Growth characteristics of aquatic macrophytes cultured in nutrient-enriched water: II. Azolla,Duckweed, and Salvinia

Seasonal growth characteristics and biomass yield potential of 4 small-leaf, floating, aquatic macrophytes cultured in nutrient nonlimiting conditions were evaluated for central Florida’s climatic conditions. Biomass yields were found to be 10.6, 11.3, 16.1, and 32.1 t (dry wt) har^?1 yr^?1, respectively, for azolla (Azolla caroliniana), giant duckweed (Spirodela polyrhiza), common duckweed (Lemna minor), and salvinia (Salvinia rotundifolia). Operational plant density was in the range of 10–80 g dry wt m^?2 for azolla, 10–88 g dry wt m^?2 for giant duckweed, 10–120 g dry wt m^?2 for common duckweed, and 35–240 g dry wt m^?2 for salvinia. Specific growth rate (% increase per day) was maximum at low plant densities and decreased as the plant density increased. Results suggest that small-leaf, floating plants may not be suitable in monoculture biomass production systems because of low biomass yields, but they may be suitable for inclusion in poly culture systems with larger aquatic plants. The high N content (crude protein = 20–33%) of small-leaf,floating plants suggests the use of biomass as animal feed.     

Flow-resistance adaptations of rigid-stemmed aquatic macrophytes in simulated water channels

This study investigated the development of interspecific adaptations of flow-resistance mechanisms to higher flow rates in rigid-stemmed Hygrophila salicifolia (Vahl) Nees (willow leaf Hygrophila sp.) plants placed in simulated water channels. The results indicate that adaptations to higher flow rates include a reduction in: growth rate, average fresh weight, average dry weight, and average diameter; but an increase in the number of parallel shoots. These effects combine to create a streamlined profile, reduce plant damage, and increase propagation through adventitious budding. Higher flow rates also reduced the ratio of average plant height to average root length in rigid-stemmed Hygrophila sp. The increased root length, strengthening of plant anchors, and reduction of uprooting seen at higher flow rates are likely to increase slope stability and reduce riverbank topsoil runoff. Moreover, rigid-stemmed aquatic macrophytes develop different adaptations than flexible-stemmed water plants (e.g., water celery); for these plants, higher flow velocities trigger an increase in the average density of vascular bundles and a reduction of the average root length, which results in uprooting and movement to different locations. These results suggest that different aquatic macrophytes play different roles in water channels. Our methods and findings can inform further investigations into the roles played by different aquatic macrophytes in ecological engineering and help to identify optimal planting materials or precursors for riverbanks.     

Phytoremediation of landfill leachate waste contaminants through floating bed technique using water hyacinth and water lettuce

Abstract

In the present study, the effectiveness of water hyacinth and water lettuce was tested for the phytoremediation of landfill leachate for the period of 15?days. Fifteen plastic containers were used in experimental setup where aquatic plants were fitted as a floating bed with the help of thermo-pole sheet. It was observed that both plants significantly (p?<?0.05/p?<?0.01/p?<?0.001) reduce the physicochemical parameters pH, TDS, BOD, COD and heavy metals like Zn, Pb, Fe, Cu and Ni from landfill leachate. Maximum reduction in these parameters was obtained at 50% and 75% landfill leachate treatment and their removal rate gradually increased from day 3 to day 15 of the experiment. The maximum removal rate for heavy metals such as for Zn (80–90%), Fe (83–87%) and Pb (76–84%) was attained by Eichhornia crassipes and Pistia stratiotes. Value of bioconcentration and translocation factor was less than 1 which indicates the low transport of heavy metals from roots to the above-ground parts of the plants. Both these plants accumulate heavy metals inside their body without showing much reduction in growth and showing tolerance to all the present metals. Therefore, results obtained from the study suggest that these aquatic plants are suitable candidate for the removal of pollution load from landfill leachate.     

