Trace elements removal ability and antioxidant activity of Phragmites australis (from Algeria)

Evaluation of heavy metal accumulation and tolerance in oxalic acid-treated Phragmites australis wetlands for textile effluent remediation

Water contamination with metals poses significant environmental challenges. The occurrence of heavy metals (HMs) prompts modifications in plant structures, emphasizing the necessity of employing focused safeguarding measures. Cadmium (Cd), lead (Pb), and chromium (Cr) emerge as particularly menacing toxins due to their high accumulation potential. Increasing the availability of organic acids is crucial for optimizing toxic metal removal via phytoremediation. This constructed wetland system (CWs) was used to determine how oxalic acid (OA) treatments of textile wastewater (WW) effluents affected morpho-physiological characteristics, antioxidant enzyme activity, oxidative stress, and HM concentrations in Phragmites australis. Multiple treatments, comprising the application of OA at a concentration of 10 mM and WW at different dilutions (25%, 50%, 75%, and 100%), were employed, with three replications of each treatment. WW stress decreased chlorophyll and carotenoid content, and concurrently enhanced HMs adsorption and antioxidant enzyme activities. Furthermore, the application of WW was found to elevate oxidative stress levels, whereas the presence of OA concurrently mitigated this oxidative stress. Similarly, WW negatively affected soil-plant analysis development (SPAD) and the total soluble proteins (SP) in both roots and shoots. Conversely, these parameters showed improvement with OA treatments. P. australis showed the potential to enhance HM accumulation under 100% WW stress. Specifically, there is an increase in root SP ranging from 9% to 39%, an increase in shoot SP from 6% to 91%, and an elevation in SPAD values from 4% to 64% compared to their respective treatments lacking OA inclusion. The OA addition resulted in decreased EL contents in the root and shoot by 10%-19% and 13%-15%, MDA by 9%-14% and 9%-20%, and H2O2 by 14%-21% and 9%-17%, in comparison to the respective treatments without OA. Interestingly, the findings further revealed that the augmentation of OA also contributed to an increased accumulation of Cr, Cd, and Pb. Specifically, at 100% WW with OA (10 mM), the concentrations of Cr, Pb, and Cd in leaves rose by 164%, 447%, and 350%, in stems by 213%, 247%, and 219%, and in roots by 155%, 238%, and 195%, respectively. The chelating agent oxalic acid effectively alleviated plant toxicity induced by toxins. Overall, our findings demonstrate the remarkable tolerance of P. australis to elevated concentrations of WW stress, positioning it as an eco-friendly candidate for industrial effluent remediation. This plant exhibits efficacy in restoring contaminants present in textile effluents, and notably, oxalic acid emerges as a promising agent for the phytoextraction of HMs.

The traces elements absorption, accumulation and translocation ability of Phragmites australis

In this study, the wastewater analyses of Oued K'sob for one year showed a spatiotemporal diminution of zinc content seasonally, it rest light than copper. But Zinc and copper a threat to the environment of the region. The wastewater analyses of Oued K'sob water for one year showed a spatiotemporal diminution of zinc content seasonally, with a minimum and maximum range of 249 ± 219 µg/l and 2382 ± 3426 µg/l obtained in autumn and summer for the zinc and 75 ± 24 µg/l and 433 ± 310 µg/l obtained in winter and spring at the first and fifth station for the copper. These concentrations of zinc and copper a threat to the environment of the region. Like a solution for this problem, the absorption, accumulation and translocation abilities of Phragmites australis were determined toward iron (Fe), copper (Cu), zinc (Zn) and lead (Pb). In the soils contaminated by different concentrations (100, 200 and 500 mg/L), the absorption, accumulation and transport ability of elements were evaluated via the Bio-concentration (BCF), Bioaccumulation (BF) and Translocation (TF) factors. A proportional increase between the BCF, BFs, TFs and the irrigation concentrations, where BCFs of all metallic elements exceed 1 and the Zn BCF, BFs and TFL are the highest and exceed 1 relative to the other elements which remain lower than 1, which has a low accumulation. Therefore, according to the BCFs obtained and which exceed 1, we can consider this plant as a hyper-accumulator of Zn, Fe, Cu and Pb. Extraction of fatty and organic acids followed by HPLC confirmed the oxalic, citric, malic, succinic, fumaric, formic, acetic, propionic, and butyric acid presence, which are responsible for the transport of the metal from roots to leaves. In the light of these results, we can therefore propose Phragmites australis species as an alternative and natural solution to reduce the high concentrations of zinc and copper in the Oued k'sob (region of Bordj Bou Arreridj, Algeria).

Reclamation of wastewater in wetlands using reed plants and biochar

To cope with water crisis, wastewater reuse has been introduced as a potential source for irrigation. On the other hand, irrigation with wastewater may negatively affect the surroundings. In this study, reed plant (Phragmits australis) and its biochar were tested as low-cost treatments to enhance the efficiency of wastewater reclamation in wetlands within only 72 h. The investigated water was of low irrigation quality and exhibited high contents of BOD₅ and fecal coliform. Moreover, this water contained high levels of soluble cations and anions; besides, being marginally contaminated with Cu, Mn and Cd. After 2 days in the sedimentation unit, wastewater was subjected to three reclamation treatments in parallel (each lasted for 24 h): (1) a "sand & gravel bed", (2) "reed plants grown on a sand & gravel bed" and (3) "biochar + a sand & gravel bed". The results showed that all treatments decreased BOD₅, fecal coliform, total cations and anions, with superiority for the second and third treatments. The levels of the potentially toxic elements also decreased to values within the permissible levels. Although the aforementioned wastewater treatment processes upgraded the quality of this water, it remained in the poor grade. Biochar or reed plants grown on sand and gravel beds significantly improved wastewater quality to the medium quality grade, with superiority for biochar treatment. In conclusion, investigated treatments are guaranteed in wetlands for wastewater reclamation; yet, further protocols should be followed to achieve safe handling of this water and attain the sustainable goals.

