Throughout the world, there is a long tradition of farming intensively within and at the edge of cities (Smit et al., 1996). However, most of these peri-urban lands are contaminated with pollutants including heavy metals, such as Cu, Zn, Pb, Cd, Ni, and Hg. The major sources of heavy metal contamination in agricultural soils are discharge of effluents from domestic sources, coal-burning power plants, non-ferrous metal smelters, iron and steel plants, dumping of sewage sludge and metal chelates from different industries. Once the heavy metals are released into soils, plants can absorb and bio-accumulate these heavy metals and thereby affect humans and animals’ health upon consumption (Seghal et al., 2014). Hence, there is a great need to develop effective technologies for sustainable management and remediation of the contaminated soils. There are conventionally physicochemical soil remediation engineering techniques, such as soil washing, incineration, solidification, vapour extraction, thermal desorption, but they destroy the plant productive properties of soils. Moreover, they are usually extremely expensive, limiting their extensive application, particularly in developing countries and for remediation of agricultural soils (Kokyo et al., 2014). Phytoremediation has been increasingly receiving attentions over the recent decades, as an emerging, affordable and eco-friendly approach that utilizes the natural properties of plants to remediate contaminated soils (Wang et al., 2003). Phytoremediation includes phytovolatilization, phytostabilization, and phytoextraction using hyper-accumulator species or a chelate-enhancement strategy. The future of this technique is still mainly in the research phase, and many different Hyperaccumulators and crops that can be cultivated in heavy metal contaminated are still being tested.
Heavy metals and its effects on plants and environmentHaider Ali Malik
Heavy metals are natural constituents of the earth’s crust , but indiscriminate human activities have drastically altered their geochemical cycles and biochemicals balance.
Any toxic metals may be called heavy metals.
Since heavy metals have a propensity to accumulate in selective body organs.
The average safety levels in food or water are often misleading high.
Heavy is any metal or metalloid of environmental concern.
Heavy metals are metallic element that have relatively high density usually greater than 5 g/cm3, or their density is greater than the density of water.
The term heavy metal refers to any metallic chemical element that has a relatively high density and is toxic or poisonous at low concentrations.
Heavy metals are Globally distributed
pollutants
This ppt covers sources, natural and anthropogenic processes, and impacts of heavy metals pollution on environment with Mechanisms of Remediating Heavy Metals.
Heavy metals and its effects on plants and environmentHaider Ali Malik
Heavy metals are natural constituents of the earth’s crust , but indiscriminate human activities have drastically altered their geochemical cycles and biochemicals balance.
Any toxic metals may be called heavy metals.
Since heavy metals have a propensity to accumulate in selective body organs.
The average safety levels in food or water are often misleading high.
Heavy is any metal or metalloid of environmental concern.
Heavy metals are metallic element that have relatively high density usually greater than 5 g/cm3, or their density is greater than the density of water.
The term heavy metal refers to any metallic chemical element that has a relatively high density and is toxic or poisonous at low concentrations.
Heavy metals are Globally distributed
pollutants
This ppt covers sources, natural and anthropogenic processes, and impacts of heavy metals pollution on environment with Mechanisms of Remediating Heavy Metals.
Vegetables are grown all over the world for human needs and proper supply nutritional supplement. Recently due to various anthropogenic activities such as mining, industrialization and agricultural activities like application of pesticides, fungicides and fertilizers, heavy metals are released in to the atmosphere, soil and water. These released heavy metals enter into the plant system through various physiological processes and it affects the plant growth and development. The concentration of heavy metals in the environment varies due to various activities and it becomes toxic when it reaches above the permissible limits. Accumulation of heavy metals occurs only when the vegetable crops are exposed to heavy metal contaminated environment, thus it enters into the food chain. When these heavy metals contaminated vegetables are consumed by human beings it causes various severe health ailments. In order to reduce the heavy metal toxicity, proper remediation steps have to be carried out in soil and irrigation water. Before consumption of any vegetables washing has to be done to reduce the adhered heavy metal particulates and through these simple steps we can remove the heavy metal adhered on the vegetable surface.
Common Heavy Metal Contaminations and Its Hazard Sotheara Kong
This piece of education slide provide you a general information about 4 Common Heavy Metal Contamination and its Hazard in ground water. It consist of many information that may has advantage to the researcher especially someone who researching on removable of chemical contamination from ground water.
