Inside Cover: The cover image presents a lotus and a piece of duckweed floating on water surface, with the outmost cymbiform petals of the lotus half immersed in water. This indicates a new support ...method in photocuring 3D printing process in which partially cured resin material is used as weak support to fabricate overhang structures or even completely suspended parts, while the weak support is easy to design, fabricate, and remove. Further details can be found in the article 2100613 by Longqiu Li and co‐workers.
Over the past 50 years, different strategies have been developed for the remediation of polluted air, land and water. Driven by public opinion and regulatory bottlenecks, ecological based strategies ...are preferable than conventional methods in the treatments of chemical effluents. Ecological systems with the application of microbes, fungi, earthworms, plants, enzymes, electrode and nanoparticles have been applied to varying degrees in different media for the remediation of various categories of pollutants. Aquatic macrophytes have been used extensively for the remediation of pollutants in wastewater effluents and aquatic environment over the past 30 years with the common duckweed (L. minor) as one of the most effective macrophytes that have been applied for remediation studies. Duckweed has shown strong potentials for the phytoremediation of organic pollutants, heavy metals, agrochemicals, pharmaceuticals and personal care products, radioactive waste, nanomaterials, petroleum hydrocarbons, dyes, toxins, and related pollutants. This review covers the state of duckweed application for the remediation of diverse aquatic pollutants and identifies gaps that are necessary for further studies as we find pragmatic and sound ecological solutions for the remediation of polluted environment for sustainable development.
•Several tonnes of chemicals are produced annually from the global chemical industry.•Many of these chemicals are released into the environment after their domestic or industrial application.•These chemicals are difficult to remediate using conventional wastewater treatment methods.•Lemna minor is an effective macrophyte for the treatment of chemicals in the environment using constructed wetlands.
The phyto-Fenton process, which generates hydroxyl radicals through Fenton and Fenton-like reactions using plant-derived hydrogen peroxide (H2O2) and ferrous iron (Fe (II)) can degrade organic ...pollutants. Duckweed, an aquatic plant, is promising for a co-beneficial phytoremediation process that combines wastewater treatment and biomass production for biofuel feedstock. However, the phyto-Fenton process using duckweed has not been extensively studied. Because sulfamethoxazole (SMX), a major antibiotic, is distributed widely and is an emerging contaminant, its effective removal from contaminated water is necessary. The present study investigated the possibility of the simultaneous efficient removal of SMX from polluted water and biomass production for fuel feedstock by the phyto-Fenton process using duckweed. This is the first attempt to demonstrate the co-benefits of SMX removal and biomass production using duckweed. Intracellular H2O2 was produced using four duckweeds, Lemna aequinoctialis, L. minor, Landolina punctata, and Spirodela polyrhiza, in the range of 16.7–24.6 μ mol g−1 fresh weight, and extracellular H2O2 was released into the water phase. Consequently, duckweed could be used as an H2O2 supply source for the phyto-Fenton process. Specifically, 0.5 g fresh duckweed almost completely eliminated 1 mg L−1 SMX after 5 d in 50 mL sterile modified Hoagland solution containing 10 mM Fe (II). Fe (II)-dependent elimination of SMX indicated the occurrence of phyto-Fenton reaction. The phyto-Fenton process using duckweed effectively removed SMX. S. polyrhiza duckweed similarly removed 1 mg L−1 SMX even in sewage effluent containing other organic contaminants. During this treatment, duckweed biomass was generated at 7.95 g dry weight m−2 d−1, which was converted into methane at 353 normal liters CH4 kg−1 volatile solids by anaerobic digestion. For the first time, this study clearly demonstrates the potential for simultaneous SMX removal and biomass production from SMX-contaminated wastewater using duckweed.
