Phytoremediation of ethion by water hyacinth (Eichhornia crassipes) from water

The potential of water hyacinth (Eichhornia crassipes) to remove a phosphorus pesticide ethion were investigated. The disappearance rate constants of ethion in culture solutions were 0.01059, 0.00930, 0.00294, and 0.00201 h-1 for the non-sterile planted, sterile planted, non-sterile unplanted, and sterile unplanted treatment, respectively, which were significantly different and implied that plant uptake and phytodegradation contributed 69% and that of microbial degradation took up 12% to the removal of the applied ethion. The accumulated ethion in live water hyacinth plant decreased by 55-91% in shoots and 74-81% in roots after the plant growing 1 week in ethion free culture solutions, suggesting that plant uptake and phytodegradation might be the dominant process for ethion removal by the plant. This plant might be utilized as an efficient, economical and ecological alternative to accelerate the removal and degradation of agro-industrial wastewater polluted with ethion.     

Nutrient limitation to the decomposition of water hyacinth ( Eichhornia crassipes)

The responses of decomposition to N and P supply were investigated in three leaf types of water hyacinth (Eichhornia crassipes (Mart.) Solms): dead green leaves collected from Donghu Lake; green, and brown leaves collected from outdoor tanks. The ratios of C:N, C:P, lignin:N and lignin:P were lowest in the green leaves collected from Donghu Lake, and highest in the brown leaves collected from outdoor tanks. Decomposition constant (k) of water hyacinth varied greatly, ranged from 0.006 to 0.099 d^–1. Leaf litters decayed most quickly within the initial two weeks during the experimental period, but decomposition rate decreased significantly in the following days. Decomposition and nutrient (N and P) release were fastest in the green leaves collected from Donghu Lake, intermediate in the green leaves collected from outdoor tanks, slowest in the brown leaves collected from outdoor tanks. Statistical analyses revealed that the effects of P-availability on decomposition rate and N, P release rate of the three litter types were significant, whereas the impacts of N-availability was insignificant (p > 0.05) except for the brown leaves collected from outdoor tanks. These results suggest that decomposition rate and nutrient content dynamics of water hyacinth differ with their growth habitats, and could partly be regulated by nutrient availability, especially by P-availability, in the environments.     

Extraction and retrieval of potassium from water hyacinth (Eichhornia crassipes)

Studies were carried out on extraction and retrieval of potassium from water hyacinth (Eichhornia crassipes). The stem and leaf were subjected to 13 treatments. The highest rate of K removal following HCl treatment was 69.7% K. Most effective removal of suspended organic substances, Ca2+ and Mg2+ were achieved at pH approximately 13, when 88.0% of K remained in filtrate. Maximum K in precipitate following this step was achieved with tartaric acid additions at n(C4H6O6)/n(K+) of 1.72 when precipitating at 4 degrees C for 3h, which resulted in 72.3% of K removal from the solution. Over the entire process, 44.3% of K in the dried stem-leaf sample of water hyacinth was retrieved in the form of KC4H5O6. This process demonstrated the potential for use of water hyacinth as a resource of potassium to produce potassium salts and provide a valuable end use for the plant, which could be highly invasive in aquatic ecosystems.     

Seasonal variation in the nitrate content of water hyacinth (Eichhornia crassipes [Mart.] solms)

Water hyacinth was cultured in a flow-through system with constant nutrient availability and 1.4 mg 1^?1 NO₃-N as the nitrogen source. Tissue nitrate content ranged from 0.05 to 0.21% of dry wt. and accounted for 1.7–6.6% of the total nitrogen in the plant. Highest tissue nitrate levels occurred during the winter period of low plant growth rates and decreased as dry matter productivity increased. In the winter, the nitrate content of water hyacinth exceeded levels considered safe for conventional forage crops used for livestock feed.     

High-rate composting-vermicomposting of water hyacinth (Eichhornia crassipes,Mart. Solms)

In an attempt to develop a system with which the aquatic weed water hyacinth (Eichhornia crassipes, Mart. Solms) can be economically processed to generate vermicompost in large quantities, the weed was first composted by a 'high-rate' method and then subjected to vermicomposting in reactors operating at much larger densities of earthworm than recommended hitherto: 50, 62.5, 75, 87.5, 100, 112.5, 125, 137.5, and 150 adults of Eudrilus eugeniae Kinberg per litre of digester volume. The composting step was accomplished in 20 days and the composted weed was found to be vermicomposted three times as rapidly as uncomposted water hyacinth [Bioresource Technology 76 (2001) 177]. The studies substantiated the feasibility of high-rate composting-vermicomposting systems, as all reactors yielded consistent vermicast output during seven months of operation. There was no earthworm mortality during the first four months in spite of the high animal densities in the reactors. In the subsequent three months a total of 79 worms died out of 1650, representing less than 1.6% mortality per month. The results also indicated that an increase in the surface-to-volume ratio of the reactors might further improve their efficiency.     

