Crassipes Roots Research Articles

Distribution and Biological Response of Nanoplastics in Constructed Wetland Microcosms: Mechanistic Insights into the Role of Photoaging.

Concern over nanoplastic contamination of wetland ecosystems has been increasing. However, little is known about the effect of photoaging on the distribution and biological response of the nanoplastics. Here, palladium-labeled polystyrene nanoplastics (PS-Pd NPs) at 0.05-50 mg/L were exposed to constructed wetland microcosms containing floating (Eichhornia crassipes) and submerged (Vallisneria natans) macrophytes. Results demonstrate that PS-Pd NPs' concentration in surface water after 2-4 weeks of exposure was decreased by over 98.4% as compared with that in the 1st week. Photoaging enhanced the surface charge and colloidal stability of PS-Pd NPs, with a subsequent increase of the content of PS-Pd NPs in surface and middle layer water by 264.6 and 207.4%, respectively. Additionally, photoaging significantly enhanced the accumulation of PS-Pd NPs in E. crassipes roots by 6.9-65.0% and significantly decreased it in V. natans shoots by 59.7-123.0%. PS-Pd NPs inhibited the growth of V. natans by 43.8% at 50 mg/L. Mechanistically, PS-Pd NPs induced oxidative stress in V. natans, leading to the disruption of the metabolic pathway. Interestingly, PS-Pd NP exposure inhibited nitrification in wetland ecosystems due to the alteration of the related bacterial community (Ellin6067 decreased by 13.19%). These findings deepen our understanding of the environmental fate and risk of plastic particles in wetland ecosystems.

Mimicking biological method with inorganic and organic compounds modified clays for continuous controlling of Microcystis aeruginosa

Although clay dispersion is one of the few techniques currently used in the field to control cyanobacterial harmful algal blooms (CyanoHABs), low flocculation efficiency and resuspension of flocculated algal cells are its main drawbacks. This study simulated the "flocculatio-lysis-degradation-nutrient regulation" model of biocontrol technique to develop a modified clay (ECRE-CS-PFS-CPL) using polyferric sulfate (PFS), chitosan (CS) and Eichhornia crassipes root extracts (ECRE) to modify the clinoptilolite (CPL). The results revealed that ECRE-CS-PFS-CPL introduced functional groups, specifically aldehyde group —CHO and amide group —CO-NH—, leading to an enhanced void structure. At 0.2 g/L concentration, ECRE-CS-PFS-CPL demonstrated a removal efficiency of 98.02 % within 30 min. ECRE-CS-PFS-CPL exhibited a positive charge in nature water, leveraging charge neutralisation to expedite the flocculation of M. aeruginosa cells. The combination of coated CS and algal cells resulted in the formation of large, dense flocs through net sweeping and bridging, which was 58.28 times larger than control. Subsequently, the loaded ECRE inhibited the algal cells via allelopathy. The inhibition activated the antioxidant system of M. aeruginosa, with significant increases in catalase (CAT) and superoxide dismutase (SOD) activities. Photosynthetic pigments (Chl-a), photosynthetic efficiency (Fv/Fm) and maximum relative photosynthetic electron transfer rate (ETRmax) were markedly reduced, indicating the damage to photosynthetic system. Furthermore, Chl-a remained consistently low during extended monitoring, registering at 4.98 % of control after 40 days. ECRE-CS-PFS-CPL effectively reduced microcystins by 81.48 % and phosphate levels in algal cultures by 91.92 % compared to control. Consequently, ECRE-CS-PFS-CPL offers an efficient, environmentally safe and sustainable solution for CyanoHABs control.

