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REVIEW ARTICLE
Archives of Agriculture and Environmental Science 4(3): 326-341 (2019)
https://doi.org/10.26832/24566632.2019.0403011
This content is available online at AESA
Archives of Agriculture and Environmental Science
Journal homepage: www.aesacademy.org
e-ISSN: 2456-6632
ARTICLE HISTORY ABSTRACT
Received: 22 July 2019
Revised received: 26 August 2019
Accepted: 06 September 2019
Quick jump of urbanization and industrialization is responsible for birth of heavy metal
pollution. In the aquatic systems, heavy metals are one of the most dangerous pollutants that
may be found. It can have both natural and anthropogenic origins. In aquatic ecosystem heavy
metal pollution have a serious hazard to biodiversity of aquatic ecosystems, and drinking
polluted water contaminated with heavy metals can have severe health risks in humans as well
as in all living-beings. The commercial characteristics and side effects of conservative treat-
ment equipment in aquatic environment agged the way to eco-sustainable technology like
phytoremediation. In phytoremediation, Plants are used to clean up the environment from
numerous dangerous contaminants. Phytoremediation is cost-effective and ecofriendly exper-
tise for environmentally friendly cleanup. The present review reects the characteristics of
heavy metals and possible environmental threats together with this, review also inspects the
role played by the macrophytes in phytoremediation studies in the recent past. In the reduc-
tion of heavy metal contamination in aquatic environments which receive the industrial
discharges and municipal wastewater, aquatic macrophytes are powerful tools to remediate
them.
©2019 Agriculture and Environmental Science Academy
Keywords
Contamination
Eco-Friendly
Heavy metals
Hyperaccumulators
Industrialization
Phytoremediation
Citation of this article: Kumar, V. and Kumar, P. (2019). A review on feasibility of phytoremediation technology for heavy metals
removal. Archives of Agriculture and Environmental Science, 4(3): 326-341, https://dx.doi.org/10.26832/24566632.2019.0403011
A review on feasibility of phytoremediation technology for heavy metals removal
Vinod Kumar and Piyush Kumar*
Agro-ecology and Pollution Research Laboratory, Department of Zoology and Environmental Science, Gurukula Kangri
Vishwavidyalaya, Haridwar-249404 (Uttarakhand), INDIA
*Corresponding author’s E-mail: kumarpiyushgkv@gmail.com
INTRODUCTION
Fast industrialization and urbanization have ended
in multiplied emission of toxic heavy metals getting into the
biosphere (Gazsó, 2001). Activities together with mining and
agriculture have polluted good sized regions throughout the
sector (Smith et al., 1996; Shallari et al., 1998). Earth’s crust is
the home for metals where they are found naturally. The compo-
sition of metals varies from locality to locality, resulting in spa-
tial differences of surrounding concentrations (Jaishankar et al.,
2014). In waste water the generally present heavy metals are
arsenic, copper, cadmium, chromium lead, nickel, and zinc, which
are quite toxic and have potential risks for human health and the
environment (Lambert et al., 2000). The release of heavy metals
in biologically to be had forms with the aid
of human interest, may additionally damage or modify
each herbal and man-made ecosystems (Taylor et al., 1989).
Heavy metal ions consisting of Cu2+, Zn2+, Fe2+
are vital micronutrients for plant metabo-
lism however whilst found in excess, can emerge
as extraordinarily toxic. Many heavy metals are categorized as
precedence pollutants with the aid of US Environmental protec-
tion agency. Lead, mercury, arsenic, and cadmium ranked as
rst, second, third, and sixth risks at the listing from US Agency
for Toxic Substances and Disease Registry (ATSDR) that lists all
hazards present in toxic waste websites consistent with their
occurrence and the severity in their toxicity. The heavy metals
like Cd, Pb, Co, Zn and Cr which are very common are phytotox-
ic at both low and very high concentration are found in waste
water. If these metals reach in sediments then they got engaged
in the food chain via aquatic plants and animals. In small
portions, a few heavy metals are nutritionally important for a
nourishing life, however large measures of any of the heavy
metal may also cause toxicity (poisoning). In the recent past,
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Vinod Kumar and Piyush Kumar /Arch. Agr. Environ. Sci., 4(3): 326-341
there had been increasing a vast number of cases of heavy
metallic pollutions in the environment reputedly because of
poisonousness and supercial persistency of heavy metals
inside the aquatic ecosystems (Tijani et al., 2005). Contamina-
tion by heavy metals is a worldwide stress, even though harsh-
ness and levels of pollutants differ from locality to locality. At
least 20 metals are labeled as toxic with half of them emitted
into the environment that poses huge risks to human health
(Akpor and Muchie, 2010). Heavy metal polluted sites must be
remediated to reduce the associated risks. Metals cannot be
degraded like organic compounds and cleanup typically needs
removal of heavy metals. Utmost of the conventional remedia-
tion techniques are costly and reduce the fertility of the soil; this
afterwards would responsible for bad impacts on the
environment (Kumar et al., 2016).
Phytoremediation is a budget operational, eco-friendly, artisti-
cally attractive approach best appropriate for developing
countries like India. For applications in phytoremediation and
phytomining, various effective metal hyperaccumulators are
being discovered. Vegetation have the capacity to accumulate
nonessential metals such as Cd and Pb, and this capacity may be
harnessed to do away with pollutant metals from the environ-
ment (Salt et al., 1995; Das et al., 1997; Rogers et al., 2000).
Currently there is a large interest in growing inexpensive and
environmental friendly technologies for the remediation of soil
and wastewater polluted with hazardous heavy metals (Zayed et
al., 1998). Plants based bioremediation technologies have
obtained current interest as techniques to easy-up contaminat-
ed soil and water (Sadowsky, 1999). Many sorts of plants have
been tested for phytoremediation, amongst various plant organ-
isms, participants of Lemnaceae and Azollaceae have been docu-
mented as capacity accumulators of metals therefore may be
utilised for the enrichment of water contamination to decrease
the pollution load (Horvat et al., 2007; Rai, 2010). The
submerged macrophytes are mainly benecial within
the abatement and tracking of heavy metals (Gupta and
Chandra, 1998). Earlier works in the eld of waste water treat-
ment conrmed that aquatic macrophytes can be used to
partially accumulate or absorb trace metals present in
wastewaters (Chandra et al., 1993). The aquatic macrophytes
suck/absorb heavy metals by the use of their oor adsorption
and/or absorption and store them in a bonded form. Efuent
treated by these macrophytes therefore becomes less toxic to
the aquatic environment. At metals polluted locations, plants
are used to stabilize and remove the metals from the soil and
ground water through mechanisms such as phytoextraction,
rhizoltration, and phytostabilization (Kumar et al., 2019a).
The present review will be helpful to understand the concept of
heavy metal sources, their harsh effects and need of their
removal from contaminated sites. It would also explain the
phytoremediation technology and its applications in remedia-
tion of heavy metals by different processes. The goal of this
review is to give vision into the sources of heavy metals and
their dangerous properties on the surroundings and living
creatures and remediation strategies to get rid of them or to
minimize their effects by the use of some hyper accumulator
plants which usually absorb them and decrease their effects.
CHARACTERISTICS OF HEAVY METALS
Arsenic (As)
Although arsenic occurs as the 20th most abundant element in
the geosphere, arsenic is extremely poisonous to the biota. In
many zones, arsenic levels in the environment have beaten the
safe threshold for human welfare viz, 10 µg/l. Its inorganic forms
are poisonous to the environment and living beings such as
arsenite and arsenate complexes. Humans may be exposed to
arsenic by natural phenomenon unintended sources or from
industrial sources (Jaishankar et al., 2014). Arsenic is very chief
heavy metal causing anxiety at both ecological and individual
health levels (Hughes et al., 1988). Arsenic displays poisonous-
ness even at low exposures (Dikshit et al., 2000) and causes
diseases like black foot (Lin et al. 1998). It is now well document-
ed that ingestion of arsenic, even at low levels, leads to carcino-
genesis (Mandal and Suzuki, 2002). Gastrointestinal indications
such as severe vomiting, injury to the nervous system, disorders
of the blood and circulation and ultimately death can be the
result of consumption of large amounts of arsenic. Large doses
of arsenic when not deadly, may break up red blood cells in the
circulation, decrease blood cell production, color the skin,
enlarge the liver, produce burning and loss of consciousness in
the limbs, and also damage the brain (Mahurpawar, 2015).
