Fate of Heavy metal in soil , causing soil and water pollution and its consequences and possible mitigation option

1. Soil pollution with special reference
to heavy metal toxicity
Bidhan Chandra Krishi Viswavidyalaya
Mohanpur-741252 District: Nadia West BengalMohanpur-741252 District: Nadia West Bengal
Dr. P.K. Mani
Lecturer (Res), Sr. Scale
pabitramani@gmail.com
www.bckv.edu.in
Department of Agricultural Chemistry & Soil Science
AICRP on Cropping Systems, Kalyani Centre
Winter school presentation

2. Fig. 1: How healthy soil is linked with healthy people

3. Rocks
in
Earth’s
crust
Air
Soil
Water
Plants
Birds
Domestic
animals
Fish
Humans
Source: Brady, N. C. The nature and properties of soil, 1994
Sources of heavy metals and their cycling in the soil-water-air organism ecosystem.
•Industrial
Products
•Burned
fuel
•Fertilizers
Pesticides
It should be noted that the content of metals in
tissue generally builds up from left to right, indicating
the vulnerability of humans to heavy metal toxicity

4. Heavy metalHeavy metal
Transition metals
Ia IIa
IIIa IVa Va VIa VIIa
Ib IIb
Lanthanides
Actinides

5. Oxidative stress: Redox active transition
metals (e.g. Fe2+, Cu2+) produce free radicals
Replace other essential metals in pigments
and enzymes
Some metal ions (Hg2+, Cu2+) react to thiol
groups to interfere protein structure and
functions
Some metals occur as radioactive isotopes
(238U, 137Cs etc.) to pose health risks`
Why metals are toxic to living organisms?Why metals are toxic to living organisms?

6. Chemical Major uses and sources of soil contamination
Arsenic Pesticides, plant desiccants, animal feed additives, coal and
petroleum, mine tailings and detergents
Cadmium Electroplating, pigments for plastics and paints, plastic
stabilizers and batteries, fertilizers
Chromium Stainless steel, chrome–plated metals, pigments and
refractory brick manufacture
Copper Mine tailings, fly ash, fertilizers, wind blown copper-
containing dust
Lead Combustion of oil, gasoline, and coal; iron and
steel production
Mercury Pesticides, catalysts for synthetic polymers,
metallurgy, thermometers
Nickel Combustion of coal, gasoline, and oil; alloy
manufacture, electroplating, batteries
Zinc Galvanized iron and steel, alloys, batteries, brass,
rubber manufacture
Source: Moore and Ramamoorthy (1984)

7. Anthropogenic
sources of heavy
metals in soil
Tannery
BatteryDistillery
Steel Fly ash
Electroplating
Mining
Smelting

8. Global Emissions of trace Metals into theGlobal Emissions of trace Metals into the Atmosphere, Water and SoilAtmosphere, Water and Soil
Element
Air Water Soil
(in 1000 metric tones/yr)
As 18.8 41.0 82.0
Cd 7.6 9.4 22.0
Cr 30.0 142.0 896.0
Cu 35.0 112.0 954.0
Hg 3.6 4.6 8.3
Mn 38.0 262.0 1670.0
Mo 3.3 11.0 88.0
Ni 56.0 113.0 325.0
Pb 332.0 138.0 796.0
Sb 3.5 18.0 26.0
Vd 86.0 12.0 132.0
Zn 132.0 226.0 1372.0
Third North Sea Conference( Nriagu,1988)

9. ElementElement Essential or beneficial toEssential or beneficial to Potential toxicity toPotential toxicity to
PlantsPlants AnimalsAnimals PlantsPlants AnimalsAnimals
Arsenic (As)Arsenic (As) NoNo YesYes YesYes YesYes
CadmiumCadmium(Cd)(Cd) NoNo NoNo YesYes YesYes
ChromiumChromium(Cr)(Cr) NoNo YesYes YesYes DUDU
Cobalt (Co)Cobalt (Co) YesYes YesYes YesYes YesYes
Copper (Cu)Copper (Cu) YesYes YesYes YesYes YesYesbb
Lead (Pb)Lead (Pb) NoNo NoNo YesYes YesYes
Marcury (Hg)Marcury (Hg) NoNo NoNo DUDUaa
YesYes
Molyb (Mo)Molyb (Mo) YesYes YesYes DUDU YesYesbb
(5-20 ppm)(5-20 ppm)
Nickel (Ni)Nickel (Ni) NoNo YesYes YesYes YesYes
SeSe YesYes YesYes YesYes Yes(4ppm)Yes(4ppm)
Zinc (Zn)Zinc (Zn) YesYes YesYes DUDU DUDU
a
DU = Critical data on limits unavailable.b
Toxic to ruminants (sheep, cattle).
After Adriano 1986.