Environmental concentrations of 6PPD and 6PPD-Q cause oxidative damage and alter metabolism in Eichhornia crassipes

N-(1,3-dimethylbutyl)-N ′-phenyl-p-phenylenediamine (6PPD) and N-(1,3-dimethylbutyl)-N′-phenyl-p-phenylenediamine-quinone (6PPD-Q) are ubiquitous in the environment and can cause toxicity to aquatic animals. However, research on the toxicological effects of 6PPD and 6PPD-Q on aquatic plants remains limited. The present study investigated the physiological, biochemical, and metabolic responses of the floating aquatic plant Eichhornia crassipes (E. crassipes) to environmentally relevant concentrations (0.1, 1, and 10 μg·L−1) of 6PPD and 6PPD-Q. We found that 6PPD and 6PPD-Q elicited minimal effects on plant growth, but 6PPD induced a concentration-dependent decrease in the content of photosynthetic pigments. Low doses (0.1 μg·L−1 and 1 μg·L−1) of 6PPD-Q significantly elevated Reactive Oxygen Species (ROS) content in E. crassipes roots, indicating oxidative damage. Furthermore, 6PPD-Q induced a more pronounced osmotic stress compared to 6PPD. Metabolic analyses revealed that carbohydrates were significantly altered under 6PPD and 6PPD-Q treatments. The findings of this study enhance the understanding of the environmental risks posed by 6PPD and 6PPD-Q to plants and reveal the potential mechanisms of phytotoxicity.

Understanding the bacterial community structure associated with the Eichhornia crassipes rootzone.

Plant microbiome acts as an interface between plants and their environment, aiding in the functioning of the ecosystem, such as protection against abiotic and biotic stress along with improving nutrient uptake. The rhizosphere is an essential interface for the interaction between plants and microbes and plays a substantial part in the removal as well as uptake of heavy metals and antibiotics from contaminated locations. Eichhornia crassipes is a promising plant that contains a rich community of microbes in its rhizosphere. Microorganism's association with plants embodies a crucial pathway via which humans can also be exposed to antibiotic-resistant genes and bacteria. In our earlier study enhanced removal of ciprofloxacin was observed by plant growth-promoting Microbacterium sp. WHC1 in the presence of E. crassipes root exudates. Therefore, the V3-V4, hypervariable region of the 16S rRNA gene was studied to assess the bacterial diversity and functional profiles of the microbiota associated with plant roots. Using the QIIME software program, 16S rRNA data from the Next Generation Sequencing (NGS) platform was examined. Alpha diversity including Chao1, Observed Shannon, and Simpson index denote significantly higher bacterial diversity. Proteobacteria (79%) was the most abundant phylum which was present in the root samples followed by Firmicutes (8%) and Cyanobacteria (8%). Sulfuricurvum (36%) is the most abundant genus belonging to the family Helicobacteraceae and the species kujiense in the genus Sulfuricurvum is the most abundant species present in the root sample. Also, the bacterial communities in the rhizoplane of Eichhornia crassipes harbor the genes conferring resistance to beta-lactams, tetracycline, fluoroquinolones, and penams. Metagenomic studies on the E. crassipes microbiome showed that the bacterial communities constituting the root exudates of the Eichhornia aid them to survive in a polluted environment.

Eichhornia crassipes-rhizospheric biofilms contribute to nutrients removal and methane oxidization in wastewater stabilization ponds receiving simulative sewage treatment plants effluents

Wastewater stabilization ponds (WSPs) have been used in treating sewage treatment plants (STPs) effluents. However, little is known about the role of rhizospheric biofilms on methane release in WSPs with floating plants. In the present study, the nutrient removal, CH4 fluxes, CH4 oxidization potential and rhizospheric bacterial community were investigated in WSPs with Eichhornia crassipes under simulate STPs effluents for 31 days. At the end of the experiment, E. crassipes biomass was 5.60–8.81 times of initial weight and increased with increasing nutrients concentration. E. crassipes effectively reduced methane release and nutrients. Compared to control, E. crassipes reduced 52.30%–83.21% of CH4 fluxes at water-atmosphere interface and had better inhibition effect on CH4 fluxes in treatments with high nutrients. However, methane oxidization rates of E. crassipes roots were higher in low nutrients (0.83 ± 0.046 mg CH4 (kg fresh plant)−1 day−1) than high nutrients (0.12 ± 0.04 mg CH4 (kg fresh plant)−1 day−1). Structural equation modeling revealed that biomass of E. crassipes has negative effect on CH4 fluxes (−0.453, p = 0.000). Proteobacteria, Bacteroidetes, Planctomycetes, Chloroflexi and Actinobacteria were the predominant phyla in the rhizospheric biofilm of E. crassipes and contributed to nutrients removal. Aerobic methanotrophs and pomA abundances were higher in rhizospheric biofilm exposed to high nutrients than low nutrients and aerobic methanotrophs had close interactions with other microorganisms and participated in the carbon and nitrogen cycle, demonstrating that many bacteria harboring pmoA gene did not fully involve in methane oxidization. These data highlight plants E. crassipes have an important role in both reducing methane release and nutrients removal.

