Table I: Removal efticiency 0(' metal iUml by some common aquatIc macrophytesMetals Removing cfQclcncyFe . Cu. Zn . Cd SU.OHg 93.0Pb, Zn and Cu 80,0IIll 900Ph <)00II:' 1)1),\

( 'J, Hg and CI ~~ 1)0,0.)·a/lillia herzugii C.;_·.;_r___ 708_'3 _SOlircc: Sn vastava ..2008

HIC hhornia eras sipesAZ(J//a spp('e/" /' oph) 'llum deniers IIl11

\rSE OF AQUATIC "I.A~TS AS NOTIUENT SINKAquatic vegetation absorbs large amount of nutrients and which is an effective means of strippingnutnents from effluents or natural waters, Boyd (I (70) reported that nutrients could possibly beabsorbed from effluents by aquatic plants prior to their release intu natural water. or plants could heculuvuted In lakes and then harvested. A comparative study carried out by Une at "I (1988) revealedthat some plant species grow well in nutrient rich water. 1\. P and K levels in these species. It wasfound thai the tissue concentration 01' all these elements was high (Oki et (II 1989a). Shallow,eutrophic, aquatic ecosystems stocked With macrophytes arc among the most product rve In the world(Schicrup. 197X) 1he capacity of such systems to dl:C()1I1pO~eorganic mailer and assumlate nuincnthas long been recogruvcd (Bnx and Schierup, I%9), It IS ""I.!IIknown that streams. lakes. coastal areasand wetlands centum a considcrublc 5(.'1 r punticauon •sci f pun ticauon' capacity (Seidel .197(».During the growing season the plants absorb anL incorporate the nuuicnt-, into their own structuresand function as a substrate for microorganism. Bnx (1/ al 1989 reponed that mternauonal aucnuon I~110\\ tilted towards the ability of aquatic macrophytes tu control pollution and also to treat municipaland mdustnal wastewater. Therefore. macrophytes can be efficient indicators of water quality, andtheir presence may enhance water quality due to their ability to absorb excessive load of nutrients(Pctr. 1987), It has been demonstrated that aquatic weeds such as Eichhornia crassipes . Lemma spp,Salvinia, Typha ssp, Phraginites spp and Azolla sp has been utilized as a means of reducing thenutrient levels of polluted water (Oki. 19Y4).Table 1 shows the removal efficiency of metal ions bysome common aquatic macrophytes.

INTllODUCflONAquatic macrophytes are plants growing on water, on submerged soil or on soil that is saturated withwater (Agbogidi ct al 2000), Aquatic plants affect water adversely by blocking canals and pumps inirrigation project. mrcrfering with hydroelectric production, wasting water through cvapotranspirauon,hmdcnng boat traffic. increasmg water borne diseases. Interfering With li"hing and fish culture: anddoggmg rivers and canals so that drainage 1:-'impossible IS and flood result (NAS 1(76). Aquaucplants playa useful role for special purposes. The extents to which aquatic plants are desirable dependon the water USCI I·:g. a reservoir manager wants clear water that IS free of weeds, algae and otherorgarnsrns. However, conscrx ationists encourage plant cover 011 watersheds and along the banks orstreams. lakes and ponds to control erosion and to protect water quality (Oki. 1994) Plants such aswater hyacinth and Salvmia 111 aquatic environment absorb heavy metals and excess dissol vcdrutrogcn and phosphorus released from fertilizer washed off from farmlands and urban sewagesystem", which can cause environmental pollution in the absence of effective Sinh. This paperreviews the efficacy of aquatic macrophytes In nutrients and heavy metal sequestering,

ABSTRACt' ../The activities of man have directly or indirectly influenced the aquatic ecosystem by increasinglypolluting wetlands. Water quality influences the growth or fish. The utilization of aquatic weeds forthe recovery of nutrients and heavy metals in polluted wetlands is a proffered management strategy.This paper reviews the role of aquatic macrophytes in nutrients and heavy metal sequestering.