Cadmium (Cd)
According to ATSDR ranking, Cadmium is the seventh most
poisonous heavy metal. Cadmium is generated by zinc produc-
tion as a by-product to which humans or animals may get
exposed at labor or in the surroundings. It will accumulate inside
the body throughout life if once gets absorbed by humans
(Jaishankar et al., 2014). Because of its high rate of soil-to plant
handover, Cadmium is largely found in vegetables and fruits
(Satarug et al., 2011). Cadmium is an extremely poisonous
unnecessary heavy metal which is well known for its adverse
effect on the enzymatic systems of cells, oxidative pressure and
for encouraging nutritive deciency in plants (Irfan et al., 2013).
Consumption for people is assessed as 0.15μg from air and 1μg
from water for normal day by day. Inhalation and ingestion of
cadmium by humans can affect the health but the main health
impacts reported in the literature are through dietary exposure
(kidney and bone damage) and inhalation by tobacco, smoking
and work-related exposure (lung damage). The highest human
organ affected by cadmium is the kidney in both the general
population and the occupationally exposed (Mahurpawar,
2015). Smoking a packet of 20 cigarettes can prompt the inward
inhalation of around 2-4μg of cadmium, due to which levels may
on large scale (Clinton et al., 2014).
Chromium (Cr)
Burning of oil and coal, petroleum from ferrocromate refractory
material, catalyst, chromium steel, fertilizers, pigment oxidants,
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Vinod Kumar and Piyush Kumar /Arch. Agr. Environ. Sci., 4(3): 326-341
metal plating tanneries and oil well drilling are the natural
sources of chromium occurrence. Chromium is discharged into
the environment through waste material and fertilizers, anthro-
pogenically (Ghani, 2011). Chromium is used on a large scale in
industries like metallurgy, tanning, electroplating, paints
production, pigments chemical manufacture and pulp and paper
making. Oxygen is present in the environment in excess due to
which, Cr (III) is oxidized to more toxic Cr (VI), which is tremen-
dously poisonous and greatly soluble in water (Cervantes et al.,
2001). In the capital of Japan, Tokyo, during August 1975, the
underground water holding Cr (VI) spoil masses had a 2,000
times higher limit than the permissible limit of chromium (Zayed
and Terry, 2003). The chromium level in underground water has
been witnessed to be more than 12 mg/L and 550–1,500 ppm/L
in India. (Jaishankar et al., 2014). The industrial wastes discharge
and ground water pollution has harshly amplied the chromium
concentration in the soil (Bielicka et al., 2005). The toxicity of
chromium signicantly affects the biological processes in
several plants like maize, cauliower, barley, citrullus and in
vegetables. Chlorosis and Necrosis occurs in plants due to the
chromium toxicity (Ghani, 2011).
Mercury (Hg)
The metallic mercury is a metal which occurs naturally and is a
glossy silver-white, unscented uid and winds up dull and s
centless gas when warmed. Mercury is exceptionally lethal and
exceedingly bio-accumulative. Its presence unfavorably
inuences the marine condition and henceforth numerous stud-
ies are coordinated towards the spreading of mercury in water
environment. Main sources of mercury contamination include
anthropogenic activities such as agriculture, municipal
wastewater discharges, mining and discharges of industrial
wastewater (Chen et al., 2012). Real sources of mercury
contamination incorporate anthropogenic exercises, for
example, horticulture, municipal wastewater releases, mining,
incineration, and releases of industrial wastewater (Chen et al.,
2012). Mercury is widely utilized in thermometers, indicators,
pyrometers, hydrometers, mercury circular segment lights, uo-
rescent lights and as a catalyst. It is additionally being utilized in
pulp and paper businesses, as a part of batteries and in dental
arrangements, for example, amalgams. Methyl mercury is a
neurotoxic compound which is accountable for microtubule
obliteration, mitochondrial harm, lipid peroxidation and accu-
mulation of neurotoxic molecules, for example, serotonin,
aspartate, and glutamate (Patrick, 2002). The mind remains the
objective organ for mercury, yet it can damage any organ and
prompt breaking down of nerves, kidneys and muscles. It can
make interruption the membrane potential and interrupt
intracellular calcium homeostasis. Mercury vapors can cause
asthma, bronchitis, and transitory respiratory issues. Mercury
assumes a key part in harming the tertiary and quaternary
protein structure what's more, changes the cell work by joining
to the selenohydryl and sulfhydryl bunches which experience
response with methyl mercury and hamper the cell structure
(Jaishankar et al., 2014).
Lead (Pb)
Lead is one of the very poisonous heavy metals that accumulate
in individuals and affect the whole food chain and disturb the
health system of animals, phytoplanktons and human beings.
Lead reaches water system together with urban runoff and
discharges as for example, sewage treatment plants and indus-
trial plants. The primary sources of lead are Industrial processes
of production and their discharges, operations of mining, smelt-
ing, combustion sources and solid waste incinerators and some
other sources of lead are batteries, lead paint, lead piping used
in water delivery system (Singh et al., 2011). Lead is a standout
amongst the most noxious metals that have a serious risk to
individuals, creatures and phytoplanktons. It can also disturb
the kidney and most signicantly the brain and nervous system
and lead can accumulate over a lifespan and it causes diseases
as for example anemia, hepatitis and nephritic syndrome,
encephalopathy. It go beyond the WHO (2004) permissible
standard 0.15 mg/L and continuous contact may lead to inter-
ruption in mental or physical growth in infants and youngsters
though adults may have kidney complications and high blood
pressure. The aquatic system is also inuenced by lead in which
young sh are more prone than adults or eggs.
Iron (Fe)
On the earth’s crust, iron is the second preeminent abundant
metal (EPA, 1993). Elemental position of Iron in the Periodic
Table is 26th. For the development and survival of every living
life form Iron is a standout amongst the most essential compo-
nents (Valko et al., 2005). Men made activities such as mining
exercises are the sources of iron in surface water. High
acceptance of Fe2+ by roots, acropetal translocation process
towards leaves, tanning of rice leaves and yield loss are incorpo-
rated in highlights of iron poisonousness (Becker and Asch,
2005). For different organic redox procedures because of its
inter-conversion process amongst ferrous (Fe2+) and ferric
(Fe3+) ions, iron is an appealing progress metal (Phippen et al.,
2008). Rice generation is limited by the Corrosive soils and the
cause of a macronutrient issue in wetland rice is Zn inadequacy.
In ooded soils, the reduced iron (Fe2+) present in great concen-
trations which affected the production of lowland rice tremen-
dously. According to the study of Phippen et al. (2008), the
poisoning effects of iron on water plants especially rice, reviled
that the progression of species of aquatic reed was found to be
restrained by convergence of 1 mg/L add up to iron. When the
absorbed iron is not capable to bind with the protein, a varied
kind of injurious free radicals are formed, which in mammalian
cells and biological uids, consecutively harshly affects the iron
concentration (Jaishankar et al., 2014). Destructive effect on the
abdominal tract and biological uids are the fallouts of this
circulatory unbound iron. Iron crosses the rate-constraining
assimilation step and ends up saturated, when enters into the
body in an extremely high level. These free irons enter into cells
of the liver, mind and heart. Lipid peroxidation by the free iron
results in severe injury to microsomes, mitochondria and other
cellular organelles (Albretsen, 2006).