Antiproliferative Effects of Methanolic Root Extracts of Eichhornia crassipes Against a Skin Melanoma Cell Line: An In Vitro Study.

Background Melanoma is the most aggressive form of skin cancer, accounting for 3% of all malignant cancers. Phytochemicals and their related compounds are found in various parts of the plant Eichhorniacrassipes and have a variety of pharmacological actions. The current research was intended to compare and evaluate the anti-proliferative action of methanolic extracts of E. crassipes roots and petioles against the Sloan Kettering Melanoma (SK-Mel-5) cell line. Materials and methods The waters around Ezhikkara, Ernakulum, Kerala, were discovered to contain E. crassipes. We used a Soxhlet extractor to get this concentrated liquid. For this test, we employed a methanolic extract of roots and petioles to determine the extent to which different concentrations of the extract inhibited cell proliferation. Data on absorbance were reported as a mean standard deviation. Using Probit analysis, the IC50 was calculated by evaluating the gradient of the regression line to get a value. Results Concentrations of methanolic root and petiole extracts of 12.5 µg/ml, 25 µg/ml, 50 µg/ml, 100 µg/ml, and 200 µg/ml were analyzed. The methanol petiole extract reduced the viability of SK-Mel-5 cells more than the root extract, with IC50 values of 323.59 µg/ml and 174.70 µg/ml of the test sample concentration, respectively. The regression equation for the root extract was y = -0.1264x + 90.902 and R2 = 0.845, and for the petiole extract, it was y = -0.2187x + 88.206 and R2 = 0.917. Conclusion The current study found that increasing the concentration of methanolic extracts of roots and petioles of E. crassipes exhibited an increased cell growth inhibition rate. However, methanolic petiole extracts were more cytotoxic than the roots. Thus, the current study demonstrated the therapeutic use of E. crassipes as an anticancer agent, thereby providing a valuable alternative for enabling the early management of melanoma.

Bagarius bagarius, and Eichhornia crassipes are suitable bioindicators of heavy metal pollution, toxicity, and risk assessment

Water quality index (WQI) of Narora channel and health of endemic fish Bagarius bagarius and plant Eichhornia crassipes, district Bulandshahar, Uttar Pradesh, India were studied. Among the physicochemical properties of water, pH, D.O, Cr, Fe, Ni, and Cd were above the recommended standards. These factors lead to high WQI (4124.83), indicating poor quality and not suitable for drinking and domestic usage. In fish tissues, the highest metal load was reported in the liver (58.29) and the lowest in the kidney (33.73). Heavy metals also cause a lowering of condition indices. As expected, decreased serum protein (− 63.41%) and liver glycogen (− 79.10%) were recorded in the exposed fish. However, blood glucose (47.22%) and serum glycogen (74.69%) showed elevation. In the plant, roots (21.50) contained the highest, and leaves (16.87) had the lowest heavy metal load. Bioaccumulation factor (BAF) > 1, indicates hyperaccumulation of all metals. E. crassipes roots showed the highest translocation factor (TF) > 1 for Ni (1.57) and Zn (1.30). The high mobility factor (MF) reflected the suitability of E. crassipes for phytoextraction of Mn, Cd, Zn, Fe, Ni, and Cu. Moreover, Bagarius sp. consumption could not pose any non-cancer risk. Although, lower cancer risk can be expected from Ni and Cr.

