Phytoremediation Potential of Populus Alba and Morus alba for Cadmium, Chromuim and Nickel Absorption from Polluted Soil

Transcription

1 Int. J. Environ. Res., 5(4):961-97, Autumn 211 ISSN: Phytoremedition Potentil of Populus Al nd Morus l for Cdmium, Chromuim nd Nickel Asorption from Polluted Soil Rfti, M. 1*, Khorsni, N. 2, Mottr, F. 1, Shirvny, A. 3, Morghei, F. 4 nd Hosseinzdeh, S. 5 1 Deprtment of Environmentl Sciences, Fculty of Environment nd Energy, Science nd Reserch Brnch, Islmic Azd University, Tehrn, Irn 2 Deprtment of Environmentl Science, Fculty of Nturl Resources, University of Tehrn, Tehrn, Irn 3 Deprtment of Forestry nd Forest Economic, Fculty of Nturl Resources, University of Tehrn, Tehrn, Irn 4 Islmic Azd University, Shhrerey Brnch, Tehrn, Irn 5 Forestry nd Forest Economic Deprtment, Fculty of Nturl Resources, University of Tehrn, Krj Irn Received 8 Mrch 211; Revised 2 June 211; Accepted 9 June 211 ABSTRACT: Metl pollution hs ecome one of the most serious environmentl prolems resulting from humn ctivity. Phytoremedition utilizes plnts to uptke contminnts nd cn potentilly e used to remedite metl-contminted sites. The present study investigtes hevy metl uptke (Cd, Cr, nd Ni) from soil y different orgns of Populus l nd Morus l. For this purpose, Cd (4, 8, nd 16 mg/kg), Cr (6, 12, nd 24 mg/kg) nd Ni (12, 24, nd 48 mg/kg) were dded to the soil in pot experiments over the course of growing seson in open ir. The totl concentrtion of these metls ws mesured in the roots, stems, green leves, fllen leves, nd the corresponding soil. Our results show tht the highest ccumultion of ll studied metls ws found in the leves. Furthermore, the fllen leves hd higher concentrtions of Cd nd Cr in P. l nd Cr nd Ni in M. l when compred to the green leves. In the two species, Cd nd Ni did not trnsport from the leves to the roots nd stems, or vice vers, in the fll seson, ut Cr ws trnsported from the roots nd stems to the leves in the 24 nd 48 mg/kg tretments.in ddition, the determintion of ioconcentrtion fctor nd trnsloction fctor showed tht P. l nd M. l were suitle for phytoextrction of Cd nd Ni in ll tretments respectively; however, none of the plnts ws suitle for phytostiliztion. Key words: Hevy metl, Bioconcentrtion, Phytostiliztion, Phytoextrction, Phytoremedition INTRODUCTION The term hevy metl refers to ny metllic element with n tomic density greter thn 6 g/cm 3. These metls re uiquitous, highly persistent nd noniodegrdle. (Torresdy et l., 25). The concentrtion of hevy metls increses s result of the nturl wethering of rocks, the disposl of wste, nd the use of fertilizers, pesticides, nd industril effluent tht cn contminte the soil (Adullhi et l., 27 ; Adullhi et l.,29 ). Although trditionl methods for clening contminted soil, such s ionexchnge nd ultr-filtrtion, hve proven to e efficient, they my not e economiclly fesile ecuse of their reltively high cost, prticulrly when used for the *Corresponding uthor E-mil: mriminus_152@yhoo.com removl of hevy metls t low concentrtions (<1 mg/l) (sngi et l., 27; Torresdy et l., 25). Phytoremedition, or the use of green plnts to extrct, sequester, nd detoxify pollutnts, hs shown considerle promise s low-cost technique nd hs received much ttention in recent yers. Additionlly, this method cn e ccomplished in situ, it is environmentlly friendly nd the soil cn e utilized immeditely fter tretment (Pulford et l., 21). Phytoremedition of hevy metls cn e divided into three groups: phytoextrction, which is the use of plnts to remove hevy metls from soil y concentrting the metl in oveground plnt orgns 961