329
Zinc (Zn)
Zinc has a significant role in numerous biological processes
involving development of organisms and normal growth as it is a
part of several metal- proteins and metal- enzymes (Zinicovscaia
et al., 2018). Actuate oxidative pressure, destruction of DNA
molecules, and also can lead to the impairment of growth and
reproduction can happen if in any case, zinc is present in abun-
dance in water (Finocchio et al., 2010; Zinicovscaia et al., 2015). In
this way, the presence of zinc ions in wastewaters indicates a risk
to the aquatic ecosystem and increases numerous perils for
human beings (Finocchio et al., 2010). Effluents released from
industries engaged in electroplating, galvanization, amalgam
production are the frequent source of zinc and other sources of
zinc are acid mine drainage, metropolitan wastewater treatment
plants, common ores (Ahuja et al., 1999; Kumar et al., 2006;
Zinicovscaia et al., 2015). Extra quantity can cause system dys-
functions that outcome in impairment of growth and reproduc-
tion. However, Zinc is thought to be generally non-dangerous,
particularly if taken orally. (INECAR, 2000; Nolan, 2003). The
clinical indications of zinc toxicosis are spewing, bloody urine,
diarrhea, icterus (yellow mucus membrane), kidney failure, liver
failure and iron deficiency. World Health Organization (WHO)
prescribed the greatest allowable concentration of zinc in
drinking water as 5.0 mg/L (Kumar et al. 2006).
Copper (Cu)
Copper is a metallic element occurs naturally in soil at a usual
concentration of about 50 ppm (parts per million). Copper exists
in all animals and plants and for humans and animals it is a vital
nutrient in small amounts. The smelting, mining and refining of
copper, industries manufacturing products from copper for
example wire, pipes and metal sheet, and burning of fossil fuels
are the main reasons of environmental copper release
(Mahurpawar, 2015). Water pipes are regularly made of copper
and bath fittings might be produced using brass and bronze com-
pounds that contain copper. Leaching of copper from pipes and
bath fittings because of acidic water is the major foundation of
copper in drinking water. Blue-green stains left in shower instal-
lations indicate the existence of copper in water. Different reliefs
of copper to the environment incorporate agricultural use
against plant ailments and medicines connected to water bodies
to dispose of green growth (Mahurpawar, 2015). As a constitu-
ent of metallo enzymes, it is a vital component in mammalian
nourishment. In metallo enzymes it performs as an electron
donor or acceptor. On the other hand, introduction to abnormal
amounts of Cu can result in various unfavorable wellbeing
impacts. The utilization of sustenance and drinking water is the
main reason of introduction of people to Cu. incidental ingestion
is connected with Serve Cu poisonousness; though, some mem-
bers of the population might be more defenseless to the unfavor-
able impacts of high Cu intake because of hereditary inclination
or infection (Stern et al., 2007). Inordinate human consumption
of Cu may prompts serious mucosal disturbance and corrosion,
extensive capillary destruction, hepatic and renal injury and
central sensory system aggravation tracked by depression.
Vinod Kumar and Piyush Kumar /Arch. Agr. Environ. Sci., 4(3): 326-341
Extreme gastrointestinal aggravation and conceivable necrotic
changes in the liver and kidney can likewise happen. The impacts
of Ni exposure change from skin aggravation to harm to the lungs,
sensory system, and mucous membranes (Argun et al., 2007).
SOURCES OF HEAVY METALS
Soil, surface water, and groundwater may emerge as infected
with risky compounds resulting from human activities (e.g.,
enterprise, agriculture, wastewater treatment, production and
mining) as well as natural activities (e.g., soil erosion and saline
seeps). Pollutants can be traced to a selected source, factor
source, or result from massive vicinity, nonpoint source.
Contaminants are both inorganic and natural compounds (heavy
metals, nitrate, phosphate, inorganic acids, radionuclides and
natural chemicals) from sources which include waste substanc-
es, explosives, pesticides, fertilizers, prescribed drugs, acidic
deposition, and radioactive fallout (Sparks, 1995). The two
predominant resources of heavy metals in wastewater are natu-
ral and anthropogenic. The natural elements include city run
offs, volcanic activities, soil erosion and aerosols particulate at
the same time as the anthropogenic sources include steel nish-
ing and electroplating tactics, mining extraction operations,
textile industries and nuclear power (Akpor et al., 2014). Then
foremost usual sources of heavy metal pollutants in wastewater
efuents are soil erosion, volcanic activities, aerosol particles
and city run offs. it is suggested that volcanic eruptions produce
dangerous affects to the surroundings, climate and health of
uncovered individuals. other than the deterioration of social and
chemical situations and the gases (carbon dioxide, sulphur
dioxide, carbon monoxide, hydrogen sulphide) released all
through eruptions, diverse natural compounds and heavy
metals, consisting of mercury, lead and gold also are launched
(Akpor et al., 2014). The activities from volcanoes are mentioned
to be answerable for the discharge of metals which includes
arsenic, mercury, aluminum, rubidium, lead, magnesium, copper,
zinc and a number of others (Amaral et al., 2006). In addition, a
few aerosol (high-quality colloidal debris or water droplet within
the air, in a few cases they may be gas) particles may additionally
deliver one of a kind forms of contaminant; like cloud, smoke
and heavy metals. These heavy metal containing aerosols com-
monly acquire on leaf surfaces in the form of excellent particu-
lates and can input the leaves thru stomata (Sardar et al., 2013).
Certain of the human resources of heavy metals in wastewater
efuents are metal nishing and electroplating, mining and
extraction processes, textiles activities and nuclear activity.
Metal nishing and electroplating involve the deposition of
skinny protecting layers into prepared surfaces of metal the use
of electrochemical methods. Whilst this takes place, toxic
metals can be launched into wastewater efuents. This can be
both through rinsing of the product or spillage and dumping of
method baths. It is also indicated that the cleaning of process
tanks and cleaning of wastewater can generate extensive
portions of soggy sludge containing high amount of poisonous
metals (Cushnie, 1985). In addition, mining processes can launch
poisonous metals to the environment. Metal mining and
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Vinod Kumar and Piyush Kumar /Arch. Agr. Environ. Sci., 4(3): 326-341
smelting activities are seemed as important resources of heavy
metals in surroundings. In environments in which those activi-
ties take vicinity, it's miles indicated that massive amount of
toxic metals deposits are found in their water, plants, soils and
vegetable (Wei et al., 2008).
IMPACTS OF HEAVY METALS
Impact on soil environment
Heavy metal pollution affects adversely numerous parameters
related to plant quality and production together with variety in
composition, size and activity of the microbial community (Yao
et al., 2003). Because of this, heavy metals are said to be the
important source of the soil pollution. The contamination of soil
is generally brought out by the numerous metals like Cu, Cd, Ni,
Zn, Cr (Hinojosa et al., 2004). Various enzymatic activities of the
soil get affected indirectly by the heavy metals as they are
responsible for the shifting of the microbial community which
synthesizes enzymes (Huang et al., 2009). Heavy metals leave
the poisonous effects on soil biota by altering key microbial
activities and decline in the number and activity of soil microbes.
It is very valuable to monitor the functioning of soil microbes in
ecosystems having long term contamination by heavy metals
(Wang et al., 2007).
Impact on plants
Heavy metals like As, Cd, Hg, Pb and Se are not compulsory for
growth of the plants as they do not engaged in any known physi-
ological activity in plants. Other i.e. Co, Cu, Mn, Fe, Mo, Ni and
Zn are essential elements for the plants for their growth and
metabolism, but when their concentration reaches more than
optimal values, these elements can lead to poisoning (Garrido,
2005; Rascio, 2011). Heavy metals uptake by plants and conse-
quent accumulation along the food chain is a latent risk to
animal and human health (Sprynskyy et al., 2007). One of the
main routes of entrance of heavy metals in the food chain is
absorption by plant roots (Jordao et al., 2006). Different plant
species and efciency of different plants in absorbing metals is
responsible for the heavy metal accumulation and is evaluated
by either soil to plant transfer factors or plant uptake of the
metals (Khan et al., 2008). Heavy metals are poisonous in nature
for plants and phytotoxiciy of heavy metals for plants is respon-
sible for chlorosis, weak plant growth, yield declination and may
be even go together with by cheap nutrient uptake, disorders in
plant metabolism and decreased ability to xate nitrogen in
leguminous plants (Guala et al., 2010).
