The Phytoremediation Potential and Physiological Adaptive Response of Tamarix tetrandra Pall. Ex M. Bieb. during the Restoration of Chronosequence Fly Ash Deposits

Abstract

The challenging process of identifying and selecting plant species suited to the phytoremediation of fly ash (FA) dumps involves studying their functional properties and physiological response to a deficit of essential elements and toxicity from heavy metal(loid)-induced oxidative stress. We hypothesised that Tamarix tetrandra has high potential to be used for the phytoremediation of FA deposit sites thanks to its secretion strategy and antioxidative system. In this study, this hypothesis was examined by determining the bioconcentration and translocation factors for As, B, Cr, Cu, Mn, Ni, Se and Zn at the FA disposal lagoons at the ‘Nikola Tesla A’ thermal power plant in Obrenovac, Serbia, three (lagoon L1) and eleven (lagoon L2) years after the phytoremediation process had begun, and by measuring parameters of photosynthetic efficiency and chlorophyll concentration, non-enzymatic antioxidant defence (carotenoids, anthocyanins and phenolics), oxidative stress (concentration of malondialdehyde—MDA) and total antioxidant capacity to neutralise DPPH free radical activity. Tamarisk not only showed the ability to phytostabilise As, Cr and Ni and to accumulate low-availability Mn, Zn and Cu, but also the potential to maintain the structural and functional integrity of cell membranes and stable vitality at L1 under multiple stress conditions due to the high synthesis of phenols and tolerance to increased salinity. However, toxic concentrations of B and Se in leaves induced oxidative stress in tamarisk at L2 (reflected in higher MDA content and lower vitality) and also decreased the synthesis of chlorophyll, carotenoids, anthocyanins and total antioxidant activity. In addition, the prooxidative behaviour of phenols in the presence of spin-stabilising metals from FA could also have resulted in their weaker antioxidant protection at L2. These findings indicate that the choice of tamarisk was justified, but only at the beginning of the phytoremediation process because its presence contributed to an improvement in the harsh conditions at FA deposit sites and the creation of more favourable conditions for new plant species. This knowledge can be of great importance when planning sustainable ash deposit site management worldwide.

A Green Approach Used for Heavy Metals ‘Phytoremediation’ Via Invasive Plant Species to Mitigate Environmental Pollution: A Review

“…Pontederiaceae, Asteraceae, and Fabaceae are the most representative plant families with a large number of species that bio-accumulate HMs [ 118 ]. Furthermore, recent studies have shown that the IPS can be used as biosensors for heavy metal-contaminated sites, such as Tamarix tetrandra Pall , Alliaria petiolata ( M. bieb ), Robinia pseudoacacia L., Miscanthus , Amorpha fruticosa L., and Populus alba L., and can eliminate different HMs with phytoremediation [ 119 , 120 ]. Wei et al [ 88 ] experimentally proved that C. odorata , B. pilosa , and P. clematidea enhance tolerance to Cd stress and have more ability to phytoextract Cd without morphological and physiological disturbance.…”

Ecophysiological response of Populus alba L. to multiple stress factors during the revitalisation of coal fly ash lagoons at different stages of weathering

“…Karst., Fagus sylvatica L., and Alnus glutinosa (L.) Gaertn. ( Gajić et al., 2020 ; Bęś et al., 2021 ; Kostic et al., 2022c ; Qadir et al., 2022 ).…”

“…Concentrations of Cu, Ni, and Se were higher than the average for sandy to silt-loam substrates and concentrations of Mn and Zn were lower than the range of average values (<270 mg kg -1 and<45 mg kg -1 , respectively; Kabata-Pendias and Pendias, 2001 ). The surface association of As, B, Cr, and Zn on FA particles contributes to their greater solubility, making these elements extremely hazardous to plants at FA landfills if they are accumulated in high concentrations ( Gajić et al., 2020 ; Kostić et al., 2022b ; Kostic et al., 2022c ). However, it also contributes to their significantly lower content in FA at L11, although the content of B at L11 was still in the critical range for plants.…”

“…The most susceptible to leaching, and therefore most accessible to plants, are the partially volatile chemical elements (As, B, Cr, Se, and Zn) that condense in the surface layer of ash particles as the flue gases cool during the coal combustion process, while the less volatile elements such as Mn and Ni accumulate in the inner layer and are not directly exposed to leaching ( Tian et al., 2018 ). The alkalinity of FA can cause the formation of insoluble forms of elements and thus a deficit of essential nutrients, most commonly phosphorus (P), manganese (Mn), and copper (Cu), but also increased solubility of arsenic (As), boron (B), and selenium (Se) and their accumulation in plants in toxic concentrations ( Pandey et al., 2011 ; Gajić et al., 2020 ; Kostic et al., 2022c ).…”

“…However, the synergistic effect of multiple abiotic stress factors, such as drought, low organic matter content, lack of essential nutrients (N, P, Mn, etc. ), alkaline pH, and phytotoxicity due to high PTE and soluble salt content, limits the number of species that can grow under such conditions (Kostic et al, 2018;Kalashnikova et al, 2021). Due to its dark grey colour, FA absorbs enormous amounts of heat from the sun, which increases surface temperatures at the landfill and reduces humidity.…”