Phytoremediation of Cadmium and Lead contaminated soil types by Vetiver grass

The statistical analysis indicated that vetiver’s uptake ability o f Cd and Pb increase as the level o f Pb, Cd in various soil types increase.[r]

VNU Journal of Science, Earth Sciences 25 (2009) 98-103

Phytorem ediation o f C adm ium and L e a d contam inated soil

ty p es by V etiver grass

V o V an M inh1’*, Le Van K h o a2

1 D anang University o f Education

2 College o f Science, VNU

Received 11 Juỉy 2009; received in revised form 22 July 2009

A bstract Phytoremediation is an altemative technology to remove heavy metals in contaminated

soil Vetiver g rass ( Vetìveria zizanioides (Linn.) Nash) was used for Cadmium (Cd) and Lead (Pb)

removal experiments in 4 various soil types: (S l) sandy soil vvith abundant o rg a n ic matter; (S2)

sandy soil vvith poor organic matter; (S3) clay soil vvith abundant organic matter; (S4) clay soil

vvith poor organic matter Plants were grown for 30 days beíòre transferring to experimentaỉ pots

P b(N 03)2 solution was added to the soil types in each experimental pot at 0, 100, 300 and 700ppm;

similarly CdCl2: 0, 10, 30 and 60ppm Pỉants vvere observed for their growth and harvested after 3

months Cd and Pb accumulation in roots and shoots was analyzed The results shovved that

Vetiver grass grew in 4 various soil types The statistical analysis indicated that vetiver’s uptake

ability o f Cd and Pb increase as the level o f Pb, Cd in various soil types increase Cd accumulation

rates between shoots and roots o f vetiver grass were fairly ỉovv (< 13.32%); on the contrary, the

accumulation rates o f Pb shoot/ root is very high (9.72%-88.14%) Thereíòre, vetiver grass can use

to phytoextration o f Pb and phytostabiỉization o f Cd

Keywords: Phytoremediation; Vetiver; Cadmium; Lead; Contaminated soil

1 I n tr o d u c tio n

H eavy m etal co n tam in a tio n is cau sed by

v arious so u rces, such as indu strial pro cesses,

m anu facturing , dispo sal o f in d u strial and

d o m estic refuse, and a g ric u ltu ra l practices

P hy to rem ediatio n is co n sid ere d a n innovative,

econom ical, and en v iro n m en ta lly co m p atib le

solution fo r rem ed iatin g som e o f h eavy m etal

co n tam in ated sites [3,4] T h e m ain factors

co n tro llin g th e ab ility o f p h y to rem ed iatio n are

plant sp ecies, m etal a v a ilab ility to p la n t roots,

‘ Tel.: 84-905234706

E-mail: vominhdn@gmail.com

m etal u p ta k e b y ro o ts, m etal tran slo catio n from

ro ots to sh o o ts an d p la n t to leran ce to to xic

m etals T h e re are m a n y ty p es o f plants cu rrently

used in p h y to re m e d ia tio n , su ch as T hlaspi careru ỉescen s, A ỉy s s u m m urơle, A ỉesbiacum ,

a n d A íe n iu m Hovvever, th e rem ediation

potential m a y b e lim ited d u e to th e slovv grow th and low b io m a s s o f th e se plants

R ece n tly p h y to rem ed ia tio n researchers have

d isco v ered th a t v etiv er g rass ( V etiveria ziza n io id e s (L in n ) Nash,) can accum ulate high

levels o f m e ta ls T h e m etal accu m u latin g ability

o f th is p la n t, c o u p le d vvith m etal to leran ce and hig h sho ot b io m a s s, m akes th is plant ideal for

v v M inh, L v Khoa / V N U Ịoum aỉ o f Science, Earth Sciences 25 (2009) 98-103 99

