollutant fate, and general modeling, taking into account all (or most of all) processes taking place in a wetland. Modeling have several purposes such as: 1) help in understanding a complex set of entangled processes, 2) definition of a control strategy, although the handles are usually limited to flow control, or 3) forecasting the development of a wetland to define the best maintenance strategy on the long term such as vegetation harvesting or sediment removal.

      1.14.1 Aquatic Plant Development Models

      Due to their large distribution, both in natural wetlands and CWs, Phragmites sp. have received a lot of interest in terms of modeling their seasonal life cycle. The model proposed by Asaeda and Karunaratne (2000) and Asaeda et al. (2002) takes into account the plant roots, rhizomes, shoots, stems, leaves, and panicles, whose development is governed by air temperature and solar irradiation (Asaeda and Karunaratne, 2000; Asaeda et al., 2002). After senescence, leaching, mineralization, and nutrient fixation of the litter are also modeled. This model has served as a basis for the modeling of the seasonal life cycle of Typha sp. (Eid et al., 2012).

       1.14.1.1 Submerged Aquatic Plants

       1.14.1.2 Duckweed

      Duckweed is a widespread floating plant family, whose five main genera are Lemna, Spirodela, Wolffia, Wolffiella, and Landoltia (Zhang et al., 2014b). Their growth, based on Monod’s equations, can be described in function of temperature, light, and nutrients (N and P). The mechanistic model developed by Peeters et al. (2013) takes also into account losses due to mortality, grazing, and respiration (Peeters et al., 2013). Growth is limited by crowding, meaning that when there is no more enough space (around 180 g dry weight per square meter) duckweed stops to develop (Driever et al., 2005). Although a general modeling structure can be proposed, parameters may differ according to the species, some of them being for example favored by high nutrient availability (Njambuya et al., 2011). In the case of mixed vegetation, duckweed mats induce shading for submerged plants and algae, i.e., a decrease of the solar irradiance necessary for their photosynthesis. In large surface-flow CWs wind can displace duckweed mats, changing their thickness and therefore the shading of submerged vegetation.

      1.14.2 Micropollutants Sorption

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