Transcript Slide 1

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Treatment of polluted soil with
lead by Bio-phytoremediation
technique
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• Dr. Mohammed Elanwar Osman
Professor of Plant Physiology, Botany Department,
Faculty of Science, Tanta University
• Dr. Mohammed Ismail Elshahawy
Professor of Soil, Water and Environment, Research
Department, Agricultural Research Sakha Station
• Dr. Soad El-Feky
A. Professor of Plant Physiology, Botany
Department, Faculty of Science, Tanta University
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studying the effect of different pb levels on
growth and some stress markers and
metabolic activities in flax tissues.
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Studying the ability of flax plant to accumulate
and tolerate high concentrations of pb which
are often associated in polluted areas.
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Studying the ameliorative effect of some
biofeltilizers on growth, metabolic activities
and yield of flax grown
under high
concentrations of pb.
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• The objectives are to discuss the potential of
phytoremediation technique on treating heavy
metal-contaminated side, to provide a brief view
about heavy metals uptake mechanisms by plant, to
give some description about the performance of
several types of plants to uptake heavy metals and
to describe the fate of absorbed pb metal in plant
tissue.
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• Since the dawn of the Industrial revolution, mankind has been
introducing numerous hazardous compounds into the environment
at an exponential rate.
• These hazardous pollutants consist of a variety of organic
compounds and heavy metals, which pose serious risks to human
health.
• Heavy metals are primarily a concern because they cannot be
destroyed by degradation. Frequently, the remediation of
contaminated soils, groundwater, and surface water requires the
removal of toxic metals from contaminated areas .
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Heavy metals
• In an ecological research, any metal or metalloid that causes
environmental problem which cannot be biologically degraded should be
considered as a heavy metal. several HMs has reached toxic levels due
to
consequence
of
anthropogenic
activities.
(Padmavathiamma and Loretta, 2007)
• Fifty three elements fall into the category of heavy metal till date and
defined as the group of elements whose densities are higher than 5 g
cm3 and recognized as ubiquitous environmental contaminants in
industrialized societies . (Padmavathiamma and Loretta, 2007)
• The most common heavy metal contaminants are: Cadmium (Cd),
Chromium (Cr), Copper (Cu) Mercury (Hg), Lead (Pb), Nickel (Ni) and
Zinc (Zn). (Lasat et al., 2001)
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Lead
• lead represent one of the most frequently distributed heavy
metal pollutants on agriculturally exploited soils.
( Miroslav, et al., 2005)
• Among heavy metals, lead is considered one of the
dangerous environmental pollutants in soil, sediments, air
and water and considered one of the most difficult pollutants
to control. Over recent decades, the annual worldwide
release of lead 783,000 t .
(Abdul Ghani, 2010)
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Sources of Lead
• Frequent use in many industrial processes is the main reason for lead
contamination of the environment such as mining, smelting,
manufacture of pesticides and fertilizers, dumping of municipal sewage
and the burning of fossil fuels that contain a lead additive.
• Many commercial products and materials also contain lead including
paints, ceramic glazes, television glass, batteries, medical and electrical
equipment .
• The uses of lead for roofing and the production of ammunition has
increased from previous years .
• Total annual emission of lead by motor vehicles & industrial plants alone
throughout the world amounts more than half a million ton.
(Sharma and Dubey, 2005).
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Health Effects
• Lead is not only a toxic element but also can be
accumulated in plant organs and agricultural products.
(El-Beltagy, 1998)
• Also, introduction of this metal to man and animals through
drinking water or food will help in occurring many diseases
to them such as renal failure, brain and liver damage.
(Abdul Ghani, 2010)
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The effect of pb on plants has been studied by
several workers:-
• Soils contaminated with Pb cause sharp decreases in crop
productivity thereby posing a serious problem for agriculture.
(Johnson and Eaton,1980)
• At a high Pb content in soil, photosynthesis can also be
reduced due to both a lower carboxylase activity and the
effects on metabolites of the carbon reduction cycle.
(Carlson et al., 1995)
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• Enhanced level of lead in soil caused significant reduction in
plant height, root-shoot ratio, dry weight, nodule per plant,
chlorophyll
content
in
Vigna
radiata.
(Bekiaroglou and Karatagli, 2002)
• Pb toxicity leads to decreases germination percent, length
and dry mass of root and shoots, disturbed mineral nutrition
and reduction in cell division. (Paivoke, 2002)
• Exposure of maize varieties to excess Pb resulted in a
significant root growth inhibition though shoot growth
remained less affected. (Abdul Ghani, 2010)
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• Several methods are already being used to clean up the
environment from contaminants such as heavy metals, but
most of them are costly and far away from their optimum
performance such as chemical and thermal methods. Both
technically difficult and expensive that all of these methods
can also degrade the valuable component of soils .
• In recent years, scientists and engineers have started to
generate cost effective technologies which includes use of
microorganisms/ biomass or live plants for cleaning of
polluted areas called phytoremidiation.