10. Sewage sludge –a potential threat to
heavy metal pollution in Indian soils
Fly-Ash: A meanace to the environment
Ground water pollution- Nitrate and ArsenicGround water pollution- Nitrate and Arsenic
Nuclear fallout and radioactive hazardsNuclear fallout and radioactive hazards
Inorganic fertilsersInorganic fertilsers
Tanery efflents and Waste waterTanery efflents and Waste water

11. Some of the potentially adverse Environmental and Health effects
Caused by forms of Nitrogen
Effect Causative Agent
Environmental quality
Eutrophication Nitrogen sources in surface waters
Corrosive damage HNO3
in rainfall (acid rain)
Ozone layer depletion Nitrous oxides from fuels, denitrification
And industrial stack emissions
Human Health
Methemoglobinemia Excess NO3
–
and NO2
–
in water and food
In infants, livestock
Respiratory illness PANs and other nitrogen oxides
Cancer Nitrosamines from NO2
–
and
secondary Amines in foodSoils- An Introduction to Soils and Plant Growth, Miller and Donahue

12. Heavy metal concentrations in soil amendments, expressed inHeavy metal concentrations in soil amendments, expressed in ppmppm
on a dry weight basison a dry weight basis
Soil amendment Cd Co Cr Cu Ni Pb Zn
Triple superphosphate 9 5 92 3 36 3 108
(0-46-0)
Urea (46-0-0) <0.1 <1 <3 <0.4 <1 <3 <1
Potassium chloride <0.1 2 <3 <0.6 4 3 <1
(0-0-60)
Agricultural lime <0.1 <1 <3 <0.2 5 <3 <2
Cow manure 1 6 56 62 29 16 71
Sewage sludgea 5 5 350 660 35 980 800
After Freedman and Hutchinson 1981, except aWebber and Nichols 1995

13. Contents of some heavy metals in fertilizers and sludges
Source Metal mg/kg dry material
Cd Cr Cu Pb Zn
Ammonim
Niitrate (A/N)
1.1 2.5 3.6 5.4 11.7
SSP 16.6 157.0 22.6 20.6 244.0
Compound
8-10-8
4.9 54.3 8.3 3.2 97.5
Sewage Sludge 20.0 500.0 250.0 700.0 3000.0
Source: Pain et al., 1991

14. Heavy metal composition of sewage sludge from different
cities in India
City Cu Zn Cd Cr Ni Pb
mg/kg
Ahmeda
bad
535 2147 3.5 60.4 32.3 76.8
Delhi 440 1610 5.5 53.5 81.5 34.5
Nagpur 272 832 1.5 49.2 14.8 24.3
Chennai 210 935 8.3 38.5 60.5 16.6
Jaipur 265 1720 7.3 17.6 37.5 66.9
Source : Maity et al (1992).

15. Reported range
(mg/kg dry digested sludge)
Element
Minimum Maximum
As 1.1 230
Cd 1.0 3410
Co 11.3 2990
Cu 84.0 17000
Cr 10.0 99000
F 80.1 33500
Hg 0.60 56
Mn 32.0 9870
Pb 13.0 26000
Se 1.70 17.2
Zn 101.0 49000
Concentrations of Trace elements in Municipal Sewage Sludges
Source: Lagon, T.J. (1990) Advances in Soil Science, Vol. 11

