Eichhornia crassipes mediated copper phytoremediation and its success using catfish bioassay

Salvinia molesta phytoremediation capacity as a nature-based solution to prevent harmful effects and accumulation of ciprofloxacin in Neotropical catfish

Phytoremediation has been a potential solution for the removal of pharmaceuticals from water. Here, we evaluated the toxicological safety of ciprofloxacin-contaminated water treated by 96 h with Salvinia molesta. The Neotropical catfish Rhamdia quelen was used as a model, and the potential of the phytoremediation technique for mitigating the drug accumulation in the fishes was also studied. Fish exposed to Cipro (1 and 10 µg·L^-1) in untreated water showed toxic responses (alteration of hematological, genotoxicity, biochemical, and histopathological biomarkers) and accumulated Cipro in their muscles at concentrations high for human consumption (target hazardous quotient > 1). Fish exposed to water treated with S. molesta showed no toxic effect and no accumulation of Cipro in their tissues. This must be related to the fact that S. molesta removed up to 97% of Cipro from the water. The decrease in Cipro concentrations after water treatment with S. molesta not only prevented the toxic effects of Cipro on R. quelen fish but also prevented the antimicrobial accumulation in fish flesh, favouring safe consumption by humans. For the very first time, we showed the potential of phytoremediation as an efficiently nature-based solution to prevent environmental toxicological effects of antimicrobials to nontarget organisms such as fish and humans. The use of S. molesta for Cipro-removal from water is a green technology to be considered in the combat against antimicrobial resistance.

Potential of Lemna minor and Eichhornia crassipes for the phytoremediation of water contaminated with Nickel (II)

Phytoextraction of Nickel (II) in water by two types of aquatic macrophytes (Lemna minor and Eichhornia crassipes) was investigated using synthetic aqueous solutions of NiSO₄ at concentrations of 0.5, 1.5 and 2.5 mg/L. The toxic effects of nickel salt in plants were evaluated through the presence of necrosis and chlorosis. The bioconcentration factor, Nickel (II) removal efficiency and kinetics of removal were also calculated. Results of this study show bioconcentration factors higher than 1000, which categorize L. minor and E. crassipes as hyperaccumulators. Besides, L. minor presented a removal percentage higher than 68%, compared to E. crassipes that did not exceed 50% in any of the three concentrations studied. However, E. crassipes showed better resistance to the effects of nickel and obtained a greater removal capacity during the phytoremediation process that lasted for 10 days. In contrast, L. minor suffered necrosis and chlorosis in a concentration-dependent way. Consequently, both macrophytes are sustainable alternatives for nickel removal from contaminated water.

Can Lemna minor mitigate the effects of cadmium and nickel exposure in a Neotropical fish?

We aimed to evaluate if Lemna minor can mitigate the observed effects of cadmium (Cd) and nickel (Ni) exposure in Prochilodus lineatus. Fish were exposed for 96 h to 20 µg L^-1 of Cd, 1.5 mg L^-1 of Ni, or to a mixture of these two metals. In all tests, one group was exposed to the metals with duckweed on the water surface, and other group was exposed only to the metals, without plants. After each exposure, samples of P. lineatus tissues were collected to evaluate multiple biomarkers. Duckweed prevented bioaccumulation in some fish tissues and attenuated changes in acetylcholinesterase activity, increases in erythrocytic nuclear abnormality frequency, and hyperglycemia. However, the changes in plasma ion concentrations, reduction in activity of ion transport enzymes, and histological damage were not mitigated. Therefore, we concluded that L. minor partially attenuates the effects caused by Cd and Ni exposure.

Integrated emergent-floating planted reactor for textile effluent: Removal potential, optimization of operational conditions and potential forthcoming waste management strategy

Native emergent and floating plants; local reed grass (Phragmites karka) and water hyacinth (Eichhornia crassipes), respectively, were used to treat textile wastewater using an integrated emergent-floating planted reactor (IEFPR) system at hydraulic retention times (HRTs) of 8, 14, and 19 days. Real textile effluent having characteristics of 1686.3 ADMI for colour, 535 mg/L for total suspended solid (TSS), 647.7 mg/L for chemical oxygen demand (COD) and 124 mg/L for biochemical oxygen demand (BOD) was used throughout this study. The IEFPR system experienced maximum removal of colour (94.8%, HRT 14 days, day 3), TSS (92.7%, HRT 19 days, day 7), and COD (96.6%, HRT 8 days, day 5) at different HRT and exposure time. The process conditions (HRT and exposure time) were optimized for maximum colour, TSS and COD removal from textile effluent by employing response surface methodology (RSM). The optimization has resulted 100% removal of colour, 87% removal of TSS and 100% removal of COD at HRT of 8 days and exposure time of 5 days, with 0.984 desirability. The integrated plant-assisted treatment system showed reliable performance in treating textile wastewater at optimum operational conditions to improve effluent quality before disposal into water bodies or being recycled into the process. The potential of phytoremediator (produced plant biomass) to be utilized as resources for bioenergy or to be converted into value added products (adsorbent or biochar) provides an alternative to management strategy for better environmental sustainability.

