Effects of inorganic arsenic species on the antioxidant enzyme system of the Amazon Sword Plant (Echinodorus amazonicus Rataj)

This study aims to examine the effects of Arsenite (As⁺³) and Arsenate (As⁺⁵) on the aquatic macrophyte Amazon Sword Plant (Echinodorus amazonicus Rataj). To this aim, different concentrations of As⁺³ and As⁺⁵ (0, 6, 18 and 54 μM) were analyzed. At the end of the trail, photosynthetic pigment contents, total protein amounts, the enzymatic antioxidants superoxide dismutase (SOD), peroxidase (POX) and catalase (CAT) activities and the amount of malondialdehyde (MDA) in the leaf samples of E. amazonicus were investigated. The antioxidant enzyme activities increased at low concentrations (32.13% for SOD, 185% for CAT and 201.5% for POX in the groups of 6 μM As⁺⁵), but decreased at high concentrations (64.98% for SOD, 21.64% for CAT and 21.29% for POX in the groups of 54 μM As⁺³). MDA increased in all the treatment groups. The highest MDA contents were observed as 96% for 54 μM As⁺³ and 71.50% for 54 μM As⁺⁵. Photosynthetic pigment contents and the amount of protein were decreased with higher concentrations. The most significant decreases in protein content were 65% for 54 μM As⁺³ and 34.9% for 54 μM As⁺⁵. As a result, the toxicity of As⁺³ was higher and the toxic effect increased at higher concentrations.

Comparisons of cadmium bioaccumulation potentials and resistance physiology of Microsorum pteropus and Echinodorus grisebachii

To better monitor and remediate environments contaminated by cadmium (Cd), plants are used as hyperaccumulators or biomonitors; however, few have been identified for aquatic Cd pollution. In our study, two aquatic ornamental plants, Microsorum pteropus (Blume) Copel. and Echinodorus grisebachii Small, were studied for their Cd accumulation capacity, morphological characteristics, and leaf physiological indexes. Microsorum pteropus (Blume) Copel. leaf has the potential to hyperaccumulate Cd (166 mg/kg dry weight for 1 mg/L exposure), with no significant physiological difference under exposure. Echinodorus grisebachii Small had sensitive diagnostic responses to Cd toxicity, such as significant decreases in Chl (a + b) and Chl-a/b, increased peroxidase (POD) activity, greater malondialdehyde (MDA) content, and increased soluble sugar content. These results suggest that Microsorum pteropus (Blume) Copel. could have the potential to be a Cd hyperaccumulator, while Echinodorus grisebachii Small could serve as a biomonitor for Cd-contaminated water bodies.

Physiological mechanisms of a wetland plant (Echinodorus osiris Rataj) to cadmium detoxification

Physiological responses of Echinodorus osiris Rataj plant under cadmium (Cd) stress (5 and 15 mg L^-1) were studied by researching the change of non-enzymatic antioxidants and the exudation of root organic acids. There was a significant increase of ascorbic acid, glutathione, and non-protein thiols in the plant, and the increment was much obvious in roots than that in leaves with increased Cd stress. The accumulation of Cd was associated with mitochondrial structural damages in roots, while the organelle structure, such as chloroplast, in leaves remains intact. In exudates collected from the plants in the treatment with 15 mg L^-1 Cd, oxalate, citric, and succinic acids responded intensively than other organic acids.

Differential distribution of amino acids in plants

Plants are a rich source of amino acids and their individual abundance in plants is of great significance especially in terms of food. Therefore, it is of utmost necessity to create a database of the relative amino acid contents in plants as reported in literature. Since in most of the cases complete analysis of profiles of amino acids in plants was not reported, the units used and the methods applied and the plant parts used were different, amino acid contents were converted into relative units with respect to lysine for statistical analysis. The most abundant amino acids in plants are glutamic acid and aspartic acid. Pearson's correlation analysis among different amino acids showed that there were no negative correlations between the amino acids. Cluster analysis (CA) applied to relative amino acid contents of different families. Alismataceae, Cyperaceae, Capparaceae and Cactaceae families had close proximity with each other on the basis of their relative amino acid contents. First three components of principal component analysis (PCA) explained 79.5% of the total variance. Factor analysis (FA) explained four main underlying factors for amino acid analysis. Factor-1 accounted for 29.4% of the total variance and had maximum loadings on glycine, isoleucine, leucine, threonine and valine. Factor-2 explained 25.8% of the total variance and had maximum loadings on alanine, aspartic acid, serine and tyrosine. 14.2% of the total variance was explained by factor-3 and had maximum loadings on arginine and histidine. Factor-4 accounted 8.3% of the total variance and had maximum loading on the proline amino acid. The relative content of different amino acids presented in this paper is alanine (1.4), arginine (1.8), asparagine (0.7), aspartic acid (2.4), cysteine (0.5), glutamic acid (2.8), glutamine (0.6), glycine (1.0), histidine (0.5), isoleucine (0.9), leucine (1.7), lysine (1.0), methionine (0.4), phenylalanine (0.9), proline (1.1), serine (1.0), threonine (1.0), tryptophan (0.3), tyrosine (0.7) and valine (1.2).

