ORIGINAL PAPER

Bioremediation potential of genus Portulaca L. collectedfrom industrial areas in Vadodara, Gujarat, India

Sanjay Dwivedi • A. Mishra • A. Kumar •

P. Tripathi • R. Dave • G. Dixit • K. K. Tiwari •

S. Srivastava • M. K. Shukla • R. D. Tripathi

Received: 16 December 2010 / Accepted: 13 May 2011 / Published online: 27 May 2011

� Springer-Verlag 2011

Abstract During the present study, two species of

Portulaca, i.e., P. tuberosa and P. oleracea were collected

from two field sites in Vadodara, Gujarat, India; one irri-

gated with industrial effluent and other with tube well

water, and were analyzed for heavy metal accumulation in

different plant parts viz., roots, stem, leaves, and flowers.

Plants collected from effluent irrigated areas showed high

accumulation of all the investigated heavy metals in all

plant parts with the maximum being in roots and the least

in flowers. Interestingly, both species of Portulaca dem-

onstrated hyperaccumulation of multiple elements viz., Cu,

Ni, Hg, and Pb. The total shoot concentrations (lg g-1 dw)

of Cu, Ni, Hg, and Pb in P. tuberosa were 1538, 1191, 789,

and 2744, respectively, while in P. oleracea, these were

1940, 1542, 534, and 2312, respectively. Besides this,

selective hyperaccumulation of Se (2,327 lg g-1 dw) and

Al (1,164 lg g-1 dw) was shown by P. tuberosa and

P. oleracea, respectively. Total shoot concentrations

(lg g-1 dw) of Mo were about 399 and 668 in P. tuberosa

and P. oleracea, respectively. Overall, P. oleracea accu-

mulated higher amounts of multiple metals from industrial

effluent contaminated site, hence appears to be a suitable

candidate for phytoremediation purposes of metal con-

taminated areas.

Keywords Industrial effluent � Lead � Mercury �Portulaca oleracea � Portulaca tuberosa � Selenium

Introduction

Industrial activities, mining and refining of ores, electro-

plating and manufacturing of essential commodities pro-

duce huge volumes of wastewater as effluent that contains

heavy metals and other toxicants, which deteriorate the

quality of aquatic systems upon discharge. Local farmers

indiscriminately use the industrial effluent for irrigating

their crops (Warning et al. 1996). Though treated effluent is

enriched with several useful ingredients as well, such as N,

P, and K, providing fertilizer value to the growing crops,

presence of high amounts of heavy metals like Pb, Hg, Ni,

Se, etc., high salinity, electrical conductivity, total dis-

solved solids, and low pH affects the crops negatively

resulting in loss of yield (Freedman and Hutchinson 1981;

Sigel 1986). Over a period of time, severe loss of soil

fertility may occur due to heavy contamination of metals

making it unsafe for future use.

The need exists to develop an appropriate and cost-

effective method to remediate such effluent contaminated

sites. Available traditional methods for metal decontami-

nation do not satisfy the requirement primarily due to their

cost intensiveness (McIntyre 2003; Mudgal et al. 2010).

Phytoremediation is an emerging, solar-driven, low-cost

technology for the removal of toxic heavy metals through

S. Dwivedi (&) � A. Mishra � A. Kumar � P. Tripathi �R. Dave � G. Dixit � M. K. Shukla � R. D. Tripathi (&)

Ecotoxicology & Bioremediation Group, National Botanical

Research Institute (CSIR), Rana Pratap Marg,

Lucknow 226001, UP, India

e-mail: drs_dwivedi@yahoo.co.in

R. D. Tripathi

e-mail: tripathi_rd@rediffmail.com

K. K. Tiwari

Sophisticated Instrumentation Centre for Applied Research

and Testing, Sardar Patel, Centre for Science and Technology,

Vallabh, Vidyanagar, Anand, Gujarat 388120, India

S. Srivastava

Nuclear Agriculture & Biotechnology Division, Bhabha Atomic

Research Centre, Mumbai 400085, India

123

Clean Techn Environ Policy (2012) 14:223–228

DOI 10.1007/s10098-011-0389-6

uptake, and accumulation of metals in harvestable shoots of

the plants. Certain plant species, known as hyperaccumu-

lators, are attractive candidates as they accumulate metals

in 50- to 500-times higher concentrations than normal

plants, without showing any severe toxicity (Roosens et al.

2003; Dwivedi et al. 2008; Kramer 2005; Tiwari et al.