2 Rfti, M. et l. (Sestini et l., 24); phytostiliztion, in which the plnts re used to stilize the soil surfce y retining the metls in the roots [Mrques et l., 28]; nd rhizofiltrtion, which is the use of plnt roots to /dsor metls from wter nd queous wste strems (Erkhrumen nd Agontlor, 27). The uptke nd ccumultion of pollutnts cn vry from plnt to plnt nd mong species within genus. The proper selection of plnt species for phytoremedition plys n importnt role in the development of remedition methods, especilly for low or medium polluted soil (Fischerov et l., 25). Fst-growing tree species could e suitle to tret hevy metl-polluted soil nd to produce economiclly vlule non-food iomss tht is exploitle for energy production. These trees, such s Poplr, hve dditionl dvntges, including high iomss production, rpid growth, esy propgtion nd deep root growth, which mke them possile cndidtes for ppliction in phytoremedition pproches (Cstiglion et l., 26; Sestini et l., 24). In this pper, we consider the mulerry plnt (Morus l) nd poplr (Populous l) ecuse oth hve reltively high environmentl dptility; they re inexpensive nd esily found in Irn. There is lso no risk of livestock poisoning ecuse they re not food source for livestock. The responses of these plnts to hevy metls (especilly for Cd nd Zn) hve een investigted for Populous l (Roinson et l., 2; Mdejon et l., 24; Borghi et l., 27; Dominguez et l., 27; Roinson et l., 27; Dominguez et l., 28) nd less so for Morus l (Prince et l., 2; Wng, 22; Wng et l., 23; Ashfgh et l., 29). The min gol of this study ws to determine the ccumultion of hevy metls, such s Cd, Cr nd Ni in different sections of studied plnt, including the roots, stems, green leves nd fllen leves grown in contminted soil. The detiled ojectives of this screening were s follows: To ssess the trnsport trend of the studied elements from the leves to other orgns in the fll seson. To introduce suitle plnt species for phytoextrction nd phytoremedition sed on the ioconcentrtion fctor (BCF) nd trnsloction fctor (TF) indictors. MATERIALS & METHODS The two species, Morus l nd Populus l, were plnted in pots under nturl conditions. This experiment ws performed using one-yer seedlings etween Ferury nd Decemer 29. No significnt differences were oserved etween trees of the sme ge in terms of their structure (i.e., they hd identicl dimeters long the entire length of nodes nd hd similr root systems), nd t the onset of this experiment, they hd no folige, nd their lengths rnged from 8±5 cm for M. l to 11±5 cm for P. l. The seedlings were ctched from the Alorz frm nursery in Krj, Irn, nd the pots were filled with 1 kg soil derived from the sme plce. This soil ws mixed well with snd nd niml fertilizer mnure in 3:1:1 (v/ v/v) rtio efore eing plced in the pots. Five smples of this soil were tken efore plnting nd nlyzed for physico-chemicl chrcteristics. The pots were plced outdoors with tp wter irrigtion (three times in week) nd were prtilly covered to protect them from rinfll. Two months fter plnting nd fter the leves hd udded, 4, 8, nd 16 mg/kg of Cd; 6, 12, nd 24 mg/kg of Cr; nd 12, 24, nd 48 mg/kg of Ni in the forms of CdN 2 O 6.4H 2 O, CrN 3 O 9.9H 2 O nd NiN 2 O 6.6H 2 O, respectively, were dded to the pots over three week period (1/3 of the totl solution ech week insted of one irrigtion turn).this tretments mounts cme from literture review such s Prince et l., 2; Sestini et l., 24; Zcchini et l., 28 nd norml rnge of this metls in Kt Pendis, Ech pot ws treted with one metl to prevent interction effects. One control (with no tretment) ws lso performed. The first smpling of leves ws conducted in August. At this time, the green leves were collected rndomly from different prts of the tree crown nd were ulked into homogenous smple. During the flling time of the leves in Novemer, the second smpling ws performed. The yellow leves from ech tree stnd tht were redy to fll were collected in the mnner stted ove. All lef smples were plced in polythene gs, leled nd tken to the lortory for the next nlysis. For ech tree, one soil smple ws tken t -25 cm (root zoon) t the time when ll leves hd fllen. At the end of Septemer, the entire structures of ll of the plnts were dug out, nd the Cd, Cr, nd Ni contents of the different prts were determined. Soil smples from ech pot were homogenized nd ir dried in n oven t 3 C overnight to constnt weight nd were then pssed through 2 mm sieve [U et l., 29] efore nlysis. Approximtely.25 g of soil smple ws digested with 6 ml of H 2 So 4 :15 ml H 2 O 2 in closed Digesdhl system (Hch Co., USA) t 44 C to otin totl extrction of hevy metls. The smples were then filtered nd diluted with deionized wter to 5 ml (Brinin et l.,24). The totl 962