Kinetics and Thermodynamic Studies of Biosorption of Cadmium (ii) from Aqueous Solution onto Garden Grass (GAG)
Original Research Article
Journal of Chemistry and Materials Research Vol. 1 (1), 2014, 12–22
B.O. Evbuomwan, M.M. Atuka
Vegetables are grown all over the world for human needs and proper supply nutritional supplement. Recently due to various anthropogenic activities such as mining, industrialization and agricultural activities like application of pesticides, fungicides and fertilizers, heavy metals are released in to the atmosphere, soil and water. These released heavy metals enter into the plant system through various physiological processes and it affects the plant growth and development. The concentration of heavy metals in the environment varies due to various activities and it becomes toxic when it reaches above the permissible limits. Accumulation of heavy metals occurs only when the vegetable crops are exposed to heavy metal contaminated environment, thus it enters into the food chain. When these heavy metals contaminated vegetables are consumed by human beings it causes various severe health ailments. In order to reduce the heavy metal toxicity, proper remediation steps have to be carried out in soil and irrigation water. Before consumption of any vegetables washing has to be done to reduce the adhered heavy metal particulates and through these simple steps we can remove the heavy metal adhered on the vegetable surface.
Common Heavy Metal Contaminations and Its Hazard Sotheara Kong
This piece of education slide provide you a general information about 4 Common Heavy Metal Contamination and its Hazard in ground water. It consist of many information that may has advantage to the researcher especially someone who researching on removable of chemical contamination from ground water.
Kinetics and Thermodynamic Studies of Biosorption of Cadmium (ii) from Aqueous Solution onto Garden Grass (GAG)
Original Research Article
Journal of Chemistry and Materials Research Vol. 1 (1), 2014, 12–22
B.O. Evbuomwan, M.M. Atuka
Biosorption of Copper (II) Ions by Eclipta Alba Leaf Powder from Aqueous Solu...ijtsrd
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Role of Copper in Environment as a Potential and Challengesijtsrd
Copper is a normally mixing component. Present in the worlds shell, in seas, lakes and waterways, wellsprings of copper extend from minute follow sums to rich mine stores. Copper is a fundamental component, implying that all plants, fish and creatures need copper to work appropriately. All around the market for copper is one of the biggest of all metals following iron and aluminium. Copper can be delivered into the earth by both characteristic sources and human exercises. Present day life has various applications for copper, extending from coins to colours, and interest for the metal stays high, particularly in industrialized countries. Dharmpal Meet A | Rathod Zalak R "Role of Copper in Environment as a Potential and Challenges" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-4 | Issue-6 , October 2020, URL: https://www.ijtsrd.com/papers/ijtsrd33515.pdf Paper Url: https://www.ijtsrd.com/biological-science/biotechnology/33515/role-of-copper-in-environment-as-a-potential-and-challenges/dharmpal-meet-a
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HEAVY METAL POLLUTION AND REMEDIATION IN URBAN AND PERI-URBAN AGRICULTURE SOILS
1. @2013, ICE, All rights reserved
Heavy Metal Pollution & Remediation In Urban and
Peri-Urban Agriculture
Larry Chikukura
CESCRA
NEW DELHI
2. @2013, ICE, All rights reserved
Outline
• What is a heavy metal?
– What causes heavy metal pollution?
– International examples: Basel , Sandoz, Japan
– Regulatory limits for HM
• Remediation Techniques
– Traditional techniques
– Modern techniques
– Phytoremediation/Hyperaccumulation
– Nanoremediation
– Options for resource poor farmers
• Conclusion
3. @2013, ICE, All rights reserved
Introduction
Throughout the world, there is a long tradition of farming
intensively within and at the edge of cities (Smit et al., 1996).
However, most of these peri-urban lands are contaminated with
pollutants including heavy metals i.e. Cu, Zn, Pb, Cd, Ni, and Hg
soil quality in these areas is closely associated with human health
and welfare
hence much focus on soil quality degradation from heavy metal
contamination and soil remediation (Wilcke et al., 1998; Li et al,
2001; Lu et al., 2003; Imperato et al., 2003; Hu et al., 2004; Zhang
and Ke, 2004).
4. @2013, ICE, All rights reserved
What is a Heavy Metal (HM)??