Biosorption as a Perfect Technique for Purification of Wastewater Contaminated with Ammonia

Eichhornia crassipes root powder (ECRP) has been used to remove ammonia from aqueous solutions. The biosorption factors such as biosorbent dosage, pH, initial ammonia concentration, and contact time have been considered in batch conditions. The optimal conditions, at pH (6), sorbent dose 5 g/l, time (30 min) ammonia concentration (10 mg/l). Langmuir is better suited than Freundlich isotherm. The kinetic models Thomas, Yoon-Nelson, and Bohart-Adams were applied. These models showed that the adsorption capacity decreased with flow rate increases as follows: 32.57, 31.82, 31.25, and 30.17 mg/g, respectively, at a flow rate 10, 15, 20, and 25 ml/min. The root powder of Eichhornia crassipes was used to treat specific drainage wastewater obtained from the Sabal drain at Menoufia, Egypt. The average efficiency of ammonia removal was 87% per batch adsorption method at pH value = 7.5, sorbent dose 5 g/l, uptake period (30 min), and primary load 7.1 mg/l; however, ammonia removal by column continuous adsorption method exceeded 94%. In addition, ECRP is efficient in removing arsenic, sulfate, nitrates, nitrite, silica, iron, manganese, copper, zinc, aluminum, and lead from actual sewage wastewater, in addition to removing more than 75% COD.

Enhanced removal of antibiotics using Eichhornia crassipes root biomass in an aerobic hollow-fiber membrane bioreactor

The impact of water hyacinth (Eichhornia crassipes) root biomass (WHRB) on pharmaceutical wastewater treatment with an aerobic hollow-fiber membrane bioreactor (HF-MBR) was investigated. The performance of the bioreactor was assessed in terms of COD (Chemical Oxygen Demand) and antibiotic removal and membrane biofouling rate. For deeper insight, microbial communities in sludge and biofilm layers were analyzed through Illumina sequencing. The addition of WHRB into the HF-MBR increased the COD (by 6%), as well as antibiotics and transformation products removal efficiency. Removal efficiencies of 97%, 98% and 84% were obtained for removal of erythromycin, sulfamethoxazole, and tetracycline. Furthermore, WHRB modified the biodegradation network, increased the relative abundances of Chloroflexi, Proteobacteria and Nitrospirae and decreased Firmicutes, compared with the control with antibiotics. The addition of WHRB also enriched Actinobacteria and Bacteroidetes while decreasing the phylla Chloroflexi and Saccharibacteria in the biofilm.

Eichhornia crassipes root biomass to reduce antibiotic resistance dissemination and enhance biogas production of anaerobic membrane bioreactor

ABSTRACT To address the inadequate removal of antibiotic resistance genes in wastewater treatment plants, this study investigated the impact of bioaugmentation with dried Eichhornia crassipes roots on removal of antibiotics sulfamethoxazole, tetracycline and erythromycin from pharmaceutical wastewater while optimizing potential for reclaiming value through biogas production, utilizing an anaerobic membrane bioreactor (AnMBR). Three sets of AnMBRs were set up for the experiment, C1 (inoculum), C2 (inoculum + antibiotics) and EC (inoculum + antibiotics + E. crassipes). The results showed that E. crassipes mitigated some of the toxic effects of antibiotics on the microbial community and prevented negative impact on the archaeal community, and significantly increased average biogas production (by 37% compared to control without antibiotics and 42% compared to control with antibiotics) as well as antibiotics removal. Furthermore, bioaugmented reactor showed significant reduction of erythromycin (97%) and tetracycline (83%) concentrations in effluent. Utilization of E. crassipes root offers a simple yet powerful tool for preventing the emergence of antimicrobial resistance and dissemination of such pollutants into the environment.