3 Int. J. Environ. Res., 5(4):961-97, Autumn 211 concentrtions of Cd, Cr, nd Ni were determined y ICP-OEC (Inductively Coupled Plsm Emission Spectroscopy, GBC, Austrli). After the plnts were hrvested, they were wshed with tp wter to remove ny residul soil or dust nd seprted into roots nd stems. All of the plnt prts (green leves, stems, roots nd fllen leves) were rinsed with distilled wter to remove surfce contmintion, oven dried t 7 C for 48 h (to constnt weight, nd the dry weight ws recorded efore grinding), nd grinded nd sieved to <1 mm. The resulting smple (.5 g) ws digested using mixture of 4 ml H 2 SO 4 :13 ml H 2 O 2 in closed Digesdhl system t 44 C (Hch Co., USA). Smples were filtered nd diluted with deionized wter to 5 ml. These finl solutions were nlyzed for Cd, Cr nd Ni using ICP- OEC (Brinin et l., 24; Unterrunner et l., 26). The ioconcentrtion fctor (BCF) nd trnsloction fctor (TF) indicte the ility of plnts to tolerte nd ccumulte hevy metls. These fctors were clculted using the rtio of metl concentrtion in the plnt roots to the soil (root BCF), the rtio of totl metl concentrtion in plnt shoots (stem + leves) to the soil (shoot BCF) nd the rtio of metl concentrtion in plnt shoots to the roots (TF) (Srwet nd Ri, 27; Zcchiini et l.,28). All chemicls used were of nlyticl grde (Anl R), nd chemicl nlyses were vlidted y lnks (one lnk for every 2 smples), duplicte smples nd reference mterils. All dt presented re the men vlues, nd mesurements were tken with three independent replictes for metl concentrtion. The sttisticl nlysis ws performed with SPSS (v.17.) softwre. One-wy ANOVA ws used to compre the trce element concentrtion in the plnt structures nd in the soils etween treted nd untreted soils. Additionlly, the Gmes-Hwel test ws used for men comprison t significnce level of pd.5. RESULTS & DISCUSSION The min chrcteristics of the primry soil nd hevy metls (efore treting) re shown in Tle 1. The soil in the pots hd lomy texture, with n verge EC nd CEC of pproximtely 12 ms/m nd 16.5 meq/ 1 g, respectively, nd they were slightly lkline (ph=7.5), which mens the ph conditions were suitle for plnt growth. After the tretment with the hevy metls nd the removl of the plnts, the totl concentrtions of Cd, Cr, nd Ni were mesured. The results in Tle 2 show tht the totl concentrtions for the three hevy metls were significntly different etween the treted nd control soils t some of the tested levels in the two species. In treted P. l, the Cd concentrtion in treted soils ws significntly different t the 8 nd 16 levels compred to the control. In treted M. l, the Cd concentrtions in treted soils were significntly different t the 4 nd 16 levels compred to the control for Cd, nd t the 24 nd 48 levels compred with the control for Ni. Furthermore, there were no significnt differences etween Ni nd Cr concentrtions in the treted soil of P. l nd no difference in the Cr concentrtion in the treted soil of M. l compred to the control. Tle. 1 Primry soil chrcteristics Chrcteristics vlue ph 7.5 EC (ms/m) 1.2 CEC (meq/1gr) 16.5 Texture Lom O.C% 1.2 Totl N%.15 P (ppm) 9.8 K (ppm) 34 Vlues re men (n= 5) Becuse the smpling times were different for different orgns (green leves in August nd fllen leves, roots nd stems in Decemer), comprison etween hevy metl uptke ws conducted in orgns tht hd simultneous smpling times (roots, stems nd yellow or fllen leves). Therefore, the uptke mounts in green leves were only mentioned to nlyze plnt interctions with the hevy metls in the fll seson. In plnts, hevy metls cn ply different roles tht cn e roughly divided into the following: () essentil (i.e., Zn, Cu, nd Ni), which re required for vriety of metolic processes; nd () non-essentil (i.e., Cr nd Cd). However, Cr (III) is n essentil element t low levels, s seen in few references such s Shmone et l., 28. Independent from their iologicl function, oth essentil nd non-essentil hevy metls cn e toxic ove certin threshold (Sestini et l., 24; McGee et l., 26). 963