AQVA TiC ;\lACi{OPHYTI(S ROLES IN i'\UTlUENT Ai\J) HEAVY METAL REGliLATIOi\'

CKA, (J.N .• MOHAMMED, B.A. & BIRNIN-YAURI, Y.A.National Institute for Freshwater Fisheries Research, New-Bussa

:'\ftITnU~NTANI) ilEA VY METAL REMOVAL .RYPistia srnuiotes, Ipomoea aqutttica; Satviniamolesta and Ceratophylliun demersumPistia stratiotes IS reported to reduce the ammonium ions from the water as It utihzes NH4-N pnor toNOr).l as nitrogen source and does not switch on the utilization of Nl lr-N get consumed entirely (Amand Hayashi. 1996). Ptstin stratiotes has been ured 10 remove metals like Zn, NI, Cd and Zn lromwater column (Sridhar, 10R6).Studies by Miretzky et al lOO() reveal that P.•Stratiotes biomass werelower as compared to Spirodella iutermedia and L minor when grO'\11 U1water conrauung metals Ionsof Cd, NI. Cu. Zn and Pb. Ipomoea aquatica can accumulate higher content of metals such as Fe,CU,Cr,Cd.Mn.Hg and Pb (SInha et al 1996). It also sequesters organic form methyl-IIg which is apotential toxicant (Boening. 2000). Salvinia l1Iolesra il> wdl auaptl'u for the r<:moval Cr fromwastewater (Maine el £II 2004), Aml1a spp acts as biofilter as It binds heavy metals and IShelpful inthe purification of waters polluted by Hg and Cr (Benmcellt et al 2004). Cerarophyllum demcrslIlII IScapabe of removing the different chemical species of phosporus (Dierberg et a1. 2002), Studlcs haveequally shown that submerged plants are useful in r.:ducing heavy melal euncentrations III waler, asbiomass of their shoot can accumulate large amounts of heavy metals (Rai el ai, 1995; Jackson, 1998and Fntioff et a12005. Ceratophyllum demersum act as effective biosorbent for Zn, Pb and eu metals

Nl ITRIFNT ANI) TTF.AVY METAL REMOVAL BY DUCKWEEDDuckweed can be used for nutnent removal. lhe dense cover of duckweed on the ...-atei surfaceinhibits both oxygen entering the water by diffusion and the photosynthetic production of oxygenphytoplankton because of poor light concentration. The water consequently becomes anaerobic whichIn tum faVOUl" dcrutr itication Being relatively thin. the duckweed arc readily harvested and used asammal fodder. Lemma SfJP recovers a high percentage or nitrogen Iiurn wastewater and mayaccumulate protem content as high as 40%: It has been used (0 recover nnrogen and phosphorus fromanaerobic effluent from digested pig waste (Hernandez et al, 1997), Lemma spp bas a mtrogcnconcentrauon 01' 200mgll a fact thaI may portray this aquatic plant the high potential to treatconcentrated effluent such as those that originated Iiom anunal pioduction units. L minor has bl.'C:11

investigated lor the removal of heavy metals from water column (Jam et ul 1{)')O,Wahaah {'I a! 1()95and Maine et £II 200 I). Lminor can sequester 7U-~0% of lead m Its viable biomass (Sternberg ct ul.(999), '111L:uptake of metals like Ni, Cd and Zn by different Lcmna spp, has been reponed byMirctzky I!( al (200().

Water HyacinthWater hyacinth IS a common weed in a eutrophicated water bodies clue 10 itx high producti vity In therange 106 to l44 tons of dry weight per hectare per year (Reddy and Debusk, 1985; Casablanca. ct aJI992).The mean daily producuon of water hyacinth b.ornas in tropical areas mav be more than 2)g_ m! day ·1 of dry mailer Thus more than 0.8 gN and 0.1Sg P m day t can be removed by harvesting.Similar amount of nitrogen may be removed as a consequence of nunficauon. dcnirnficauon andvolanlisauon of a1111110l1la(Bnx et al 19X9). It has been reported by (OIg_IUll. ct al 10%) that under thechmatc of Flonda, Eiclihornia crassipes has shown a very high mtrogen (XO"/il)and phosphorusremoval (-10%). Fhis aquatic plant is suited for nrrrienr removal systems because it is not rooted andnoall> on the surface and so can easily be removed by mechanical means and moreover mineral uptakerate per unit dry matter increase aTCgreater in plants in a rapid grow th phase (Anonymous, 1969.1(70) in \\ hich water hyacinth Il>one. Water hyacinth 1S being used in countries such as Brazil astertiary treatment systems, removing, nitrogen and phosphorus. lhc lnomass i-, har vested 1"1 equently tosustam maximum productivity and to remove incorporated nutnents (Mason, 19(2).