Uptake prediction of nine heavy metals by Eichhornia crassipes grown in irrigation canals: A biomonitoring approach

The principal objective of this study is to generate mathematical regression equations that facilitate the estimation of the extent to which Eichhornia crassipes (C. Mart.) Solms, water hyacinth, absorbs heavy metals (HMs) into four plant organs (laminae, petioles, roots, and stolons). This study considers the absorption of nine HMs (Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, and Zn), and the E. crassipes evaluated in this study were located in three irrigation canals in the North Nile Delta in Egypt, with sampling being conducted in both monospecific and homogenous E. crassipes. Samples of both E. crassipes and water were collected on a monthly basis during one growing season. Analysis of the water samples showed that the HM concentrations ranged from 1.1 μg/l for Cd to 2079.8 μg/l for Fe. All HMs were more concentrated in the E. crassipes roots than in any other organ. Typically, there was a significant correlation between the HM levels in the water and the HM levels in the E. crassipes organs. E. crassipes was documented by a bioconcentration factor > 1.0 for all HMs. The translocation factor in this study was <1.0 for all HMs. The t-values that referred to the discrepancies between the measured and predicted values of the HMs in the four E. crassipes organs were not significant. This finding can be considered to be an indication of the goodness of fit with respect to the ability of the equations to forecast HM uptake. Therefore, the developed equations will benefit the prediction of HM uptake by E. crassipes grown in irrigation canals in the Nile Delta. The efficacy of E. crassipes as a metric for gauging the aggregate impact of environmental pollution in water sources and its potential application in biomonitoring are confirmed in this study.

Effects and Mechanisms of Calcium Ion Addition on Lead Removal from Water by Eichhornia crassipes.

Karst water is rich in calcium ions (Ca2+) and exhibits poor metal availability and low biodegradation efficiency. This study sought to analyze the effects and mechanisms of Ca2+ on lead (Pb) removal and absorption by Eichhornia crassipes (a floating plant common in karst areas). Moreover, the morphology and functional groups of E. crassipes in water were characterized via SEM, and FTIR. The results demonstrated that the removal rate of Pb in karst water (85.31%) was higher than that in non-karst water (77.04%); however, the Pb bioconcentration amount (BCA) in E. crassipes roots in karst water (1763 mg/kg) was lower than that in non-karst water (2143 mg/kg). With increased Ca2+ concentrations (60, 80, and 100 mg/L) in karst water, the Pb removal rate increased (85.31%, 88.87%, and 92.44%), the Pb BCA decreased (1763, 1317, and 1095 mg/kg), and the Ca BCA increased (6801, 6955, and 9368 mg/kg), which was attributed to PbCO3 and PbSO4 precipitation and competitive Ca and Pb absorption. High Ca2+ concentrations increased the strength of cation exchange, alleviated the fracture degree of fibrous roots, reduced the atrophy of vascular bundles, protected the cell wall, promoted C–O combined with Pb, enhanced the strength of O‒H, SO42−, C=O, and reduced the oxidization of alkynyl acetylene bonds.

Application of the KIM Equation for direct analysis of Pb and Ni by EDXRF in lignocellulosic fibers used as adsorbents of metals

Abstract The disposal of metals such as Ni and Pb resulting from anthropogenic activities is a matter of great concern due to the high solubility of these ions in water resources. Recent studies have used lignocellulosic adsorbents for the adsorption of these metals due to their high adsorption capacity. However, the methods developed for the quantification of these metals in lignocellulosic adsorbents have involved lengthy sample preparation processes and generated acid residues from their digestion. This work proposes a methodology for the quantification of Ni and Pb in lignocellulosic adsorbents using direct analysis by EDXRF associated with the simple application of the KIM Equation for matrix effect correction. For this, we used a standard with characteristics similar to the adsorbent matrix, the certified reference material Pine Needles. The adsorbents selected for this study were endemic species from the region, Eichhornia crassipes root, Attalea funifera fiber, Cocos nucifera bark and Eucalyptus globulus. FTIR and XRD analyzes confirmed the similarity between these matrices. According to the Kolmogorov–Smirnov test, matrix effect correction was efficient for the Eichhornia crassipes Pb curve, p = 0.999, Ni curve for Eucalyptus globulus, p = 0.963, and Pb and Ni curves for Cocos nucifera, p = 0.937 and p = 1.000, respectively. The statistical test showed marked proximity between the curve points of the standard and the adsorbents after the application of the KIM Equation.