Impact on aquatic environment
Ecological balance of the aquatic environment can tremendous-
ly get affected by the contamination of a river with heavy met-
als, and the variety of aquatic animals may become limited with
the extent of contamination (Ay et al., 2009). Heavy metals
reached to aquatic environment are normally tied up in particu-
late matter which ultimately settle down and become assimilat-
ed in sediments (Singh and Kalamdhad, 2011). Therefore,
surface deposit is very important sink of metals and other
pollutants in aquatic systems. These sediment-bound pollutants
can be absorbed by rooted aquatic macrophytes and other
aquatic life (Peng et al., 2008). The accumulation of heavy metals
by an aquatic organism can be moved through the higher classes
of the food chain. Carnivores include humans which are present
at top of the food chain, attain utmost of their heavy metal
burden from the aquatic environment by way of their nutrition,
especially where sh are present so there exist the potential for
considerable biomagnications (Ay et al., 2009). One of the most
important pollutant for both marine organisms and humans is
mercury (Hg) because its effects on marine organisms and
potential hazards to humans. A form of mercury which is formed
in aquatic sediments by bacterial methylation of organic
mercury is Methyl mercury, which is toxic compound of mercu-
ry, actually, all the mercury in sh muscles found as methyl
mercury (Soliman, 2006). Salmonid species depend upon drift-
prone macro invertebrates commercially or recreationally, so it
is very important to assess the effects of heavy metal contami-
nation on drift-prone macro invertebrates (Iwasaki et al., 2009).
Impact on humans
By exposure heavy metal pollution can affect the population in
many ways causing disorders like insomnia, depression, irritabil-
ity, fatigue, decreased concentration, gastric symptoms, sensory
symptoms (Hanninen and Lindstrom, 1979). The use of heavy
metal contaminated food crops is an important food chain path
for exposure of humans to heavy metals (Singh and Kalamdhad,
2011). The farming of such plants which have a great ability of
removing elements form soils reflects a possible threat as the
plant tissue can accumulate heavy metals (Jordao et al., 2006).
When metabolization of the heavy metals is not done by the
body and they get accumulate in the soft tissues, they become
toxic (Sobha et al., 2007). It is reported that the heavy metals are
responsible for encouraging tumor and mutations at larger
extents in animals (Degraeve, 1981). Heavy metals have the ca-
pacity of creating genetic damage to germ cells animals. (Hayes,
1984; Groten and Vanbladeren, 1994; Wagner, 1993). Heavy
metals are tremendously toxic in living beings even in smaller
amount. Consumption of food or water drinking with very great-
er grade of heavy metals persistently inflames the stomach
which results as diarrhea and vomiting. Similarly, more amount
of Lead (Pb) may be responsible for reducing response time, and
outcome in anemia, a disease of blood in humans (ATSDR, 1993).
Contaminated food by heavy metals can harshly decrease some
vital nutrients in the body which decrease immunological defens-
es, reduced psychosocial abilities, growth delay, incapacities
related with malnutrition and larger incidence of upper gastroin-
testinal cancer degrees (Iyengar and Nair, 2000; Türkdogan et al.,
2003; Arora et al., 2008). Cadmium, Copper, Lead, Nickel and
Zinc are the heavy metals which can result in deadly health com-
plications in humans when contact is long termed (Reilly, 1991).
These heavy metals have lengthy biotic half-lives and also these
can store in many organs of the body and so results in irritating
side effects (Jarup, 2003; Sathawara et al., 2004; Ata et al., 2009).
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PHYTOREMEDIATION PROCESSES
The diverse activities of plants and their related rhizosphere
bacteria on pollutants comprise phytoextraction, phytostabili-
zation, phytodegradation, rhizodegradation, rhizoltration and
phytovolatilization (Salt et al., 1995; USEPA, 2001).
Phytoltration or rhizoltration
It is dened as the use of plants either terrestrial or aquatic; to
absorb, concentrate, and precipitate pollutants from polluted
aqueous sources with low contaminant concentration in their
roots. Partially detoxication of industrial release, agronomic
runoff, or acid mine drainage can be achieved by rhizoltration.
Rhizoltration may be applicable for lead, cadmium, copper,
nickel, zinc and chromium, which are chiey engaged with in the
roots (Chaudhry et al., 1998; USPA, 2000). There are various
benets of rhizoltraion like it can be used as in-situ or ex-situ
applications and numerous species are also applicable other
than hyperaccumulators. Plants like sunower, Indian mustard,
rye, tobacco spinach and corn have been tested for their capa-
bility to eliminate lead from efuent, with sunower having the
highest ability. It is proved by the tests that Indian mustard has
ability to remove a varied concentration range of lead (4-500
mg/l) (Raskin and Ensley, 2000). A number of species of
Sargassum biomass (nonliving brown algae) was found to be an
effective biosorbent for heavy metals, like Cu and Cd (Davis et
al., 2000). Tomato and tobacco roots gathered from eld-grown
plants were found greatly effective bioadsorbents that could
adsorb strontium (Sr) from an aqueous solution of SrCl2. Tang
and Willey (2003) examined the plant uptake of 134Cs. Plants
from the Asteraceae family accumulated great concentrations
of radiocesium than Beta vulgaris and provided a new applicant
for phytoremediation of radiocesium-polluted soils. Zurayk et al.
(2001) assessed the role of wetland plants (Nasturtium ofcinale,
Mentha longifolia, Veronica beccabunga, and Cardamine uliginosa)
in aquatic phytoremediation of Cr and the result was that Cr
was chiey stored in roots with slight shoot translocation.
Accumulation had gotten 6700 mg Cr kg−1 in roots of V.
beccabunga.
Phytostabilisation
Phytostabilisation is typically applicable in decontamination of
soil, residue and sludges (USPA, 2000; Mueller et al., 1999) and
depends on roots skill to limit pollutant movement and
bioavalability in the soil. It can happen through the sorption,
precipitation, complex action, or metal valence decline. Reduc-
ing the quantity of water percolating by the soil matrix is the
chief resolution of plants which may form dangerous leachate
and prevent soil erosion and distribution of the noxious metal to
other areas. A compact root system stabilizes the soil and avoids
erosion (Berti and Cunningham, 2000). Phytostabilisation does
not remove the pollutant from the soil, but it reduces the
characteristic hazard of the pollutant (Li et al., 2000). It is
valuable for the decontamination of lead (Pb) chiey along with
arsenic (As), chromium (Cr), cadmium (Cd), copper (Cu) and zinc
(Zn). The disposal of dangerous material/biomass is not required
(USPA, 2000) and it is very useful when quick immobilization is
desired to preserve ground and surface waters are some of the
benets linked with this technology. Reduction of soil erosion
and declination the amount of water available in the system is
also due to the presence of Plants (USPA, 2000). Polluted land
areas affected by mining activities and Superfund sites have
been treated by phytostabilization. Jadia and Fulekar (2008)
conducted the experiment on phytostabilization in a green-
house, using sorghum to remediate heavy metal polluted soil
and the vermicompost generated by the experiment was used in
contaminated soil as a natural fertilizer. The study reviled that
at the higher concentration of 40 and 50 ppm the growth was
unfavorably affected by heavy metals, on the other hand, the
lower concentrations (5 to 20 ppm) inspired enhanced plant
biomass and shoot growth. Reduced leaching by stabilization of
soil and immobilizing and concentrating heavy metals into the
roots was done by the large surface area of brous roots of
sorghum and intensive penetration of roots into the soil.