Phytoremediation of mercury- and methyl mercury-contaminated sediments by water hyacinth (Eichhornia crassipes)

Phytoremediation has the potential for implementation at mercury- (Hg) and methylHg (MeHg)-contaminated sites. Water hyacinths (Eichhornia crassipes) were investigated for their ability to assimilate Hg and MeHg into plant biomass, in both aquatic and sediment-associated forms, over a 68-day hydroponic study. The suitability of E. crassipes to assimilate both Hg and MeHg was evaluated under differing phosphate (PO4) concentrations, light intensities, and sediment:aqueous phase contamination ratios. Because aquatic rhizospheres have the ability to enhance MeHg formation, the level of MeHg in water, sediment, and water hyacinth was also measured. Hg and MeHg were found to concentrate preferentially in the roots of E. crassipes with little translocation to the shoots or leaves of the plant, a result consistent with studies from similar macrophytes. Sediments were found to be the major sink for Hg as they were able to sequester Hg, making it non-bioavailable for water hyacinth uptake. An optimum PO4 concentration was observed for Hg and MeHg uptake. Increasing light intensity served to enhance the translocation of both Hg and MeHg from roots to shoots. Assimilation of Hg and MeHg into the biomass of water hyacinths represents a potential means for sustainable remediation of contaminated waters and sediments under the appropriate conditions.     

Azotobacter chroococcum in the phyllosphere of water hyacinth (Eichhornia crassipes Mort. Solms)

Summary Water hyacinth (Eichhornia crassipes) harbours Azotobacter chroococcum in large numbers on and in its leaves. This may account for its prolific growth of the plants in water containing only traces of combined nitrogen. re]19721201     

Effect of physical pretreatment on dilute acid hydrolysis of water hyacinth (Eichhornia crassipes)

Effects of different physical pretreatments on water hyacinth for dilute acid hydrolysis process (121 ± 3 °C, 5% H₂SO₄, 60 min) were comparatively investigated. Untreated sample had produced 24.69 mg sugar/g dry matter. Steaming (121 ± 3 °C) and boiling (100 ± 3 °C) for 30 min had provided 35.9% and 52.4% higher sugar yield than untreated sample, respectively. The highest sugar yield (132.96 mg sugar/g dry matter) in ultrasonication was obtained at 20 min irradiation using 100% power. The highest sugar production (155.13 mg sugar/g dry matter) was obtained from pulverized samples. Hydrolysis time was reduced when using samples pretreated by drying, mechanical comminution and ultrasonication. In most methods, prolonging the pretreatment period was ineffective and led to sugar degradations. Morphology inspection and thermal analysis had provided evidences of structure disruption that led to higher sugar recovery in hydrolysis process.     

Distribution of cytokinin-like activity in different plant parts of the water hyacinth, Eichhornia crassipes

Cytokinin-like activity in extracts of leaf laminae, petioles, shoots, roots and flowers of young plants of the water hyacinth, Eichhornia crassipes S. was analyzed following Sephadex LH-20 column chromatography using the soybean callus bioassay. In all plant parts analyzed, two prominent peaks of cytokinin activity having elution volumes similar to zeatin and zeatin riboside were detected. Putative cytokinin gluco-side-like activity was detected only in leaves and flowers. The cytokinin complements of the leaves and the roots were qualitatively different. It would appear that cytokinins supplied by the roots are metabolized in the leaves or certain cytokinins are synthesized in the leaves themselves. The possible significance and distribution of cytokinins in different plant parts in relation to roots is discussed.     