p h y to ex tractio n (R andloíT e t al., 1995; K noll,

1997; T ru o n g and B aker, 1998; C h en , 20 0 0 ) [2,

5-7] V etiv er grass has b een w id e ly k n o w n for

it e ffectiv en e ss in ero sio n a n d se d im e n t control

(T ru o n g et al., 1995) In A u stra lia , v e tiv e r grass

vvas used to stab ilize la n d íìll an d industrial

w aste sites co n tam in ated w ith h eav y m etals

s u c h a s A s, C d , C r, N i, C u , P b a n d H g (T ru o n g

and B aker, 1998) In C h in a , v e tiv e r g rass was

plan ted in a large scale for p o llu tio n c o n tro l and

m in c tail stab ilizatio n (C h en , 2 0 0 0 ) [2]

In V ictnam , v etiv er g ra s s h a s been

s u c c e s s f u l ly f o r erosion c o n t r o l a n d s lo p e

stabilizatio n H ow ever, to th e b est o f our

k n o w led ge, th e stud y o n p h y to e x tractio n o f

h eavy m etal b y v e tiv e r g ra ss is still lacking

H ence, th e ob jectiv es o f th is re s e a rc h w ere to

in vestigate p h y to rem ed iatio n o f C d an d Pb in

v ario u s soil types

2 M a te r ia ls a n d m e th o d s

2.1 Soil and Pỉant Preparaíion

Soil sam p les w ere c o lle c te d fro m to p soils

It vvas air-d ried an d th o ro u g h ly m ix e d before

use P h y sical an d ch em ica l p ro p e rtie s (/.e , soil

texture, so il pH , o rg an ic m a tte r, to ta l nitrogen,

to tal p h o sp h o ru s an d p o ta ssiu m ) w e re analy zed

(T able 1) Initial C d an d P b c o n te n t in th e soil

vvere an aly zed p rio r to th e e x p e rim e n t F o u r soil

types w ere used in th e e x p e rim e n t: ( S l ) the

sandy soil w ith ab u n d an t o rg a n ic m a tte r; (S2)

the sandy soil w ith p o o r o rg a n ic m a tter; (S3)

th e d a y so il vvith p o o r o rg a n ic m a tte r; an d (S 4)

th e clay so il vvith ab u n d a n t o rg a n ic m atter

(a) s 1: G ard en soil a d d in g m u c k w as

sam pled in th e N o 10 H o a M in h w ard , Lien

C hieu d istrict, D an ag city

(b) S2: G ard en soil w ith o u t m u c k w as

sam pled in th e N o 10 H o a M in h vvard, Lien

C hieu d istrict, D an ag city

(c) S3: H ill soil w a s sam pled in th e N o rth o f

H oa K h anh vvard, L ien C hieu district, D anag city

(d ) S4: R ic e íĩe ld soil w as sam p led in Dien

H oa co m m u n e, D ien Ban d istrict, Q u a n g N am province

T h e e x p e rim e n t w as co nd ucted in greenhouse a t B io -exp erim ental H ouse, the faculty o f B io lo g y & E nv iro nm en tal Science,

T h e U n iv ersity o f E du cation - D anang

U niversity T h e exp erim en tal p o t vvas plastic

w ith 25 cm u p p er diam eter, 20 cm low er

d iam eter an d 35 cm heig ht T he ex perim ental

p o ts vvere s e t up by ad d in g 10 kg o f soil sam ple into each p o t F u rth er cu llin g vvas d o n e to obtain 5 p la n ts in eac h pot T he v etiv er grass

w ere p lan ted in 4 diíTerent P b co n cen tratio n s (0,

100, 3 0 0 an d 700 ppm ) an d 4 diíTerent Cd

c o n c e n tra tio n s (0 , 10, 3 0 a n d 6 0 p p m ) A fte r 1

m onth o f grovvth, lead nitrate (P b (N Ơ3)2) and

C adm ium c h lo rin a te (C d C h ) so lu tio n s w ere added and 3 rep licates vvere done fo r each

co m p o sitio n T h e ex pcrim ental p o ts w ere arran ged in a w ay th a t a C om pletely

