STUDIES ON ION BEAM APPLICATION TO IMPROVE AQUATIC MACROPHYTE REMEDIATION CAPACITY IN EUTROPHIC WATERS

Using ion beam biotechnology in combination with soil-less plant cultivation on artificial substratum (floating beds), the experiments were conducted with Ipomoea aquatica Forsk. Plants were attached to floating-beds which were placed on the surface of artificially nutrient-enriched tank water, in order to study the purification and remediation efficiency of ion beam-treated I. aquatica cultivars. The results show that N + ion beams with 25keV energy and dosages of 0, 2.6, 3.9, 5.2, 6.5, 7.8, 9.1×10 13N +(ions)/cm 2 affected I. aquatica dry seeds differently, with the dose of 3.9×10 13N + (ions)/cm 2 improving effectively the performance as expressed by various biological indices. After ion beam application, I. aquatica cultivars grew well in nutrient-enriched water bodies, increasing the growth of leaves and stem, number of leaves, length and area of roots, plant height, and weight more remarkably than observed in the control. The net removing rates of TN, TP were as high as 75% and 82%, respectively. Especially under the dose of 3.9×10 13N +(ions)/cm 2, the net removing rates of TN, TP were highest, for 77% and 85%, respectively. It was proved that ion beam application improves phytoremediation and may be used to purify nutrient rich water bodies.

Removal of Heavy Metals by Two Free Floating Aquatic Macrophytes

A concentration-dependent decrease in biomass, protein, RNA, DNA, and nutrient (NO3- and PO43-) uptake of Lemna minor and Azolla pinnata by Cr, Ni, and Zn was detected. Cr was found to exert maximum toxicity followed by Ni and Zn. Metal uptake was dependent on time and concentration of metal in the external rnedium. Both the macrophytes, however, showed preference for Zn followed by Ni and Cr. The uptake kinetics also revealed a low Vmax and high Km for Cr. L. minor was more effcient in accumulating Zn and Cr than A. pinnata in Ni. Compared to immobilized algae and bacterial capsules the test macrophytes showed a greater efficiency for metal removal

Green Liver Systems for Water Purification:Using the Phytoremediation Potential of Aquatic Macrophytes for the Removal of Different Cyanobacterial Toxins from Water

The protection and reasonable use of freshwater is one of the main goals for our future, as water is most important for all organisms on earth including humans. Due to pollution, not only with xenobiotics, but also with nutrients, the status of our water bodies has changed drastically. Excess nutrient load induces eutrophication processes and, as a result, massive cyanobacterial blooms during the summer times. As cyanobacteria are known to produce several toxic secondary metabolites, the so-called cyanotoxins, exhibiting hepato-, neuro- and cell-toxicity, a potential risk is given, when using this water. There is an urgent need to have a water purification system, which is able to cope with these natural toxins. Using aquatic plants as a Green Liver, the Green Liver System?, was developed, able to remove these natural pollutants. To test the ability of the Green Liver System?, several cyanobacterial toxins including artificial and natural mixtures were tested in a small-scale laboratory system. The results showed that within 7 - 14 days a combination of different aquatic macrophytes was able to remove a given toxin amount (10 μg·L-1) by 100%. The phytoremediation technology behind the Green Liver Systems? uses the simple ability of submerged aquatic plants to uptake, detoxify and store the toxins, without formation and release of further metabolites to the surrounding water.

Algal-bloom control by allelopathy of aquatic macrophytes—A review

Algal-bloom control is an important issue for water environment protection as it induces several negative impacts on the lives of aquatic organisms,aquaculture,landscaping,and human health.The development of an environment-friendly,cost-effective,and convenient alternative for controlling algal bloom has gained much concern.Using the allelopathy of aquatic macrophytes as a novel and safe method for algal-bloom control is a promising alternative.This paper reviews the development and potential application about allelopathy of aquatic plants on algae,including the allelopathic research history,the potential research problems,the research methodology,and the reported aquatic macrophytes and their inhibitory allelochemicals.Potential modes of inhibition action of allelochemicals on algae,possible ways for application,and future development directions of research on algal-bloom control by aquatic macrophytes were also presented.

