Fly ash and mycorrhiza on heavy metal availability and uptake

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Influence of fly ash application and mycorrhiza
inoculation on heavy metals availability and
survival of different Acacia species in heavy
metal contaminated soils from Selebi-Phikwe,
Botswana

• Venecio U. Ultra. Jr. and Trust Manyiwa
• Department of Earth and Environmental Sciences
• Faculty of Science
• Botswana International Univeristy of Science and
  Technology
• Palapye, Botswana

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Mining Industry of Botswana

• Case of Botswana
• mining sector 85 of national foreign exchange
  earnings, one-third of government revenue, and a
  quarter of GDP. 
• Diamonds, nickel-copper, coal, soda ash, gold,
  silver, semi-precious stones, and granite
  currently accounts for about a third of
  government revenue.
• untapped uranium, lead and zinc reserves  

• Environmental impacts negatively affecting the
  people, plants and wildlife

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Motivation
Continued operation and projected expansion ?
increase the emissions and mine waste ?
threat to the environment
Control off-site pollution to secure safety and
health
Provision of clean and comfortable living
environment
Ecologically stable ecosystem
Convert dumpsite into productive resources
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The CHALLENGES on MINE TAILINGS REHABILITATION
and ECOLOGICAL RESTORATION

• Extreme pH
• Devoid of some essential nutrient
• Presence of heavy metals at high quantity

• poor soil structure
• develop a cemented or compacted layers

• Low microbial diversity and activities that will
  carry out nutrient cycling

Chemical Properties
Physical properties
Biological properties
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The CHALLENGES on MINE TAILINGS REHABILITATION
and ECOLOGICAL RESTORATION
Detrimental to plant growth

• Nutrient imbalance
• Heavy metal toxicity
• Unfavorable to root growth and development

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Soil Amendments
Effective Microorganism
Adaptive Plants
Successful Remediation and Ecological
Rehabilitation of MINE TAILINGS dumpsite
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Fly ash application and mycorrhiza inoculation ?
heavy metals availability and survival of
different Acacia sp.
Fly ash

• primary components of power station fly ash are
  silica (SiO2), alumina (Al2O3) and iron oxides
  (Fe2O3), with varying amounts of carbon, calcium
  (as lime or gypsum), magnesium and sulfur
  (sulfides or sulfates).
• Morupule Fly ash id Type F, produced when
  anthracite, bituminous or sub-bituminous coal is
  burned and is low in lime (B7) and contains more
  silica, alumina and iron oxide.
• Hydrophillic surface and is extremely porous
  good for adsorption of contaminants depending on
  pH.
• Ameliorating the low pH of soils
• Lowered bulk density, reduced hydraulic
  conductivity and improved moisture retention
• accumulation of boron, zinc and other
  microelements to phytotoxic levels

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Fly ash application and mycorrhiza inoculation ?
heavy metals availability and survival of
different Acacia sp.
Mycorrhiza

• Mycorrhiza consistently conferred heavy metal
  tolerance on a variety of plants in diverse heavy
  metal soils under optimum fertilization.
• Increases uptake of essential elements such as K,
  P, and Mg but less heavy metals such as Ni, Fe,
  Zn or Cu.
• Heavy metals such Zn, Cu and Cd accumulated in
  the cell wall and in electron-dense granules in
  the cytoplasm of the fungi, vesicles might serve
  as storage compartments for heavy metals in
  fungi.
• Glomalin (insoluble glycoprotein produced by
  hyphae of AMF) binds to potentially toxic
  elements including heavy metals

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Objectives

• Evaluate the effect of fly ash amendments and
  mycorrhiza inoculation on survival, growth and
  heavy metal uptake of seedlings of different
  plants species grown in tailings form BCL mines.
• Evaluate the effect of fly ash amendments and
  mycorrhiza inoculation on the chemical properties
  and heavy metal availability in tailings from BCL
  mines

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Materials and Methods

• 2 Factor in Complete Randomized Design
• Factor 1 0 Fly Ash and 10 Fly Ash (w/w)
• Factor 2 - Mycorrhiza and Mycorrhiza
• 4 replicates
• Plants Species
• Acacia albida
• Acacia luederitzii
• Acacia tortiles
• Delonix regia

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Materials and Methods

• Mine tailings collection and properties
• BCL Mines, Selibe-Phikwe, Botswana
• Tailings from the main storage dump site

Heavy metals Total Water Soluble Ammonium Acetate Exchangeble
As
Cu
Mn
Ni
Pb
Zn
Properties Method Values
pH 12 (soilwater)
EC
OM
Sand
Clay
Silt
Total N
Total P
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Materials and Methods

• Plant establishment
• Seed were scarified and sown directly into the
  prepared pots at 2 seeds per pot. After
  germination, thinning was done to 1 plant per
  pot.
• Potting medium preparation and Fly ash
  incorporation
• Mine tailings was air-dried and sieve prior to
  mixing with desired amount of fly ash.
• Fly As was collected from Morupule Power Plant
  Fly ash dumpsite.
• Mycorrhiza inoculation
• 5 grams of inoculant composed of mycorrhizal
  roots and soil was placed at the base of the hole
  before seeds are sown.
• Maintenance
• Plants are grown inside the screen house and
  irrigated regularly for 16 weeks.

