The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform

Alexis Zrimec - One of the best experts on this subject based on the ideXlab platform.

  • oxidative stress in duckweed Lemna Minor l caused by short term cadmium exposure
    Environmental Pollution, 2008
    Co-Authors: Jaka Razinger, Marina Dermastia, Jasna Dolenc Koce, Alexis Zrimec
    Abstract:

    The mechanisms of plant defence against cadmium toxicity have been studied by short-term exposure of Lemna Minor L. (common duckweed) to concentrations of CdCl2 ranging from 0 to 500microM. High accumulation of cadmium was observed (12,320+/-2155microgg(-1) at 500microM CdCl2), which caused a gradual decrease of plant growth, increased lipid peroxidation, and weakened the entire antioxidative defence. Total glutathione concentration decreased significantly; however, the concentration of oxidized glutathione remained stable. The responses of four antioxidant enzymes showed that catalase was the most inhibited after CdCl2 exposure, ascorbate peroxidase and guaiacol peroxidase moderately, and glutathione reductase least. The total antioxidative potential revealed an induced antioxidative network at 0.1microM CdCl2 (137+/-13.2% of the control) and its reduction to only 47.4+/-4.0% of the control at higher cadmium concentrations. The possible application of the examined biomarkers in ecotoxicological research is discussed.

Hongwen Sun - One of the best experts on this subject based on the ideXlab platform.

  • potential of duckweed Lemna Minor for removal of nitrogen and phosphorus from water under salt stress
    Journal of Environmental Management, 2017
    Co-Authors: Chunguang Liu, Zheng Dai, Hongwen Sun
    Abstract:

    Duckweed plays a major role in the removal of nitrogen (N) and phosphorus (P) from water. To determine the effect of salt stress on the removal of N and P by duckweed, we cultured Lemna Minor, a common species of duckweed, in N and P-rich water with NaCl concentrations ranging from 0 to 100 mM for 24 h and 72 h, respectively. The results show that the removal capacity of duckweed for N and P was reduced by salt stress. Higher salt stress with longer cultivation period exerts more injury to duckweed and greater inhibition of N and P removal. Severe salt stress (100 mM NaCl) induced duckweed to release N and P and even resulted in negative removal efficiencies. The results indicate that L. Minor should be used to remove N and P from water with salinities below 75 mM NaCl, or equivalent salt stress.

Ivana Ivancev Tumbas - One of the best experts on this subject based on the ideXlab platform.

  • myriophyllum aquaticum versus Lemna Minor sensitivity and recovery potential after exposure to atrazine
    Environmental Toxicology and Chemistry, 2012
    Co-Authors: Ivana Teodorovic, Varja Kneževic, Tanja Tunic, Mico Cucak, Jelena Nikolic Lecic, Anita Leovac, Ivana Ivancev Tumbas
    Abstract:

    The relative sensitivity and recovery potential of two aquatic macrophyte species, Lemna Minor and Myriophyllum aquaticum, exposed to atrazine (concentration ranges 80–1,280 µg/L and 40–640 µg/L, respectively) were evaluated using slightly adapted standard protocol for Lemna spp.: relative growth rates (RGR) and yield of both plants were measured in 3-d-long intervals during the exposure and recovery phase. Myriophyllum aquaticum was also exposed to atrazine-spiked sediment (0.1–3.7 µg/g) in a water-free system. The results of M. aquaticum sediment contact tests showed that root- and shoot-based growth parameters are equally sensitive endpoints. In the water (sediment-free) test system, L. Minor recovered after short (3 d) and longer exposure (7 d) to all atrazine concentrations after only a 5- to 6-d-long recovery phase. The recovery of M. aquaticum after short exposure was slower and less efficient: after 12 d of recovery phase the final biomass of plants exposed to 380 and 640 µg/L was below the initial values. The last interval RGR provides a good indication of plant recovery potential regardless of species growth strategy. If compared to L. Minor, the difference in growth rate, sensitivity, lag phase, recovery potential from water-column substances, and also suitability for studies investigating the effect of sediment-bound pollutants advocates the use of M. aquaticum as an additional macrophyte species in risk assessment. Environ. Toxicol. Chem. 2012;31:417–426. © 2011 SETAC

Chunguang Liu - One of the best experts on this subject based on the ideXlab platform.