4 Phytoremedition Potentil of Populus Al nd Morus l Tle2. Totl hevy metls concentrtions in soil Element Tretments (mg/kg) Populus l Morus l (control) 3.6 ±.34 c 3.7 ±.2 c Cd ±.96 c 7.24 ± ± ± 1.71 c ± ± 1.66 (control) 4.87 ± ± 4.66 Cr ± ± ± ± ± ± 5.68 (control) ± ± 5.36 c Ni ± ± 8.75 c ± ± ± ± 3.52 Vlues re men ± stndrd devition (n=3), Units re mg/kg. Mens in columns fllowed y different letters (c) re significntly different t P=.5 level (Gmes-Hwel test) Bsed on this informtion, there re three different prdigms relted to the flling time in plnts: () the movement of metls from the leves into the stems nd roots (essentil elements, such s K) to prevent their loss in the fll, () the movement of metls from the stems nd roots into the leves (i.e., C), nd (c) the loss of the sme mount of metls in the fll tht were tken up y green leves (Hssnzdeh, 28). The highest metl concentrtions mong treted P. l smples were seen in fllen leves for Cd (13.97 mg/kg t level 8), Cr (15.39 mg/kg t level 24) nd in green leves for Ni (85.54 mg/kg t level 12) (fig 1).These findings coincide with the results of other studies tht descried higher concentrtion of Cd in poplr leves thn in other orgns (Fischerov et l., 25; Dominguez et l., 27; Mrtens et l., 27); ut in contrst with Pulford et l., 21 who found tht the roots contined the highest level of Cr in P. euromericn nd P. trichocrp. Moreover, Golovtyi et l., 1999 hve shown tht Cr distriution in crops is stle nd does not depend on soil properties nd concentrtions of this element; the mximum quntity of Cr ws lwys contined in the roots, nd the lowest concentrtions were found in the vegettive nd reproductive orgns. This finding ws in contrst with our results too. The fllen leves in treted P. l contined, on verge, 2.5 nd 3.2 times the mount of Cd, 5.5 nd 28.9 times more Cr nd 4.5 nd 4.8 times more Ni thn the roots nd stems, respectively. There is evidence in the literture tht poplr leves typiclly hve higher metl concentrtions thn the stems or roots, prticulrly for Cd nd Zn (Roinson et l., 2; McGee et l., 26). Fig. 1 illustrtes the rtes of ccumultion of Cd, Cr, nd Ni in vrious orgns of P. l. Bsed on these results (Fig. 1), in the control P. l nd in those treted with 4, 8 nd 16 mg/kg, there ws no significnt difference etween the Cd uptke rtes in green nd fllen leves. The reson for this is tht the green leves retined their ccumulted Cd until the fll seson. Therefore, the ccumulted Cd ws not trnsported to the stem nd root. The difference etween these three doses ws tht there ws significnt difference etween the ccumulted Cd in yellow leves when compred to the roots in the 16 mg/kg tretment, while in the 4 nd 8 mg/kg tretments, the mount of ccumulted Cd in the yellow leves showed no significnt difference in comprison to the stems nd roots. In P. l, there ws no significnt difference in the mount of Cr ccumultion etween the fllen 964

5 Int. J. Environ. Res., 5(4):961-97, Autumn 211 leves nd the green leves in the control plnt (Fig. 1).However, there ws difference when compring the stem nd root concentrtions, in which the mount of Cr in the yellow leves ws higher thn tht found in the stems nd roots. In the 6 mg/kg tretment of Cr, there ws significnt difference etween the roots nd stems, with higher mounts in the roots. However, the trend of Cr uptke in the 12 nd 24 mg/kg tretments differed from the control nd 6 mg/kg doses, nd the trend ws the sme when compred with ech other. In oth tretments, the lrgest content of Cr ws found in the fllen leves, which ws significntly different when compred to the green leves. This reveled tht in ddition to the ccumulted Cr in green leves, Cr ws lso trnsported to the yellow leves through the roots nd stems. Another possiility is tht the difference in time ffected the high uptke of Cr in yellow leves in comprison to the green leves ecuse, in this study, the smpling time of the yellow leves ws three months lter thn tht of the green