R an d o m ized B lo ck D esign could be conducted Physical ch an g e s o f p lants in each p o t w ere

ob serv ed daily

Table 1 The physical and chemical properties o f soil

studied Parameters Unit Soil types

Nitrogen

phosphorus

2.2 Pb, Cd analyiation in plants and soils

P lan ts w e re h arv ested a fte r 3 m o th s o f

p la n tatio n E ach p la n t vvas rinsed, cut, and

100 v.v M inh, L.v Khoa / V N U ìoum al o f Science, Earth Sciences 25 (2009) 98-103

g ro u p selected into sh o o ts an d roots Each part

o

w as d rie d in an oven at 65 c fo r 72 hours Both

vvet an d dry w eig h ts w ere reco rd ed A ll d ried

p a rts w ere ground u sin g m o rtar, m ixed

th o ro u g h ly , and dig ested w ith H N O3 Sam ple

so lu tio n s vvere analy zed fo r C d an d Pb by ílam e

ato m ic ab so rp tio n on a S p ectrop ho tom eter The

soil w as air-dried an d d ig ested w ith H N O3

A n aly sis o f C d an d Pb w as co n du cted by the

sam e p ro ced u re d escrib ed ab o ve [1 ]

2.3 The E ffìcien cy o f Pb, C d R em o va l

T h e EíTiciency o f P b, C d R em oval vvas

c a lc u la te d using the eq u ation belovv:

c n - ■ f D U r A ( p b / c d i n s h o o t s + P b / C d

ĩ n ° o ọ g g x T 0 0 Total Pb/Cd in pot (mg)

T h en , d ata w ere statistically an aly zed using

an aly sis o f v ariance and D u n c a n ’s m ultiple

ran g e te sts fo r m ean co m p ariso n A probability

level o f p< 0.05 vvas co n sid ered for sign ifican t

d iíĩe re n c e

3 R e s u lts a n d d isc u ssio n

3.1 G ro w lh ob servation

D u rin g th e ex p erim en tal perio d, all vetiver

g ra ss su rv ied u n đ er all co n d itio n s o f P b, C d

co n ce n tratio n in soils T h e re w as an increase in

p la n t h eig h t until h arv est at th ree m o n th s afìer

Pb, C d w e re ad ded (F ig 1)

Fig 1 Height (cm) o f vetiver grass planted in soil types contaminated with Cd/Pb added in 4 levels, taken at 1, 2 and 3 months after application

In ad d itio n , th e v e tiv e r grass grevv best in

th e sand so il vvith ab u n d an t o rg an ic m atter ( S l) and vvorst in th e c la y so il w ith p o o r organic

m atter (S 4)

F rom statistic al an aly sis, it w a s found that

th e vetiv er g rass co u ld g ro w w ell ev en on soils

co n tam in a ted w ith C d an d Pb It m ight be

co n clud ed th a t P b/C d in soil even at th e level

ab ov e c ritica l v alue to p la n t grovvth has no neg ative e íĩe c t on v etiv er g ro w th T h is íìnding

is sim ilar to th e resu lts o f T ru o n g (1999),

R o o n g ta n ak iat an d C hairoj (2 00 1) It w as

co n íirm ed th a t v etiv er g rasses are highly

to leran t, a n d th u s co u ld grovv in highly Pb-

co n tam in a teđ soils

3.2 C d a n d P b a ccu m u la tio n in p ỉa n í

T h e re su lts sh ow ed th a t a v etiv er could take

u p m ore a m o u n ts o f C d a n d Pb w h en there are

p lẹn ty o f C d an d Pb in 4 soil ty p es (T ab le 2 and

F ig 2 ) T h e re w a s sig n iíĩc a n t d iíĩe re n c e am ong soil ty p e s reg ard in g V e tiv e r’s accum ulation o f

