Nitrogen and Phosphorus Removal-capacity of Four Chosen Aquatic Macrophytes in Tropical Freshwater Ponds

Abstract

The nutrient removal-capacity of four chosen aquatic macrophytes was tested in both natural and laboratory conditions. Laboratory experiments were performed under controlled conditions using ‘microcosm’ methods wherein the plants were grown in three different nutrient concentrations. For field experiments, three ponds were selected that had different levels of plant nutrient concentrations and accordingly were treated as polluted, moderately polluted, and relatively unpolluted, respectively, the object being to study the nutrient removal-capacity of chosen aquatic macrophytes living in ‘natural’ conditions. For the present investigation, four common and widespread aquatic plants growing in all three ponds were chosen: Water-hyacinth (Eichhornia crassipes [Mart.] Solms), Water-lettuce (Pistia stratiotes L.), Round-leafed Water-fern (Salvinia rotundifolia Willd.), and Lesser Duckweed (Lemna minor L.). These plants were selected also because of their frequent presence in aquatic bodies in the region and their high reproductive capacity.From the results it is revealed that, during the summer and rainy seasons, the highest content of nitrogen was removed by the Eichhornia, followed by the Pistia > Lemna > Salvinia, while during winter the highest content of nitrogen was removed by the Eichhornia followed by the Lemna > Pistia > Salvinia. Higher phosphorus removal was found in summer than in the rainy or the winter season. Phosphorus removal by the macrophytes was in the order of the Eichhornia > Pistia > Lemna > Salvinia, during the summer and rainy seasons, whereas the highest content of phosphorus was removed by Lemna in the winter months.The nutrient removal-capacity was rated to be highest by the Water-hyacinth, followed by the Pistia, then the Lemna, and lowest by the Salvinia. It was also evident that the nutrient removal increased with increasing nutrient concentration in the wastewater. The removal of nitrate by the selected macrophytes ranged from 42.0% to 96.2%, while phosphate removal ranged from 36.3% to 70.2%. A positive and significant correlation was obtained between the concentration of nitrate and phosphate in the waters and plant tissues that were studied, and it is thought that a useful strategy to employ might be to grow the Eichhornia and the Lemna together at least where winter temperatures were likely to be low enough to favour the Lemna at that season, though at other times it is apt to be a nuisance.

Presence of tropical hydrophytes in relation to limnological parameters - a study of two freshwater ponds in Kolkata, India

“…Unlike V. spiralis, the presence of L. aequinoctialis was found to have a significant effect only on one water quality variable, namely total phosphorus (Figure 1f). The phosphorus uptake capacity of Lemna has been reported in tropical ponds (Tripathi et al 1991) and being a free-floating plant, water possibly happens to be its sole source of phosphorus. Philipose et al (1970) also observed an association between the free-floating form specially Lemna and phosphorus rich water (0.05 to 3.6 mgl -1 ) in a survey of Indian water bodies including farm ponds.…”

“…Due to mild winters in tropical regions, plants grow throughout the year thus, annual data is necessary to understand habitat tolerance and preference limit of individual species. There is a paucity of data on the occurrence of different plant species in relation to the water quality in tropical ponds (Mukhopadhyay & Dewanji 2002) although there are reports of independent studies of aquatic plants (Tripathi et al 1991) as well as of water quality in relation to the growth of phytoplanktons (Bhaskaran et al 1991). This data could also be valuable in respect to botanical conservation (Angélibert et al 2004).…”

Influence of photoperiod on the uptake of nitrogen and phosphorus in the water by Eichhornia crassipes and Salvinia auriculata

“…For the concentrations of total nitrogen values between 50% and 96% of reduction were found, and for phosphorus between 36% and 90%, allowing for the environmental conditions to which E. crassipes is exposed (Debusk & Reddy, 1987;Tripathi et al, 1991;Sharma & Oshodi, 1991;Zakova et al 1994). …”

“…Thus, showing the high potential of this species to remove many compounds. The species of the genus Salvinia exhibit a lower efficiency in systems of sewage treatment, when compared to other floating aquatic macrophytes (Reddy & Debusk, 1985;Tripathi et al, 1991). According to ROOM (1986), these plants can offer efficient pollution removal only when carefully managed.…”

Approche multicritère pour la sélection de plantes aquatiques en vue d’une exploitation rationnelle

“…Ainsi, il serait possible d'entrevoir la possibilité de cultiver une plante aquatique sur un plan d'eau donné subissant une pollution continue en composés azotés et phosphorés (MARIN, 1993), pour assurer une certaine productivité en biomasse. Dans ce sens, les données présentées dans le tableau 1 mettent en évidence l'importance du choix de la plante aquatique pour optimiser les procédures d'épuration, en concordance avec les potentiels valorisables désirés (AXTELL et al, 2003;FONKOU, 1996;REDDY et DEBUSK, 1987;TRIPATHI et al, 1991). Le choix de la plante à cultiver n'est pas aisé, car il doit satisfaire plusieurs critères (HAUSLER et al, 1994).…”