Water hyacinth can also be used as integrated secondary and tertiary treatment. systems,removing ROn and nutrient both decomposition of organic matter ami the nucrobial transformarion ofnitrogen proceeding simultaneously; in this system harvesting is only carried for maintenancepurposes and performance with respect to phosphorus removal is poor (Bnx et a/l,)H<»). Halder et al1981 reported absorption 01' Pb, Cu. Cd Co Zn, Hg. Cr. Ni. Ca, and Mg from pulp and paper 111I1IsbyWater hyacinth The plant has been used in treating palm oil effluents in Malaysia (Abdulahi at al19X3).l-ar licr tCpOI Lor Ruchrl ('I (II (1983) showed the succcssful uuhzauor of Water hyacinth in thetreatment 01 domcsuc sewage, uutucnt rcmov al liol'l \\ all'l \)0<11(...., '("II;lgL' .md industrial waste.Water hyacmih obtumcd :'1'0111 t\II.!,Cn:lIl water bodies contains heavy and toxic metal" uidrcating Itshigh absorbing capacity 1'01 these clements (Ogi.nladc. 1996), I\M~ ( I') /6} reported mat when sewagewas passed through a pond at a rate of 2.2 million lures per hectare per day. \\ uter hyacmth growingin the pond removed 80",,, of the nitrogen compound and 4U'}oof the phosphorus compound In 2 cays.

REFEREI'CESAbdullahi.I3.Y; Ongkon, Sand Yeoh, B.G (l985).Advance treatment of Palm oil effluents using

Water Hyacinth.UNt'P Reports and Proceedings Sesies 7 Water J Iyacinth 676.Agbogidi. 0.\1: Bamidele, 1.K ; Ekokotu, P.A and Olele. N.F (1999). The role and management of

Aquatic macrophytes in Fisheries and aquaculture In: Issues in Animal Sciences. Omeje, S. I (Ed).Endnme Publishers.pp221-235.

Anonymous (1969).Production, Mineral Nutrient Absorption and Biochemical assimilation by JusticraAmericana and Altemanthera philoxeroidcsArch.Hydrobiology 66: 139-160.

Anonymous (1970).MlI1eral nutrient losses from decomposing Typha latifoha. Arch.Hydrobiology67:78 -X5.

Aoi T, and Hayashi,T (1996).~utrient removal by water lettuce (Pistia stratiotes). Water Sci Techno!34(7-8):407- 412.

Bennicelli, Rand Stezpniewska, Z; Banach, A, Szajnocha, K, (2004).The ability of Azolla carohmanato remove heavy metals from municipal waste water. Chemosphere 55: 141 -146.

Boening,D.W. (2000).Ecological effects.transport and fate of mercury: a general review.Chemosphere55:141 -146.

Boyd, C.E (1970). Vascular aquatic plants for mineral nutrient removal from polluted waters.Economic Botany 23:95- 103.

Brix. H and Schicrup, H-H (1Y~9).The use of aquatic macrophytes innwater pollution control. AmbiaVol x-u., ~0.2 pp 100- 107.

Casabianca-Chassany, M; Bonne, C and Basseres, A. (1992).Eichhornia crassipes systems on threeammonium-containing industrial effluents.Production and Purification.Storesccrce Technology42:95 -101.

Fritioff, A; Kautsky, J. and Greger M, (2005). Influence of temperature and salinity on heavy metaluptake by submersed plants.Environ Pollut 133:265 274.

II ern andcz, E; Olguin.E ; Trujillo, Sand Yivanco, J (l997).Recycling and treatment of anaerobiccftluents from pig waste using Lemna sp. Under temperate.In: Global EnvironmentalBiotechnologywise, D.L (ed), Ihe Netherlands: 293-304.