C d an d P b V e tiv e r’s acc u m u la tio n ability o f

C d and P b in sho ot an d root in various soil

ty p es d e scen d in g S 1 > S 2 > S 3 > S 4 Surpris:ngly,

th e S3 g av e h ig h grovvth b u t lovvest C d and Pb accu m u latĩo n co m p ared to th o se o f the other

v.v M inh' L.v Khoa / V N U Ịournal o f Science, Earth Sciences 25 (2009) 98-103 101

th re c soil types T hese íìn d in g su gg ested th at

th e so il ty p e could cause th e diíTerence in Cd

an d P b accum ulation in v etiv er plants Allovvay

(1 9 9 7 ), B aker and S en ít (1 9 9 7 ) rep o rted that

p la n t sp ecies as w ell as cu ltiv ars d iíĩe r w idely

in th c ir uptake ab ility an d accum ulatio n o f

h e a v y m etals

T h e average high est h eavy m etal

co n ce n tratio n s in shoo t o f v etiv er g rass for Cd

an d Pb w ere 2 95ppm an d 74.65ppm ,

rcsp ectiv ely T h ey w ere lo w er than th e tox ic

th resh o ld levels (T ru o n g , 1999) In v etiv er

ro o ts, v etiv er grass could accu m u late the

h ig h c st am ount o f C d and Pb at th e h ig h est Cd

and Pb level in soil g ro u p S I an d S4 The

av e ra g e hig hest C d an d Pb co n cen tratio n s in

ro o ts o f v etiv er grass w ere 4 3 2 4 p p m and

85.7 lp p m , respectively

C o m p a rin g th e d istrib ution o f C d and Pb

co n ce n tralio n in th e p arts o f v etiv er grass, Cd

and Pb vvas found to accu m u late m ore in roots

than in shoots Hovvever, Pb vvas tran slo cated

m o re to sh oo t (th e accu m u latio n rate in

sh o o t/ro o t is from 9 9 2 % to 8 7 9 4 % ) w h ile C d

w as accu m u lated m ore in root (the

accu m u latio n rate in sh o o ư ro o t is form 1.85%

to 13 32% ).T his find in g is sim ila r to th e results

o f T ru o n g (1 9 9 9 ) and R o o n g tan ak iat et al

(2 0 0 2 ) [5, 8] T h ey found th a t a sm all am ount

o f C d and a m o derate prop ortio n o f P b w ere tran slo cated to th e shoot

14

12

10 *

8 1 •»

6 6

4 *

7

0

Fig 2 Concentration o f Cd (a) and Pb (b) in shoot and root o f vetiver pỉanted in soil types contaminated vvith Pb, Cd added in 4 levels

102 v.v M inh, L v Khoa / VN U Ịournal o f Science, Earth Sàetĩces 25 (2009) 98-103

Tabỉe 2 Concentrations o f Cd and Pb in the shoots and roots o f vetiver grass planted in 4 various soil types with

Pb, Cd in 4 levels

Heavy metal Soil types Cd/Pb ỉevels (ppm) Cd/Pb in shoot (ppm) Cd/Pb in root

(ppm )

% Cd/Pb in shoot /root

C d

Pb

Note: The same letters on the same com er means that there is no signiíìcant difference at 95% coníìdence ỉevel 3.3 The E ffìcietìcy o f C d a n d P b R e m o v a ỉ

In gen eral, th e rem oval o f C d an d Pb from

co n tam in ated soil vvas co rrelated vvith m o re Cd

an d P b accum u latio n b y ro o ts an d sh o o ts o f

p la n ts ( Table 3) T he p re se n t stu dy indicated

th a t th e Pb rem oval effic ien cy o f V etiv er grass

w a s very low (th e h ig h est eíTiciency w as

0 2 6 % ) O n the co n tra iy , th e C d rem oval

efficien cy o f V etiv er g rass w a s q u ite high (the

h ig hest e ííìc ie n c y w a s 0 72% ) T h e highest effic ien cy o f C d a n d Pb rem o val o f vetiver grass w e re a t lOOppm in soil g ro u p S I (table 2)