Phytoextraction
Phytoextraction is the nest method to eliminate the contami-
nation primarily from soil and separate it, without harming the
soil arrangement and productiveness. It is also called phytoac-
cumulation (USPA, 2000). As the plant absorb, concentrate and
precipitate toxic metals and radionuclide from contaminated
soils into the biomass, it is appropriate for the remediation of
diffusely contaminated areas, where noxious waste occur solely
at comparatively low concentration and supercially (Rulkens et
al., 1998). Numerous methodologies have been used but the two
simple strategies of phytoextraction, which have lastly devel-
oped are; i) Chelate assisted phytoextraction or induced
phytoextraction, in which non-natural chelates are added to rise
the movement and uptake of metal pollutant. ii) Nonstop phyto-
extraction, in this the elimination of metal depends on the natu-
ral capacity of the plant to remediate; only the number of plant
growth repetitions are controlled (Salt et al., 1995, 1997). Most
plants do not accumulate metals to noteworthy levels in above-
ground biomass, while metal-tolerant plants are comparatively
common. However, some plant species are skilled of hyper
accumulation of metal ions as they are capable to take up and
accumulate metals at concentrations of higher than 0.1 percent
(by dry weight of plant) or greater (Brooks, 1998). Hyperaccu-
mulators have been used as applicants for phytoextraction due
to their capability to uptake metals and translocate those metals
from soil into harvested above-ground biomass (Kumar et al.,
1995). A range of terrestrial plant species have been recognized
as having the capability to hyper accumulate certain metals
from soil including Brassica, Aeollanthus, Thlaspi, Apocynum and
Paspalum among others (Baker, 1995; Kramer et al., 1996).
Phytovolatilization
Phytovolatilization is the process in which plants take up
pollutants from the soil, convert them into volatile form and
transpire them into the atmosphere. Phytovolatilization take
place as growing trees and other plants absorb water and the
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Vinod Kumar and Piyush Kumar /Arch. Agr. Environ. Sci., 4(3): 326-341
organic and inorganic pollutants. Some of these pollutants can
pass through the plants to the leaves and volatilize into the
atmosphere at relatively low concentrations (Mueller et al.,
1999). Phytovolatilization has been mainly used for the removal
of mercury; the mercuric ion is converted into less noxious
elemental mercury. The drawback is mercury released into the
atmosphere is expected to be recycled by precipitation and then
redeposit back into bionetwork (Henry, 2000). Phytovolatiliza-
tion of selenium can be done by Indian mustard and canola
(Brassica napus) and have been reported that it accumulate the
selenium (Bañuelos et al., 1997).
Phytodegradation
One of the most signicant phases in the procedure of remedia-
tion of organic pollutants is degradation of the pollutant.
Degradation of a compound denotes to its breakdown into
smaller constituents, or its conversion to a metabolite (Arthur et
al., 2005). Plants have enzymes which can breakdown and trans-
form ammunition wastes, chlorinated solvents like trichloroeth-
ylene and other herbicides. The enzymes are typically dehalo-
genases, reductases and oxygenases (Black, 1995). In a phytore-
mediation, degradation can occur in the rhizosphere (soil
surrounding plant roots), as well as inside the plant itself. The
latter, phytodegradation, occurs when a plant absorb the
contaminant into the tissues, and enzymes within the plant got
engaged into converting the compound, frequently into
molecules that can be more readily cracked down or released in
root exudates. Enzymes exuded from microorganisms or plants
are applicable in rhizodegradation or transformation of the
pollutant in the rhizosphere, in soil organisms such as bacteria
and fungi (for example, Schultz et al., 2001; Siciliano et al., 1998).
Moreover, degradation of organics done by the microorganisms
can be supported by plants, by the nutrient potential of plant
root exudates (Kumar et al., 2019b).
Phytoremediation studies
Various plant species which can accumulate the heavy metals
has been comprehensively studied and to date substantial
growth has been made in the area of hyper accumulation of
heavy metals by plants. Different plant species has different
mechanisms of metal accumulation, exclusion and compartmen-
tation (Lone et al., 2008). Elimination of contaminants from the
polluted waters by accumulation into plant biomass is termed as
Rhizoltration. Hyperaccumulators can be utilized for phytore-
mediation of lethal and dangerous overwhelming metals and in
addition for phytomining of valuable substantial metals, (for
example, Au, Pd and Pt). The utilization of hyper-accumulators
for phytoremediation may result in the production of a
bio-mineral of some business incentive to adapt to a portion of
the expenses of soil remediation (Brooks et al., 1998). For
specic heavy metals some plants have natural capability of
hyper accumulation. These plants of having such a capacity are
known as natural hyperaccumulators. Then again, the accumula-
tion capacity of a few plants for particular heavy metals can be
improved by their genetic change through biotechnological
techniques. Such genetically altered plants have indicated
promising outcomes for phytoremediation of some heavy
metals. In any case, since some environmental researchers are
doubter about the bio-safety of genetically modied organisms
(GMOs), subsequently there is an overall worry about the
commercialization of such items (Prakash et al., 2011).
Phytoremediation of heavy metals from the contaminated
water by numerous aquatic species have been acknowledged
and tested. Some of the hyperacuumulators are duck weed
(Lemna minor L.), water hyacinth (Eichhornia crassipes), sharp
dock (Polygonum amphibium L.), water dropwort [Oenathe
javanica (BL) DC], calamus (Lepironia articulate), pennywort
(Hydrocotyle umbellate L.) water lettuce (P. stratiotes), (Vara and
Freitas, 2003). Removal of Cd, Ni, Pb, Cr, Cu and Zn by the roots
of Indian mustard is found to be effective and sunower can
eliminate Pb, Cs-137, U, and Sr-90 from the solutions which are
hydroponic (Zaranyika and Ndapwadza, 1995; Wang et al.,
2002; Vara and Freitas, 2003). The efciency of duck weed was
examined by Zayed et al. (1998) for the removal of Cd, Ni, Cr,
Cu, Pb and Se from the solution which was nutrient-added. It
was found that duck weed is a decent accumulator for Cd, Se
and Cu, but accumulate Cr moderately and poorly accumulate
Ni and Pb.
Water hyacinth (Eichhornia crassipes) claims a well-built stringy
root framework and substantial biomass and has been effective-
ly utilized in wastewater treatment frameworks to enhance
water quality by diminishing the levels of natural and inorganic
nutrients. Eichhornia crassipes was found to be effective in the
elimination of Pb from industrial efuents in a green-house
study (Santos and Lenzi, 2000). This plant can likewise decrease
the concentrations of heavy metals in corrosive mine water
while showing few indications of poisonous quality. Water
hyacinth amasses follow components, for example, Ag, Pb, Cd,
etc., and is benecial for phytoremediation of wastewater
contaminated with Cd, Cr, Cu and Se (Zhu et al., 1999).
Five wetland plant species, i.e., sharp dock, duckweed, water
hyacinth, water dropwort and calamus was investigated by
Wang et al. (2002) with the help of pot experiment for their
conceivable use in improving the contaminated waters. The
results revealed that sharp dock was a decent accumulator of N
and P Duckweed and Water hyacinth largely accumulated Cd
with a concentration of 14200 and 462 mg/kg, respectively.
Water dropwort accumulated the highest concentration of Hg,
whereas the calamus attained Pb (512 m/kg) considerably in its
roots. Hydroponic examinations to explore the uptake of As, Cr,
Hg, Ni, Pb and Zn by water hyacinth from the aqueous solution
at the concentrations extending from 5 to 50 mg/L was conduct-
ed by Ingole and Bhole (2003) and found that in aqueous
solutions containing 5 mg/L of As, Cr and Hg, the most extreme
uptake was 26, 108 and 327 mg/kg dry weight of water
hyacinth, respectively. Pteris vitta commonly known as Brake
fern among the ferns is well recognized for hyperacccumulation
of As from polluted soils and waters. It can collect up to 7500 mg
As/kg on a polluted site (Ma et al., 2001) without indicating
poisonous quality side effects.