leves. However, ecuse the mximum metolic interctions of the plnt occurred in August nd lef ctivity declined y forming cllus during this time, this explntion is less prole. In oth of these tretments, Cr trnsporttion from the roots nd stems to the fllen leves did not result in significnt difference in the mounts of this element seen in the root nd stem. In treted M. l, the highest vlues for Cr (6.25 mg/kg in level 6) nd Ni (11.18 mg/kg in level 12) were found in the fllen leves, while Cd ws highest in the green leves (4.6 mg/kg in level 4) (fig. 2). These results re in contrst with Wng, 22 nd Prince, 2 who showed tht Cd in M. l ccumultes more in roots, with limited trnsport to the leves. Only Zn ws found to ccumulte in the leves of M. l in previous studies (Ashfgh et l., 29). Also, fllen leves vlues in treted M. l reched to 1.9 nd 2 times Cd, 6.8 nd 3.3 times Cr nd 11.1 nd 9 times Ni more thn the roots nd stems, respectively. Fig. 2 illustrtes the concentrted mount of Cd, Cr nd Ni in different orgns of M. l. As cn e seen in Fig. 2, in the control M. l, the Cd content in the yellow leves ws significntly higher thn the green leves, roots nd stems. With time, more uptke of Cd occurred in the yellow leves in comprison to the green leves (s discussed for the dt shown in Fig. 1). Alterntively, during the flling period of the leves, portion of this element entered the fllen leves through the roots nd stems of the plnt. Yet, time hd greter effect on the higher uptke in the yellow leves in M. l thn in P. l ecuse the flling time of P. l is sooner thn tht of M. l. Additionlly, Cd trnsporttion from the roots nd stems to the fllen leves did not induce significnt difference in the mounts of this element in the root nd stem. The trend of Cd concentrtion in the flling leves ws the sme in the 4, 8, nd 16 mg/kg tretments. The sme mount of Cd in the green leves ws removed from the plnt in the fll, with no trnsport from the root nd stem to the yellow leves. However, in the 4 nd 8 mg/kg doses, the concentrted mount of Cd in the yellow leves displyed significnt differences when compred to the content of Cd in the stems nd roots; t the 16 mg/kg dose, the Cd content in the yellow leves ws only significntly different from tht found in the roots. The comprison of Cr uptke in vrious orgns of M. l (Fig. 2) reveled tht there ws no significnt difference etween the control level nd the 6 mg/kg dose mong the different orgns. In ddition, in the 12 nd 24 mg/kg tretments, the fllen leves retined high levels of Cr tht ws significntly different when compred to the green leves ecuse of either the trnsport of this element from the roots nd stems to the yellow leves or the long uptke time in yellow leves (s discussed for the dt shown in Fig. 1). In oth of these tretments, Cr trnsporttion from the root nd stem to the yellow leves showed no significnt difference to the levels of Cr in the roots nd stems. The mount of Ni uptke in the fllen leves of the control M. l (Fig. 2c) followed the sme trend of Cd uptke in the control soil for this plnt. Also, there ws no significnt difference etween the concentrted Ni in green nd yellow leves in the 12, 24 nd 48 mg/ kg tretments. The only difference mong these doses ws higher concentrtion of Ni in the stem in comprison to the root in the 12 mg/kg tretment, nd higher ccumultion of Ni in yellow leves in comprison to the stem nd root in the 48 mg/kg tretment. The interction of M. l nd P. l species in the control soil nd the tolernce trends to hevy metls were importnt ecuse these plnts were not exposed to the contmintion stress nd were insted locted in ordinry conditions. The chnges seen when compring tretments my e ttriuted to vriety of items nd needs to e further investigted. But, under conditions in which these species were exposed to contminnts, they displyed the sme rection to hevy metls, such s Cd, Cr nd Ni. In oth species, these three elements re not considered s essentil elements for the plnts tht would e trnsported from the leves to the root nd stem in the fll seson. Consequently, M. l nd P. l hve the tendency to remove these metls in the fll seson. Both species 965