T h e C d and Pb rem o v a l efficien cy o f V etiver

g rass in 4 v a rio u s soil ty p es d escending

S 1 > S 2> S 3 > S 4 T h e s e fin d in g sug gested that

th e soil lype could cau se the d iíĩe re n c e in Cd and Pb d istribu tio n in v etiv er g rass as vvell as

th e rem o val eíTiciency

v.v M inh, L v Khoa / V7sỈU Ịournal o f Science, Earth Sciences 25 (2009) 98-103 103

T a b le 3 E íĩic ien cy o f C d a n d Pb rem oval o f V etiver

g rass p ỉan ted in soil ty p es c o n ta m in a te d w ith Pb, Cd

ad d ed in 3 levels

H eavy C d/Pb ỉevcỉs S o il types

m etal (ppm ) S I S2 S3 S4

C d 10 0 7 2 0.62 0.60 0.44

30 0 6 9 0.64 0.56 0.53

60 0 5 8 0.54 0.44 0.39

Pb 100 0 2 6 0 2 4 0.19 0.22

300 0.23 0 2 2 0.21 0.1 9

700 0 1 8 0.16 0.14 0.15

4 C o n c lu sio n

T h e v etiv er grass h ad a high to leran ce to Cd

a n d P b It c a n grovv in v a r io u s so il ty p e s (san d

and c la y ; ab u n d an t an d p o o r o rg an ic m atter)

vvith hig h C d a n d Pb lev els in soil (C d: 10 -

60 ppm , o v er V ietn am ’s Standard -T C V N 7209-

20 0 2 - fro m 5 to 30 tim e s; Pb: 100 - 700ppm ,

o v e r V ietn am ’s Standard -T C V N 7209-2002-

fro m 1.5 to 10 tim e s) T h e h eav y m etal

accu m u latio n betw een sh o o ts and roo ts o f

V e liv e r g rass for P b w a s q u ite high (9.92 -

8 7 9 4 % ); in co ntrary, fo r C d vvas very low

(< 13.32% ) T h e re ío re , th e im portant

im p lication o f th e se íìn d in g s is th a t v etiv er can

be used for p h y to e x tractio n o f P b and

ph y to stab ilizatio n o f C d on sites con tam inated

w ith h igh levels o f h eav y m etals

R e íT e re n c e s

[1] G.R Blake, B ulk density M ethod o f soi!

analysis, M onograph N o.9 Part I American

Society o f A gronom y Inc., M adison, W isconsin, 1965

[2] H Chen, Chemical methơd and

phytorem ediation o f soiỉ contam inated with

heavy m etals, C hem osphere 41 (2000) 229-234.

[3] R L Chaney, et aỉ Phytoremediation of soil

m elals, C urrent opinion in B iotechnol 8 (1997)

279-284

[4] Environmental Protection Agency, Introducíion

to phytoremediation, State o f the Science

C onĩerence, B oston, M assachusètts, 2000

[5] N Roongtanakiat, p Chairọị, Uptake potential

o f som e heavy m elals by vetiver grass, K a setsart

J (Nat Sci.) 35 (2001) 46-50.

[6] P.N.V Truong, D B aker, The role o f vetiver

grass in the rehabiỉitation o f toxic a n d contam inated ỉands in Australia, Proceeding of

the International V etiver W orkshop, Fuzhou, China, 1998

[7] P.N V Truong, D Baker, Vetiver grass fo r

stabiỉization o f acid suựaíe soily In Proceedings

o f Second National C onĩcrcnce on A cid Su!fate Soils, C o íĩs H arbour, Sydncy, 1998, 196-198

[8] P.N.V Truong, Vetiver Grass Technology for

M ine R ehabilitation O ffice o f Royal

D evelopm ent Projects Board, Bangkok

Technìcal B suỉỉetin 1999/2 (1999) 12.