Effect of growth irradiance on the maximum photosynthetic capacity of water hyacinth [Eichhornia crassipes (Mart.) Solms]

We grew water hyacinth [Eichhornia crassipes (Mart.) Solms]for 60 days in a greenhouse under natural light and in a controlledenvironment room at 31/25?C day/night temperatures and 90, 320and 750/µEm^–2sec^–1. We then determined maximumphotosynthetic rates in 21% and 1% oxygen, stomatal diffusionresistances, contents of chlorophyll and soluble protein, andthe size and density of the photosynthetic units (PSU) in representativeleaves from the four treatments. In air containing 21% oxygen,maximum photosynthetic rates were 14, 27 and 29 mg CO₂ dm^–2hr^–1for plants grown in artificial light at 90, 320 and 750µEm^–2sec^–1,respectively. Plants grown in natural light (maximum of 2000µEm^–2sec^–1) had maximum photosynthetic ratesof 34 mg CO₂ dm^–2hr^–1. In all treatments, photosyntheticrates in 1% oxygen were about 50% greater than rates in normalair, indicating the presence of photorespiration in water hyacinth.There was no apparent relationship between maximum photosyntheticrate per unit leaf area and stomatal conductance, chlorophyllcontent per unit area, or PSU density per unit area. However,the higher maximum photosynthetic rates were associated withgreater mesophyll conductances, specific leaf weights and proteincontents per unit area. When plants grown at 90µEm^–2sec^–1for 120 days were transferred to 750µEm^–2sec^–1for 5 days, only young leaves that were just beginning to expandat the time of transfer exhibited adaptation to the higher irradiance.The 40% increase in light-saturated photosynthetic rate in theseyoung leaves was associated with increases in mesophyll conductance,soluble protein content per unit area, and specific leaf weight. ¹ Mississippi Agricultural and Forestry Experiment Station cooperating. (Received July 19, 1978; )     

Productivity and nutrient uptake of water hyacinth,Eichhornia crassipes I. Effect of nitrogen source

Water hyacinth,Eichhornia crassipes, growth and nutrient uptake rates, as influenced by different N sources and N transformations, were measured using microcosm aquaculture systems. Net productivity was highest in the system receiving equal amounts of NH₄ ⁺ and NO₃ ^- (at 10 mg N 1^-1 each) and decreased in the order of NO₃ ^-, NH₄ ⁺, urea (added at 20 mg N 1^-1 each), and methane digestor effluent (at 6 mg N 1^-1). During the first 7-wk study (average ambient air temperature was 26–28°C), biomass yields were in the range of 19–53 g dry wt m^-2 day^-1, while between the 8th and 12th wk (average ambient air temperature was 16–22°C), biomass yields were in the range of 10–33 g dry wt m^-2 day^-1. In the systems with either NH₄ ⁺ or NO₃ ^-, or both added in equal proportions, about 14–20% of the total yield was contributed by roots, whereas in the system with urea and digestor effluent, roots contributed about 23 and 44% of the total yield, respectively. Nitrogen and P uptake per unit area followed trends similar to biomass yields. Nitrogen uptake rates were in the range of 533–2, 161 mg N m^-2 day^-1 for the systems receiving NH₄ ⁺, NO₃ ^-, and urea, while uptake rates were in the range of 124–602 mg N m^-2 day^-1 for the system receiving methane digestor effluent. Phosphorus uptake rates were found to be in the range of 59–542 mg P m^-2 day^-1. Under the most favorable conditions, maximum recorded biomass yield was 53 g dry wt m^-2 day^-1, with N and P removal rate of 2,161 mg N m^-2 day^-1 and 542 mg P m^-2 day^-1, indicating the potential of water hyacinth to produce large amounts of biomass which can be potentially used as a feedstock to produce methane.     

Phytoremediation of wastewater toxicity using water hyacinth (Eichhornia crassipes) and water lettuce (Pistia stratiotes)

This paper elucidates the phytoremediation potential of water hyacinth and water lettuce on the reduction of wastewater toxicity. Acute toxicity tests were performed in an aquarium with a population of Sarotherodon melanotheron, contaminated by different concentrations of wastewaters before and after phytoremediation with Eichhornia crassipes and Pistia stratiotes. Lethal concentrations (LC₅₀) of the fish's population obtained during 24 hours of exposures were determined. COD, BOD, ammonium, TKN and PO₄^3? concentrations in wastewaters were of 1850.29, 973.33, 38.34, 61.49 and 39.23 mg L^?1, respectively, for each plant. Phytoremediation reduced 58.87% of ammonium content, 50.04% of PO₄^3?, 82.45% of COD and 84.91% of BOD. After 15 days of the experiment, metal contents in treated wastewaters decreased from 6.65 to 97.56% for water hyacinth and 3.51 to 93.51% for water lettuce tanks. Toxicity tests showed that the mortality of fish exposed increased with increase in concentration of pollutants in wastewaters and the time of exposure. Therefore, the highest value of LC₅₀ was recorded for fish subjected to 3 hours of exposure (16.37%). The lowest rate was obtained after an exposure of 20 to 24 hours (5.85%). After phytoremediation, the effluents purified by Eichhornia crassipes can maintain the fish life beyond 24 hours of exposure.     