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Vinod Kumar and Piyush Kumar /Arch. Agr. Environ. Sci., 4(3): 326-341
Plant species Parameter
treated
Site/
Location Treatments Results/Key ndings References
R. carnea,
A.gramineus,
A. orientale,
A.calamus,
I.pseudacorus,
L. salicaria
Cr, Cu,
Mn, Pb,
Cd, Fe
Sewage of some
Factories in Jinhua,
Zhejiang, China.
Total nitrogen (TN),
Total phosphorus (TP),
Biological oxygen
demand (BOD5),
Chemical oxygen
demand (COD)
Commitment of plants to TN decrease rose from 11.24% to 21.95%
at that point diminished to 17.95% as time expanded. The commit-
ment of plants reduced from 33.15% at 5 d to 19.97% at 10 d, and
after that to 11.29% at 15 d, which recommends the hydrophytes
have a trait for fast retaining phosphorus in short time (inside 5 d).
The maximum elimination noticed in the I. pseudacorus group,
cleaning ability Cr > Pb > Cd > Fe > Cu > Mn, which are 24.58%,
21.30%, 15.37%, 1.94%, 1.54%, 0.5% greater than CK (unplanted
pots watered with sewage taken as Control), respectively.
Zhang
et al. (2007)
E. crassipes,
L. minor,
S. polyrrhiza
Hg and As
Tropical Opencast
Coalmine Efuent
(coal mines of
Northern
Coalelds
Limited (NCL),
Singrauli, (India).
Hg and As
Concentration
Removal by
phytoremediation
Maximum removal of Hg and As from the efuent by E. crassipes (80%
and 71% and As and Hg, respectively). Translocation factor of E.
crassipes, L. minor and S. polyrrhiza was recorded as 0.73, 0.77, and
0.61 for arsenic and also 0.64, 0.65, and 0.65 for mercury separately
on 20th day.
Mishra
et al. (2008)
L. minor,
A. pinnata,
E. crassipes
Cu, Cr, Fe, Mn,
Ni, Pb, Zn, Hg,
Cd
The Singrauli
region, G.B. Pant
Sagar, India.
Physicochemical
characteristics of the
water of G.B. Pant Sagar
contaminated with
industrial efuent,
Heavy metal
analysis in efuent,
water, and sediments
The rate diminish for various metals was in the scope of 25% to
67.90% at Belwadah, 25% to 77.14% at Dongia nala. 25% to 71.42%
at Ash lake site of G.B. Gasp Sagar. The rate decrease recorded at 40,
80, and 120 m additionally considered weakening component.
Rai (2010)
A. dubius
Cr, Hg, As, Pb,
Cu and Ni
Laboratory scale
study
Bioaccumulation of
heavy metals from leach-
ate.
Study demonstrated that it can endure As levels of 75 ppm, and can
likewise translocate the majority of the As to the elevated parts of
the plant up to 100 ppm. In this way the end from this examination
was that A. dubius is a hyperaccumulator of As. The impact of intro-
duction of A. dubius to Pb indicated uniform development rate at 25
and 75 ppm of Pb, and somewhat bring down development rate at
100 ppm.
Mellem
et al. (2012)
A. pinatta and L. minor
Fe, Mn, Cu, Zn,
Ni, Pb, Cr and
Cd
Dudhichua mining
Site, NCL, Singrauli
,India)
Phytoremediation of the
coalmine efuent
In efuent phytoremediated by Azolla, the amount of Mn and Cu
diminished radically by 58.5% and 55% individually inside a brief time
of 24h. But Fe, measures of Mn, Cu, Zn, Cr and Cd lessened consider-
ably by 87%, 82.84%, 71.85%, half and 61.7% individually inside
initial four days and from that point the decline was unimportant.
Abatement level of Fe, Ni and Pb was beneath half Fe (48.02%), Ni
(38.38%) and Pb (37.7%). This examination demonstrates that A.
pinnata could disinfect Mn, Cu, Zn, Cr and Cd more rapidly than Fe, Ni
and Pb. Then again, in Lemna-phytoremediated gushing the centrali-
zation of Fe, Mn, Cu, Zn and Ni diminished by 60%, 76.9%, 80.8%,
66% and 78.2% separately after 4d.
Bharti and
Banerjee (2012)
Table 1. Phytoremediation of different heavy metals by various hyperaccumulator plants at laboratory scale.
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Vinod Kumar and Piyush Kumar /Arch. Agr. Environ. Sci., 4(3): 326-341
Eichhornia
crassipes Cd and Zn Lab scale study
Removal of Cadmium
and Zinc
Water hyacinth aggregated the most noteworthy grouping of metals in
roots (2044 mg/kg for Cd and 9652.1 mg/kg for Zn). Be that as it may,
moderately little Cd (113.2 mg/kg) was translocated to the shoot, while Zn
was translocated at a considerably higher xation (1926.7 mg/kg). This
outcome exhibited that Zn was signicantly more portable than Cd.
Lu et al. (2004)
E. crassipes
and P. stratiotes
Al, As, Cd, Cr,
Cu, Fe, Mn, Pb
and Zn
Foundry located in
Hayatabad Industrial
Estate, Peshawar
Phytoremediation of
steel foundry efuent
Deposition of As was in the scope of 0.8132 mg/kg to 1.3124 mg/kg in P.
stratiotes and E. crassipes, separately; 0.7706 mg/kg and 0.6013 mg/kg As
was caught up in the shoots of P. stratiotes and E. crassipes, while the roots
of P. stratiotes and E. crassipes aggregated 0.0426 mg/kg and 0.7111 mg/
kg As, separately. P. stratiotes and E. crassipes saved Cd in their tissues to
the degree of 0.0139 mg/kg and 0.0231 mg/kg, individual. The shoots of
the test plants put away 0.0018 mg/kg Cd each. Similarly, these plants
gathered 0.0121 mg/kg and 0.0123 mg/kg in the roots, separately. Cr was
stored in E. crassipes and P. stratiotes at concentrations of 1.7826 mg/kg
and 1.1778 mg/kg separately; 0.0934 mg/kg and 0.7277 mg/kg of the ag-
gregate Cr was kept in the shoots of P. stratiotes and E. crassipes. So also,
1.0844 mg/kg and 1.0549 mg/kg stayed in the roots of test plants, individ-
ually.
Aurangzeb
et al. (2014)
Canna x. generalis Phosphorus
and nitrogen Sewage Treatment Plant
Phytoremediation of
Phosphorus and
nitrogen
The pH somewhat turned out to be more alkaline amid the treatment, it
was seen to have hardly expanded from 6.73 in the channel to 6.76 at the
wetland outlet. Nitrate evacuation is anyway at a higher greatness with
an extreme decrease of around 52% in its incentive after the treatment.
The mean phosphate decrease in the treatment is 8.9% while the wetland
indicates irrelevant expulsion of 1% phenolic compound following a
month.
Ojoawo
et al. (2015)
Phragmites
australis,
Typha angustifolia
Cd and Pb Bogdanka river catchment
Accumulation of Cd and
Pb in water, sediment
and two littoral plants
High collection of Cd and Pb in plant organs was noticed toward the nish
of the season. In addition, a higher leaf/rhizome translocation proportion
was noted on account of Pb in P. australis. The translocation of estimated
parameters was additionally for the most part higher in T. angustifolia
plants. In general, plants revealed potential for phytoremediation in char-
acteristic conditions, when moderately low Cd and Pb concentration hap-
pened.
Borowiak
et al. (2016)
Eichhornia
crassipes
pH, EC, TDS,
BOD, COD,
TKN, P, Ca2+,
Mg2+, Na+, K+
Star paper mill efuent,
Saharanpur
phyto-kinetic removal
of pollutants of paper
mill efuent
The results showed that E. crassipes signicantly reduced the contents of
EC (62.23%), TDS (72.54%), TKN (89.27%), P (72.39%), Ca2+ (51.79%),
BOD5 (79.93%), COD (85.66%), Mg2+ (51.02%), Na+ (57.10%) and K+
(71.47%) from the paper mill efuent at 2 months of phytoremediation
experiments.