  • catalytic production of levulinic acid and ethyl levulinate from uniconazole induced duckweed Lemna Minor
    Bioresource Technology, 2018
    Co-Authors: Chunguang Liu, Qingna Feng, Jirui Yang
    Abstract:

    Abstract Duckweed (Lemna Minor) with a high starch content of 50.4% was cultivated by uniconazole-induction method. The cultivated duckweed was used to produce value-added chemicals such as glucose, levulinic acid and formic acid in diluted HCl aqueous solution. A high glucose yield of 93.4% (471 g/kg based on loading duckweed mass) could be achieved at 180 °C in short reaction time, and the generated glucose was converted into levulinic acid and formic acid with yields of 52.0% and 34.1%, respectively, for 150 min, corresponding to 262 g/kg levulinic acid yield and 171 g/kg formic acid yield based on the mass of loading duckweed, respectively. Moreover, the duckweed was efficiently converted to ethyl levulinate with 55.2% yield (400.6 g/kg) at 200 °C in ethanol. This work provides a promising strategy for the production of value-added chemicals from phytoplankton that is able to purify the wastewater containing high content of P and N.

  • potential of duckweed Lemna Minor for removal of nitrogen and phosphorus from water under salt stress
    Journal of Environmental Management, 2017
    Co-Authors: Chunguang Liu, Zheng Dai, Hongwen Sun
    Abstract:

    Duckweed plays a major role in the removal of nitrogen (N) and phosphorus (P) from water. To determine the effect of salt stress on the removal of N and P by duckweed, we cultured Lemna Minor, a common species of duckweed, in N and P-rich water with NaCl concentrations ranging from 0 to 100 mM for 24 h and 72 h, respectively. The results show that the removal capacity of duckweed for N and P was reduced by salt stress. Higher salt stress with longer cultivation period exerts more injury to duckweed and greater inhibition of N and P removal. Severe salt stress (100 mM NaCl) induced duckweed to release N and P and even resulted in negative removal efficiencies. The results indicate that L. Minor should be used to remove N and P from water with salinities below 75 mM NaCl, or equivalent salt stress.

Athanasios S. Stasinakis - One of the best experts on this subject based on the ideXlab platform.

  • removal mechanisms of benzotriazoles in duckweed Lemna Minor wastewater treatment systems
    Science of The Total Environment, 2017
    Co-Authors: Georgia Gatidou, Maria Oursouzidou, Aimilia Stefanatou, Athanasios S. Stasinakis
    Abstract:

    The fate of five benzotriazoles (1H-benzotriazole, BTR; 4-methyl-1H-benzotriazole, 4TTR; 5-methyl-1H-benzotriazole, 5TTR; xylytriazole, XTR and 5-chlorobenzotriazole, CBTR) was studied in batch and continuous-flow Lemna Minor systems and the role of different mechanisms on their removal was evaluated. Single and joint toxicity experiments were initially conducted using the Organization for Economic Co-operation and Development (OECD) protocol 221 and no inhibition on specific growth rate of Lemna Minor was observed for concentrations up to 200μgL-1. All tested substances were significantly removed in batch experiments with Lemna Minor. Excepting 4TTR, full elimination of CBTR, XTR, 5TTR and BTR was observed up to the end of these experiments (36d), while the half-life values ranged between 1.6±0.3d (CBTR) and 25±3.6d (4-TTR). Calculation of kinetic constants for hydrolysis, photodegradation, and plant uptake revealed that for all BTRs the kinetic constants of plant uptake were by far higher comparing to those of the other mechanisms, reaching 0.394±0.161d-1 for CBTR. The operation of a continuous-flow Lemna Minor system consisted of three mini ponds and a total hydraulic residence time of 8.3d showed sufficient removal for most target substances, ranging between 26% (4TTR) and 72% (CBTR). Application of a model for describing micropollutants removal in the examined system showed that plant uptake was the major mechanism governing BTRs removal in Lemna Minor systems.