Criteria used to define heavy metals have included density, atomic
weight, atomic number, or periodic table position
Density criteria range from above 3.5 g/cm3 to above 7 g/cm3
Atomic weight definitions start at greater than sodium (22.98) to
greater than 40
Atomic numbers of heavy metals are generally given as greater
than 20; - sometimes this is capped at 92 (uranium).
The term heavy metals has been called “meaningless and
misleading” due to the contradictory definitions and its lack of a
“coherent scientific basis (Duffus, 2002).
5. @2013, ICE, All rights reserved
Introduction
Heavy metal is a member of an ill-defined subset of elements that exhibit metallic
properties, which would mainly include the transition metals, some, metalloids
lanthanides and actinides
6. @2013, ICE, All rights reserved
Categorization of heavy metals
There are two categories of heavy metals:
i) Essential heavy metals
essential trace elements needed in very low quantities - vital to the
proper functioning of the various biological systems.
The essential heavy metals include iron, zinc, manganese, copper,
cobalt, selenium etc.
ii) Non-essential heavy metal
occur in traces in the human body but have been designated as
non-essential - harmless below their “threshold level”
These metals include chromium, silicon, nickel etc.
7. @2013, ICE, All rights reserved
Metals have unique chemical properties
1. Do not decay like organics
2. Necessary and beneficial to plants
3. Always present at background levels from parent rock weathering
4. Often occur as cations, which are actively exchanged in plant cell processes
8. @2013, ICE, All rights reserved
What causes heavy metal pollution?
Sediment from solid wasteIndustrial waste
Mining waste
9. @2013, ICE, All rights reserved
Some heavy metals and their environmental and physiological
effects
Brady and Weil, 1999
*
*
*
*
10. @2013, ICE, All rights reserved
REGULATORY LIMITS FOR HEAVY METALS
11. @2013, ICE, All rights reserved
THE BIGGEST DISASTERS WITH „A SPECIAL
APPEARANCE” OF HEAVY METALS
1932-1952 Minamata
Sewage containing mercury was released by Chisso's chemicals
works into Minimata Bay in Japan. The mercury accumulated in
sea creatures, leading eventually to mercury poisoning in the
population.
In 1952, the first incidents of mercury poisoning appear in the
population of MinimataBay in Japan, caused by consumption of
fish polluted with mercury, bringing nearly 1000 fatalities. Since
then, Japan has had the strictest environmental laws in the
industrialised world.
12. @2013, ICE, All rights reserved
THE BIGGEST DISASTERS WITH „A SPECIAL
APPEARANCE” OF HEAVY METALS
• Itai-itai disease was the documented case of mass cadmium
poisoning in Toyama Prefecture, Japan starting around 1912.
• The cadmium was released into rivers by mining companies in the
mountains. The cadmium poisoning caused softening of the bones
and kidney failure.
• The mining companies were successfully sued for the damage.
Itai-itai disease is known as one of the Four Big Pollution Disease
of Japan.
13. @2013, ICE, All rights reserved
THE BIGGEST DISASTERS WITH „A SPECIAL
APPEARANCE” OF HEAVY METALS
1986-11-01 Sandoz
Water used to extinguish a major fire carried 30 t fungicide containing
mercury into the Upper Rhine.
a fire at a chemical factory Sandoz near Basel, Switzerland, sending
tons of toxic chemicals into the nearby river Rhine and turning it
red
Fish are killed over a stretch of 100 km.
14. @2013, ICE, All rights reserved
THE BIGGEST DISASTERS WITH „A SPECIAL
APPEARANCE” OF HEAVY METALS
1998-04 Spanish nature reserve contaminated after
environmental disaster
Toxic chemicals in water from a burst dam belonging to a mine
contaminate the Coto de Donana nature reserve in southern Spain.
5 million m3_ of mud containing sulphur, lead, copper, zinc and
cadmium flow down the Rio Guadimar. Experts estimated that
Europe's largest bird sanctuary, as well as Spain's agriculture and
fisheries, will suffer permanent damage from the pollution.
15. @2013, ICE, All rights reserved
TRADITIONAL TREATMENTS FOR SOIL CONTAMINATION
Traditional treatments (engineering-based remediation methods for
metal contamination in soils
Treatments can be done in situ (on-site), or ex situ (removed and
treated off-site).
Some treatments that are available include:
High temperature treatments (produce a vitrified, granular, non-
leachable material).
Solidifying agents (produce cement-like material).
Washing process (leaches out contaminants)
These are expensive and cost prohibitive when large areas of soil
are contaminated.