Genetic uniformity characterizes the invasive spread of water hyacinth (Eichhornia crassipes), a clonal aquatic plant

Aquatic plant invasions are often associated with long‐distance dispersal of vegetative propagules and prolific clonal reproduction. These reproductive features combined with genetic bottlenecks have the potential to severely limit genetic diversity in invasive populations. To investigate this question we conducted a global scale population genetic survey using amplified fragment length polymorphism markers of the world’s most successful aquatic plant invader –Eichhornia crassipes (water hyacinth). We sampled 1140 ramets from 54 populations from the native (South America) and introduced range (Asia, Africa, Europe, North America, Central America and the Caribbean). Although we detected 49 clones, introduced populations exhibited very low genetic diversity and little differentiation compared with those from the native range, and ～80% of introduced populations were composed of a single clone. A widespread clone (‘W’) detected in two Peruvian populations accounted for 70.9% of the individuals sampled and dominated in 74.5% of the introduced populations. However, samples from Bangladesh and Indonesia were composed of different genotypes, implicating multiple introductions to the introduced range. Nine of 47 introduced populations contained clonal diversity suggesting that sexual recruitment occurs in some invasive sites where environmental conditions favour seedling establishment. The global patterns of genetic diversity in E. crassipes likely result from severe genetic bottlenecks during colonization and prolific clonal propagation. The prevalence of the ‘W’ genotype throughout the invasive range may be explained by stochastic sampling, or possibly because of pre‐adaptation of the ‘W’ genotype to tolerate low temperatures.     

Effects of water hyacinth Eichhornia crassipes root extracts on midge Chironomus ramosus larvae: a preliminary note

The effects of crude root extracts of Eichhornia crassipes (Marts) Solms on Chironomus ramosus Chaudhuri eggs and larvae are studied under laboratory conditions. Egg masses of C. ramosus that are subjected to varying concentrations of exudates (final concentrations 0.25–2.5%) show 100% viability. However, larvae reared further at these concentrations reveal a dose–response relationship, with an LC₅₀ value of 1.33% and an LC₉₀ value of 2.05%. A striking feature is the occurrence of supernumerary salivary glands in larvae (three glands per larva) reared in the 1%, 1.25%, 1.5% and 1.75% extracts. This deviates from the normal two glands per larva and may be explained by altered growth as a result of the putative bioactive compounds present in the hyacinth extracts. In nature, hyacinth and midges co‐exist in many freshwater habitats, implying that hyacinth compounds present from natural leaching could be encountered by the larvae. These preliminary findings suggest that hyacinth can influence the larval development of midges, giving rise to long‐term ecological implications.     

Biomass yield and nutrient removal by water hyacinth (Eichhornia crassipes) as influenced by harvesting frequency

The effects of harvesting frequency on productivity, nutrient storage and uptake, and detritus accumulation by water hyacinth (Eichhornia crassipes /Mart/ Solms) cultured outdoors in nutrient-enriched waters were evaluated for a period of 13 months. Significant differences in hyacinth standing crop and productivity were measured with harvesting regimes of 1, 3 (harvest at maximum density) and 21 harvests over a 13-month period. The average plant standing crop decreased from 65 to 20 kg (fresh wt) m⁻² for systems with 1 and 21 harvests, respectively. Total harvested plant biomass was 67 kg (fresh wt) m⁻², 110 kg (fresh wt) m⁻² and 162 kg (fresh wt) m⁻² for 1, 3 and 21 harvests, respectively. The mean net productivity increased from 7·7 to 16·5 and 24·5 g (dry wt) m⁻² day⁻¹ for 1, 3 and 21 harvests, respectively. Nutrient storage in water hyacinth biomass (live, dead and detrital) at the end of the study decreased from 93 to 46 and 30 g N m⁻², and from 20 to 12 and 5 g P m⁻², for 1, 3 and 21 harvests, respectively. For the system with one harvest, 46% of the stored N and 25% of the stored P were recovered in dedrital tissue at the bottom of the tank. For the systtem with 21 harvests, only 11% of the stored N and 15% of the stored P were recovered in detrital tissue at the bottom of the tank. Ammonium-N and soluble reactive P concentrations in the water column were significantly higher for the treatment with one harvest compared to the treatments with 3 and 21 harvests.     