6 Rfti, M. et l. concentrtion(mg/kg) c c () stem Green lef Fllen lef tretments (mg/kg) concentrtion(mg/kg) c c c tretments (mg/kg) () Stem Green lef Fllen lef concentrtion(mg/kg) c tretments (mg/kg) 966 c c Stem Green lef Fllen lef Fig. 1. A comprison mong Cd (), Cr (), Ni (c) concentrtions in different orgns of Populus l.dt indicte mens ± SD(n=3).Different letters in the sme tretment indicte significnt differences (p<.5) (c)

7 Int. J. Environ. Res., 5(4):961-97, Autumn c () concentrtion(mg/kg) c c c c c c Stem Green lef Fllen lef tretments (mg/kg) concentrtion(mg/kg) concentrtion(mg/kg) tretments (mg/kg) Stem Green lef Fllen lef Stem Green lef Fllen lef tretments (mg/kg) Fig. 2. A comprison mong Cd (), Cr (), Ni (c) in different orgns of Morus l. Dt indicte mens ± SD (n=3). Different letters in the sme tretment indicte significnt differences (p<.5) () (c) 967

8 Phytoremedition Potentil of Populus Al nd Morus l remove the sme mounts of Cd nd Ni in green leves in the fll seson (there ws no significnt difference etween yellow nd green leves in tking up these elements), which could e due to two things: the levels of tretments were not high enough to force the plnts to rect nd trnsport the extr Ni nd Cd from the root nd stem to the leves in the fll seson, or these two plnt species re highly resistnt to Ni nd Cd ecuse they retin certin mount of these hevy metls in their stems nd roots. However, in these species, in ddition to the Cr uptke in the green leves for the 24 nd 48 tretments, Cr ws trnsported to the leves from the roots nd stems. This could tke plce ecuse of the high rnge of toxicity to Cr in these species t higher concentrtions. Therefore, they hve tendency to reduce the mximum mount of Cr in the fll seson, which is ccomplished y Cr trnsporttion from the roots nd stems to the leves of the plnts. The results presented in Tle 3 show the BCFs nd TFs for different hevy metls. These fctors re key vlues tht re needed to estimte plnt s potentil for phytoextrction nd phytostiliztion. Plnts exhiiting shoot BCF >1 re suitle for phytoextrction, nd plnts with root BCF >1 nd TF<1 hve the potentil for phytostiliztion (Srwet nd Ri, 27; Zcchiini et l.,28). The results show tht the two plnt species t the different levels (tretments nd control) hd TFs>1 nd root BCFs<1 for Cd, Cr nd Ni; therefore, they were not suitle for phytostiliztion of these metls. The TF results re similr to the findings of Zcchini et l., 28 who reported high TF vlues (pproximtely 1) for Cd in P. l. However, P. l hd shoot BCF>1 for Cd t the 4, 8, nd 16 levels (3.9, 4.7 nd 2.2, respectively) nd shoot BCF>1 for Ni t the 24 nd 48 levels (2.5 nd 3.2, respectively) nd were thus suitle for phytoextrction of Cd nd Ni in these tretments. These results for Cd re in greement with the findings of Dominguez et l., 27 (BCF of the leves ws pproximtely 2 in P. l) nd Zcchini et l., 28 (eril BCFs were 2.5 nd 4 for P. l L. clone 6K3 nd P. l L. clone 14P11, respectively). Additionlly, Migeon et l., 29 identified three poplr hyrids tht were considered Cd ccumultors; these were P. deltoides P. nigr, P. tremul P. tremuloides, P. trichocrp P. deltoids, with leves BCF of pproximtely 1.39, 2.26 nd 1.98, respectively. P. l ws cple of phytoextrcting in ll the tretment conditions of Cd nd in the high concentrtion of Ni dded to the soil. Whether this species is le to phytoextrct t higher nd lower levels of Cd in the soil nd concentrtions higher thn 48 mg/kg Ni is still unnswered. Additionlly, the pproprite plnt concentrtion threshold for Ni etween the 12 nd 24 mg/kg tretments needs to e determined in future investigtions. In M. l, the shoot BCF for Ni t ll levels (vlues were 2.3, 1.2, 3.3, nd 1 for, 12, 24, nd 48 mg/kg, respectively) nd the shoot BCF for Cd in the control (3.3) hd vlues greter thn 1, which indictes tht Tle 3. Bioconcentrtion (BCF) nd trnsloction fctors (TF) for Cd, Cr nd Ni in Populus l nd Morus l Populu l Morus l Element Tretments (mg/kg) BCF Shoot BCF TF BCF Shoot BCF TF (control) Cd Cr Ni (control) (control)

