Abstract
Anthropogenic activities can be the source of saline solid wastes that need to be treated to reduce their salt load to meet the purposes of reuse, valorization or storage. In this context, chloride remediation can be achieved using high-salt accumulating plants. However, there is very limited information on the comparative potential of different species in the same environment, and only scarce data concerning their efficiency as a function of growth stage. In order to rationalize these selection criteria, three macrophytes i.e., common reed (Phragmites australis), sea rush (Juncus maritimus), and cattail (Typha latifolia), were cultivated at two growth stages (6-months old and 1-year old) for 65 days in Cl− spiked substrates (from 0 up to 24 ‰ NaCl). The plants’ survival and potential capacity for removal of Cl− from substrates and accumulation in shoots were investigated. For the three studied species, mature and juvenile plants display a high tolerance to salinity. However, mature specimens with higher shoot biomass and Cl− contents are capable of greater chloride removal than juvenile plants. The sole exception is P. australis which displays just the same phytoremediation potential for both mature and juvenile specimens. Moreover, P. australis has the lowest potential when compared with other species, being 1.5 and 3 times lower than for J. maritimus and T. latifolia. When considering the plant growth and the shoot biomass production, chloride removal rates from the substrate point that mature J. maritimus should preferentially be used to design an operational chloride remediation system. The results highlight the relevance of considering the growth stage of plants used for Cl− removal.Highlights1) Mature and juvenile specimens of J. maritimus, P. australis, and T. latifolia have high salinity tolerance in solid media spiked up to 24 ‰ NaCl.2) Mature plants have generally better Cl− removal and phytoremediation performances than juvenile specimens.3) J. maritimus is the most effective species for chloride phytoremediation with high survival and high Cl− sequestration in shoots.4) T. latifolia has high Cl− removal in shoots and good remediation capacities but also shows sign of stress.5) P. australis shows low Cl− sequestration and is a poor candidate for chloride remediation from substrate.Supplementary InformationThe online version contains supplementary material available at 10.1007/s11356-021-17591-3.
Highlights
Soil salinization represents a major environmental issue of our time
The mature plants of J. maritimus and T. latifolia show excellent survival rates of 100% whatever the salinity whereas P. australis yield different results according to microcosms, with values of 100% for C0, C3 and C4, 92 ± 8% for C1 and 88 ± 12% for C2 (Fig. 2)
Oldest plants of all three selected species are shown to have the higher survival rates, underlying the need to take into account the growth stage of plants when dealing with Cl− phytoremediation
Summary
Soil salinization represents a major environmental issue of our time. Being an extensive phenomenom which involves the accumulation of high concentrations of saline and sodic ions, soil salinization is expected to affect more than 8301 3 Vol.:(0123456789)Environmental Science and Pollution Research millions hectares of the continents (Daliakopoulos et al 2016; Ivushkin et al 2019). Harbour dredging is pointed out as a maintenance activity producing large amounts of saline sediments whose management is clearly challenging (Wang et al 2018). This global context of salinization and the environmental issues raised have led to setting up of new regulations which promote the remediation of saline effluents, saline wastes and marine sediments, with the aim of protecting the environment. It would be of great interest to use high-salt accumulating plants to phytoremediate chloride-rich soils, effluents, and wastes since this passive treatment process has a low ecological and economic imprint (Jesus et al 2015)
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