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•Duckweed produced H2O2 and released it to water phase.•Duckweed supplied enough H2O2 for the phyto-Fenton process.•Sulfamethoxazole (SMX) was efficiently removed by the phyto-Fenton process.•Duckweed biomass (7.95 g-dry weight) m−2 d−1 was produced during SMX removal.•Duckweed biomass was converted to 353 NL methane kg−1 volatile solids.
Polyamines (PA) cellular levels are maintained through a balance between synthesis and catabolism, achieved by two classes of enzymes polyamine oxidases (PAOs) and copper amine oxidases (CuAO). Here ...we investigated the occurrence, molecular evolution and role(s) of PAOs and CuAO gene families in aquatic duckweed and their comparison with other aquatic plants -sea eelgrass, bladderwort, and Lotus. We identified eight bona fide PAO genes (SpPAO1–SpPAO8) and one SpCuAO1 in the greater duckweed genome from three genome assemblies. Interestingly, duckweed PAO genes increased their number through a tandem duplication event, while contrary to this CuAO genes were significantly lost to a single gene SpCuAO1. Phylogenetic analysis revealed that tandemly duplicated SpPAO2–7 share close similarity to well-known terminal catabolism (TC) pathway PAO genes while SpPAO1 and SpPAO8 seem to segregate along with back conversion (BC) participating known PAO genes, suggesting that all tandem duplicated PAOs are involved in TC pathway which is contrary to known trend in land plants where CuAOs are mainly involved in TC pathway. Comparative transcript abundance studies indicated that all eight PAOs and one CuAO gene respond to multiple stresses and principal component analysis identifies SpPAO4 as a highly active gene in response to multiple stresses. Results showed that oxidation of higher polyamines (SPD/SPM) through the TC pathway is diversified in duckweeds. Taken together this study reveals unique insights into the genomic losses and gains of polyamine metabolism possibly involved in achieving the structural and physiological adaptations required for aquatic lifestyle of duckweeds.
•Polyamine oxidases (PAO) encoding genes for higher polyamines (spermidine/spermine) catabolic pathway diversified through tandem duplication while genes encoding for primary/di amine/putrescine catabolic pathway significantly lost in duckweeds.•Out of total eight PAOs, six tandem duplicated PAOs seem to participated in terminal catabolism leaving 2 PAOs for back conversion pathway.•Due to only one CuAO gene, the terminal catabolism pathway is shifted towards polyamine oxidases which is opposite to most known land plants.•Both gene families are transcriptionally active in response to phytohormones, acidic pH and salt stress where PAO4 is identified as a highly active common gene among MeJA and salt responses.
In continuously-flooded paddies, the small, fast-growing aquatic plant duckweed (Lemna minor L.) considered to compete with rice for nitrogen, thereby having a negative impact on early rice growth. ...While duckweed overpopulation was known can be effectively overcome through field water management, the influence of such management on the N fate and its use efficiency in rice-duckweed systems is poorly documented. Accordingly, a three-year (2020–2022) field experiment was conducted to examine the combined impact on rice yield, as well as N loss and utilization, of two water management approaches (flood irrigation, FI vs. alternate wetting and drying irrigation, AWD), factorially combined with two rice production systems (rice-duckweed, +D, vs. duckweed-free rice, -D). In AWD+D fields, the density of duckweed generally remained below 250 g m−2 (about 85 % coverage), whereas in FI+D fields it reached 100 % coverage (300 g m−2) within 5 days after transplanting, with individual duckweeds overlapping one another. Following AWD irrigation, duckweed performed as a nitrogen “cache,” akin to a split fertilizer application, with the first of several splits occurring at the rice crop's early tillering stage. Within the first 2 days of a specific wet-dry cycle, duckweed can store 0.5–1.5 g N m−2, and then, within a further 3 days, release 0.3–1.0 g N m−2. In contrast, in FI+D paddies, this caching function occurred once under mid-season drainage, with further N being stored in the duckweeds during the remaining rice production season. As a result, at harvest the 0–0.10 m soil layer's N level increased significantly (p<0.05) in both FI+D (8.5–16.8 %) and AWD+D (14.9–20.8 %) compared to FI-D and AWD-D, respectively. Due to the coverage and storage-release function of duckweed, apparent N loss decreased in rice-duckweed system by 1.4–12.5 % in the FI field and 22.1–31.3 % in the AWD field compared to their respective duckweed-free systems. In FI fields, except for a 10 % relative reduction in nitrogen recovery efficiency (NRE) in 2020, duckweed didn't significantly affect rice yield or NRE. The yield reduction (3.5–6.7 %) and the NRE increase (0.8–7.4 %) under AWD-D (vs. FI-D) was, in the presence of duckweed, compensated for and overrun, resulting in a greater yield (5.3–6.7 %) and NRE (5.4–28.9 %) in the AWD+D vs. AWD-D field. When duckweed was present, AWD irrigation improved the by-path nitrogen cycling through duckweed, making the AWD+D system more beneficial for rice cultivation and the agroecosystem's environment health. The AWD+D system offers a promising measure for building an efficient and sustainable rice-duckweed agroecosystem.