Aquatic macroinvertebrate assemblages associated with two floating macrophyte species of contrasting root systems in a tropical wetland

Aquatic macrophytes play an important role in structuring biotic communities. A comparative study of macroinvertebrate community structures associated with Salvinia auriculata Aublet and Eichhornia crassipes (Mart.) Solms was conducted in a Brazilian wetland (Sao Paulo State) during two periods. Our working hypothesis is that the aquatic macrophyte with the highest root system biomass and volume (E. crassipes) will result in the highest abundance and richness of associated macroinvertebrates. There were significant differences in the taxa richness and density of macroinvertebrates between macrophytes and sampling periods. The density of macroinvertebrates was higher in S. auriculata than in E. crassipes during both sampling periods, but there was little difference in mean taxa richness. Negative correlations between the macrophyte root biomass and volume and macroinvertebrate density were found. Insecta, Crustacea and Annelida were the most numerous groups of invertebrates sampled during the study, and Diptera (Insecta) dominated in the root systems of both macrophytes. Macroinvertebrates associated with E. crassipes roots may have undergone a vertical gradient of decreased oxygen concentration in the water, as well as of the available periphyton biomass, because of the low penetration of light in the region of the root system, which resulted in a lower density of macroinvertebrates.

Toxicological responses of Fe3O4 nanoparticles on Eichhornia crassipes and associated plant transportation

This work investigated the interaction of Fe3O4 nanoparticles (NPs) with a floating water plant (Eichhornia crassipes). The effects of Fe3O4 NPs on E. crassipes physiology and root morphology as well as the migration and transformation of Fe3O4 NPs in plant were studied emphatically. Fe3O4 NPs (200 mg/L) showed significant growth inhibition on E. crassipes roots and leaves after a 21-day exposure, while dissolved Fe3+ ions and Fe3O4 bulk particles had no obvious effect on E. crassipes growth. Scanning electron microscopy showed that the roots of E. crassipes were significantly damaged, the root tips became thin and the root epidermis began to peel off after Fe3O4 NPs exposure. In addition, there was disordered cell arrangement and a destroyed elongation zone of the root tips. The physiology of E. crassipes was also affected. In particular, after exposure to Fe3O4 NPs (200 mg/L), a distinct decrease in chlorophyll content and catalase activity and an increase of malondialdehyde (MDA) content could be seen. Transmission electron microscopy and energy dispersive spectroscopy revealed that Fe3O4 NPs were present in the root epidermis, intercellular space and protoplasts, as well as in the leaf cytoplasm and chloroplasts. Vulcanization in the leaves was also found through diffraction analysis, which may be due to the small number of absorbed nanoparticles, some of which still existed in the original form in the leaves while others were reduced to FeS through interactions with plant components during translocation. These findings are helpful for better understanding the fate of NPs in aquatic plants. Moreover, it is important to evaluate the water environment safety of NPs.