16. • Accumulation of Heavy Metals in Soil and Plant (mg/g)
Zn Cu Pb Cd Cr
Soils of Dhapa 1038-1256 154-196 79-113 0.38-0.52 9.1-17.0
Spinach 320-340 60-72 60-82 0.8-2.2 6.5-15.8
Cauliflower
Head
300-1100 20-30 30-90 Trace 5.2-5.7
Source: S. K. Gupta et al., 1997, Calcutta University
• Accumulation of Heavy Metals in Rohu fish (1.5 kg) on dry weight Basis (µg/g)
Parts Zn Cu Pb Cd Cr
Brain 3.2 trace 2.9 0.4 11.3
Muscle 29.1 3.4 2.4 0.5 0.9
Liver 53.1 79.5 3.3 6.1 3.2
Kidney 62.6 8.9 11.9 12.3 14.9
Source: Dr. R. N. Bhattacharyya, Head, CPCB, Kolkata, 1997

17. DTPA-extractable heavy metal in soils under different crops
irrigated with sewage and underground water
Crop Source of
irrigation
water
Zn Fe Cu Mn Cd
mg/kg
Berseem Sewage 13.4 75.3 24.4 33.2 0.119
Underground 4.2 38.0 7.8 28.4 0.074
Spinach Sewage 41.2 65.6 32.2 28.8 0.253
Underground 4.2 59.4 7.0 24.4 0.079
Coriander Sewage 21.1 69.0 49.4 23.0 0.208
Underground 6.6 32.4 9.5 18.4 0.054
Source : Sharma and Kansal (1986).

18. Some characteristics of waste water from domestic and
industrial locations in Ludhiana – An industrial city of Punjab
Location pH BOD Cr Ni CN
mg/kg
Electroplating
Industry
6.2-7.2 60-380 0.2-2.5 1.0-3.0 0.42-0.97
Sugar
Industry
7.1-7.9 1058-
1640
- - -
Paper
Industry 7.0-10.1 560-1113 - - -
Household 6.7-7.8 80-460 0.1-0.2 0.2-2.0 0.05-0.07
Max. limits for
disposal on
agril. land
5.5-9.0 100 0.1 0.005 0.2
Source : Tiwana et al (1987).

19. Tolerance limits for disposal of tannery effluents
Parameters Effluents to be discharged
Into inland surface
water
On land for
irrigation
pH 6.0-9.0 6.0-9.0
BOD (mg.L-1
) 30 100
Suspend solids 100 200
Chloride (as Cl) 1000 200
Cr 2.0 2.0
Sulphides 2.0 -
Na+
- 60
Oil and grease 10 10
Source: Environmental (Protection ) Rules (1986)

20. Recommended maximum concentrations (ppm) of heavy metals in
soils based on their cation exchange capacities (CEC)
CECa
Cu Co Hg Cd Cr Zn Pb Ni
CEC>15 50 34 0.14 2.4 120 160 70 60
CEC<15 25 >17 0.07 1.2 0 80 35 30
a
Measured as milliequivalents per 100 grams.
Source: Giroux et al. 1992.
“In agriculture CEC is next to photosynthesis ”-C.E .Marshal

21. Ash (generated from coal combustion) which is fine and carried away with
the flue gases is known as FA
Fly ash (FA) is finely divided residue resulting from the combustion of
pulverized bituminous coal or lignite
FA is gray in colour, abrasive, acidic, refractory in nature, fineness
4000-8000 sq. cm/g, size 5-120 equivalent diameter
FA is essentially an Amorphous ferroaluminosilicate minerals
Concentration of heavy metals in sized fractions of Fly-ash
Particle size Cr Mn Ni Pb Cd Cu
µg/g (average)
>150 67 355 86 86 15 67
150-106 78 368 98 54 16 66
106-75 86 425 98 62 15 64
75-53 80 445 102 59 13 69
<53 87 390 116 56 13 80
Average 80 396 100 57 14 61
Fulekar and Dave, 1986Fulekar and Dave, 1986