Glass, 1999
16. @2013, ICE, All rights reserved
TRADITIONAL TREATMENTS FOR SOIL CONTAMINATION
Once metals are introduced and contaminate the environment,
they will remain.
The only exceptions are Hg & Se, which can be transformed and
volatilized by microorganisms.
However, in general it is very difficult to eliminate metals from the
environment.
17. @2013, ICE, All rights reservedReeves and Baker , 2000; Koyko et al., 2014
uptake and
transpiration of
contaminants,
primarily organic
compounds, by plant.
Roots stimulates soil
microbial communities in
plant root zones to
breakdown contaminants
Plant enzymatic
breakdown of organic
contaminants both
internally & thru
secreted enzymes
Adsorption of
contaminants &
stored above
ground shoots &
their harvestable
parts & roots
Roots & exudates
immobilize
contaminants thru
adsorption,
accumulation,
precipitation
within the root
zone
Phytoremediation => green technology that uses plants systems for remediation and restoration
18. @2013, ICE, All rights reservedReeves and Baker , 2000
Use of hyperaccumulator plants
Synthetic chelates stimulate the release of metals into soil solution and enhance the potential for
uptake into roots.
A variety of synthetic chelates have this potential to induce Pb desorption from the soil matrix eg.
EDTA > HEDTA >DTPA >EGTA >EDDHA.
Natural (A) & (B) Assisted phytoextraction.
19. @2013, ICE, All rights reserved
Brassica juncea (Indian mustard)Thlaspi caerulescensAlyssum serpyllifolium
The ability to hyperaccumulate toxic metals compared to related species is
because of their ‘Detoxification or Tolerance Mechanism’ .
20. @2013, ICE, All rights reserved
Case Studies
Aim => to efficiently utilise Brassica juncea L.to remove lead (Pb).
effect of different concentration of EDTA on lead accumulation
EDTA is the typical chelating agent
Different concentrations of EDTA (3mmol/kg, 4mmol/kg, and 5mmol/kg)
electrodic phytoremediation. The eletrodic phytoremediation system included
electrodes, a power supply, EDTA and plants. Copper wires were used for
electrodes.
21. @2013, ICE, All rights reserved
Results
The addition of EDTA was shown to significantly increase the accumulation of lead in
Brassica juncea
However, the use of electric potential with EDTA caused increased phytoremediation
to manyfolds
However, at high EDTA concentration it proved to be necrotic for the plants resulting
in burning effect.
22. @2013, ICE, All rights reserved
Nanoremediation
use of nanotech in the improvement of a contaminated site to prevent, minimize or
mitigate damage to human health or the environment.
potential not only to reduce the overall costs of cleaning ;
reduction in clean-up time,
eliminate the need for treatment and disposal of contaminated soil,
reduce the contaminant concentrations to near zero— all in situ
Nano alginite
nZVIbentonite
Nano carbon
Nano scale zero valent
iron “nZVI”,
used as a potential sorbents to eliminate Cd and Pb from polluted soil
The “nZVI” is reported as an ideal candidate for in-situ remediation because of its
large active surface area and high heavy metal adsorption capacity [Yaacob et al.,
2012].
23. @2013, ICE, All rights reserved
Adsorption & Desorption isotherms of
Cd & Pb
Marzoog et al., 2014
isotherms show that high
quantities of Cd (approximately 30-
40 g kg-1 ) - Cd was completely
removed from solutions
Generally the quantities of Pb
adsorbed on nano particles are
lower than their corresponding of
Cd
quantities of Pb & Cd desorbed
from the previously adsorbed ones
– tho ratios are low
Fate of the desorbed
contaminants???
24. @2013, ICE, All rights reserved
Cluin, 2014
Cost Implication of Nanoremediation
Remediation Technology Cost of Remediation ($)
Traditional remediation methods using
pump and treat (without nano-enhancement) 5,000, 000
Traditional remediation methods e.g.