Heavy metals uptake and translocation of typical wetland plants and their ecological effects on the coastal soil of a contaminated bay in Northeast China

Heavy metal pollution in coastal zone is a global environment problem concerning the international society. As an eco-friendly and economical method, phytoremediation is a promising strategy for improving heavy metal pollution in coastal soil. In order to alleviate the ecological risk of heavy metal pollution in Jinzhou Bay, a typical and important heavy industrial area in China, three local wetland plants (Scirpus validus, Typha orientalis and Phragmites australis) were selected and planted in the field. The plants showed strong tolerance of high concentrations of heavy metals. Stressed by the heavy metals, the root weight of S. validus and P. australis increased 114.74% and 49.91%, respectively. The concentrations of heavy metals (Cd, Cr, Cu, Ni, Pb, Zn, As, Hg) accumulated in the plant roots were 4-60 times higher than that in plant shoots. The SEM analysis found that abundant heavy metals were adhered to the root surface closely. Bioconcentration factor of heavy metals on the plant roots were 0.08-0.89 (except Cr, Ni), while the translocation factor from roots to above ground of plants were 0.02-0.27. Furthermore, the wetland plants improved the regional ecological environment quality. The concentrations of heavy metals in the rhizosphere soil decreased significantly. Compared with the bulk soil, the potential ecological risk index in the rhizosphere soil reduced 26.51%-69.14%. Moreover, the microbial diversity in rhizosphere soil increased significantly, and the abundances of Proteobacteria and Bacteroidetes also increased in rhizosphere soil. Pearson correlations indicated that Hg, As, Ni and Cr were negatively correlated with Proteobacteria (p < 0.05), and Cu was significantly negative correlated with Bacteroidetes (p < 0.05). The results support that using suitable local plants is a promising approach for repairing heavy metal contaminated costal soil, not only because it can improve the regional ecological environment quality, but also because it can enhance the landscape value of coastal zone.

The role of Cyperus alopecuroides Rottb. sedge in monitoring water pollution in contaminated wetlands in Egypt: a phytoremediation approach

Many macrophytes have heavy metal phytoremediation potential from contaminated watercourses. Therefore, the present study investigated the seasonal potential of the sedge plant Cyperus alopecuroides to remediate heavy metals from contaminated water bodies. Water, sediment, and plant samples were collected from four contaminated watercourses and the uncontaminated Nile River. Summer was the blooming season of C. alopecuroides with the highest shoot density, leaf size, fresh production, and dry biomass, while winter represented the lowest growth season. The photosynthetic pigments were distinctly decreased in plants growing in contaminated compared to the uncontaminated sites. Plant roots accumulated concentrations of all measured heavy metals, except Ni, Cu, Zn, and Pb, more significant than the shoot. The maximum concentrations of Al, Ni, and Pb were recorded during spring, while the highest Cd, Cr, Fe, and Mn were recorded during summer. The bioconcentration factor (BCF) of all investigated metals (except Al) was > 1, while the translocation factor (TF) of all elements (except Pb) was ˂ 1. These results indicated the capability of C. alopecuroides for metal phytostabilization and considered the target species a powerful phytoremediator for monitoring water pollution in contaminated wetlands. In this context, the above- and belowground parts of C. alopecuroides should be harvested in summer for efficient phytoremediation.

Temporal Potential of Phragmites australis as a Phytoremediator to Remove Ni and Pb from Water and Sediment in Lake Burullus, Egypt

In the current work, we investigated the concentration of Ni and Pb in different organs of Phragmites australis to evaluate its potential application as a phytoremediator to remove these two metals from contaminated water and sediment in Lake Burullus (a Ramsar site in Egypt). Above- and below-ground biomass of P. australis, water and sediment were sampled monthly for 1 year at six sites of Lake Burullus (three sites represent each of the northern and southern parts of the lake) using six randomly distributed quadrats (each of 0.5 × 0.5 m) at each sampling site. Significant variation was detected for Ni and Pb concentrations in the sediments and waters between the northern and southern sites of the lake. The biomass of P. australis in the southern sites was greater than that in the northern sites; in addition, the above-ground biomass was higher than the below-ground biomass. The above-ground organs accumulated higher concentrations of Ni and Pb than the below-ground organs. The Ni and Pb standing stocks data indicated that the organs of P. australis extracted higher amounts of Ni and Pb per its area from the southern rather than the northern sites. In the current study, the Ni and Pb above-ground standing stocks increased from the early growing season (February) and reached its peak during August and then decreased. The highest monthly Ni and Pb standing stock (18.2 and 18.4 g m^- 2, respectively) was recorded in the above-ground organs of plants in the southern sites in August. The bioaccumulation factor of Ni was 157.6 and 153.4 in the northern and southern sites, respectively, whereas that of Pb was 175.3 and 158.3. The translocation factor of Ni and Pb from the below- to above-ground organs was generally > 1. Thus, this reed species is a potential candidate for Ni and Pb phytoextraction. Based on our results, P. australis could be used for the extraction of Ni and Pb to reduce the pollution in Lake Burullus, if the above-ground biomass is harvested at its maximum value in August, as was the case regarding the maximum standing stock of Ni and Pb.