2008). A plant is considered as a hyperaccumulator when

the minimum threshold tissue concentration for a particular

metal viz., 0.001% for Hg while 0.1% for Cu, Pb, Ni, Al, or

Se of the dry weight of plant, is achieved (Pickering et al.

2003; McIntyre 2003; Gratao et al. 2005). However, the

drawback of using hyperaccumulators is that most of them

have slow growth and restricted distribution. Hence, the

need is to find fast growing plants having ability to grow in

wide range of habitats.

In the Umaraya town of district Vadodara, Gujarat, India

a common effluent discharge channel (about 100 km) has

been constructed. Several industrial units of pharmaceuti-

cals, pigments, petrochemicals, dyes, paints, pesticides,

chemicals, lubricants, etc. are located near the channel,

which discharge their effluents into this channel. In many

areas located around this channel, farmers use the effluent

for irrigating their crops. Plants of common purslane

(Portulaca spp.) have been found to grow in these areas

naturally. These plants are also available commercially as

both ornamental and culinary cultivars (Lim and Quah

2007).

Portulaca spp. is an annual succulent plant of the family

Portulacaceae, which is native to India and the Middle

East, but is naturalized elsewhere and is considered an

invasive weed in some regions (Tiwari et al. 2008). Thus,

the present investigation was conducted to evaluate heavy

metal (Cu, Ni, Mo, Se, Hg, Pb, Al) accumulation by two

species of Portulaca, i.e., P. tuberosa and P. oleracea to

understand how these plants survive the toxicity of indus-

trial effluent. The physico-chemical analysis of industrial

effluent and tube well water was performed. The level of

heavy metals was analyzed in effluent, tube well water,

soils irrigated with them, and in different plant parts (roots,

stem, leaves, and flowers).

Material and methods

The study area in the present investigation was around

common effluent discharge channel, Vadodara, Gujarat,

India. For physico-chemical analysis, effluent samples were

collected from the discharge point of the channel while the

samples of tube well water were collected from the area

situated one km away from the channel, and were stored in

plastic bottles. The pH, electrical conductivity (EC), total

dissolved solids (TDS), and salinity were determined on site

with the help of portable water quality laboratory system

(HACH, model DREL/2016). Chloride, sulfate, sulfide,

calcium, phosphate, potassium, sodium, magnesium, am-

monical and total nitrogen, and nitrate were estimated as per

guidelines of APHA (2004). Total, inorganic, and organic

carbon contents were determined by Total Organic Carbon

Analyzer (TOC-VCSH, TNM-1; Shimadzu Corp., Japan).

Soil and plant samples were randomly collected in large

plastic bags from fields situated near the channel (2–10 m),

which were being irrigated with effluent and also from fields

that were situated one km away from the channel and irri-

gated with tube well water. After collection the material were

brought to the laboratory for further studies. Plant samples

were firstly wiped with 0.01 N HCl and then washed with tap

water followed by rinsing with deionized water. The various

plant parts viz., roots, stem, leaves, and flowers were then

separated and dried in an oven at 70�C for 48 h. For analysis

of heavy metals (Cu, Ni, Mo, Se, Hg, Pb, Al), all the samples

were digested with HClO4:HNO3 (1:4 v/v) and diluted with

milli-Q water. Metal concentrations were determined on the

Inductively Coupled Plasma Mass Spectrometer, Perkin

Elmer Corporation (ICP Optima 3300 RL).

The standard reference material of Ni (BND 1001.02;

provided by the National Physical Laboratory, New Delhi,

India), Cu, Pb (EPA quality control samples; Lot TMA

989) and Mo, Se, Hg, and Al (E-Merck, Germany) were

used for the calibration and quality assurance. Analytical

data quality of the metals was ensured through repeated

analysis (n = 6) of standard reference samples and the

results were found to be within ±2.03 to ±2.95% of cer-

tified values. The mean recovery was about 96–98.5% for

different metals. The blanks were run in triplicate to check

the precision of the method with each set of samples. The

detection limits for Cu, Mo, Ni, Pb, Se, Hg, and Al were

0.9, 0.4, 0.5, 1.5, 4, 0.1, and 0.9 ppb, respectively. The

transfer factor (TF) was calculated for each metal accord-

ing to the formula, TF = Ps (lg g-1 dw)/St (lg g-1 dw)

where Ps is the plant metal content and St is the total metal

content in the soil (Tiwari et al. 2009).

Two-way analysis of variance (ANOVA) was done on

all the data to confirm the variability of data and validity of

results, and Duncan’s multiple range test (DMRT) was

performed to determine the significant differences between

treatments (Gomez and Gomez 1984).