22. Concentration of HM in coal ash generated in power plants of
West Bengal
BTPS KTPS STPS DTPS FSTPS
Cr 20-100 40-80 80-200 <10-20 120-180
Cu 10-25 20-30 10-15 <10-15 10-20
Pb 10-20 10-40 10-35 <10-50 10-45
Mn 150-1000 300-2100 150-800 200-1000 400-800
Ni 10-35 74 - - -
V 15-90 - 15-150 - -
Mo - <10 <10 <10 <10
Zn - 200 200 200 200
Cd - BDL - - -
After: Saha, A. K., CSME, Kolkata

23. Nitrate concentration in Ground waters amples from
Tubewells located in Cultivated areas of Punjab
BlockBlock
No. ofNo. of
samplessamples
Mean NOMean NO33
mg/lmg/l
N-fert.applicationN-fert.application
kg/ha/yrkg/ha/yr
DehlonDehlon 8484 17.017.0 249.0249.0
LudhianaLudhiana 3333 13.813.8 258.0258.0
SudharSudhar 4343 17.417.4 242.0242.0
KartarpurKartarpur 3434 12.112.1 193.0193.0
JandialaguruJandialaguru 2424 18.318.3 172.0172.0
MalerkotlaMalerkotla 1818 17.817.8 151.0151.0
Bajwa et al. 1992Bajwa et al. 1992

24. Gary Bañuelos, Soil Scientist with the USDA
Agricultural Research Service, inspects the
leaves of a transgenic Indian mustardIndian mustard
plant used to remove seleniumselenium from
contaminated soil. (Photo by Stella
Zambrzuski, USDA ARS)

25. Canola and Kenaf plants do a good job of cleaning
up of soil and water contaminated with Selenium

26. The ultimate solution is to volatilise Se completely from the
ecosystem using plants like Indian mustardIndian mustard and pickleweedpickleweed that
convert toxic selenateselenate and seleniteselenite into volatile non-toxic Se
forms such as dimethyl selenidedimethyl selenide. A recent breakthrough has
enabled Prof Terry'Terry's team to genetically engineer Indian mustard
to enhance the rate of Se volatilisation. Both Prof Terry and Dr
David Salt10 from Purdue University are looking at ways to use
plants like Indian mustard11 to clean up cadmium-laden soils.

27. Arsenic source in groundwater in the Ganga basin
Holocene periodHolocene period
Basalt rock

28. NArsenic affected districts of
West Bengal, India
108 blocks108 blocks

29.
Air
As2O5 As2O3 (CH3)3As (CH3)2AsO(OH)
Water Oxidation
H3AsO4 H3AsO3 (CH3)3As (CH3)2AsH
microbes
Sediment
biomethylation
AsO2(OH)2
-
AsO(OH) (CH3)2AsO(OH)
redn.
FeAsO4 As2S3 (CH3)3As
Arsenic speciation in soil, water and air

30. The Eh -pH diagram for As at 250
C,1 atm. with total arsenic 10-5
mol L-1
and total sulfur 10-3
mol L-1
(Ferguson and Gavis,1972)
Eh,Volts
pH

31. Source: Arsenic is a new terror; Asit Kumar Roy; Desh
D
R
A
W
D
O
W
N
Radius of influence
Cone of
Depression
WT
Vadose zone
Arseno
pyrite
Darcy’s Law
Pitticite

32. Crop Arsenic conc. (mg/kg) at harvest
Leaf Stem Root Eco. Produce
Ele-foot-yam 4.30 8.0 - 4.0
Green gram 5.10 4.9 4.7 4.3
Cowpea 4.91 5.1 5.2 2.1
Maize 3.30 6.2 5.2 2.6
Rice (boro) 10.2 5.7 5.9 10.0
Jute 3.5 8.0 6.8 4.0
Potato 3.9 9.3 - 5.9
Mustard 7.1 9.8 5.7 3.3
Ground nut 2.0 2.0 2.2 4.0
Sesame 2.0 2.0 4.0 0.6
 Crops were subjected to irrigation with water containing 0.22 mg As / lit of water 
Soil had an Olsen-extractable arsenic content of 1.23 to 1.37 mg/kg of soil (initial)
Source : Prof. S. K. SanyalSource : Prof. S. K. Sanyal
Arsenic uptake by different plant parts of crops grown in Gotera, Chakdah