Using aquatic vegetation to remediate nitrate, ammonium, and soluble reactive phosphorus in simulated runoff

Within the agriculturally-intensive Mississippi River Basin of the United States, significant conservation efforts have focused on management practices that reduce nutrient runoff into receiving aquatic ecosystems. Only a small fraction of those efforts have focused on phytoremediation techniques. Each of six different aquatic macrophytes were planted, in monoculture, in three replicate mesocosms (1.2 m × 0.15 m × 0.65 m). Three additional unvegetated mesocosms served as controls for a total number of 21 mesocosms. Over two years, mesocosms were amended once each summer with sodium nitrate, ammonium sulfate, and potassium phosphate dibasic to represent nitrogen and phosphorus in agricultural runoff. System retention was calculated using a simple aqueous mass balance approach. Ammonium retention in both years differed greatly, as Panicum hemitomon and Echinodorus cordifolius retentions were significantly greater than controls in the first year, while only Myriophyllum aquaticum and Typha latifolia were significantly greater than controls in the second year. Greater soluble reactive phosphorus retention was observed in T. latifolia compared to controls in both years. Several other significant differences were observed in either the first or second year, but not both years. In the first year's exposure, P. hemitomon was significantly more efficient than the control, Saururus cernuus, and T. latifolia for overall percent nitrate decrease. Results of this novel study highlight inherent variability within and among species for nutrient specific uptake and the temporal variations of species for nutrient retention. By examining this natural variability, scientists may design phytoremediation systems with greater impact on improving agricultural runoff water quality.

Red mud (RM)-Induced enhancement of iron plaque formation reduces arsenic and metal accumulation in two wetland plant species

Human activities have resulted in arsenic (As) and heavy metals accumulation in paddy soils in China. Phytoremediation has been suggested as an effective and low-cost method to clean up contaminated soils. A combined soil-sand pot experiment was conducted to investigate the influence of red mud (RM) supply on iron plaque formation and As and heavy metal accumulation in two wetland plant species (Cyperus alternifolius Rottb., Echinodorus amazonicus Rataj), using As and heavy metals polluted paddy soil combined with three rates of RM application (0, 2%, 5%). The results showed that RM supply significantly decreased As and heavy metals accumulation in shoots of the two plants due to the decrease of As and heavy metal availability and the enhancement of the formation of iron plaque on the root surface and in the rhizosphere. Both wetland plants supplied with RM tended to have more Fe plaque, higher As and heavy metals on roots and in their rhizospheres, and were more tolerant of As and heavy metal toxicity. The results suggest that RM-induced enhancement of the formation of iron plaque on the root surface and in the rhizosphere of wetland plants may be significant for remediation of soils contaminated with As and heavy metals.

Phytoremediation of Mono-, Di-, and Triethylene Glycol by Echinodorus cordifolius L. Griseb

Mono-, di-, and triethylene glycol are chemicals used in various industrial (polyester products, plasticizers, printing, etc.) and domestic settings. The toxicity of these compounds is relatively low, but they do pose risks to the environment. Phytoremediation of the three glycols by Echinodorus cordifolius L. Griseb. were studied. The glycols were degraded in the leaves and roots, but leaves were the main source of degradation. The results of this study indicate that the plant can degrade triethylene glycol to diethylene glycol, diethylene glycol to 1,4-dioxan-2-one, or even further to monoethylene glycol. Moreover, 2-methoxy-4-vinylphenol, 1,2-cyclopentanedione, 1,4:3,6-dianhydro-.alpha.-d-glucopyranose, 2-propenamide, and 2,5-anhydro-1,6-dideoxyhexo-3,4-diulose were produced by this plant in response to the glycols.