Ecological and socio‐economic impacts of invasive water hyacinth (Eichhornia crassipes): a review

1. Water hyacinth (Eichhornia crassipes) is one of the world’s most invasive aquatic plants and is known to cause significant ecological and socio‐economic effects. 2. Water hyacinth can alter water clarity and decrease phytoplankton production, dissolved oxygen, nitrogen, phosphorous, heavy metals and concentrations of other contaminants. 3. The effects of water hyacinth on ecological communities appear to be largely nonlinear. Abundance and diversity of aquatic invertebrates generally increase in response to increased habitat heterogeneity and structural complexity provided by water hyacinth but decrease due to decreased phytoplankton (food) availability. 4. Effects of water hyacinth on fish are largely dependent on original community composition and food‐web structure. A more diverse and abundant epiphytic invertebrate community may increase fish abundance and diversity, but a decrease in phytoplankton may decrease dissolved oxygen concentrations and planktivorous fish abundance, subsequently affecting higher trophic levels. 5. Little is known about the effects of water hyacinth on waterbird communities; however, increases in macroinvertebrate and fish abundance and diversity suggest a potentially positive interaction with waterbirds when water hyacinth is at moderate density. 6. The socio‐economic effects of water hyacinth are dependent on the extent of the invasion, the uses of the impacted waterbody, control methods and the response to control efforts. Ecosystem‐level research programmes that simultaneously monitor the effects of water hyacinth on multiple trophic‐levels are needed to further our understanding of invasive species.     

Impact of nutrients and herbivory by Eccritotarsus catarinensis on the biological control of water hyacinth,Eichhornia crassipes

Many water hyacinth infestations in South Africa are the symptom of eutrophication, and as a result, biological control of this weed is variable. This study examined the effects of herbivory by the mirid, Eccritotarsus catarinensis, on water hyacinth grown at high, medium and low nitrogen (N) and phosphorus (P) nutrient concentrations. Water nutrient concentration appears to be the overriding factor affecting plant growth parameters of water hyacinth plants—at high nutrient concentrations, leaf and daughter plant production were more than double than at low nutrient concentrations, while stem length was twice as great at high nutrient concentrations compared to low concentrations. Chlorophyll content was also twice as high at high nutrient concentrations than low concentrations. Conversely, flower production at high nutrient concentrations was less than half that at low concentrations. Herbivory by E. catarinensis did not have as great an effect on water hyacinth vigour as nutrient concentration did, although it significantly reduced the production of daughter plants by 23 ± 9%, the length of the second petiole by 13 ± 5%, and chlorophyll content of water hyacinth leaves by 15 ± 6%. In terms of insect numbers, mirids performed better on plants grown under medium nutrient conditions (99 ± 28 S.E.), compared to high nutrient concentrations (52 ± 27 S.E.), and low nutrient concentrations (25 ± 30 S.E.). Thus, these results suggest that the fastest and most significant reduction in water hyacinth proliferation would be reached by lowering the water nutrient concentrations, and herbivory by E. catarinensis alone is not sufficient to reduce all aspects of water hyacinth vigour, especially at very high nutrient concentrations.     

Mineral nutrient demands of the water hyacinth (Eichhornia crassipes (Mart.) Solms) in the White Nile

The possibility that the stunted growth of the water hyacinth in Bahr el Ghazal river in Sudan is influenced by nutrient elements is considered. Greenhouse experiments were carried out to determine the effects of deficiency and mineral nutrient additions on the growth of this plant. The water hyacinth was found to grow at a wide range of nutrient levels. Maximum growth was recorded at 21 mg l^–1 N, 62 mg l^–1 P, and 0.60 mg l^–1 Fe.     

净化水域的水生花卉—凤眼莲

凤眼莲 (ＥｉｃｈｈｏｒｎｉａｃｒａｓｓｉｐｅｓＳｃｌｍｓ) 又称水葫芦、水浮莲 ,为雨久花科凤眼莲属多年生宿根草本。原产热带美洲 ,喜生于向阳温暖的富含有机质的静水中 ,不耐寒。凤眼莲漂浮水面或生于浅水泥中。根状茎粗短 ,密生多数须根 ,叶基生成丛 ,莲座状 ;叶片宽卵心形至近扁圆形 ,浓绿而有光泽 ,叶柄基部膨大成葫芦形 ,内部具海绵质的通气组织。夏秋开蓝紫色花 ,集成穗状花序 ,亭亭玉立 ,与碧翠的绿叶丛显示出丰腴的身姿 ,端庄而艳丽 ,成为园林中装饰湖面、河沟、水体的良好花卉。凤眼莲具有净化水体的功能。特别在富营养化的水…