Kumar
et al. (2017)
Table 1. Continued……….
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Vinod Kumar and Piyush Kumar /Arch. Agr. Environ. Sci., 4(3): 326-341
Table 1. Continued……….
Eichhornia
crassipes Zn, Ni and Cr Laboratory scale study
A stock solution (1000
μg/L) each was
prepared in distilled
water with analytical
grade K2Cr2O7, ZnCl2,
and NiCl2.6H2O
The least uptake of Zn was 1.6 μg/mg d.w. of Eichhornia crassipes at
600 μg/L at a 2h time break of which 41% was concentrated by the
shoot and most of the 60% by the root. The uptake amount augment-
ed about vefold after 15 days at the same concentration of test
metal. After 15 days of treatment, Zn uptake was 18.2 μg/mg-1 d.w. at
6000μg/L test metal level.
Irfan and AlAtawi
(2017)
Pistia stratiotes L.
TKN, TP, EC, TDS,
BOD, COD, Ca2+,
Mg2+, Na+, K+ ,
MPN, SPC,
Uttam Sugar Mills Ltd.
Libberheri, Roorkee,
Haridwar
sugar mill efuent
Use of P. stratiotes was found to have the potential to eliminate chief
pollutants such as COD, BOD, P, and N from efuent of sugar mill.
Application of P. stratiotes plant biomass after phytoremediation
process was found to have great efciency to yield biogas.
Kumar
et al. (2017)
Eichhoria
crassipes,
Pistia stratiotes L.
Spirodela
polyrhiza
TSS, TDS TP, DO,
BOD, COD, EC,
PO43-, SO42-, PH,
Na, K, Pb, Cu, Fe,
As, Zn, Cr, color,
The Abed Textiles
Processing Mills Limited
at Ghoradia in Narsingdi
Sadar, Bangladesh
Treatment of Textile
Wastewater
Eichhornia crassipes was found most efcient in reducing TDS, EC, TSS
and BOD and COD. Assorted treatment was most operative in
decreasing pH and amongst the macrophytes and algae; E. crassipes
had best potential in reducing pH. Spirodela, Nostoc, Pistia, and
Eichhornia, all indicated efciency in eliminating heavy metals, though,
Eichhornia was utmost effective because of its ability to stock greater
quantity of heavy metals than other algae and macrophytes.
Roy et al. (2018)
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Vinod Kumar and Piyush Kumar /Arch. Agr. Environ. Sci., 4(3): 326-341
Rai (2008) conducted an experiment to encounter phytoremedi-
ation of Hg and Cd from industrial efuents using A. pinnata, an
aquatic free oating macrophyte. The conclusion of the experi-
ment was that the A. pinnata has a tremendous potential of
phytoremediation. Azolla pinnata accumulated heavy metals,
i.e., Hg and Cd (70–94%) and may be utilized as a bioaccumula-
tor to control heavy metals in chlor-alkali efuent and ash
slurry. Mishra et al. (2008) investigated tropical opencast
coalmine efuent and studied the phytoremediation of heavy
metals mercury and arsenic through naturally occurring aquatic
macrophytes and concluded that three species of aquatic mac-
rophytes L. minor, E. crassipes and S. polyrrhiza showed extremely
operative in eliminating heavy metals from the efuent of coal
mining throughout 25 days experimentation. The macrophytes
eliminated considerable quantities of the Hg and As. However,
these metals had led their poisonous effects by reducing chloro-
phyll, protein and Nitrogen, Phosphorus, potassium, content of
the experimental macrophytes.
Roots of the macrophytes indicated improved collector of the
heavy metals as they always exposed to greater quantity of Hg
and As in contrast to the leaves. Rai and Tripathi (2009)
performed a comparative valuation of Azolla pinnata and
Vallisneria spiralis in Hg elimination from G.B. Pant Sagar and
concluded that Aquatic plants might be capable applicant for
phytoremediation of Hg from thermal power plant, coalmine
and chlor-alkali efuent. The results got suggested that both A.
pinnata, and V. spiralis, a can eliminate Hg from industrial
discharges. A. pinnata taken up Hg more prociently than V.
spiralis and is thus suggested for elimination of Hg from polluted
waters. Being submerged macrophytes V. spiralis may be more
valuable to eliminate Hg from sediments in natural/eld sites.
Rai (2009) assessed a microcosm examination on phytoremedia-
tion of Chromium Using Azolla Pinnata. The study concluded
that Azolla pinnata has the wonderful capability to accumulate
Cr (III) and Cr (VI) (70–88%) and can be utilized as a bioaccumu-
lator to control heavy metals in, coalmine, ash slurry and
tannery efuent. Prasad and Singh (2011) performed an experi-
mentation to nd out the metabolic responses of Azolla pinnata
to cadmium stress and concluded that Azolla can be utilized for
the treatment of heavy metal to condent degree and as a
sustainable performance to eliminate the heavy metal from
contaminated sites. Baruah et al. (2014) studied the Phytoreme-
diation of Arsenic by Trapa natans in a Hydroponic System and
the study concluded that T. natans is a decent hyperaccumulator
of arsenic in the roots as well in aboveground plant portions.
Irrespective of the concentration, the roots were found to be
best effective in the taking up of arsenic. While some external
symptoms of poisonousness were detected at greater arsenic
concentration, the plants were incapable to ght arsenic toxicity
because of proline synthesis and amassing. Study concluded
that T. natans can be suggested for the elimination of arsenic
from polluted water. Kooh el al. (2016) used Azolla pinnata for
the Separation of poisonous rhodamine B from aqueous solution
by adsorption method and reviled that thermodynamics study
showed endothermic, spontaneity and physisorption-dominant
adsorption process. The adsorbent, while showed a reduction in
the rst cycle of renewal, was able to afterward uphold up to
ve cycles of renewal with distilled water, HNO3 and NaOH.
Akinbile et al. (2016) conducted an experiment to nd out the
Phytoremediation of domestic wastewaters in constructed
wetlands using Azolla pinnata and concluded that Azolla pinnata
had proven to be a very reliable in treating municipal
wastewater going by the results obtained. Kumar et al., (2017)
inspected the potential of Eichhornia crassipes using the paper
mill efuent and found Eichhornia crassipes a very promisive
agent for the phytoremediation of paper mill efuent. They
reported that the greatest reduction was detected in the EC
(62.23%), COD (85.66%), TDS (72.54%), BOD (79.93%), TKN
(89.27%), Ca2+ (51.79%), P (72.39%), Mg2+ (51.02%), Na+
(57.10%) and K+ (71.47%). Kumar et al. (2017) did an experi-
mental and kinetics study for phytoremediation of sugar mill
efuent using water lettuce (Pistia stratiotes L.) and used its
biomass for the production of biogas. The study concluded that
P. stratiotes achieved remarkable decrease in nutrient (TKN,
72.86%; TP, 71.49%) and pollutant load (EC, 25.69%; BOD,
69.40%; COD, 61.80%; TDS, 57.26%; Ca2+, 56.79%; Mg2+,
55.01%; Na, 42.86%; K, 54.38%; MPN, 78.13%; SPC, 60.13%)
from 75% sugar mill efuent at the end of the experimentation
(Table 1 and 2).
NECESSITY OF PHYTOREMEDIATION
There is an urgent need for alternative, cheap and efcient
methods to clean up heavily contaminated industrial areas.