Cadmium uptake, chemical forms, subcellular distribution, and accumulation in Echinodorus osiris Rataj

Phytoremediation is a technology for extracting or inactivating pollutants in soil. Echinodorus osiris (E. osiris) is a fast growing perennial wetland plant that is common in tropical and subtropical areas and has a high tolerance to cadmium (Cd). However, the absorption dynamics, subcellular distribution and accumulation of Cd by E. osiris had not been investigated. In this paper, hydroponic experiments with different levels of Cd(2+) (0, 5.0, 15.0 mg L(-1)) were carried out to determine these characteristics of E. osiris. The results indicated that the Cd absorption rate of Echinodorus osiris decreased over time, and the absorption rate within 0.5-1.0 h was faster than after 1.0 h. In a 6.0 hour time period, the rate of Cd uptake fit a quadratic polynomial curve when E. osiris was grown under the 5 mg L(-1) Cd treatment. However, the rate of Cd uptake by E. osiris fit a cubic polynomial model with the 15 mg L(-1) Cd treatment. In the roots, the ethanol-extractable Cd, water-extractable Cd, and NaCl-extractable Cd were the largest proportions of the total Cd. The HAc-extractable Cd, HCl-extractable Cd, and residual-Cd represented a larger proportion of the total Cd in the leaves which was combined with phosphate including CdHPO4, Cd3 (PO4)2, and oxalic acid. When analyzing the subcellular distribution of Cd in the plant, the soluble fraction containing Cd accounted for the largest part (69.49-88.39%) followed by the Cd bound to the cell wall (8.44-25.62%). Both the lower and the higher Cd treatments demonstrated that compartmentation by the vacuole and cell wall binding were two effective defense mechanisms of the plant. However, the vacuole became the main site for Cd accumulation in the leaves under the 15 mg L(-1) Cd treatment. E. osiris was able to accumulate high concentrations of Cd in both the roots and the leaves. The Cd concentration reached 502.97 mg kg(-1) and 2742.95 mg kg(-1) in the shoots and roots, respectively, after 27 days of cultivation. It was concluded that E. osiris is a potential hyperaccumulator of Cd.

Phytoremediation of wastewater with Limnocharis flava, Thalia geniculata and Typha latifolia in constructed wetlands

Phytoremediation is thought to be the most sustainable wastewater treatment option for developing countries. However, its application is often limited by unavailability of suitable candidate species. In the present study, the potentials of Limnocharis flava, Thalia geniculata and Typha latifolia for remediation of heavy metal contaminated wastewater with a constructed wetland system were evaluated. The wetland consisted of three treatment lines each planted with sufficient and equal number of a species. Duplicate plant and water samples were collected bi-monthly and analyzed for Fe, Cu, Zn, Pb, and Hg using the atomic absorption spectrophotometer over a six month period. Bioaccumulation rates generally increased over time and varied among plants for these metals, with Fe (456-1549 mg kg1 roots; 20-183 mg kg(-1) shoot) being the most sequestered and Pb (1.2-7.6 mg kg(-1) roots; 1.55-3.95 mg kg(-1) shoot) the least. Translocation factors differed among the species but generally remained stable over time. L flava showed potential for hyperaccumulating Hg. Removal efficiencies varied for the studied metals (approximately 20-77 %) and were generally related to metal uptake by the plants. These results demonstrate the suitability of the species for phytoremediation, and the usefulness of the technique as an option for improving irrigation water quality in Ghana.

Interactions between contaminated aquatic environments and element uptake by Echinodorus amazinocus and Cryptocoryne undulata

The objectives of this experimental study were to examine the interaction between metal contaminated aquatic environments and element uptake by Echinodorus amazinocus and Cryptocoryne undulata. Changes in element concentrations were investigated in three phases in aquatic environments: water, pore water and sediment. Additionally, the amounts of partial elements, relative uptakes, translocation factor and bio-concentration factor were evaluated for each plant. Growth analyses of both plants, as well as physical parameters of the water quality obtained from the reactors, were statistically evaluated by a two-sample t-test. Following the analyses, it was observed that the amount of all of the elements in each of the phases was different for each intermittent sample. Studies with C. undulata and E. amazinocus demonstrated that the concentration of all of the elements in the plants was changing relatively. It was also found that existing environmental conditions did not affect plant life negatively.

Phytoremediaton of diethylene glycol contaminated wastewater by Echinodorus cordifolius

Diethylene glycol (DEG) is one of several diols used as a raw material in the production of plasticizers and polyester resins. It has been associated with a number of mass poisonings in several countries. Conventional methods of remediation of DEG contaminated wastewaters are still not very effective. This paper presents an alternative method for remediation of DEG-contaminated waters using the plant Echinodorus cordifolius. The effects of DEG on E. cordifolius were studied along with the plant's efficiency at treating DEG-contaminated wastewater in a constructed wetland. We found that DEG was toxic to the plants with an LD50 of 6238 mg L(-1). The plants exhibited decreased water uptake and showed wilting, chlorosis and necrosis. SEM images showed injury to the cortex tissue. In the constructed wetland, E. cordifolius plants were able to remove and degrade DEG from wastewater, decreasing the pH from 12 to 6.8 and the COD and TDS by approximately 98% and 67%, respectively, in 7 days, while accumulating Ca in the cells.