33.  Measured total Arsenic content in the various
plant parts
 Total arsenic is not so fatal-it is only theTotal arsenic is not so fatal-it is only the
trivalent form which is highly toxic thantrivalent form which is highly toxic than otherother
formsforms
 So we need speciation of arsenicSo we need speciation of arsenic
 Speciation of arsenic can be done by FlameSpeciation of arsenic can be done by Flame
Ionisation Atomic Spectrometer (FIAS)Ionisation Atomic Spectrometer (FIAS)
attachment in AASattachment in AAS

34. Mechanism of As mobilization in groundwater in Bengal Basin
Hypothesis1 ‘ Pyrite oxidation hypothesis’
Arsenic rich iron bearing minerals like “Arsenopyrite” may be present in the aquifer
sediments. Aresenopyrite is being oxidized by atmospheric oxygen which invades the
aquifer in response to lowering of groundwater level (Mandal et al. 1996)
♣ Hypothesis 2 ‘Oxyhydroxide reduction hypothesis’
ii) The burial of the sediments, rich in organic matter, has led to strongly reducing
groundwater conditions. Arsenic may be released when arsenic-rich iron oxyhydroxides, which
are efficient arsenic –scavengers, are reduced in anoxic groundwater.
♣ Order of toxicity : AsH3
> (CH3
)2
AsH, > (CH3
)3
As >As2
O3
>H3
AsO3
>As2
O5
> H3
AsO4
♣ Max. Health permissible limit in drinking water : 0.05 ppm (WHO)
♣ Biochemical effects
SH O S
+ As O-
As O-
SH O S
enzyme
enzyme

35. Arsenic affected people of Chakdaha blockArsenic affected people of Chakdaha block
Can Arsenicum 30 reduce the toxicity?Can Arsenicum 30 reduce the toxicity?
A
R
S
E
N
I
C
O
S
I
S

36. Then what is the way out???Then what is the way out???
PHYTOREMEDIATION
THE GREEN-CURE TECHNOLOGY

37. Natural Microbial Bioremediators
On March 24, 1989, an oil tanker ( Exxon Valdez) crashed into a reef
Alaska, spilling 11 million gallons of oil . 10 weeks after the spill, the
U.S.E.P.A applied P and N fertilizers
to 750 oil-soaked sites.
Hudson River in New York with polychlorinated biphenyls (PCBs) by the
Company GEC
Buried anaerobic bacteria strip off chlorines.
In the water column, aerobic bacteria cleave the two organic rings of the
PCBs.
Other microorganisms degrade the dechlorinated, broken rings into
CO2,H2O,Cl .
Natural Plant Bioremediators
Hyperaccumulators, cope with excess heavy metals in the environment by
taking them in and sequestering them in vacuoles.
Chelation : when the plant combines a pollutant with another molecule,
Organic acids often serve this role.
Citric acid, detoxifies cadmium, and malic acid does the same for zinc.
phytochelatins -a class of polypeptides can also bind metals and escort
them .
metal-lothioneins - metal-binding proteins

38. Natural phytoremediators.
Sebertia acuminata, a tree ( tropical rain forest of New Caledonia,
Australia.)
Up to 20 percent of the tree's dry weight is Ni
If slashed, the bark oozes a bright green. This plant can perhaps be
used to clean up nickel-contaminated soil.
Soybeans also preferentially take up nickel from soil.
Another phytore-mediator is Astragalus, also know as locoweed
(accumulates Se)
Genetically Modified Bioremediators
Super bug-Ananda Mohan Chakrabarty (1980) GEC
The four plasmids in the oil eater gave the bacterium the
ability to degrade four components of crude oil.
Plasmids are rings of DNA that can be transferred from one
cell to another

39. What is phytoremediation?
“Use of green plants to remove pollutants
from the environment or render them
harmless”
Salt et al. (1998)
This concept has emerged from a broader
philosophy of Bioremediation where besides
plants, soil microorganisms are also used for
amelioration of organic and inorganic
contaminants