Results and discussion

The present investigation was conducted with a view to

investigate the feasibility of two Portulaca species

P. tuberosa and P. oleracea for metal accumulation in con-

taminated sites. The physico-chemical analysis of effluent

and tube well water is presented in Table 1. The pH of

effluent was found to be slightly acidic while that of tube well

224 S. Dwivedi et al.

123

water was around neutral range. All analyzed parameters

showed significantly higher concentrations in effluent than in

tube well water. The concentration of all the investigated

heavy metals in effluent was also significantly higher as

compared to that in tube well water (Table 2). The concen-

tration order of metals in effluent was Cu [ Ni[ Se [Pb [ Al [ Hg [ Mo while in soils irrigated with the effluent,

it was Cu [ Se[ Pb [ Al[ Ni[ Hg [ Mo. However, in

tube well water and in soils irrigated with that, the concen-

tration of the metals was in similar order viz., Cu [ Pb [Ni[ Mo. Selenium, Hg, and Al were not present in detectable

amount in tube well water and soils irrigated with it, while Cu

was present in the highest concentration in both effluent and

tube well water and the respective soil systems. The value of

transfer factor of different elements of both the tested species

of Portulaca genus is presented in Table 2. The data revealed

that the transfer factor varied from one metal to another. The

results indicated highest translocation of Pb (233.33) and

lowest for Ni (9.17) in P. oleracea in tubewell water irrigated

areas in P. oleracea collected from tube well water irrigated

areas.

The metal accumulation profiles of P. tuberosa (Fig. 1)

and P. oleracea (Fig. 2) depicted higher accumulation of all

the metals in plants growing in effluent irrigated fields than in

plants growing in tube well water irrigated fields. In plants

irrigated with effluent, roots contained higher amount of

metals than total shoot metal content (stem ? leaf ?

flower) except Cu, Se, Pb, and Al in P. tuberosa and Cu and

Mo in P. oleracea. Flowers showed the least accumulation of

metals. In both the varieties, roots and shoots showed the

highest accumulation of Ni and Pb, respectively. Nickel and

Mo showed more accumulation in leaves than in stem, while

other metals showed more accumulation in stem than in

leaves. Hyperaccumulation of metals (Cu, Ni, Hg, and Pb) by

both P. oleracea and P. tuberosa was observed. The total

shoot concentrations (lg g-1 dw) of Cu, Ni, Hg, and Pb in

P. tuberosa were 1538, 1191, 789, and 2744, respectively,

while in P. oleracea, these were 1940, 1542, 534, and

2312, respectively. Besides this, selective hyperaccumulation

of Se (2,327 lg g-1 dw) and Al (1,164 lg g-1 dw) was

shown by P. tuberosa and P. oleracea, respectively.

Total shoot concentrations (lg g-1 dw) of Mo were

about 399 and 668 in P. tuberosa and P. oleracea,

respectively.

Previous studies on Portulaca by Mukesh et al. (1996),

Thangavel et al. (1999), Anandi et al. (2002) and Deepa

et al. (2006) concentrated primarily on investigating the

ability of the plants to regenerate under stress conditions

exerted by Cu, Hg, Cd, Zn, Pb, Se, and Al. They demon-

strated that metal exposurs reduced the capacity of regen-

eration and toxicity order was reported to be Cd [ Cu [Al [ Zn [ Hg [ Se [ Pb. In a recent study, Deepa et al.

(2006) studied accumulation of Cu by plants and showed

that plants could regenerate in up to a maximum of

1,600 lg g-1 dw Cu in soil and accumulated [1,000 lg

g-1 dw copper. Thus, despite the negative effect of Cu on

regeneration ability, next to Cd only, plants showed high

accumulation of Cu.

Hyperaccumulation of various metals (Cu, Ni, Hg, and

Pb) by both P. oleracea and P. tuberosa along with

Table 1 Physico-chemical

characteristics of mix industrial

effluent and tube well water

All the values are in mg l-1

except otherwise stated. Values

are mean ± SD (n = 3)