Effects of aquatic macrophytes on water quality and phytoplankton communities in shallow lakes

We investigated aquatic macrophytes, water quality, and phytoplankton biomass and species composition in three shallow lakes with different levels of vegetation cover and nutrient concentration in Kushiro Moor, during August 2000. Trapa japonica can live in a wide range of nutrient levels. This species forms an environment with a steeper extinction of light, higher concentrations of dissolved organic carbon (DOC), lower concentrations of dissolved oxygen (DO) near the bottom, and lower concentrations of nitrate+nitrite and soluble reactive phosphorus (SRP) than other vegetation types. The pH was much higher in a Polygonum amphibium community, and the DO near the bottom did not decrease compared to a T.japonica community in the summer. The relationship between chlorophyll a and the limiting nutrient (total phosphorus (TP) when total nitrogen (TN):TPis 10 and TN/10 when TN:TP is <10) significantly differed between lakes with and without submerged vegetation. The chlorophyll a concentrations at a given nutrient level were significantly lower in water with submerged macrophytes than in water without them. Correspondence analysis showed that the difference in phytoplankton community structure across sites was largely due to the presence or absence of submerged macrophytes, and the ordination of phytoplankton species in the lakes with submerged macrophytes is best explained by environmental gradients of TN, chlorophyll, pH and SRP.     

Chemical composition studies on some aquatic macrophytes in three Scottish lochs. I. Chlorophyll,ash, carbon,nitrogen and phosphorus.

The chlorophyll, ash, carbon, nitrogen and phosphorus levels in seven species of freshwater macrophytes (Juncus effusus L., Iris pseudacorus L., Carex rostrata Stokes, Glyceria maxima (Hartm.) Holmberg, Nuphar lutea (L) Sm., Polygonum amphibium L. and Schoenoplectus lacustris (L) Pallas) in three Scottish lochs of different trophic levels were studied during 1975. Mean chlorophyll levels varied from a minimum of 1.73 mg g^–1 dry weight in Balgavies Loch Juncus to 10.22 mg g^–1 dry weight for Forfar Loch Iris. Carbon contents ranged from 450 to 520 mg g^–1 ash-free dry weight. For ash, nitrogen and phosphorus, significant differences in mean concentrations were detected among plant species as well as within one plant species growing in different lochs. Positive correlations were apparent between the degree of eutrophication in the study areas and the amount of ash, phosphorus and nitrogen present in the plants growing in them.     

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.     

The effects of lime addition on aquatic macrophytes in hard water: in situ and microcosm experiments

1. Aquatic macrophytes are abundant in ponds and canals that are constructed in semi‐arid regions for water storage and conveyance, as well as in lakes that are culturally enriched. 2. Addition of Ca(OH)₂ to two hardwater ponds at 250 or 275 mg L^–1 caused an immediate eradication of submersed aquatic plants. Although these ponds are well‐buffered (alkalinity: 2.57–3.94 mequiv L^–1; pH: 8.1–9.0), lime addition caused an immediate increase in pH of 0.2–3 units. 3. Application of 135 mg L^–1 Ca(OH)₂ for 24 h or 210 mg L^–1 Ca(OH)₂ for 65 h to two irrigation canals had no effect on macrophyte biomass at the lower concentration and duration, but resulted in the elimination of aquatic macrophytes 1 month after the higher concentration, longer duration treatment. 4. Unlike the macrophyte control achieved following application of 210–275 mg L^–1 Ca(OH)₂ to ponds or canals, microcosm experiments in which lime formulation [slaked lime (Ca(OH)₂), calcite (CaCO₃), or a 1 : 1 mixture] and concentrations (up to 1500 mg L^–1) were manipulated failed to elicit a consistent change in macrophyte biomass. Macrophytes in microcosms treated for the short‐term (23–33 days) with ≥ 200 mg L^–1 Ca(OH)₂ or a mixed Ca(OH)₂/CaCO₃ formulation always lost pigmentation, but biomass was not consistently reduced. 5. Declines in macrophyte biomass following treatment of ponds and canals may have been triggered by a short‐term rise in pH which, in these relatively warm (22–23 °C) alkaline (2.28–3.94 mequiv L^–1) systems, would have resulted in low concentrations of free CO₂ and bicarbonate for photosynthesis.     

Ethanol production from candidate energy crops: water hyacinth (Eichhornia crassipes) and water lettuce (Pistia stratiotes L.)