40. Phytoextraction Phytodegradation Rhizofiltration Phytostabilization Phytovolatilization
Phytorem ediation
Different approaches of phytoremediation
Accumulati
on of
metals in
shoot
tissues
followed by
harvesting
Use of plants
and
associated
microbes to
degrade
organic
pollutants
Use of plant
roots to
absorb and
adsorb
metals from
aqueous
waste stream
Reduction in
leaching,
runoff, soil
erosion and
bioavailability
of toxic
metals
Use of
plants to
volatilize
pollutants

41. Advantages and disadvantages of PhytoremediationAdvantages and disadvantages of Phytoremediation
Advantages Limitations
Amendable to a variety of organic
and inorganic compounds
Restricted to sites with shallow
contamination within rooting
zone of remediative plants
In Situ/Ex Situ application possible
with effluent/soil
May take up several years to
remediate a contaminated site
In Situ applications decrease the
amount of soil disturbance
Restricted to sites with low
contaminant concn.
Reduces the amount of waste to be
landfilled(upto 95%), can be
further utilized as bio ore of
heavy metals
Harvested plant biomass from
phytoextraction may be
classified as a hazardous waste
In Situ applications decrease
spread of contaminant via air
and water
Climatic conditions are limiting
factor

42. HYPERACCUMULATOR
INDICATOR
EXCLUDERP
L
A
N
T
Metal concentration in Soil
Conceptual response strategies of metal concentration in plant tops
in relation to increasing total metal concentrations in soil

43. Possible fates of pollutants during phytoremediation
Hydrophobicity
(log Kow)
Henry’s law
constant (Hi)

44. Pteris vittata (Chinese brake) – a reported hyper-
accumulator for arsenic

45. Chelate-assisted phytoremediation is most
promising management practice
Salt et al., 1998

46. After, Ma et al. 2000

47. Uptake,transport and metabolism in transgenic A. thaliana plants
overexpressing two bacterial genes, arsC and Y-ECS(gamma
glutamyl cysteine synthatase.

48. Tolerance mechanisms for inorganic and organic pollutants in
plant cells.
Detoxification generally involves conjugation followed by active
sequestration in the vacuole and apoplast,where the pollutant can
do the least harm
Pollutant
(inorg)
Pollutant
(organic)
Cell Wall
VacuoleVacuole
SequestrationSequestration
Conjugation
GSH,Glutathion
MT, Metallothioneins
Phytochelatins

49. Disposal of hyper-accumulator plant refuse
Harvest
Incineration
Controlled disposal of
ash to underground –
away from root zone
and aquifer
Phytomining
Jade green alkaloid from cut stem of
Phyllanthus palawanensis contains
88,580 µg Ni g-1
dry weight

50. Bio-accumulation coefficients of
Brassica sp. at maturity stage
Bio-accumulation coefficients of
Brassica sp. at maturity stage
Species Zn Cu Ni Pb Yield*
B. juncea 6.83 3.08 3.21 12.86 25.40
B.
campestris
12.48 2.59 13.61 2.56 18.66
B. carinata 11.89 1.94 12.30 17.72 37.70
B. napus 9.87 1.14 8.98 9.37 31.70
B. nigra 9.56 2.04 8.66 7.94 31.04
*Above ground biomass yield expressed in g/pot
Bioaccumulation coefficient: Metal content in plant biomass
Labile metal content in soil

51. Novel Finding!Novel Finding!
For the first time Brassica carinata is
being reported as a possible hyper-
accumulator for Zn, Ni and Pb
Chhonker et al, 2004Chhonker et al, 2004

52. Defective baby due to radioactivity is known as Down’s syndrome
Radioactivity due to nuclear fall out leads several pollution to soil
Source of radioactive contamination:
 Fallout from testing of nuclear weapons
 Waste products and effluents from nuclear reactors
Sr90
, Cs137
, I131
Max. permissible limit of absorbing radiation : 0.5 REM

53. The chemicals to which life is asked to make
its adjustment are . . . the synthetic creations
of man's inventive mind, brewed in his
laboratories, and having no counterparts in
nature.
Rachel Carson
Silent Spring

54. Upon this handful of soil
Our Survival depends
Husband it & it will grow
Our food, fiber & fuel
& surround us with beauty,
Abuse it, the soil will degrade
& collaspe taking mankind