9 Int. J. Environ. Res., 5(4):961-97, Autumn 211 this plnt hs the potentil for phytoextrction of Ni nd Cd t these levels. M. l is cple of phytoextrcting Ni t ll levels of Ni in the soil ut cn only extrct slight portion of Cd from the soil. Whether or not this species hs the cpility to phytoextrct in doses higher thn 48 mg/kg still needs to e investigted. Additionlly, finding the pproprite plnt concentrtion threshold for Cd etween the mount of the control soil (3.7 mg/ kg) nd in the 4 mg/kg tretment requires further study. For Cr, none of the plnts hd shoot BCF >1, indicting there is no potentil in P. l nd M. l for phytoextrction of Cr. CONCLUSION The im of this study ws to evlute the potentil of P. l nd M. l to uptke Cd, Cr, nd Ni from the soil. Plnts differ in their uptke of hevy metls nd the susequent distriution of metls within plnt orgns. Compring the plnt orgns in this study showed tht leves ccumulte higher concentrtions of Cd, Cr, nd Ni thn other orgns. Furthermore, Cd nd Cr in P. l nd Cr nd Ni in M. l hd higher vlues in fllen leves thn green leves. This ccumultion in leves resulted in the redistriution of metls from deeper soil lyers to the topsoil, therey incresing these elements concentrtion in the soil surfce vi lef decomposition, which my represent risk to the food chin. This knowledge is importnt for the selection of the most pproprite technology for processing metl-enriched plnt mteril fter hrvest nd cn help in phytoremedition mngement. Phytoextrction is phytoremedition strtegy in which plnts re used to uptke nd ccumulte hevy metls in ove-ground iomss, which cn e hrvested nd removed from the soil. This study shows tht P. l cn ccumulte Cd nd Ni (in high vlues in soil), ut M. l cn only ccumulte Ni in their shoots; therefore, oth species cn e considered s n ccumultor. The highest Cd nd Ni vlues in P. l leves (13.97 nd mg/kg) were within the phototoxic rnge of these two metls for the leves of plnts (5-3 nd 1-1 mg/kg, respectively,) ut the highest mount of Ni in M. l leves (11.18 mg/kg) exceeded the phototoxic rnge of this element for the leves of plnts (Awofolu, 25). This is n dditionl reson why the ccumultion of these metls in the shoots of P. l nd M. l did not result in ny toxicity symptoms. Also high iomss production, rpid growth, esy propgtion nd estlishment nd developed root system mke these two plnts suitle for the phytoextrction of Cd nd Ni from contminted soils. REFERENCES Adullhi, M. S., Uziru, A., Hrrison, G. F. S., Blre, M. L. nd Okunol,O. J. (27). Comprtive study of tomtoes nd onions from irrigted frmlnds on the nk of river Chllw, kno, Nigeri. Int. J. Environ. Res., 2 (1), Adullhi, M. S., Uziru, A. nd Okunol, O. J. (29). Quntittive determintion of hevy metl concentrtion in onion leves. Int. J. Environ. Res., 3 (2), Ashfgh, M., Afzl, W. nd Hnif, M. A. (29). Effect of Zn (II) doposition in soil on mulerry- silk worm food chin. Africn Journl of Biotechnology, 9 (11), Awofolu, O. R. (25). A survey of trce metls in vegettion, soil nd lower niml long some selected rods in Metropolitn city lgos. Environ. Monitor. Assess., 15, Borghi, M., Tognetti, R., Monteforti, G. nd Sestini, L. (27). Response of two poplr species (Populus l nd Populus x cndensis) to high copper concentrtion. J. Environmentl nd Experimentl Botny, 62, Brinin, Kh. Z., Stozhko, N. Yu., Belyshev, G. M., Inzhevtov, O. V., Kolydin,L. I. nd Cremisini, C. (24). Determintion of hevy metls in wines y nodic stripping voltmmetry with thick-film modified electrode. Anlytic. Chemicl. Act, 514, Cstiglione, S., Frnchin, C., Fossti, T., Lingu, G., Torrigini, P. nd Biondi, S. (26). High zinc concentrtions reduce rooting cpcity nd lter metllothionein gene expression in white poplr ( Populus l L. cv. Villfrnc). Chemosphere, 67, Dominguez, M. T., Mrnon, T., Murilli, J. M. nd Schulin, R. (27). Trce elements ccumultion in woody plnts of the Gudimr vlley,sw Spin: lrge scle phytomngement cse study. Environmentl Pollution, 152, Dominguez, M. T., Mdejon, P., Mrnon, T. nd