Fermentation modes and microorganisms related to two typical free-floating aquatic plants, water hyacinth and water lettuce, were investigated for their use in ethanol production. Except for arabinose, sugar contents in water lettuce resembled those in water hyacinth leaves. Water lettuce had slightly higher starch contents and lower contents of cellulose and hemicellulose. A traditional strain, Saccharomyces cerevisiae NBRC 2346, produced 14.4 and 14.9 g l(-1) ethanol, respectively, from water hyacinth and water lettuce. Moreover, a recombinant strain, Escherichia coli KO11, produced 16.9 and 16.2 g l(-1) ethanol in the simultaneous saccharification and fermentation mode (SSF), which was more effective than the separated hydrolysis and fermentation mode (SHF). The ethanol yield per unit biomass was comparable to those reported for other agricultural biomasses: 0.14-0.17 g g-dry(-1) for water hyacinth and 0.15-0.16 g g-dry(-1) for water lettuce.     

不同营养水平对外来物种凤眼莲生长特征及其竞争力的影响

入侵种凤眼莲(Eichhorniacrassipes)在中国的泛滥不仅与其强大的适应力和繁殖能力有关,还与水体的富营养化有很大的关系。作者通过盆栽实验比较了三个营养水平的模拟富营养条件下凤眼莲的生长特征和对当地种黄花水龙(Ludwigiapeploidesssp.stipulacea)和黑藻(Hydrillaverticillata)两个不同生长型的影响。结果表明:富营养条件增强了凤眼莲的生长繁殖能力,使其平均每母株克隆分株数、平均株高以及总生物量极大的增加。凤眼莲的生长优势导致了其竞争优势,对黄花水龙和黑藻都发生了明显的竞争效应。迅速繁殖的凤眼莲覆盖大量水面,通过排挤作用抑制了黄花水龙的生长(低营养水平除外);黑藻因光照缺乏,导致正常光合作用受阻,生物量急剧下降。凤眼莲对黑藻的竞争效应较黄花水龙更强。富营养化的水体为凤眼莲的成功入侵提供了优越条件,因此解决当前水体的富营养化状况能有效控制凤眼莲入侵,同时也有利于本地生物多样性的保护。     

Distribution and quantitative development of aquatic macrophytes in relation to sediment characteristics in oligotrophic Lake Kalgaard, Denmark

SUMMARY. The distribution and quantitative development of aquatic macrophytes have been studied in oligotrophic Lake Kalgaard, Denmark. The vegetation is dominated by isoetid species, which are widely distributed (about 40% of the lake bottom) compared to emergent and floating-leaved macrophytes (about 4%). Littorella uniflora dominates at depths of 0–2 m and Isoetes lacustris from 2.0 to 4.5m. Within the colonization area the mean midsummer biomass of Littorella is 112g organic dry weight m⁻² and that of Isoetes, 66 gm⁻². The total biomass of these two species constitutes 99% of the biomass of submerged macrophytes.
The perennial Littorella shows only small seasonal biomass variations. The vegetational biomass, the above-ground fraction of the biomass, and the weight of individual plants all increased with the organic content of the sediment at water depths from 0 to 0.75 m. At the same time the interstitial concentrations of carbon dioxide, extractable inorganic nitrogen, and exchangeable inorganic phosphorus increased, thus supporting the hypothesis that an increasing organic content of the sediments at this low level creates a physiologically richer medium for the plants.
The isoetid growth form is discussed in relation to the chemical environment of oligotrophic, softwater lakes.     

Growth and nutrient absorption of two submerged aquatic macrophytes in mesocosms, for reinsertion in a eutrophicated shallow lake

Aquatic macrophytes play a central role in preserving the ecological equilibrium of shallow lakes and in the restoration of eutrophic lakes that have switched to phytoplankton-dominated turbid water. Massaciuccoli Lake, a shallow lake located along the Tuscan coast in Italy, has shown a constant and progressive simplification of the submerged plant community, for anthropogenic reasons, leading, in recent years, to turbid water. The growth and nutrient absorption capability of two macrophyte species, Myriophyllum verticillatum L. and Elodea canadensis Michaux, in the lake was investigated, with the prospect of a future lake restoration programme centred on their replacement. Mesocosm experiments were conducted to monitor the plant growth and nutrient (NO₂⁻, NO₃⁻, NH₄⁺, Ntot, PO₄³⁻, Ptot) content in the plant dry matter and water at the beginning and at the end of the trial. Bacterial activity was analysed in the water in order to verify the possible nutrient absorption contribution by organisms other than plants. Both M. verticillatum and E. canadensis showed satisfactory growth and nutrient reduction in the water body. Moreover, their different growth patterns suggested that optimal replacement can be performed with their introduction in two steps, starting with M. verticillatum, which shows the best capacity to colonise the aquatic environment, due to its tendency towards lengthening.     