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•Duckweed performed as a N cache due to its rapidly N storage-release in rice season.•AWD avoid over reproduction of duckweed and N competition with rice plant.•Multiple wet-dry cycles resulted in multi-splits low dosage return of duckweed N.•Duckweed enhanced rice N recovery utilization especially under AWD irrigation.•Rice-duckweed with AWD is a promising solution for sustainable rice cultivation.
•The CM particle electrode with rich in N, P was prepared using duckweed.•Ru catalyst was dispersed uniformly on CM-650 with amorphous.•The Ru/CM-650 exhibited high activity for electrocatalytic ...dechlorination of DCF.
In order to improve degradation efficiency and reduce electrode cost, carbon microspheres (CM) particle electrode was prepared from readily available duckweed as a raw material for electrocatalytic hydrodechlorination. The surface structures and chemical characteristics of the CM were regulated by adjusting the pyrolysis temperature. When pyrolysis was performed at 650 °C, carbon microspheres (CM-650) with large surface areas that are rich in heteroatoms (N, P) and show high electrical conductivity are obtained. After the Ru catalyst was supported, the Ru/CM-650 as particle electrode forming a three-dimensional (3D) electrochemical reaction system exhibits high electrocatalytic performance for diclofenac (DCF) hydrodechlorination with dechlorination efficiency of more than 90% in 150 min. Furthermore, the Ru/CM-650 has good stability for repeated use, which is attributed to the synergistic interaction between N and P elements improving the stability of the catalyst.
High concentration of Cu2+ in swine wastewater raises concerns about its potential adverse effects on nutrient removal by aquatic plants like duckweed. In this work, the effects of copper ions on ...nutrient removal and release of dissolved organic matter (DOM) were investigated in duckweed systems. Results showed that the removal performance of ammonia nitrogen (NH3N) and total phosphorus (TP) increased at 0.1–1.0 mg/L of Cu2+, while dropped at 2.0–5.0 mg/L of Cu2+. A novel kinetic model in which Cu2+ was taken into account was then developed which was used to optimize Cu2+ concentration at 0.96 mg/L for nutrient removal in duckweed systems. NADH, detected in DOM by the parallel factor (PARAFAC) analysis, exhibited high capacities of binding copper ions, so it played an important role on the decrease of Cu2+ concentrations in duckweed systems. The principle component analysis (PCA) showed that the dominant DOM were lower molecular weight compounds at 1.0 mg/L of Cu2+ and higher molecular weight compounds at 2.0–5.0 mg/L of Cu2+. The bonds of CH (humic-like), NO (NO3−) and ArH (tyrosine) in DOM were responsible for not only the fastest binding with Cu2+ from the result of the two-dimensional Fourier transform infrared correlation spectroscopy (2D-FTIR-CoS) but also the variations of DOM conformations at a critical concentration of 0.5 mg/L Cu2+ from the perturbation correlation moving window two-dimensional (PCMW2D) analysis. These findings lead to a better understanding on the environmental behaviors and mechanisms of Cu2+ in duckweed systems.