Phytoremediation, using plants to bio remediate infected soil,
water, and air, has emerged as an inexpensive, noninvasive, and
publicly acceptable manner to address the elimination of
environmental contaminants (Boyajian and Carreira, 1997;
Singh et al., 2003). For countries like India, which are still
developing, such capabilities of the aquatic macrophytes could
be of huge importance where many shallow ponds and
marshlands are having unfavorable condition for traditional sh
farming and agriculture (Mohan Ram, 1978). Various species
show different behavior regarding their efcacy to accumulate
elements in roots, stems and/or leaves. Therefore, it will be very
useful to nd out the better trace element accumulator and its
organ that absorbs the highest amount of trace factors
(Baldantoni et al., 2004). By the wetland treatment the
production of edible biomass of aquatic macrophytes can give
back economic returns to harvester. These economic paybacks
can be realized by the generation of “bio-gas”, animal feed, ber
for paper making, compost etc. (Lakshman, 1987). Phytoremedi-
ation of water bodies may be grabbed as an opportunity along
with ordinary treatment approaches like ion exchange resins
and electrodialysis, microltration, chemical precipitation,
sedimentation, and reverse osmosis (Rai, 2009). The treatment
of the heavy metal contamination by modern machineries
is very expensive for many developing countries like India
which may not be able to meet the expense of the huge
costs required for the treatment (Rai and Tripathi, 2007;
Rai, 2008).
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Vinod Kumar and Piyush Kumar /Arch. Agr. Environ. Sci., 4(3): 326-341
Table 2. Biomonitoring of some sites by means of phytoremediation by naturally occurring hyper accumulator plants.
Plant species/ Soil/
Water sample Site/Location Parameters/
heavy metals Conclusion/Key Finding References
Bergia odorata,
Hydrilla verticillata,
Ipomoea aquatic, Najas
graminea,
Nelumbo nucifera,
Phragmites karka,
Typha angustata, Vel-
lisnaria spiralis
Nal Sarovar Bird Sanctuary,
Gujarat, India
Cd, Co, Cu, Ni,
Pb, Zn
Ipomoea sp. has the highest capability with respect to concentrating trace element with maximum concentra-
tion (639.04 mg l-1) of Zn and least concentration of Cd (0.21 mg l-1), trailed by Najas, Vellisnaria, Nelumbo,
Typha, Phragmites and Hydrilla spp. Alternately, Bergia sp. has the most reduced number of trace element focus
with high centralization of Zn (128.63 mg l-1) and low grouping of Cd (0.40 mg l-1).
Kumar
et al. (2006)
E. colonum, E. cras-
sipes, H. verticillata, I.
aquatica, N. nucifera,
T. angustata, V.
spiralis
Pariyej Community Reserve,
Gujarat, India
Cd, Co, Cu, Ni,
Pb, Zn
The estimations of the proportion between component concentrations in the sediments and those in the water
were lower (1.55-13.16 ppm) for Pb, Cd, Cu, Ni and Zn, while that of Co was watched high (19.81 ppm). The
stems and additionally leaves of submerged plants aggregated lower concentrations of trace elements than
roots which were well substantiated in other words with the discoveries of Baldantoni et al. (2005). In this man-
ner, among the chose plant species, T. angustata and I. aquatica seem, by all accounts, to be the best observing
species because of their accessibility in PCR.
Kumar
et al. (2008)
Agricultural soil Near Bindal river, Dehradun, india. Pb, Zn, Cu, Ni,
Cr, Cd Hg
Centralization of Zn was more and that of Cr was least in both regular and waste water inundated soils in
Dehradun. The centralization of Zn, Cd and Cr expanded essentially in waste water ooded soil close Bindal
waterway. Nonetheless, the expansion in the convergence of Pb, Cu, and Ni was insignicance.
Pathak
et al. (2010)
Sewage water
irrigated agricultural
soil.
Near sewage treatment plant,
Jagjeetpur, Haridwar and Control
site tube well-water irrigated agri-
cultural soil near at Gurukula Kangri
University, Haridwar
Pb, Cu, Fe, Cd,
Zn , Cr
The sewage water enhanced the organic carbon (+30.48%) and ripeness status as far as P (+59.97%), TKN
(+87.5%) and K (+25.77%) of the soil which are the fundamental nutrients (NPK) for the development of plants.
It was likewise conrmed that the sewage water system to a great degree expanded the measure of heavy
metals, for example Cu (+253.17%), Ni (+128.29%), Zn (+696.03%) and Pb (+98.95%) in the soil. As compared
with the reasonable permissible limits of Indian standards, the concentration of these metals in the soil was
below the limit.
Pathak
et al. (2011)
Agricultural soil irri-
gated by sewage
water and tube well
water
Rewari City
Physico-
chemical and
heavy metals
Utilization of sewage water enhance the richness status of the soil as it increment the yield of Rabi crops con-
trasted with irrigation done by tube-well water for the most part because of increment in OC (+49.19), K
(+49.02), N (+109.09) and P (+72.08), which are essential nutrients for the correct development of plants and
products. Be that as it may, the main danger of utilizing sewage water can be seen in expanding level of heavy
metals content in the soil Cd (+27.41), Fe (+51.40), Pb (+106.64), Cu (+232.27) and Zn (+470.05), which are in
the limits of Indian Standard, yet long period utilization of untreated sewage water surely make danger of
accumulation of heavy metals in the soil.
Tobriya (2015)
Sediment, water, and
phoomdi from Loktak
Lake
Loktak Lake (Ramsar site), north-
east, India Fe Mn Zn Cu
Results prescribe the requirement to treat the wetland freshwater for local utilization and horticultural appli-
cations because of Fe tainting. Additionally, high BAFs and great TFs found for phoomdi demonstrate its prom-
ising potential in phytoremediation of nutrients and metals and use in re-vegetation of waterlogged polluted
sites and developed wetlands intended for wastewater treatment.
Meitei
et al. (2016)
SIDCUL efuent
The State Infrastructure and
Industrial Development
Corporation of Uttarakhand
Limited (SIIDCUL), Haridwar
Cd, Cr, Cu, Fe,
Mn, and Zn
The higher assimilations of heavy metals in SIDCUL efuent are likely due to close to the disposal site. The
outcome demonstrated that accumulation of heavy metals is ceaselessly expanding in sediments and soil close-
by efuent channel. Heavy metal concentrations are greatest in amount close to the disposal site and diminish-
ing with distance 34. In aquatic frameworks metals are transported either in soils or on the surface of suspend-
ed sediments 35. The accumulation of Cd, Fe, Cr, Cu, Mn and Zn in sediments are shifted by the rate of particle
sedimentation, the rate of heavy metals deposition, the particle size and the presence or absence of organic
matter in the sediments.
Kumar and
Thakur (2017)
338
Vinod Kumar and Piyush Kumar /Arch. Agr. Environ. Sci., 4(3): 326-341
Conclusion and recommendation
Soil and Water pollution is a serious worldwide concern; to
encounter this problem effective remediation methods are
needed. Phytoremediation is environmental-friendly, cost-
effective and solar-driven technique for heavy metal elimina-
tion from aquatic environments with decent community
acceptance. Aquatic macrophytes are effective tools to elimi-
nate heavy metals from aquatic bodies and have drawn a lot of
responsiveness throughout the world. Both live and dead
macrophytes work as a tool of bio-ltration for the heavy
metals, in both the natural and manmade wetlands. The problem
of discarding of biomass and periodic growth of aquatic macro-
phytes are few of the limits in the assignment of phytoremedia-
tion technique from the laboratory to the eld of work. Though,
an environmental friendly model has been established by the
various works that may control some of the limitations. Biomass
of macrophytes can be utilized for various productive applica-
tions. Industrial discharges and secondary-treated municipal
wastewater can be improved with the application of aquatic
macrophytes and disposed biomass may be reused for the
production of biogas. Biodiversity prospecting, X-ray diffraction
spectroscopy and Genetic engineering are encouraging future
visions concerning the use of aquatic macrophytes in
phytoremediation applications. A combined methodology and
multidisciplinary approach may enable this developing technol-
ogy to become the new edge in environmental science and
technology.
Open Access: This is an open access article published under the
terms and conditions of Creative Commons Attribution-
NonCommercial 4.0 International License which permits non-
commercial use, distribution, and reproduction in any medium,
provided the original author(s) if the sources are credited.
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