Arbuscular Mycorrhizal Fungi Assisted Cadmium Removal by Water Hyacinth (Eichhornia crassipes (Mart.) Solms) in Polluted Soil and Water

Heavy metal pollution of soil and water is a major environmental problem, and most conventional remediation approaches do not provide acceptable solutions. Wetland plants are being used successfully for the phytoremediation of trace elements in natural and constructed wetlands. The present study was aimed at assessing the potential of Cadmium (Cd) removal from contaminated soil and water by Eichhornia crassipes (Mart) Solms with the inoculated arbuscular mycorrhizal fungi (AMF). A pot experiment was carried out in the planthouse at the Faculty of Applied Sciences, Rajarata University of Sri Lanka, Mihintale. The water hyacinth plants of similar heights and with number of leaves were taken from the Mihintale tank as the test plants. Pots were filled with the wetland soil, tank water and water hyacinth was introduced with the inoculated AMF and non-inoculated AMF. Different cadmium concentrations were applied to water as 0, 5, 10, 20 and 50 ppm in different treatments. Water samples were collected at several time intervals (1st, 3rd, 7th, 14th and 52nd days) and on the 52nd day, soil, roots and shoots of the E.crassipes were collected for the analysis of Cd using an Atomic Absorption Spectrophotometry. The percentage AMF colonization, relative growth rate, dry biomass of shoots and roots of E. crassipes were also estimated. The significantly different high (p<0.05) percentage AMF colonisation, shoot and root Cd concentration, relative growth rate, dry biomass of roots and shoots were observed in AMF inoculated water hyacinth than non-inoculated, in all levels of cadmium additions. The uptake of Cd was increased with the increased Cd additions with the increasing time in all tested Cd concentrations. Always cadmium accumulation was higher in E. crassipes roots than in shoots. It can be concluded that E. crassipes efficiently hyper-accumulated Cd in its biomass and tolerated higher concentrations of Cd when inoculated with AMF. Therefore, AMF can be used as root inoculants of Eichhornia to phytoremediate cadmium contaminated soil and water through making it an effective phytoremediating aquatic plant. Keywords: Phytoremediation, Arbuscular Mycorrhizal Fungi (AMF), Water hyacinth, Cadmium, Colonization

Effect of concentration and exposure time on copper accumulation in Eichhornia crassipes (Mart.) Solms. (Pontederiaceae)

Different factors can influence the absorption and storage of substances in plant biomass. In this study, we evaluated the effect of copper concentration in growth medium and plant exposure time on copper accumulation in Eichhornia crassipes (Mart.) Solms. (Pontederiaceae) roots and leaves under controlled conditions. Plants were subjected to four treatments of copper concentrations of 1, 3 and 5 μg.mL -1 , with a control treatment of 0 μg.mL -1 , and evaluated at seven-day intervals over 21 days. Copper concentration in biomass was analysed by atomic absorption spectroscopy with flame atomisation. The results showed that copper concentration in the growth medium and time of exposure had a significant effect on the amount of copper accumulated by E. crassipes roots and leaves, with roots more efficient compared to leaves. It is likely that E. crassipes has mechanisms for the translocation of metal from the root system to the leaves. Symptoms of copper toxicity were observed in the vegetative parts of the plants at the end of the experiments. This study demonstrates that E. crassipes presents great potential in the absorption and accumulation of copper under laboratory conditions, indicating its effectiveness for applications in phytoremediation processes.

A Kinetic, Equilibrium, and Thermodynamic Study on the Biosorption of Tl+and Cd2+byEichhornia crassipesRoots Using Carbon Paste Electrode

In this work, Eichhornia crassipes roots were used as a modifier for carbon paste electrode in a biosorption study of thallium (Tl+) and cadmium (Cd2+) ions. The ions were accumulated on modified electrode surfaces at open circuit potential and analyzed by square wave anodic stripping voltammetry. Before the biosorption study, the effect of ratio of biomass and binder in uptake metal was evaluated. The biosorption study shows that adsorption of ions was dependent on pH. The kinetic study showed that, for both ions, experimental data were well described by the pseudo-second order model (R2 > 0.99) and the equilibrium was better described by the Langmuir model. The value of dimensionless equilibrium parameter (RL) obtained in the equilibrium study showed that Eichhornia crassipes can be considered an effective biomaterial for Tl+ and Cd2+ removal from an aqueous solution. The thermodynamic parameters calculated, enthalpy (ΔHo), entropy (ΔSo) and Gibbs energy (ΔGo), indicated that the biosorption process was spontaneous and endothermic.

