Rev Environ Sci Biotechnol (2008) 7:255–266 DOI 10.1007/s11157-008-9135-x REVIEW PAPER Managing water quality with aquatic macrophytes Jatin Srivastava Æ Amit Gupta Æ Harish Chandra Published online: 6 June 2008 Ó Springer Science+Business Media B.V. 2008 Abstract The principal sources of water for human water current and favoring sedimentation of sus- use are lakes, rivers, soil moisture and relatively pended particles. Aquatic macrophytes also reduce shallow groundwater basins. Water quality in lakes sediment resuspension by offering wind protection. and reservoirs is subjected to the natural degradation, The use of aquatic macrophyte for treatment of processes of eutrophication and the impacts of human wastewater to mitigate variety of pollution level is activities. Water quality problems can often be as one of the most researched issues all over the world. severe as those of water availability but less attention Aquatic plant species are very specific for the uptake has been paid to them, particularly in developing of nutrients. Owing to this specificity, the selection of countries. Currently additional sustainable ways to the aquatic plant species is one of the skilled tasks mitigate the degradation of water quality are being prior to the design of a water treatment facility. An researched all over the world. Phytoremediation is effort has been made in this review to cover the most one of the serious efforts towards the sustainability. researched aquatic flora for mitigation purposes and Most of the aquatic macrophytes are naturally their possible use in a mesocosm as the selection of occurring and well adapted for their surroundings. an appropriate aquatic plant specie reduce the time Aquatic macrophytes have the capability to remove and cost of the treatment processes. excessive nutrient load from the water that otherwise cause eutrophication of the water body. Aquatic Keywords Aquatic macrophytes Á macrophytes absorb nutrient mineral ions from water Water quality Á Nutrient ions Á Metals mesocosm Á column and influence metal retention indirectly by Selection of species acting as traps for particulate matter, by slowing the J. Srivastava (&) Department of Environmental Sciences, Chhatrapati 1 Introduction Shahu Ji Maharaj University, Kanpur 208024, UP, India e-mail: [email protected] The Human Development Report (2006) of UNDP A. Gupta has focused on the global water crisis as one of the Department of Agricultural Chemistry, National Taiwan most serious problems facing by the humanity today. University, Taipei 106-17, Taiwan In many Asian countries and elsewhere the demand for potable water doubles every 10–15 years, not H. Chandra Department of Environmental Microbiology, Gayatri only because of the rising domestic consumption but College of Biomedical Sciences, Dehradun, UK, India also due to the increasing needs of industry. The 123 256 Rev Environ Sci Biotechnol (2008) 7:255–266 principal sources of water for human use are lakes, Although nitrogen contamination rarely exceeds rivers, soil moisture and relatively shallow ground- levels of potential health risk, consuming water water basins. The usable portion of these sources is having high concentrations of nitrates can cause less than 1% of all freshwater and only 0.01% of all infant methaemoglobinaemia or blue-babysyndrome water on Earth. Although, water quality is an (Sampat 2000). Enriched water provides favorable important issue and the subject of much legislation, conditions for pathogenic microorganisms to multi- sometimes the quantity is more important than ply. Direct consumption of such water can cause quality in determining the extent and type of devel- water borne diseases. Because existing surface water opment possible in a given geographic location. sources are widely polluted, ground water is the main Water quality problems can often be as severe as fresh water source for aquaculture. Consequently, those of water availability but less attention has been several areas have faced ground subsidence as a result paid to them, particularly in developing countries. of over-withdrawal of ground water, therefore it is Many countries do not have sufficient water supplies essential to reuse the wastewater after the treatment to meet demand, as a result of which, aquifer to lessen the overburden on the natural resources of depletion due to over exploitation is common. water. In addition, aquatic macrophytes absorb and Moreover, the scarcity of water is accompanied by accumulate the nutrient ions in the tissues (DeBusk deterioration in the quality of available water due to et al. 1995; Mahujchariyawong and Ikeda 2001). heavy pollution load and environmental degradation. Aquatic macrophyte influence metal retention indi- Water quality in lakes and reservoirs