  • fate of antimicrobials in duckweed Lemna Minor wastewater treatment systems
    Journal of Hazardous Materials, 2017
    Co-Authors: Evangelia I. Iatrou, Georgia Gatidou, Dimitrios Damalas, Nikolaos S Thomaidis, Athanasios S. Stasinakis
    Abstract:

    Abstract The fate of four antimicrobials (cefadroxil, CFD; metronidazole, METRO; trimethoprim, TRI; sulfamethoxazole, SMX) was studied in Lemna Minor systems and the role of different mechanisms on their removal was evaluated. All micropollutants were significantly removed in batch experiments with active Lemna Minor; the highest removal was observed for CFD (100% in 14 d), followed by METRO (96%), SMX (73%) and TRI (59%) during 24 d of the experiment. Calculation of kinetic constants for hydrolysis, photodegradation, sorption to biomass and plant uptake revealed significant differences depending on the compound and the studied mechanism. For METRO, TRI and SMX the kinetic constants of plant uptake were by far higher comparing to those of the other mechanisms. The transformation products of antimicrobials were identified using UHPLC-QToF-MS. Two were the main degradation pathways for TRI; hydroxylation takes place during both phyto- and photodegradation, while demethylation occurs only in absence of Lemna Minor. The operation of a continuous-flow duckweed system showed METRO and TRI removal equal to 71 ± 11% and 61 ± 8%, respectively. The application of mass balance and the use of published biodegradation constants showed that plant uptake and biodegradation were the major mechanisms governing METRO removal; the most important mechanism for TRI was plant uptake.

  • Assessing single and joint toxicity of three phenylurea herbicides using Lemna Minor and Vibrio fischeri bioassays.
    Chemosphere, 2015
    Co-Authors: Georgia Gatidou, Athanasios S. Stasinakis, Evangelia I. Iatrou
    Abstract:

    Abstract Single and joint toxicity of three substituted urea herbicides, namely monolinuron [3-(4-chlorophenyl)-1-methoxy-1-methylurea], linuron [3-(3,4-dichlorophenyl)-1-methoxy-1-methylurea] and diuron [1-(3,4 dichlorophenyl)-3,3 dimethyl urea], were studied. The duckweed Lemna Minor and the luminescent bacterium Vibrio fischeri were used for the toxicity assessment and they were exposed to various concentrations of the herbicides, individually and in binary mixtures. The exposure time was 7 d for the duckweed and 30 min for the bacterium. Estimation of EC50 values was performed by frond counting and reduction in light output for Lemna Minor and Vibrio fischeri, respectively. Lemna Minor was found to be much more sensitive than Vibrio fischeri to target compounds. The toxicity of the three herbicides applied solely was estimated to be in decreasing order: diuron (EC50 = 28.3 μg L−1) ≈ linuron (EC50 = 30.5 μg L−1) > monolinuron (EC50 = 300 μg L−1) for the duckweed and linuron (EC50 = 8.2 mg L−1) > diuron (EC50 = 9.2 mg L−1) > monolinuron (EC50 = 11.2 mg L−1) for the bacterium. Based on the environmental concentrations reported in the literature and EC50 values obtained from Lemna Minor experiments, Risk Quotients (RQ) much higher than 1 were calculated for diuron and linuron. In Lemna Minor experiments, combination of target compounds resulted to additive effects due to their same mode of phenylurea action on photosynthetic organisms. Regarding Vibrio fischeri, synergistic, additive and antagonistic effects were observed, which varied according to the concentrations of target compounds.