The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Qixing Zhou - One of the best experts on this subject based on the ideXlab platform.
-
toxic effects of Hydrilla verticillata exposed to toluene ethylbenzene and xylene and safety assessment for protecting aquatic macrophytes
Chemosphere, 2011Co-Authors: Sha Yan, Qixing ZhouAbstract:Little information is available about the toxicity of toluene, ethylbenzene and xylene acting on macrophytes, and their toxicity data are rarely used in regulation and criteria decisions. The results extended the knowledge on toxic effects of toluene, ethylbenzene and xylene on aquatic plants. The responses of Hydrilla verticillata to these pollutants were investigated. Chlorophyll levels, lipid peroxidation, and antioxidant enzymes (superoxide dismutase and guaiacol peroxidase) showed diverse responses at different concentrations of toluene, ethylbenzene and xylene. The linear regression analyses were performed respectively, suggesting the concentrations of toluene, ethylbenzene and xylene expected to protect aquatic macrophytes were 7.30 mg L⁻¹, 1.15 mg L⁻¹ and 2.36 mg L⁻¹, respectively. This study emphasized that aquatic plants are also sensitive to organic pollutants as fishes and zooplanktons, indicating that macrophytes could be helpful in predicting the toxicity of these pollutants and should be considered in regulation and criteria decisions for aquatic environment protection.
-
The effects of photosynthetic pigments on Hydrilla verticillata and Vallisneria spiralis induced by toluene, ethylbenzene and xylene
2011 International Symposium on Water Resource and Environmental Protection, 2011Co-Authors: Qixing ZhouAbstract:Effects of toluene, ethylbenzene and xylene on the contents of chlorophylls (a and b) were investigated in Hydrilla verticillata and Vallisneria spiralis. Hydrilla verticillata exhibited increases at lowest concentrations, while the loss in chlorophyll contents at higher chemicals concentrations occurred. Linear regression analyses were performed. IC10 values were 7.30mg/L, 1.15mg/L and 2.36mg/L for toluene, ethylbenzene and xylene. Chlorophylls contents of Vallisneria spiralis showed the erratic reduces at all concentrations of pollutants except three sampling points, showing photosynthesis of Vallisneria spiralis was negatively affected because of the toxicity of pollutants. The results indicated that the mechanism of the toxicity induced by toluene, ethylbenzene and xylene may have some differences, and Hydrilla verticillata was more suitable to be used in toxicity tests.
S F Dsouza - One of the best experts on this subject based on the ideXlab platform.
-
the effect of arsenic on pigment composition and photosynthesis in Hydrilla verticillata
Biologia Plantarum, 2013Co-Authors: Sudhakar Srivastava, Ashish Kumar Srivastava, Bhupinder Singh, Penna Suprasanna, S F DsouzaAbstract:The present study evaluated the effects of 100 and 500 μM arsenate (Na2HAsO4) on pigment composition and photosynthesis in Hydrilla verticillata (L.f.) Royle. Arsenic accumulation increased in concentration and duration dependent manner. The maximum accumulation [568 μg(As) g−1(d.m.)] was observed at 500 μM concentration and 96-h exposure. This concentration led to a significant decline in chlorophyll a content and PS II efficiency during the whole experiment, and in chlorophyll b and carotenoids after 96 h, but no significant changes in photosynthetic pigments were noticed at 100 μM arsenate. Net photosynthetic rate, electron transport rate, and water use efficiency declined whereas transpiration rate increased, and stomatal conductance and photochemical quenching did not show any effect or increased. The content of reactive oxygen species increased and content of reduced ascorbate declined at 500 μM arsenate in comparison to the control.