Accumulation, distribution and removal of triazine pesticides by Eichhornia crassipes in water-sediment microcosm

After application, pesticides remained in the field may contaminate water resources through surface runoff and leaching, posing a threat to aquatic ecosystem. In the current study, the accumulation, translocation, distribution and removal of four triazine pesticides (simazine, atrazine, terbuthylazine and metribuzin) by free floating aquatic plant Eichhornia crassipes (E. crassipes) in water-sediment microcosm were investigated and the removal mechanisms were explored. E. crassipes was exposed to an initial concentration of 50 μg·L^-1 and the pesticide levels in water, sediment, roots and shoots of E. crassipes were monitored during 30 days. The results demonstrated that E. crassipes was capable of accumulating triazine pesticides with the bio-concentration factor (BCF) ranging from 0.8 to 18.4. Triazine pesticides were mainly stored in roots, and root accumulation and translocation amount depend on the hydrophobicity of the pesticides. The removal of the pesticides in water were significantly accelerated by the presence of E. crassipes, with the removal efficiency ranging from 66% to 79% after 30 days of treatment. Though phytoaccumulation only constituted 2-18% of the total spiked pesticides in the microcosm, E. crassipes played a vital role in removing simazine, atrazine and metribuzin. However, microbial degradation in sediment was the main pathway for the removal of terbuthylazine in the microcosm. This study demonstrated the potential application of E. crassipes to accelerate removal of contaminants from aquatic environment.

Physiological mechanisms and phytoremediation potential of the macrophyte Salvinia biloba towards a commercial formulation and an analytical standard of glyphosate

Glyphosate (Gly) is the most widely used herbicide in the world and has broad-spectrum and non-selective activity. Its indiscriminate use hence risks contamination of water bodies and can affect living organisms, especially sensitive or resistant non-target plants. Despite this, studies on physiological mechanisms and Gly remediation in Neotropical aquatic plants remain limited. This study aims to evaluate the physiological mechanisms of the aquatic macrophyte Salvinia biloba on exposure to different concentrations of a Gly commercial formulation (Gly-CF) and a Gly analytical standard (Gly-AS). Furthermore, using square-wave voltammetry (SWV), we determined whether the studied plant could remove Gly from water. Our data suggest that Gly-AS and Gly-CF induce similar physiological responses in S. biloba. However, Gly-CF was more phytotoxic. Depending on the concentration, the two forms of Gly affected the plants, decreasing the chlorophyll a and b contents and the photosystem II (PSII) photochemical activity. The data also revealed that Gly promoted oxidative stress and increased the shikimic acid concentration. At the same time, the plants removed Gly from water, with 100% removal for 1 mg L-1 Gly and above 60% removal for the other concentrations studied. Therefore, our results suggest that S. biloba may be a potential phytoremediation agent for low Gly concentrations, since 1 mg L-1 Gly was completely removed and exhibited low phytotoxicity. This study deepens our scientific understanding of the Gly impact on and the phytoremediation potential of S. biloba.

Eichhornia crassipes: a Powerful Bio-indicator for Water Pollution by Emerging Pollutants

Eichhornia crassipes is well known as an invasive aquatic plant. It is also used very effectively in phytoremediation, particularly for the rhizofiltration of effluents contaminated by heavy metals. In this article, we show that it is also an excellent bioindicator of water polluted by worrying organic pollutants such as endocrine disruptors and neonicotinoids. As a proof of concept, di-n-hexylphthalate, pentabromodiphenyl ether, nitenpyram, acetamiprid and bis (3-tert-butyl-4-hydroxy-6-methylphenyl) sulfide were clearly identified by UHPLC-HRMS or GC-MS in the root system of E. crassipes after a short period of exposure. These results open up new perspectives for the remediation of water polluted by alarming organic pollutants.