Diethylene glycol removal by Echinodorus cordifolius (L.): the role of plant-microbe interactions

This work presents the use of the plant Echinodorus cordifolius for remediating diethylene glycol (DEG) contaminated waters. The potential of this plant for treating DEG wastewater in a remediation system was observed. We found that E. cordifolius was able to remove DEG from wastewater, decrease the pH to neutral and remove approximately 95% of the chemical oxygen demand within 12 days. The plants can grow well in DEG wastewater, as indicated by their root and leaf biomass, which was found to be statistically similar to control. Wilting, chlorosis and necrosis were observed in DEG-treated plants, but the relative water content was not significantly different between control and treated plants, suggesting that the plants were able to take up and tolerate DEG present in the wastewater. Plant roots changed to black colour during experimental period. The fluorescence in situ hybridisation and bacterial enrichment confirmed that 4.30 × 10(5) cells/g of sulphate reducing bacteria and 9.30 × 10(8) cells/g of acid-producing bacteria were found associated with the plant roots. Furthermore, volatile fatty acids were found in non-sterile soil treatments, indicating that soil microorganisms are associated with DEG remediation. These results demonstrated that plants and bacteria have the ability to form a relationship to remove the organic contaminant DEG.

Treatment of reactive azo dye from textile wastewater by burhead (Echinodorus cordifolius L.) in constructed wetland: Effect of molecular size

The potential of burhead (Echinodorus cordifolius L.) for the treatment of textile wastewater has been investigated. Reactive red 2; RR2 [MW=615], reactive red 120; RR120 [MW=1469] and reactive red 141; RR141 [MW=1775] were studied in order to determine the effect of molecular size on the efficiency of dye removal by plants in batch systems of constructed wetlands under soil and soil-free conditions. Dye concentrations, total dissolve solids (TDS), conductivity and pH in the effluents, and the relative growth rates (RGR) of plants were measured. The highest efficiency of dye removal during 7 days under soil-free conditions was RR2 (33.09 μmol(RR2)kg(-1)(FW)), followed by RR120 (13.35 μmol(RR120)kg(-1)(FW)) and RR141 (10.57 μmol(RR141)kg(-1)(FW)), respectively. This suggests that the structure and size of dye molecule strongly affects the efficiency of dye removal by plant. The results from a synthetic wetland experiment found that dye removal was 96 % at 4 days and 6 days under soil and soil-free conditions, respectively. Furthermore, plants were able to decrease TDS (42 %), conductivity (50 %) and pH (from 9.5 to 7.4) within 2 days in the synthetic reactive red(141) dye wastewater (SRRW141) under soil-free conditions, thus demonstrating the potential of burhead for textile wastewater treatment.

Phytoremediation of ethylene glycol and its derivatives by the burhead plant (Echinodorus cordifolius (L.)): effect of molecular size

Ethylene glycol (EG) is a group of dihydroxy alcohol that has been utilised in a variety of industrial and residential settings. EG contaminated wastewater has a high chemical oxygen demand (COD), which causes environmental problems. The aim of this research was to investigate the efficiency of the burhead plant (Echinodorus cordifolius (L.)) in the removal of mono-, di- and triethylene glycol (MEG, DEG and TEG), the first three members of the dihydroxy alcohol group, from synthetic wastewaters, to examine the toxic effect of EG on the plant and to identify differences among MEG, DEG, and TEG removal. It was found that the COD of synthetic wastewaters decreased to levels below the standard effluent (COD=120 mg L⁻¹) on day 18, 21 and 33 for MEG, DEG and TEG, respectively. On day 18 of the experiment, the burhead plant removed approximately 2000, 1950 and 730 mg L⁻¹ of MEG, DEG and TEG, respectively. The removal rate of MEG was faster than that of DEG and TEG, suggesting that the molecular size of the EG had affected its rate of removal. The concentrations of MEG, DEG, and TEG in plant tissue were measured to show that burhead can take up EG, and the major site of EG accumulation is the leaf. The molar of MEG that was taken up into the plant leaf was higher than that of DEG and TEG. This suggested that EG of smaller molecular sizes can be taken up more rapidly by the plant than EG of larger molecular sizes. EG concentrations in the leaf increased to a peak concentration and then slowly decreased. GC-MS analysis of DEG-treated plant tissue found MEG, 1,4-dioxan-2-one, neophytadiene, and 2-propenamide, that may be DEG-degradation products and/or compounds that are induced when plants are exposed to DEG. The result indicates that burhead can potentially be used for EG removal.