Root and Shoot Biomass Growth of Constructed Floating Wetlands Plants in Saline Environments

Abstract

Constructed Floating Wetlands (CFWs) are increasingly being used globally in freshwater environments such as urban lakes and ponds to remove pollutants from urban stormwater runoff. However, to date there has been limited research into the use and performance of these systems in saline environments. This study compared the root and shoot biomass growth and nutrient uptake of five different plant species, Chrysopogon zizanioides, Baumea juncea, Isolepis nodosa, Phragmites australis and Sarcocornia quinqueflora, in three different saltwater treatments over a 12-week period. The aim of the study was to identify which of the plant species may be most suitable for use in CFWs in saline environments. Plant nutrient uptake testing revealed that Phragmites australis had the greatest percentage increase (1473–2477%) of Nitrogen mass in the shoots in all treatments. Sarcocornia quinqueflora also had impressive Nitrogen mass increase in saltwater showing an increase of 966% (0.208 ± 0.134 g). This suggests that the use of Phragmites australis and Sarcocornia quinqueflora plants in CFWs installed in saline water bodies, with regular harvesting of the shoot mass, may significantly reduce Nitrogen concentrations in the water. Isolepis nodosa had the greatest percentage increase (112% or 0.018 ± 0.020 g) of Phosphorous mass in the shoots in the saltwater treatment. Baumea juncea had the greatest percentage increase (315% or 0.026 ± 0.012 g) of Phosphorous mass in the roots in the saltwater treatment. This suggests that the use of Isolepis nodosa and Baumea juncea plants in CFWs installed in saline water bodies may significantly reduce Phosphorous concentrations in the water if there was a way to harvest both the shoots above and the roots below the CFWs. The study is continuing, and it is anticipated that more information will be available on CFW plants installed in saline environments in the near future.

Understanding the mechanistic basis of adaptation of perennial Sarcocornia quinqueflora species to soil salinity

“…1000 mM). The drastic reduction in plant performance at zero salinity indicates that S. quinqueflora is an obligate halophyte as reported by Sanicola et al (2019).…”

Floating Wetland Islands Implementation and Biodiversity Assessment in a Port Marina

“…Thus, the two more resistant and more promising plant species to cope with this environment, S. maritima and S. perennis, seem to be the most suitable species for future FWI applications in highly saline water bodies. Sanicola et al [14] reported that a plant from the same genus (Sarcocornia quinqueflora) was the one with the better root biomass growth in saltwater (rather than in freshwater) among the other four wetland plant species tested in their FWI mesocosm studies. Moreover, Calheiros et al [39] used Sarcocornia fruticosa for highly saline wastewater treatment, in a constructed wetland, where this species also demonstrated a high resilience.…”

Constructed floating wetlands made of natural materials as habitats in eutrophicated coastal lagoons in the Southern Baltic Sea

“…Wang et al 2015;Olguín et al 2017;Afzal et al 2019) and even fewer in saline environments (e.g. Sanicola et al 2019). Also Colares et al (2020) conclude in their comprehensive review and bibliometric analysis that although floating wetlands have been employed all over the world, most studies remain on laboratory or pilot scale.…”