permeable reactive barriers (PRBs) 3,400,000
Nano-enhanced remediation methods
using nano-zero valent iron (nZVI) 600,000
Traditional remediation methods or technologies are costly and may
take as many as 40 years to clean up all sites across the United States
25. @2013, ICE, All rights reserved
Options for resource poor farmers
Soil and crop mgt practices will not remove the HM contaminants,
but will help to immobilize them in the soil
& reduce the potential for adverse effects from the metals
The soil becomes the sink, breaking the soil-plant animal or human
cycle through which the toxin exerts its toxic effects (Brady and
Weil, 1999)
Note that the kind of metal (cation or anion) must be considered:
26. @2013, ICE, All rights reserved
Organic matter binds heavy metals (make
sure not contaminated) --the case of Cr
Brady & Weil, 1999
Active organic matter
is effective in
reducing the
availability of
chromium
27. @2013, ICE, All rights reserved
Add lime (make sure source not contain heavy metals)
Brady & Weil, 1999
Increasing the soil pH
to 6.5 or higher -
Cationic metals are
more soluble at lower
pH levels,
less available to
plants & th4 less likely
to be incorporated in
their tissues and
ingested by humans
Raising pH has the
opposite effect on
anionic elements.
28. @2013, ICE, All rights reserved
Management of Contaminated Soils
Draining wet soils- improves soil aeration and will allow metals to
oxidize, making them less soluble. Therefore when aerated, these
metals are less available (opposite for Cr)
Applying phosphate - reduce the availability of cationic metals, but
have the opposite effect on anionic compounds like arsenic.
Care - high levels of P in the soil can result in water pollution.
Carefully selecting plants for use on metal-contaminated soils
29. @2013, ICE, All rights reserved
Which crops are safe & suitable in HM soils???
Aim =>to examine the crop species differences in HM accumulation &
distribution in various edible and non-edible plant parts
to suggest the cultivation of different vegetable crops in soil contaminated with
different HM based on their accumulation in edible plant part.
30. @2013, ICE, All rights reservedTable 1 & 2 (Combined)
remarkable difference in metal concentration of various plant parts
cauliflower and cabbage recorded highest uptake of Zn, Pb and Ni, while mustard showed higher
uptake of Zn and Cd.
radish, carrot, spinach, amaranthus, mustard, cauliflower and cabbage showed higher distribution
of metals to the edible parts
31. @2013, ICE, All rights reserved
Leafy vegetables namely, spinach, amaranthus and mustard seemed to be unsafe
and not suitable for cultivation on heavy metal contaminated soil
Most of the fruit type vegetables could be suggested for cultivation on Cd contained
soil but not for Ni and Pb contained soil.
32. @2013, ICE, All rights reserved
Conclusion
A number of options are there for remediation of soils
Cost and access determine which method will be used
Resource poor farmers can cultivate specific crops depending on the soil and HM
All methods are effective but some have be known to be more efficient , though no
study has been made to compare all
Phytoextraction - less expensive than any other clean up process and the possibility
of the recovery and re-use of valuable metals
Nanoremediation is is an emerging technology that can perhaps be used in the near
future to clean contaminated environments (cost is still prohibitive)
WHERE POSSIBLE - PREVENTION IS CHEAPER & SAFER THAN CLEANING
UP
1. Do not decay like organics
2. Necessary and beneficial to plants
3. Always present at background levels from parent rock weathering
4. Often occur as cations, which are actively exchanged in plant cell processes
In soil science, cation exchange capacity (CEC) is the capacity of a soil for ion exchange of cations between the soil and the soil solution. CEC is used as a measure of fertility, nutrient retention capacity, and the capacity to protect groundwater from cation contamination. Cations can also be easier to understand by just adding the group number.
The quantity of positively charged ions (cations) that a clay mineral or similar material can accommodate on its negatively charged surface is expressed as milli-ion equivalent per 100 g, or more commonly as milliequivalent (meq) per 100 g or cmol/kg. Clays are aluminosilicates in which some of the aluminium and silicon ions have been replaced by elements with different valence, or charge. For example, aluminium (Al3+) may be replaced by iron (Fe2+) or magnesium (Mg2+), leading to a net negative charge. This charge attracts cations when the clay is immersed in an electrolyte such as salty water and causes an electrical double layer. The cation-exchange capacity is often expressed in terms of its contribution per unit pore volume, Qv.
Anthropogenic causes
Heavy metal- released to the river/ocean from numerous sources.
Typical sources-
1. municipal wastewater-treatment plants
2. manufacturing industries,
3. mining,
4. transportation
5. rural agricultural cultivation & fertilization.
transported as either dissolved species in water/ integral part of suspended sediments.
may be volatilized to the atmosphere or stored in riverbed sediments.
Toxic heavy metal- taken up by organisms; the metals dissolved in water have the greatest potential of causing the most deleterious effects.