is subjected rectly by acting as traps for particulate matter, by to the natural degradation, processes of eutrophica- slowing the water current and favoring sedimentation tion and the impacts of human activities. Sources of of suspended particles (Kadlec 2000). Aquatic mac- pollution include untreated sewage, chemical dis- rophyte also reduces sediment resuspension by charges, petroleum leaks and spills, dumping in old offering wind protection (Brix 1997). Large aquatic mines and pits, and agro-chemicals that are washed macrophytes possess the ability to breakdown the off from farm fields. The principal chemical constit- human and animal derived pollutants in the water uents of surface water cause enrichment of the water (Kadlec and Knight 1996). Having the outlines of the if exceed the threshold limit (Table 1). These ions are issues associated with the degraded water quality, the required for the growth of micro- and macro-organ- role of aquatic macrophytes (floating and submerged) isms. Phosphorus (P) is generally considered as the in managing the water quality, has been discussed in limiting nutrient ion, playing the key role in eutro- this review. phication (Zhou et al. 2001; Varjo et al. 2003) and is one of the main factors in phytoplanktonic growth (Correll 1998). Visible effects of eutrophication are 2 The wetlands and their role in improving water development of plankton scum and rooted plant quality biomass, amplified growth of algae, enhanced organic loading, death of fishes, increase in sedimentation, Wetlands are transition areas between land and water and reduction of water transparency (Klapper 1991). bodies, characterized by shallow water overlying waterlogged soil as well as interspersed submerged, emergent or floating vegetation. The capability of Table 1 Principal chemical constituent of surface water wetlands for decontamination of waste water has long Anionsa Threshold levelb Cationsa Threshold levelb been recognized in natural wetlands in many parts of the world (Godfrey et al. 1985; Mitsch and Gosselink HCO - 200 mgl1- Ca2+ 75.0 mgl1- 3 1993; Nahlik and Mitsch 2006). Major mechanisms SO 2- 200 mgl1- Mg2+ 30.0 mgl1- 4 of pollutant removal in wetlands depend on sedi- Cl- 200 mgl1- Na+ 50.0 mgl1- - 1- + 1- mentation, adsorption on the root surface and NO3 45.0 mgl K 10.0 mgl 3- 1- + 1- absorption by the aquatic macrophytes (Hutchinson PO4 0.25 mgl Zn 5.0 mgl 1975; Serra et al. 2004). Macrophytes create condi- a Tchobanoglous and Schroeder (1985) tions for the sedimentation of suspended solids (SS) b As per Indian standards IS: 2490 and prevent erosion by reducing the velocity of the 123 Rev Environ Sci Biotechnol (2008) 7:255–266 257 water in wetlands. Macrophytes in association with EM the aquatic micro-organisms and periphytons enhance 5% the uptake of nutrients from the water (Vymazal 2002). Periphyton potentially removes metal cations (Scinto and Reddy 2003) and nutrient anions such as PO 3- and NO - by direct absorption from the water FAM 4 3 SAM 25% column (Khatiwada and Polprasert 1999). The mac- 40% rophytes transport approximately 90% of the oxygen available in the rhizosphere. This stimulates both aerobic decomposition of organic matter and pro- motes the growth of nitrifying bacteria (Scholz 2006; Lee and Scholz 2007). 3 Aquatic macrophytes Aquatic macrophytes are limited to the macroscopic FFM 30% flora including aquatic spermatophytes, pteridophytes and bryophytes. Schwarz and Haves (1997) also Fig. 1 The nutrient ion removal efficiency of aquatic macro- described the charophytes as aquatic macrophyte. phytes (EM = Emergent macrophyte, FAM = Floating Growth forms of macrophytes usually classifies them aquatic macrophyte, FFM = Floating aquatic macrophyte, SAM = Submerged aquatic macrophytes) in four group systems; emergent macrophytes (e.g., Phragmites australis, Typha latifolia), floating- leaved macrophytes (e.g., Nuphar luteum), free- SAM EM floating macrophytes (e.g., Eichhornia crassipes) 26% 30% and submerged macrophytes (e.g., Myriophyllum spicatum). The accumulation of nutrients in macro- phyte tissues determines the cleaning ability of these plants (Figs. 1 and 2). The amount of accumulated nutrients depends on the physiological capacity for further uptake and biomass of aquatic macrophytes which vary with the species (Pieczynska 1990). In most aquatic ecosystems, attention has been focused on the cycling of N and P, most likely to limit primary producers and perhaps heterotrophic micro- orgaisms (Pace et al. 1991; Suberkropp and Chauvet 1995; Smith 1998; Rosemond et al. 2002) (Table 2). FFM FAM Aquatic macrophytes act as substratum for the 32% 12% growth of periphyton communities composed of complex assemblages of cyanobacteria, eubacteria, Fig. 2 The metal ion removal