-
phytofiltration of arsenic from simulated contaminated water using Hydrilla verticillata in field conditions
Ecological Engineering, 2011Co-Authors: Sudhakar Srivastava, Penna Suprasanna, Manoj Shrivastava, S F DsouzaAbstract:Abstract The present study investigated arsenic (As) removal efficiency of Hydrilla verticillata from simulated As-contaminated water in field conditions. Plants (100 g fresh weight) were grown in simulated contaminated water (total 8 L) containing 1500 μg L−1 As [in the form of arsenate (AsV)] for 45 d and As accumulation and biochemical changes were analyzed at 15 d intervals. As accumulation in plants increased progressively approaching 388 μg g−1 dw at 45 d. Considering the total dry biomass, total As removed was 8546 μg (i.e. 72% of total As supplied). Despite significant As accumulation, no toxic effects were observed in terms of the level of hydrogen peroxide and lipid peroxidation, which could be attributed to the enhanced level of thiol metabolites (cysteine, glutathione) and enzymatic antioxidants (guaiacol peroxidase, catalase, ascorbate peroxidase). The study demonstrates that Hydrilla plants can find application in As remediation in field conditions.
-
effect of variable sulfur supply on arsenic tolerance and antioxidant responses in Hydrilla verticillata l f royle
Ecotoxicology and Environmental Safety, 2010Co-Authors: Sudhakar Srivastava, S F DsouzaAbstract:In the present study, Hydrilla verticillata plants were exposed to arsenate (AsV; 50 microM) and arsenite (AsIII; 5 microM) under variable S supply: deficient (2 microM S, -S), normal (1 mM S, +S) and excess (2 mM S, +HS). Arsenic accumulation (microg g(-1) dw) in +HS plants was about 2-fold higher upon exposure to both AsV (30) and AsIII (50) than that observed in +S (12 & 24) and -S (14 & 26) plants. Despite lower As accumulation, -S plants experienced the maximum oxidative stress owing to an inadequate response of enzymatic and molecular antioxidants and significant decline in total thiols and the ratio of reduced glutathione (GSH) to oxidized glutathione (GSSG). By contrast +HS plants had significant increase in total thiols and an improved redox status, did not demonstrate any negative impact to antioxidants except catalase and hence experienced the least increase in oxidative stress parameters. In conclusion, an increase in S supply to plants may improve their accumulation capacity for As through enhanced tolerance caused by a positive effect on thiol metabolism and antioxidant status of the plants.
-
investigation of uranium accumulation potential and biochemical responses of an aquatic weed Hydrilla verticillata l f royle
Bioresource Technology, 2010Co-Authors: Sudhakar Srivastava, Kuber C Bhainsa, S F DsouzaAbstract:Abstract The uranium (U) accumulation potential and ensuing biochemical responses were studied in Hydrilla verticillata (L.f.) Royle upon exposure to U (0, 20 and 100 mg L−1). There was a concentration-duration dependent increase in U accumulation with the maximum being 78 mg g−1 DW at 100 mg L−1 U after 24 h. Plants experienced an initial phase of the maximum toxicity (within 30 min) followed by almost complete recovery after 24 h. The recovery was attributed to an integrated modulation in the level of both enzymatic and molecular antioxidants (viz., guaiacol peroxidase, ascorbate peroxidase, catalase, proline, total phenolics) and also the constituents of thiol metabolism (viz., cysteine and glutathione). Thus, plants were found to be able to accumulate significant amount of U in a short time and to tolerate it efficiently. Hence, they may find application in U phytoremediation considering there accumulation ability, fast growth due to weed-like habit and world-wide distribution.
-
increasing sulfur supply enhances tolerance to arsenic and its accumulation in Hydrilla verticillata l f royle
Environmental Science & Technology, 2009Co-Authors: Sudhakar Srivastava, S F DsouzaAbstract:The present study was aimed to analyze the effects of variable S supply on arsenic (As) accumulation potential of Hydrilla verticillata (L.f.) Royle. Plants were exposed to either arsenate (AsV; 50 μM) or arsenite (AsIII; 5 μM) for 4 h and 1 day while S supply was varied as deficient (2 μM, −S), normal (1 mM, +S) and excess (2 mM, +HS). The level of As accumulation (μg g−1 dw) after 1 day was about 2-fold higher upon exposure to either AsV (30) or AsIII (50) in +HS plants than that being in +S (12 and 24) and −S (14 and 26) plants. The +HS plants showed a significant stimulation of the thiol metabolism upon As exposure. Besides, they did not experience significant toxicity, measured in terms of malondialdehyde accumulation; an indicator of oxidative stress. By contrast, −S plants suffered from oxidative stress probably due to negative impact to thiol metabolism. Variable S supply also modulated the activity of enzymes of glycine and serine biosynthesis indicating an interconnection between S and N metabol...