Jackson.LJ (J998).Paradlgms of metal accumulation in rooted aquatic vascular plants.Scr, Tow!Environ 21: 223 -231. J. Environ Qual 14: 459 -462

Keskinkan, O;Goksu.M.Z.L:I3asibuyuk,M;Forster,C.F (2004). Heavy metal adsorption properties orsubmerged aquatic plant (Ccratophyllum demersum). Bioresoui J echnol 92: 197- 200.

Maine M, Duarte M, and Sune N (200 I).Cadmillm uptake by floaung aquatic macrophytes. WaterResource 35: 2629-2634

Mrretzky.P; Saralegur, A; Cirelh.AF (2006).Simultaneous heavy metal removal mechanism by til-admacrophytes.Chemospi1ere 62 (2):247 -254.

National Academy of Sciences (NAS) (l976): Making aquatic weeds useful' Some perspecuveslordeveloping countries. Washington.D.C pp 175.

Ogunlade, I (1996). The Chemistry of wafer hyarinth 11I Nigeria water" ay.Govemment PrintingPress, Ibadan. Pp 42.

Oki,Y and Une, K (19!:!9).Relationship hetween occurrence of aquatic weeds and water quality ill thenatural water body (3). Weed Research Japan 34 (Supplementj.S? 98.

Petre, T (1987).Fish..Flshcries,Aquatic macrophytes and water quality in Inland waters. Water QualityBulletin Yo) 12 No.3 Pp 103-106

Rachel,S.D; Abdullahi.Y and IIaider,S.Z (1983).Uses of water hyacinth 111 wastewater treatmentWEr Reports and Proceedings.Series 7.Water Hyacinth.p229.

under diluted conditions (Keskinkan et aI2004). Ceratophyllum demersum IS used to assess the levelof heavy of heavy metal pollution in aquatic bodies (Srivastava, 2008).

CONCI,USIONNIgerian freshwater ecosystem is constantly polluted by inorganic plant nutrients and heavy metalsfrom urban sources dcri ved from domestic and industrial sewages. Aquatic macrophytes are thecornerstones of an aquatic environment, They have the physiological ability of removing mineralnutrients and heavy metals. There is therefore the need to have 3 detailed study about the use ofAquatic plants for phytorernediation in Nigeria. This IS imperative because phytoremediation IS lessexpensive and environmentally Iricmlly alternative in the control ofthese pollutants.

Rai,U.N; Sinha S,Triphau, R.O; Chandra, P (1995).Waste water treatability potential of some aquaticmacrophytes:Removal of heavy metals.Ecol Eng 5(1):5 -12.

Reddy,K.R and Debusk,W.F (1985)Nutrient removal potential of selected aquatic macrophytes.Rev. Environ.Sc BioteclmoI7:255-266.

Schierup.Il-Il (1978). Biomass and primary production in a Phragmites communis in Swamp in NorthJutland, Denmark.Verh.IntematYerein.LimnoL 20:94- 99

Scidcl,K (1976).Ubcr die Selbstremnigung naturhcher Gewasser. Naturwiss.enschaften 63:286 -291.Sinha. S;Rai,U.N,Chandra.P (1996).Metal contamination in aquatic vegetables Trapa natans L.and

lpomeae aquatic Forsk.In:Proceedi"gs of Conference on Progress in crop sciences from plantbreeding to growth regulations, 17 - 19 Junc. Mosonrnagyarovar.Hungary.

Sridhar,M (1986).Tracc clement composition of Pisna stratiotes in a polluted lake in Nigeria.Hydrobiologiu 111: 273-27(,.

Srivastava, .I., Gupta, A. and Chandra. II. (2008).Managing water quality with aquaticmacrophytes.Rev.Environ Sci.Biotechnol 7:255-266.

Sternberg, S.P.K. Rahmani. G.N.lI (I 999).Biorl.!moval of' lead hom water using Lemna minor.Bioresource Techno! 70: 225 -230.

Wahaab A, Lubbcrding H. Alacrts.G (1995). Copper and Chromium (111) uptake bay duckweed.WaterSci TecJlllo/ :12: lOS-II O.