Murillo, J. M. (28). Afforesttion of trce element pollution re in SW Spin: woody plnts performnce nd trce element ccumultion. Eur. J. Forest. Res., 129, Erkhrumen, A. nd Agontlor, A. (27). Phytoremedition: n environmentlly sound technology for pollution prevention, control nd remedition in developing countries. Eductionl Reserch nd Review, 2 (7), Fischerov, Z., Tlustos, P., Szkov, J. nd Sichorov, K. (25). A comprison of phytoremedition cpcity of selected plnt species for given trce elements. Environmentl Pollution, 144, Golovtyj, S. E., Bogtyrev, E. N. nd Golovtyi, S. E. (1999). Effect of levels of chromium content in soil nd its distriution in orgns of corn plnts. Soil. Res. Fert., 25, Hssnzdeh, E. (28). Plnt physiology, Tehrn university press. Tehrn, Irn. 969

10 Rfti, M. et l. Kt- Pendis, A. (1985). Trce elements in soils nd plnts. CRC press, Florid. Mdejon, P., Mrnon, T., Murillo, J. M. nd Roinson, B. (24). White poplr (Populus l) s iomonitor of trce elements in contminted riprin forests. Environmentl Pollution., 132, Mrques, A., Moreir, H., Rngel, A. nd Cstro, P. (28). Arsenic, led nd nickel ccumultion in Ruus ulmifolis growing in contminted soil in Portugl. J. hzrd mter, 165, Mrtens, J., Nevel, L. V., Schrijver, A. D., Piesschert, F., Oostern, A. nd Tck, F. M. (27). Tree species effect on the redistriution of soil metls. Environmentl Pollution, 149, McGee, C. J., Fernndez, I. J., Norton, S. A. nd Stus, C. (26). Cd, Ni, P, nd Zn concentrtion in forest vegettion nd soils in Mine. Wter. Air. Soil. Pollut., 18, Migeon, A., Richrd, P., Guinet, F., Chlot, M. nd Bludez, D. (29). Metl ccumultion y woody species on contminted sites in the north of Frnce. Wter. Air. Soil. Pollut., 24, Prince, W., Sentilkumr, P. nd Suurm, V. (2). Mulerry- silk worm food chin- A templte to ssess hevy metl moility in terrestril ecosystems. Environ. Monitor. Assess., 69, Pulford, I. D., Wtson, C. nd Mcgregor, S. D. (21). Uptke of chromium y trees: prospects for phytoremedition. Environmentl Geochemistry nd Helth, 23, Roinson, B., Mills, T., Fung, L., Green, S. R. nd Clothier, B. E. (2). Nturl nd induced cdmium- ccumultion in poplr nd willow: Implictions for phytoremedition. Plnt nd soil, 227, Roinson, B. H., Green, R., Chncerel, B., Mills, T. M. nd Clothier, B. E. (27). Poplr for phytomngement of oron contminted sites. Environmentl Pollution, 15, Shmoune, M. N., Louh, K. nd Boukhir, A. (28). Biosorption of Cr(III) from queous solutions using cterium iomss Streptomyces rimosus. Int. J. Environ. Res., 3 (2), Sngi, M. R., Shhmordi, A., Zolghrnein, J., Azimi,G. H. nd Ghorndoost, M. (27). Removl nd recovery of hevy metls from queous solution using Ulmus crpinifoli nd Frxinus excelsior tree leves. J. hzrd mter, 155, Srswet, S. nd Ri, J. P. N. (29). Phytoextrction potentil of six plnt species grown in multimetl contminted soil. Chemistry nd Ecology, 25 (1), Sestini, L., Sce, F. nd Tognetti, R. (24). Hevy metl ccumultion nd growth responses in poplr clones Eridno (Populus deltoids mximowiczii) nd I-214(P. eurmericn) exposed to industril wste. Environmentl nd Experimentl Botny, 52, Torresdy, J. L., Vide, J. R. P., Ros, G. D. nd Prsons, J. (25). Phytoremeditoin of hevy metls nd study of the metl coordintion y X- ry sorption spectroscopy. Coordintion chemistry Reviews, 249, U, S., Uziru, A. nd Okunol, O. J. (29). Content of hevy metls in Lumricus Terrestris nd ssocited soils in dump sites. Int. J. Environ. Res., 3 (3), Unterrunner, R., Puschenreiter, M., Wieshmmer, G. nd Wenzel, W. W. (26). Hevy metl ccumultion in trees growing on contminted sites in centrl Europe. Environmentl Pollution, 148, Wng, K. R. (22). Tolernce of cultivted plnts to cdmium nd their utiliztion in polluted frmlnd soils. Act. iotechnol., 22, Wng, K. R., Gong, H., Wng, Y. nd Vnderzee, S. E. (23). Toxic effect of cdmium on Morus l L. nd Bomyx moril L. Plnt nd Soil, 261, Zcchini, M., Pietrini, F., Mugnozz, G. nd lori, V. (28). Metl tolernce, ccumultion nd trnsloction in poplr nd willow clones treted with cdmium in hydroponics. Wter. Air. Soil. Pollut., 197,