Sudhakar Srivastava - One of the best experts on this subject based on the ideXlab platform.
-
the effect of arsenic on pigment composition and photosynthesis in Hydrilla verticillata
Biologia Plantarum, 2013Co-Authors: Sudhakar Srivastava, Ashish Kumar Srivastava, Bhupinder Singh, Penna Suprasanna, S F DsouzaAbstract:The present study evaluated the effects of 100 and 500 μM arsenate (Na2HAsO4) on pigment composition and photosynthesis in Hydrilla verticillata (L.f.) Royle. Arsenic accumulation increased in concentration and duration dependent manner. The maximum accumulation [568 μg(As) g−1(d.m.)] was observed at 500 μM concentration and 96-h exposure. This concentration led to a significant decline in chlorophyll a content and PS II efficiency during the whole experiment, and in chlorophyll b and carotenoids after 96 h, but no significant changes in photosynthetic pigments were noticed at 100 μM arsenate. Net photosynthetic rate, electron transport rate, and water use efficiency declined whereas transpiration rate increased, and stomatal conductance and photochemical quenching did not show any effect or increased. The content of reactive oxygen species increased and content of reduced ascorbate declined at 500 μM arsenate in comparison to the control.
-
phytofiltration of arsenic from simulated contaminated water using Hydrilla verticillata in field conditions
Ecological Engineering, 2011Co-Authors: Sudhakar Srivastava, Penna Suprasanna, Manoj Shrivastava, S F DsouzaAbstract:Abstract The present study investigated arsenic (As) removal efficiency of Hydrilla verticillata from simulated As-contaminated water in field conditions. Plants (100 g fresh weight) were grown in simulated contaminated water (total 8 L) containing 1500 μg L−1 As [in the form of arsenate (AsV)] for 45 d and As accumulation and biochemical changes were analyzed at 15 d intervals. As accumulation in plants increased progressively approaching 388 μg g−1 dw at 45 d. Considering the total dry biomass, total As removed was 8546 μg (i.e. 72% of total As supplied). Despite significant As accumulation, no toxic effects were observed in terms of the level of hydrogen peroxide and lipid peroxidation, which could be attributed to the enhanced level of thiol metabolites (cysteine, glutathione) and enzymatic antioxidants (guaiacol peroxidase, catalase, ascorbate peroxidase). The study demonstrates that Hydrilla plants can find application in As remediation in field conditions.
-
effect of variable sulfur supply on arsenic tolerance and antioxidant responses in Hydrilla verticillata l f royle
Ecotoxicology and Environmental Safety, 2010Co-Authors: Sudhakar Srivastava, S F DsouzaAbstract:In the present study, Hydrilla verticillata plants were exposed to arsenate (AsV; 50 microM) and arsenite (AsIII; 5 microM) under variable S supply: deficient (2 microM S, -S), normal (1 mM S, +S) and excess (2 mM S, +HS). Arsenic accumulation (microg g(-1) dw) in +HS plants was about 2-fold higher upon exposure to both AsV (30) and AsIII (50) than that observed in +S (12 & 24) and -S (14 & 26) plants. Despite lower As accumulation, -S plants experienced the maximum oxidative stress owing to an inadequate response of enzymatic and molecular antioxidants and significant decline in total thiols and the ratio of reduced glutathione (GSH) to oxidized glutathione (GSSG). By contrast +HS plants had significant increase in total thiols and an improved redox status, did not demonstrate any negative impact to antioxidants except catalase and hence experienced the least increase in oxidative stress parameters. In conclusion, an increase in S supply to plants may improve their accumulation capacity for As through enhanced tolerance caused by a positive effect on thiol metabolism and antioxidant status of the plants.