Successional patterns of aquatic macrophytes in Jebba Lake, Nigeria

Macrophyte succession in Jebba Lake, Nigeria, was observed through the first four years after impoundment. Two distinct serai phases, a floating fern phase and a draw-down flora phase could be recognized. The floristic composition of the macrophyte vegetation was also investigated to check earlier predictions (Obot & Mbagwu, 1986) on the probable structure of the macrophyte flora. The failure of obligate floating macrophytes such as Pistia, Azolla and Salvinia to establish in the lake as predicted is discussed. However, rooted emergent macrophytes were observed to be more successful than would be expected from the predictions.     

Growth physics and water relations of red-light-induced germination in lettuce seeds

Red light (R) and gibberellins (GA) each induce a water potential decrease in the axes of lettuce (Lactuca sativa L.) embryos resulting in germination of intact seeds (achenes) or an increase in growth of the axes of isolated embryos. The fruit coat and endosperm are a substantial barrier to the penetration of exogeneous GA. Isolated embryos take up 35 times as much [³H]GA₁ as the embryos of intact seeds and respond to less than 1·10^-10 M GA₃ or GA₄₊₇. We calculated that only 1·10^-8 M of either GA₃ or GA₄₊₇ would result in 50% germination if the GA were able freely to penetrate the fruit coat. Exogenous GA₃ or GA₄₊₇, at concentrations insufficient to cause germination, result in an apparent synergistic promotion of germination when suboptimal R is applied. Yet suboptimal concentrations of exogenous GA₃ or GA₄₊₇ and suboptimal R result in only additive increases in the growth response in axes of isolated embryos. Dose-response curves demonstrate quantitative increases in the growth response of the isolated axes after R or GA treatments insufficient to induce germination in intact seeds, indicating that a threshold potential must be achieved by the embryonic axes before germination can occur.Abbreviations FR far=red light - GA gibberellin - PEG poly-ethylene glycol 4000 - P_fr far-red-absorbing phytochrome - R red light III.=Carpita et al. 1979b; IV.=Carpita et al. 1979c     

Assessing water hyacinth (Eichhornia crassopes) and lettuce (Pistia stratiotes) effectiveness in aquaculture wastewater treatment

Water hyacinth (Eichhornia crassipes) and water lettuce (Pistia stratiotes) were analyzed to determine their effectiveness in aquaculture wastewater treatment in Malaysia. Wastewater from fish farm in Semanggol Perak, Malaysia was sampled and the parameters determined included, the pH, turbidity, dissolved oxygen (DO), chemical oxygen demand (COD), biochemical oxygen demand (BOD), nitrite phosphate (PO4(3-)), nitrate (NO(3-)), nitrite (NO(-2)), ammonia (NH3), and total kjedahl nitrogen (TKN). Also, hydroponics system was set up and was added with fresh plants weights of 150 +/- 20 grams Eichhornia crassipes and 50 +/- 10 grams Pistia stratiotes during the 30 days experiment. The phytoremediation treatment with Eichhornia crassipes had pH ranging from 5.52 to 5.59 and from 4.45 to 5.5 while Pistia stratiotes had its pH value from 5.76 to 6.49 and from 6.24 to 7.07. Considerable percentage reduction was observed in all the parameters treated with the phytoremediators. Percentage reduction of turbidity for Eichhornia crassipes were 85.26% and 87.05% while Pistia stratiotes were 92.70% and 93.69% respectively. Similar reductions were observed in COD, TKN, NO(3-), NH3, and PO4(3-). The capability of these plants in removing nutrients was established from the study. Removal of aquatic macrophytes from water bodies is recommended for efficient water purification.     