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•The optimal Cu2+ concentration was 0.96 mg/L for the removal of NH3N and TP.•NADH in DOMs was detected with high metal binding abilities with Cu ions.•The molecular weight of released DOMs was different at various Cu2+ concentrations.•The bonds of CH, NO and ArH were responsible for the fastest binding with Cu2+.•The conformational variation of DOMs was at a critical concentration 0.5 mg/L Cu2+.
Catfish is one of the fish that is in demand for cultivation activities because it has high market absorption, adequate nutrition, and is relatively easy to maintain. The research aims to analyze the ...hematological response of Sangkuriang catfish (Clarias sp.) after being given a feed substitute made from Duckweed flour (Lemna minor). The research was conducted in Palangka Raya City, Central Kalimantan Province. Feed from each treatment A (Commercial feed, feed without the addition of duckweed meal), B (Feed with 0% duckweed meal: 100% soybeans), C (Feed with 50% duckweed meal: 50% soybeans), D (Feed with 75% duckweed meal: 25% soybeans), and treatment E (Feed with 25% duckweed meal: 75% soybeans) was weighed at 5% of each fish's weight in the treatment container. The hematological response of Sangkuriang catfish given feed substitution made from Duckweed flour (Lemna minor) with parameters of hematocrit, leukocrit, hemoglobin, and blood plasma of Sangkuriang catfish for 45 days of research had a positive impact on fish health in this condition due to the content of Duckweed flour (Lemna minor). can help control the health of sangkuriang catfish.
Duckweed-based ponds (DP), as a modified type of waste stabilization ponds (WSP) are receiving growing attention due to the sustainable production of high-quality duckweed biomass. However, the ...comprehensive effects of duckweed cover on nutrient removal, greenhouse gas emission and microbial community of the WSP have rarely been studied. In this study, two pilot-scale WSP (12 m2) with (DP) and without (OP) a duckweed mat on the surface were compared over 1 year to determine the effects. The results showed that, compared to OP, DP had higher TP, but lower TN and NH4+-N removal efficiencies, and lower pH, dissolved oxygen (DO) and sedimentation rate of settling detritus. For both nitrogen and phosphorus removal, the dominant pathway was duckweed uptake (66.95% and 93.18%, respectively) in DP; however, it became other pathways (mainly nitrification/denitrification, 82.27%) and sedimentation (87.65%), respectively, in OP. Meanwhile, DP had lower N2O, but higher CH4 emission fluxes than OP, resulting in comparable global warming potential between OP and DP (approximately 2800 g CO2/m2/yr). Microbial community analysis indicated that the greater nitrogen removal and N2O emission in OP could be attributed to higher abundance of ammonia-oxidizing bacteria in the water and denitrifiers in the sediment, supported by higher DO and settling organic carbon, respectively. Meanwhile, the greater CH4 emission in DP could be attributed to higher abundance of methanogens and syntrophic methanogenic bacteria in the sediment. Thus, despite favourable effects on nutrient recovery and phosphorus removal mainly attributed to duckweed uptake, duckweed cover had unfavourable effects on nitrogen removal and CH4 emission reduction of the WSP mainly attributed to microbial taxa which were influenced by environmental conditions (such as DO and settling detritus) in the WSP. These findings help to clarify the influencing mechanism of duckweed cover, providing overall insight into the function and application of the DP.
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•Two pilot-scale ponds with (DP) and without (OP) duckweed were compared over 1 year.•Duckweed had favourable effects on N, P recovery and P removal due to plant uptake.•Duckweed had unfavourable effects on N removal and CH4 emission reduction.•More AOB and denitrifiers supported greater N removal and N2O emission of OP.•More methanogens and syntrophic bacteria supported greater CH4 emission of DP.
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