An Assessment of the Phytoremediation Potential of Planted and Spontaneously Colonized Woody Plant Species on Chronosequence Fly Ash Disposal Sites in Serbia—Case Study

Abstract

In this study, the potential of planted (Tamarix tetrandra Pall. ex M.Bieb. and Robinia pseudoacacia L.) and spontaneously colonized (Amorpha fruticosa L. and Populus alba L.) woody species for the phytoremediation of potentially toxic trace elements (TEs) such as As, B, Cr, Cu, Mn, Ni, Se, and Zn, from the chronosequence fly ash (FA) deposit lagoons (L1 and L2) at the ‘Nikola Tesla A’ Thermal Power Plant (TENT-A) in Serbia were analyzed. The differences in the pseodototal and bioavailable (DTPA-extractable) concentrations and mobility (AR index) of TEs in FA at the examined lagoons are a result of the time-conditioned influence of weathering (3 and 11 years respectively) and vegetation development on changing the basic physical and chemical properties of FA (texture, pH, EC, CEC, C, N, and bioavailable P and K) and its toxicity. This resulted in differences in the concentration of TEs in the roots and leaves of the examined plants at L1 and L2. All examined species accumulated Cr the most in the root (BAF > 1 and TF < 1), which suggests that they are good stabilizers of this element. Biological indices for As (BAF > 1 and TF < 1) identified T. tetrandra and A. fruticose as good stabilizers of As. P. alba stood out as accumulating the highest levels of B, Ni, and Zn, T. tetrandra the highest levels of Cu, Mn, and Se, and R. pseudoacacia the highest levels of As and B in leaves (BAF > 1; TF > 1), which makes them good extractors of these elements from the FA at TENT-A. However, due to toxic concentrations of As, B, Se, and Zn in their leaves, they are not recommended for the phytoremediation of the investigated lagoons through the process of phytostabilization. Under conditions of elevated total Cu and Ni concentration in FA, the content of these elements in the leaves of A. fruticosa at both lagoons were within the normal range. This, in addition to a good supply of essential Zn, the stabilization of As and Cr in the roots, an increase in BAF, and a decrease in TF for B with a decrease in its mobility in ash over time, singles this invasive species out as the best candidate for the phytostabilization of TEs in FA at the TENT-A ash deposit site.

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

“…The intensification of activities related to this type of electricity generation is one of the major environmental problems today because the disposal of FA in dry or wet lagoons near thermal power plants contributes to the leaching of potentially toxic elements (PTEs) into soil and groundwater, while windblown micrometre-sized and poorly aggregated particles of FA from the dry surfaces of landfills pollute agricultural land and endanger the flora, fauna, and health of residents of nearby settlements ( Raja et al., 2015 ; Ćujić et al., 2016 ; Khan and Umar, 2019 ).The formation of a vegetation cover, i.e. the revitalisation of FA landfills, is a cost-effective and environmentally sound method and the best method when it comes to stabilising this mobile substrate physically and chemically ( Haynes, 2009 ; Yan et al., 2020 ; Kostić et al., 2022b ). However, the synergistic effect of multiple abiotic stress factors, such as drought, low organic matter content, lack of essential nutrients (N, P, Mn, etc.…”

“…Thanks to the development of adaptation mechanisms based on accumulation and exclusion, tolerant species survive under conditions of PTE deficiency or toxicity in the substrate. By regulating the transfer between soil and roots and between roots and leaves, concentrations of these elements are kept within a normal range in their tissue ( Pandey et al., 2012 ; Mukhopadhyay et al., 2017 ; Kostić et al., 2022b ). Tolerant plant species also respond to abiotic stress by increasing their antioxidant capacity, which helps them to maintain a normal cellular balance between production and binding, degradation, and neutralisation of ROS by enzymatic or non-enzymatic antioxidants (carotenoids and anthocyanins) and secondary metabolites (phenols) ( Cervilla et al., 2012 ; Gajić et al., 2020 ; Kebert et al., 2022 ; Vuksanović et al., 2022 ).…”

“…Previous studies have shown that autochthonous, long-living woody species characterised by high below- and above-ground biomass and rapid growth, as well as the ability to reproduce vegetatively and capacity to tolerate various stressors, are best suited to stabilising FA landfills and reducing health problems associated with FA while restoring ecosystem functions ( Carlson and Adriano, 1991 ; Kostić et al., 2012 ; Mitrović et al., 2012 ; Pietrzykowski et al., 2018 ; Kostić et al., 2022b ). Species from the Salicaceae family stand out when it comes to being used for the phytoremediation and revitalisation of polluted habitats, and in particular those from the Populus genus, which is characterised by high tolerance to a variety of environments ( Zacchini et al., 2009 ; Guerra et al., 2011 ).…”

“…However, species of Populus , as a thoroughly mapped genus, differ widely in their uptake patterns, as well as adaptation abilities under varying abiotic conditions ( Dos Santos Utmazian et al., 2007 ; Zacchini et al., 2009 ; Di Lonardo et al., 2011 ; Tőzsér et al., 2023 ). To date, research has mostly focused on accumulation, phytoremediation potential, and tolerance of poplars to metal pollution ( Madejón et al., 2004 ; Robinson et al., 2005 ; Borghi et al., 2008 ; Todeschini et al., 2011 ; Kostić et al., 2022b ) or their physiological response to individual stress factors such as drought, salinity or high temperatures ( Chen and Polle, 2010 ; Yoon et al., 2014 ; Zhang et al., 2019 ; Kim et al., 2022 ). However, studies on the ecophysiological response of Populus alba L. to the combined effects of multiple stress factors are rare, particularly at FA landfills.…”

Culturable Bacterial Endophytes of Wild White Poplar (Populus alba L.) Roots: A First Insight into Their Plant Growth-Stimulating and Bioaugmentation Potential

“…It is considered an attractive plant for the green economy, as it provides a cheap source of raw materials and wood products, including cellulose [1] and sugars [2], which in turn can be used for biofuel production [1]. In addition, white poplar has a high potential for phytoremediation for areas subjected to strong anthropological impact [3,4], so it is often used for urban greening.…”