四种冬季水生植物组合对富营养化水体的净化效果

选择10种耐低温的水生植物构建4种植物组合,研究了冬季低温环境下不同水生植物组合对富营养化水体的净化效果.结果表明:组合1[常绿水生鸢尾(Iris hexagonus Hybrid)*羊蹄(Rumex japonicus)+金叶“金钱蒲”(Acorus gramineus“Ogan”)+反曲灯心草“蓝箭”(Juncus inflexus“Blue Arrows”)]4种植物均能在试验富营养化水体中茂盛生长,且对TN、NOx-N、NH4-N和TP的去除率分别为47.8％、52.2％、32.4％和70.1％;组合2[常绿水生鸢尾+羊蹄+金叶“金钱蒲”+大苞萱草(Hemerocallis middendorfii)]4种植物也都能在试验富营养化水体中存活,并且有一定量的生长,对TN、NOx-N、NH4-N和TP的去除率分别为44.2％、58.5％、34.6％和67.8％;而未种植物的对照对TN、NOx-N、NH4-N和TP的去除率分别为40.0％、25.9％、27.3％和64.5％;组合1和2对富营养化水体有较好的净化效果.组合3和组合4中由于吊兰(Chlorophytum comosum)和三穗薹草(Carex tristachya)等植物长势较差,仅对NOx-N具有较明显去除能力,对其他指标去除效果不明显.通过这些水生植物在富营养化水体中生长特性和对营养元素的去除能力,发现冬季组合1和2的净化效果较好,是低温条件下适宜的浮床植物组合形式.     

The aquatic macrophytes of Lake Vechten. Species composition,spatial distribution and production

The macrophytic species compositions in Lake Vechten of 1963 and 1979–80 were compared and showed a considerable change. The main vegetation types were mapped in 1973, 1978, 1979 and 1980. All macrophytic communities, i.e. submerged, floating-leaved and emergent vegetation types, declined mainly due to increasing water turbidity, increasing tree-shading and, from 1978 onwards, grazing and trampling by cattle.Production rates, derived from different combinations of measurement and calculation, were compared. The macrophytes contributed only about 7% to the total lake production in 1980.     

The role of aquatic macrophytes in microhabitatual transformation of physical-chemical features of small water bodies

The paper presents the results of an examination of the phycical-chemical parameters of water together with an analysis of the chlorophyll a concentration of 12 small water bodies situated within urban and suburban areas of the city of Poznań (mid-west Poland)—typical mid-forest, strongly anthropogenically modified in the urban landscape, strongly antropogenically modified in an agricultural area and clay-pits. There were zones of open water (Unvegetated Zone) as well as zones of rush and aquatic vegetation (Vegetated Zone) distinguished in the examined ponds. The influence of the rush vegetation, nymphaeids and elodeids on the abiotic parameters of an aquatic environment was examined. Water samples were taken during the summer of 2004 from 12 stations within the open water and 24 within macrophytes. The plant matter was randomly collected in triplicate from the central part of the vegetated stand. The influence of macrophytes on the abiotic features of water was estimated using the parameter of the plant length (cm l⁻¹) and the plant biomass (g l⁻¹). In the studied ponds 12 aquatic macrophyte communities were distinguished. A salient feature of submerged macrophytes was a great density of plant stems along with considerebly low biomass, however, the rush vegetation (Phragmitetum communis, Typhetum latifoliae) when compared to nymphaeids (Polygonetum natantis, Potametum natantis) and elodeids (Potametum lucentis) was characterised by lower stem densities and higher biomass. The water bodies were alkaline and of pronounced hardness. In most of them high trophy conditions were found with especially high concentrations of phosphorus (96 μg l⁻¹ on average). There was significant differentiation in the water chemistry (mainly in respect to mineral compounds) between the Vegetated and Unvegetated Zones as well as between particular aquatic macrophyte communities.     

Toxicity, accumulation, and removal of heavy metals by three aquatic macrophytes

A comprehensive understanding of the uptake, tolerance, and transport of heavy metals by plants will be essential for the development of phytoremediation technologies. In the present paper, we investigated accumulation, tissue and intracellular localization, and toxic effects of cadmium (Cd), lead (Pb), zinc (Zn), and copper (Cu) in three aquatic macrophytes (the angiosperms Lemna minor and Elodea canadensis, and the moss Leptodictyum riparium). We also tested and compared their capacity to absorb heavy metal from water under laboratory conditions. Our data showed that all the three species examined could be considered good bioaccumulators for the heavy metals tested. L. riparium was the most resistant species and the most effective in accumulating Cu, Zn, and Pb, whereas L. minor was the most effective in accumulating Cd. Cd was the most toxic metal, followed by Pb, Cu, and Zn. At the ultrastructural level, sublethal concentrations of the heavy metals tested caused induced cell plasmolysis and alterations of the chloroplast arrangement. Heavy metal removal experiments revealed that the three macrophytes showed excellent performance in removing the selected metals from the solutions in which they are maintained, thus suggesting that they could be considered good candidates for wastewaters remediation purpose.