(Qui et al., 2006)
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phytoremediation
• Phytoremediation is the use of plants to clean up a
contamination from soils, sediments, and water. Plants with
exceptional metal-accumulating capacity are known as
hyperaccumulator plants. (Tangahu, 2011)
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The hyperaccumulators
• Hyperaccumulators are model plants for phytoremediation as
they are tolerant to heavy metals. Metals hyperaccumulation
and tolerance are genetically inherited traits. Plants possess
a range of potential cellular mechanisms that may be
involved in the detoxification of heavy metals and thus
tolerance to metal stress. (Sarma , 2011)
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Types of phytoremediation technology
Each having a different mechanism of action
remediating metal-polluted soil, sediment or water:
for
1) Phytoextraction: Plants absorb metals from soil through
the root system and translocate them to harvestable shoots
where they accumulate. Pollutants accumulated in stems
and leaves are harvested with accumulating plants and
removed from the site.
2) Phytovolatilization: In this process, the soluble
contaminants are taken up with water by the roots,
transported to the leaves, and volatized into the
atmosphere through the stomata.
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3)
Phytostabilization: In this process, the plant roots and
microbial interactions can immobilized organic and some
inorganic contaminants by binding them to soil particles
and as a result reduce migration of contaminants to grown
water.
4)
Phytofiltration: Phytofiltration is the use of plants roots
(rhizofiltration) or seedlings (blastofiltration) to absorb or
adsorb pollutants, mainly metals, from water and aqueous
waste Streams.
5)
Phytodegradation: contaminants are taken up from
soil/water, metabolized in plant tissues and broken up to
less toxic or non-toxic compounds within the plant by
several metabolic processes via the action of compounds
produced by the plant.
(Sarma , 2011 )
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The mechanisms of heavy metals uptake by plant through phytoremediation technology. (Tangahu, 2011)
Advantages of phytoremediation technology. (Tangahu, 2011)
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The limitation of phytoremediation technology. (Tangahu, 2011)
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The presented project is focused on utilization
of some industrial crops as models for
phytoremediation problems
• Fiber crops are suitable for phytoremediation studies because they easily
accumulate heavy metals, and, in addition, they need not necessarily to
be processed in food chain, but they can be used for production of textile,
paper, paints or as a substitute of synthetic materials in car and aviation
industry as well as for non-woven textile production. There is a possibility
to use these plants as a fuel for energy production.
(Bjelkova, 1999)
• Fiber crops represent a promising group of plant species in
phytoremediation of heavy metals due to the possibility of the use of
contaminated biomass for a plethora of industrial products.
(Bjelkova, 2003)
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Flax: (also known as common flax or linseed)
Botanicalname: Linumu sitatissimu
Family: Linaceae (Linseed family)
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• Flax is suitable for growing in industrially polluted regions.
They remove considerable quantities of heavy metals from
the soil with their root system and can be used as potential
crops for cleaning the soil from heavy metals.
(Angelova, et al., 2004)
• Flax as an industrial crop utilized mainly for technical
purposes is a good candidate for heavy metal
phytoextraction from polluted soils. (Griga, et al., 2009)
• Flax which is a culture plant, is grown in order to benefit
from fiber and fat . Flax production is done approximately 56 million hectares in the world .70% of this production is to
produce oil and the rest is
to produce fiber.
(Tulukcu and Akay, 2010)
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Flax as hyperaccumulator are represented by
several reserches:
• In the uptake and accumulation of Cd and Pb. both fiber flax
and linseed well tolerated elevated heavy metal soil
concentrations without dramatic effect on the plant growth
and development. ( Miroslav, et al., 2005)
• Significant differences in Cd accumulation and tolerance
were found among commercial flax cultivars as
phytoremediation potential. (Hradilova, et al., 2010)
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• Even high soil Cd concentrations (1000 mg Cd kg−1 soil)
had not dramatic negative effect on plant growth and
development in flax. (Bjelkova, et al., 2011)
• Flax and linseed varieties variously accumulated particular
metallic elements, the highest concentrations were
recorded for Zn, followed by the Pb and Cd.
( Bjelkova, et al., 2011)
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Biofertilizers
• Biofertilizers are compounds that enrich the nutrient
quality of soil by the use of microorganisms which have a
symbiotic relationship with the plants. The main sources
of biofertilizers are bacteria, fungi, and cynobacteria
(blue-green algae).
• Biofertilizers are cost effective and renewable source of
plant nutrients to supplement the chemical fertilizers for
sustainable agriculture.
(Mishra and Dadhich, 2010)
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Compost
• Composting is a biological process in which organic
biodegradable wastes are converted into hygienic, hums
rich product (compost) for use as a soil conditioner and an
organic fertilizer. (Popkin, 1995)
• The addition of municipal solid waste compost to agricultural
soils has beneficial effects on crop development and yields
by improving soil physical and biological properties.
(Zheljazkov and Warman, 2004)
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