The Bowati in Kordofan, Sudan: Unique Aquatic Ecosystems of a Non-Nilotic In-Land Delta

This paper describes the unique in-land, non-Nilotic delta of Wadi El Galla, a seasonal water course which originates in the Nuba Mountains of Kordofan region and terminates in a chain of small ponds each known locally as a Bouta (pl Bowati). The Bowati are inhabited by a community of aquatic plants forming a wide spectrum ranging from small true (Euophytes) to large woody trees. The euophytes encountered were grouped into six categories. The free-floating species were represented by the small Lemna purpusilla Torr. and the larger Pistia stratiotes L. while only one submerged species was found: Ottelia alismoides (Planch.) Welp. One suspended species was found, Utricularia stellaris L. F. Three species of the floating-leaved plants were encountered namely, Nymphaea lotus L., N. micrantha Guill. & Perrott and Nymphoides nilotica (Kotschy & Peyr.) Léonard. The emergent Limnophyton obtusifolium (L.) Miq. was very prominent in all the Bowat constituting with N. lotus the two dominant species. Trailing from the Bouta edge and forming thick mats on the open water is Neptunia oleracea Lour., a member of the Fabaceae family. Within these euophytes and towering to over ten meters is the woody tree Mitragyna inermis Kuntze. Some of herbaceous plants are a source of food for the local community such as the bulbils of Nymphaea micrantha. These meagrely studied ecosystems are under threat from natural and anthropogenic factors. The former are the recurrent drought, climate change, and the latter are due to urbanization, overexploitation and oil activities. There is an urgent need for delineating and mapping the geomorphology, drainage patterns of Al Muglad in-land delta as well as the number and sites of the Bowati. The taxonomy of the aquatic species, their nutritive and medicinal values are other areas of research. Within such a context, a concerted national and international endeavour is called for to conserve these unique ecosystems and conceivably, declaring them as protected sites.

Photosynthesis of Submerged and Surface Leaves of the Dwarf Water Lily(Nymphoides aquatica)Using PAM Fluorometry

Dwarf Water Lilies Nymphoides aquatica(J.F.Gmel)Kuntze have floating and submerged leaves.Some submerged aquatic vascular plants have a form of CAM(Crassulacean Acid Metabolism)called Submerged Aquatic Macrophyte(SAM)metabolism.Blue-diode based PAM technology was used to measure the Photosynthetic Oxygen Evolution Rate(POER:1O_(2)≡4e^(-)).Optimum Irradiance(E_(opt)),maximum POER(POER_(max))and quantum efficiency(α_(0))all vary on a diurnal cycle.The shape of the POER vs.E curves is different in seedling,submerged and surface leaves.Both E_(opt) and POER_(max) are very low in seedling leaves(E_(opt)≈104μmol photon m^(-2) s^(-1),PPFD;POER_(max)≈4.95µmol O_(2) g^(-1) Chl a s^(-1)),intermediate in mature submerged leaves(E_(opt)≈419µmol photon m^(-2) s^(-1) PPFD,POER_(max)≈38.1µmol O_(2) g^(-1) Chl a s^(-1))and very high in surface leaves(E_(opt)≈923µmol photon m^(-2) s^(-1) PPFD,POER_(max)≈76.1µmol O_(2) g^(-1) Chl a s^(-1)).Leaf titratable acid(C4 acid pool)is too small(≈20 to 50 mol H+m^(-3))to support substantial SAM metabolism.Gross daily photosynthesis of surface leaves is≈3.71 g C m^(-2) d^(-1) in full sun and as much as 1.4 gC m^(-2) d^(-1) in shaded submerged leaves.There is midday inhibition of photosynthesis.

DIATOM COMMUNITY SUCCESSION AND NUTRIENT EVOLUTION RECORDED FROM A SEDIMENT CORE OF THE LONGGAN LAKE, A LARGE SHALLOW LAKE IN EAST CHINA

The Longgan Lake is a shallow mesotrophic macrophyte-dominated lake. According to the high-resolution diatom research from its sediment core, the diatom community succession was built, and the total phosphorus (TP) and chlorophyll-a (Chl-a) concentration were quantitatively reconstructed for the past 2000 years, based on the diatom-TP and diatom-Chla transfer functions. The shifts of diatom assemblages also mirrored the developments of aquatic plant, reflecting the characters of aquatic ecosystem evolution. The inferred epilimnetic TP concentration fluctuated within a small range of 36 to 62μg/L, indicating the lake remained a relative stable mesotrophic status in the long historical period. The periodical variations of the diatom assemblage and trophic status suggest a mitigating function of shallow macrophyte-dominated lakes to nutrient input. The changes of lakes’ trophic status don’t linearly respond to the human disturbance in the catchment. The dynamics mechanism of phosphorus in macrophyte-dominated lakes, as inferred from diatoms, will provide a scientific foundation for the prediction of trophic status change in a shallow lake, as well as the lake ecological restoration and management decisions.