English

Aquatic macrophytes and benthos are unchangeable biological filters and they carry out purification of the water bodies by accumulating dissolved metals and toxins in their tissues. In view of their potential to entrap several toxic heavy metals, 3 groups of benthos and 6 macrophytes (submerged species: Potamogeton pectinatus, Ceratophyllum demersum and Najas armata); (floating species: Lemna gibba and Eichhornia crassipes root and shoot) and (emergent species: Phragmites australis shoot) were collected from 15 different locations on Lake Burullus and analyzed for determination of 6 heavy metals (Fe, Zn, Ni, Cu, Pb and Cd) contenets. The study was aimed at understanding the importance of these benthos and macrophytes in accumulation of toxic metals and suggesting preservation and restoration of Lake Burullus ecosystem. The distribution of the investigated metals in water, sediments, benthos and aquatic plants of the lake showed that, the eastern and eastern southern parts of the lake have generally higher concentrations of heavy metals than the western and middle one. Potamogeton pectinatus showed high contents of Pb, Cd and Zn respectively. On the other hands Eichhornia crassipes showed high level of copper while in Ceratophyllum demersum high concentration of Iron was detected. The present study reveals that the aquatic macrophytes and benthos play a very significant role in removing of the different metals from the aquatic environments and they probably reduced the effect of high concentrations of these metals on the lake ecosystem. Bioaccumulation factor values showed that the trend of accumulation of most metals in the benthos was as follows: Mullusca > Arthropoda > Annelida > and in aquatic plants as: Lemna gibba> Potamogeton pectinatus > Ceratophyllum demersum > Eichhornia crassipes Root > Najas armata>phragmites australis shoot> Eichhornia crassipes shoot, which make them suitable candidates to be used in biomonitoring surveys as a good tools for heavy metal pollution markers, in the biological treatment of the polluted water and in sustainable development of Lake Burullus. Key words: Biofilter, bioaccumulation, sustainable developments, biological treatment, macro benthos, aquatic plants, sustainable management.

Identification of gene fragments related to nitrogen deficiency in Eichhornia crassipes (Pontederiaceae).

Eichhornia crassipes is an aquatic plant native to the Amazon River Basin. It has become a serious weed in freshwater habitats in rivers, lakes and reservoirs both in tropical and warm temperate areas worldwide. Some research has stated that it can be used for water phytoremediation, due to its strong assimilation of nitrogen and phosphorus, and the accumulation of heavy metals, and its growth and spread may play an important role in environmental ecology. In order to explore the molecular mechanism of E. crassipes to responses to nitrogen deficiency, we constructed forward and reversed subtracted cDNA libraries for E. crassipes roots under nitrogen deficient condition using a suppressive subtractive hybridization (SSH) method. The forward subtraction included 2,100 clones, and the reversed included 2,650 clones. One thousand clones were randomly selected from each library for sequencing. About 737 (527 unigenes) clones from the forward library and 757 (483 unigenes) clones from the reversed library were informative. Sequence BlastX analysis showed that there were more transporters and adenosylhomocysteinase-like proteins in E. crassipes cultured in nitrogen deficient medium; while, those cultured in nitrogen replete medium had more proteins such as UBR4-like e3 ubiquitin-protein ligase and fasciclin-like arabinogalactan protein 8-like, as well as more cytoskeletal proteins, including actin and tubulin. Cluster of Orthologous Group (COG) analysis also demonstrated that in the forward library, the most ESTs were involved in coenzyme transportation and metabolism. In the reversed library, cytoskeletal ESTs were the most abundant. Gene Ontology (GO) analysis categories demonstrated that unigenes involved in binding, cellular process and electron carrier were the most differentially expressed unigenes between the forward and reversed libraries. All these results suggest that E. crassipes can respond to different nitrogen status by efficiently regulating and controlling some transporter gene expressions, certain metabolism processes, specific signal transduction pathways and cytoskeletal construction.