Parameters Mix industrial effluent Tube well water

pH 6.13 ± 0.051 7.22 ± 0.26

Electrical conductivity (ds m-1) 3.46 ± 0.022 1.05 ± 0.016

Total dissolved solids 1,785 ± 32.32 194.51 ± 4.69

Salinity (%) 197 ± 10.26 0.8 ± 0.016

Chloride 1,082 ± 22.36 9.25 ± 0.31

Fluoride 35.3 ± 2.03 0.13 ± 0.003

Sulphate 2,906 ± 101.26 10.22 ± 0.069

Sulfide 87.41 ± 6.96 0.13 ± 0.005

Calcium 752 ± 12.23 5.78 ± 0.023

Phosphate 84.6 ± 4.26 1.20 ± 0.01

Potassium 183 ± 4.29 0.3 ± 0.01

Sodium 835 ± 10.36 0.9 ± 0.04

Magnesium 518 ± 12.32 22.6 ± 0.99

Available nitrogen 846 ± 16.26 6.3 ± 0.12

Nitrate 194 ± 11.02 0.84 ± 0.031

Total nitrogen 1,538 ± 10.26 10.28 ± 0.56

Total carbon 2,450 ± 152.03 92.65 ± 2.31

Inorganic carbon 62.47 ± 3.26 3.18 ± 0.23

Total organic carbon 2,388 ± 102.32 89.47 ± 9.26

Bioremediation potential of genus Portulaca L. 225

123

Table 2 Concentration of heavy metals in mix industrial effluent (MIE)/tube well water (TWW), soil, and translocation in Potulaca species

Elements MIE

(mg l-1)

Soil irrigated with

MIE (mg kg-1)

Plant irrigated with

MIE

TWW

(mg l-1)

Soil irrigated with

TWW (mg kg-1)

Plant irrigated with

TWW

P.tuberosa(TF)

P.oleracea(TF)

P.tuberose(TF)

P.oleracea(TF)

Cu 8.25 ± 0.59 33.65 ± 1.26 45.70 57.65 0.13 ± 0.005 0.48 ± 0.005 68.75 91.66

Ni 3.56 ± 0.11 8.85 ± 0.12 177.51 174.23 0.07 ± 0.002 0.17 ± 0.006 45.88 9.17

Mo 0.94 ± 0.056 3.57 ± 0.16 111.76 187.11 0.02 ± 0.0005 0.09 ± 0.001 155.55 44.00

Se 3.28 ± 0.13 11.96 ± 0.99 194.56 48.91 BDL BDL 00.00 00.00

Hg 1.47 ± 0.05 5.82 ± 0.21 135.56 91.75 BDL BDL 00.00 00.00

Pb 2.94 ± 0.06 11.76 ± 0.59 233.33 196.59 0.11 ± 0.003 0.25 ± 0.006 100.00 108.00

Al 2.13 ± 0.02 9.83 ± 0.26 93.18 118.41 BDL BDL 00.00 00.00

a

b

c

cd

ab

a

d

bc

b

d

e

d

b

a

a

ab

c

b

b

a

c

c

d

d

b

c

d

d0

1000

2000

3000

4000

Root Stem Leaf Flower

µg g

-1 d

w

Cu Ni Mo Pb Se Hg Al

a

a

a

a

c

c

b

b

bc

bc

ab

b

b

a

ab

0

15

30

45

Root Stem Leaf Flower

µg g

-1 d

w

Cu Ni Mo Pb

A

B

Fig. 1 Accumulation of various

metals in different plant parts of

Portulaca tuberose (a) and

Portulaca oleracea(b) collected from fields

irrigated with mix industrial

effluent. Values are means of

±SD (n = 3). ANOVA

significant at P B 0.01 for a

particular plant part viz., root,

stem, leaf, and flower, different

letters (a,b,c…..) indicate

significantly different values

(DMRT, P B 0.05)

226 S. Dwivedi et al.

123

selective hyperaccumulation of Se by P. oleracea and Al by

P. tuberosa was interesting. These plants also showed high

accumulation of Mo, which was higher than normal range of

Mo (1–2 lg g-1 dw) found in plants (Hale et al. 2001).

Further, tested species of Portulaca accumulated significant

amounts of Ni (Rooney et al. 2007). Thus, it seems that

plants have adapted to grow naturally on contaminated soils

by employing diverse strategies to accumulate and detoxify

high load of metals and metalloids (Grill et al. 2006; Mishra

et al. 2006; Dwivedi et al. 2008, 2010).

Conclusively, Portulaca plants grow well at site con-

taminated with multiple metals and also showed rapid

accumulation of metals and their efficient transport to

shoots. Portulaca oleracea seems a better accumulator

species for various metals than P. tuberosa and thus may

successfully be employed in phytoremediation programmes.

Acknowledgments Authors are thankful to Director, CSIR-

National Botanical Research Institute, Lucknow for the facilities

provided. SD is grateful to Council of Scientific & Industrial Research

for Pool Scientist ship. Authors are thankful to Mr. Pradeep Singh for

assistance during the study.

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