-
investigation of uranium accumulation potential and biochemical responses of an aquatic weed Hydrilla verticillata l f royle
Bioresource Technology, 2010Co-Authors: Sudhakar Srivastava, Kuber C Bhainsa, S F DsouzaAbstract:Abstract The uranium (U) accumulation potential and ensuing biochemical responses were studied in Hydrilla verticillata (L.f.) Royle upon exposure to U (0, 20 and 100 mg L−1). There was a concentration-duration dependent increase in U accumulation with the maximum being 78 mg g−1 DW at 100 mg L−1 U after 24 h. Plants experienced an initial phase of the maximum toxicity (within 30 min) followed by almost complete recovery after 24 h. The recovery was attributed to an integrated modulation in the level of both enzymatic and molecular antioxidants (viz., guaiacol peroxidase, ascorbate peroxidase, catalase, proline, total phenolics) and also the constituents of thiol metabolism (viz., cysteine and glutathione). Thus, plants were found to be able to accumulate significant amount of U in a short time and to tolerate it efficiently. Hence, they may find application in U phytoremediation considering there accumulation ability, fast growth due to weed-like habit and world-wide distribution.
-
evaluation of zinc accumulation potential of Hydrilla verticillata
Biologia Plantarum, 2009Co-Authors: R. D. Tripathi, Sudhakar Srivastava, Seema Mishra, Sanjay Dwivedi, Pramod Tandon, Dharmendra K GuptaAbstract:Biofortification of foods with essential micronutrients and phytoremediation of the contaminated sites are the two sides of the same coin for metals like zinc. In the present study, Zn accumulation potential, growth and antioxidant status of Hydrilla verticillata (L.f.) Royle plants were studied upon supplementation of Zn (0–5 000 µM) for 2 and 7 d. At 5000 µM Zn, plants accumulated about 7.60 and 18.07 mg(Zn) g−1(d.m.) after 2 and 7 d, respectively. Plants exposed to Zn concentrations up to 500 µM showed significantly increased contents of low molecular mass antioxidants and activities of antioxidant enzymes in comparison with controls. Only upon exposure of plants to 5 000 µM Zn, toxicity was observed after 7 d. Therefore, owing to their high Zn accumulation capacity, Hydrilla plants may be used both as a Zn source (via culturing in ca. 100 µM Zn supplemented nutrient medium) or as a phytoremediator.
Zhengwen Liu - One of the best experts on this subject based on the ideXlab platform.
-
nutrient addition delivers growth advantage to Hydrilla verticillata over vallisneria natans a mesocosm study
Knowledge and Management of Aquatic Ecosystems, 2019Co-Authors: Yali Tang, Xiufeng Zhang, Zhengwen LiuAbstract:Nutrient availability can affect both the morphology and the nutrient uptake strategies of submerged macrophytes, with different species responding differently to increases in nutrient levels. A 98-day mesocosm experiment was conducted to investigate the responses of co-cultured Hydrilla verticillata and Vallisneria natans to nutrient enrichments of 3.0 mg N/(L ∙ week) and 0.2 mg P/(L week), mimicking external loading. Water samples were collected every 2 weeks for measuring nutrient and total suspended solid (TSS) concentrations and biomass of phytoplankton (Chl a ). Dry biomasses of roots and shoots of both species were measured at the end of the experiment. Results showed that under nutrient-enriched conditions, both species reduced the ratio of root to shoot growth and increased nutrient storage per unit of biomass. However, only H. verticillata exhibited enhanced growth and nutrient storage, as well as a lower root: shoot ratio and greater shoot biomass than seen in Vallisneria . Our findings demonstrate that nutrient enrichment of the water column can invoke morphological plasticity in both H. verticillata and V. natans , but when both species grow together, the growth advantage goes to the former.
-
interspecific competition effects on phosphorus accumulation by Hydrilla verticillata and vallisneria natans
Journal of Environmental Sciences-china, 2011Co-Authors: Xiufeng Zhang, Zhengwen LiuAbstract:The competition between submersed plants has been recognized as an important factor influencing the structure of plant communities in shallow lakes. The ability of different species to take up and store nutrients from the surrounding ambience varies, and hence plant community structure might be expected to affect the cycling of nutrients in lake ecosystems. In this study, the uptake of phosphorus by Hydrilla verticillata and Vallisneria natans was studied and compared in monoculture and competitive mixed-culture plantings. Results showed that for both studied species the phosphorus concentrations of different tissues and of whole plants was unaffected by competition. However, the quantity of phosphorus accumulated by whole plants of H. verticillata was significantly higher in mixture culture than in monoculture, while that of V. natans was lower in the mixed culture. The results indicated that H. verticillata has a competitive advantage over V. natans, when the two species are grown in competition, and is able to accumulate a greater quantity of phosphorus.
Ashwani K Rai - One of the best experts on this subject based on the ideXlab platform.
-
packed bed column biosorption of chromium vi and nickel ii onto fenton modified Hydrilla verticillata dried biomass
Ecotoxicology and Environmental Safety, 2016Co-Authors: Ashutosh Mishra, B D Tripathi, Ashwani K RaiAbstract:The present study represents the first attempt to investigate the biosorption potential of Fenton modified Hydrilla verticillata dried biomass (FMB) in removing chromium(VI) and nickel(II) ions from wastewater using up-flow packed-bed column reactor. Effects of different packed-bed column parameters such as bed height, flow rate, influent metal ion concentration and particle size were examined. The outcome of the column experiments illustrated that highest bed height (25cm); lowest flow rate (10mLmin(-1)), lowest influent metal concentration (5mgL(-1)) and smallest particle size range (0.25-0.50mm) are favourable for biosorption. The maximum biosorption capacity of FMB for chromium(VI) and nickel(II) removal were estimated to be 89.32 and 87.18mgg(-1) respectively. The breakthrough curves were analyzed using Bed Depth Service Time (BDST) and Thomas models. The experimental results obtained agree to both the models. Column regeneration experiments were also carried out using 0.1M HNO3. Results revealed good reusability of FMB during ten cycles of sorption and desorption. Performance of FMB-packed column in treating secondary effluent was also tested under identical experimental conditions. Results demonstrated significant reduction in chromium(VI) and nickel(II) ions concentration after the biosorption process.
-
biosorption of cr vi and ni ii onto Hydrilla verticillata dried biomass
Ecological Engineering, 2014Co-Authors: Ashutosh Mishra, B D Tripathi, Ashwani K RaiAbstract:Abstract In the present study Hydrilla verticillata dried biomass was modified by Fenton reagent and its technical feasibility for removal of Cr6+ and Ni2+ ions from wastewater were investigated. Fenton modification process was optimized by varying pH, biosorbent dose, contact time, and Fe2+/H2O2 ratio. For Fenton modification process the optimum values of pH, biosorbent dose, contact time, and Fe2+/H2O2 ratio were 4, 70 g L−1, 70 min and 0.04 w/w, respectively. The modified biosorbent was characterized by using SEM-EDX, FT-IR and Malvern particle size analyzer. SEM-EDX analysis revealed the enhancement in weight percent of Cr6+ (47.38%) and Ni2+ (41.26%) ions on the surface of Fenton modified dried biomass of Hydrilla verticillata (FMB) after biosorption. Maximum biosorption of Cr6+ and Ni2+ ions were observed to be 29.43 and 48.72 mg g−1 for raw biomass and 107.64 and 106.12 mg g−1 for Fenton modified biomass respectively. Experimental data were modeled using single and multi-component isotherm models. For single-metal component, the Freundlich isotherm model fits the data better than the Langmuir isotherm model. In case of binary-metal solution the experimental data show good agreement with multi-component Freundlich isotherm model. The enhancement in the overall biosorption capacity after the Fenton modification was observed which follows the sequence: Cr6+ > Ni2+. The biosorption process followed the pseudo-second order kinetics. The equilibrium data suggest the involvement of chemisorption mechanism. Positive values of enthalpy and negative values of Gibbs free energy obtained during thermodynamic study revealed that the biosorption process was endothermic and spontaneous in nature.