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Materials and Methods

• Plant growth
• Plant height
• Dry matter yield
• Heavy metal uptake
• Mycorrhizal infection
• Nodulation

• Soil Properties
• pH and EC
• Water soluble heavy metals
• Ammonium Acetate Exchangeable Heavy metals

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RESULTS AND DISCUSSIONS
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Table 1. Survival of different plant species in
mine tailings from BCL mines as influenced by Fly
ash amendment and mycorrhiza inoculation.
Survival of Seedlings
Plant Species Mine Tailings Mine Tailings Mine Tailings 10 Fly ash Mine Tailings 10 Fly ash
Plant Species -Mycorrhiza Mycorrhiza -Mycorrhiza Mycorrhiza
Acacia albida 70 b 90 a 100 a 100 a
Acacia luederitzii 70 b 100 a 100 a 100 a
Acacia tortiles 100 a 30 b 100 a 100 a
Delonix regia 50 b 100 a 100 a 100 a
Means within the same rows (plant species)
followed by the same letter are not significantly
different from each other at 5 level of
significance based on LSD test.
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GROWTH (PLANT HEIGHT)
Table 2. Height of different plant species in
mine tailings from BCL mines as influenced by Fly
ash amendment and mycorrhiza inoculation.
Treatments Treatments Height (mm) Height (mm) Height (mm) Height (mm)
Treatments Treatments A. albida A. luederitzii A. tortiles Delonix regia
Mine tailings -Myco 72.00c 38.00 d 32.00 b 86 d
Mine tailings Myco 100.5 b 55.00 c 16.00 c 112.2 c
Mine Tailings 10 Fly Ash -Myco 188.25 a 70.30 b 32.00 b 168.40 b
Mine Tailings 10 Fly Ash Myco 194.25 a 87.70 a 47.50 a 187.60 a
Means within the same column (plant species)
followed by the same letter are not significantly
different from each other at 5 level of
significance based on LSD test.
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Dry matter yield
Table 3. Shoots, roots and total dry weight of A.
albida and A. luederitzii grown in mine tailings
as affected by fly ash amendments and mycorrhiza
inoculation at 12 weeks after planting.
Treatments Dry Matter Yield (mg/plant) Dry Matter Yield (mg/plant) Dry Matter Yield (mg/plant) Dry Matter Yield (mg/plant) Dry Matter Yield (mg/plant) Dry Matter Yield (mg/plant)
Treatments Acacia albida Acacia albida Acacia albida Acacia luederitzii Acacia luederitzii Acacia luederitzii
Treatments Shoots Roots Total Shoots Roots Total
Mine tailings
-Myco 8.12 b 51.98 b 60.09 c 17.8 d 58.6 d 76.4 d
Myco 5.28 b 62.28 b 67.56 b 27.4 c 94.2 c 121.6 c
Mine Tailings 10 Fly Ash
-Myco 93.02 a 185.26 a 278.28 a 286.8 a 344.1 b 630.9 b
Myco 89.56 a 173.51 a 263.08 a 326.3 b 400.8 a 727.0 a
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Dry matter yield
Table 3. Shoots, roots and total dry weight of A.
albida and A. luederitzii grown in mine tailings
as affected by fly ash amendments and mycorrhiza
inoculation at 12 weeks after planting.
Treatments Dry Matter Yield (mg/plant) Dry Matter Yield (mg/plant) Dry Matter Yield (mg/plant) Dry Matter Yield (mg/plant) Dry Matter Yield (mg/plant) Dry Matter Yield (mg/plant)
Treatments Acacia tortiles Acacia tortiles Acacia tortiles Delonix regia Delonix regia Delonix regia
Treatments Shoots Roots Total Shoots Roots Total
Mine tailings
-Myco 9.49 b 6.18 b 15.68 b 5.71 d 2.10 d 7.81 d
Myco 5.68 c 4.83 b 10.51 c 24.25 c 6.78 c 33.91 c
Mine Tailings 10 Fly Ash
-Myco 10.54 b 5.64b 16.18 b 37.67 a 33.96 b 71.63 b
Myco 24.43 a 9.48 a 33.91 a 54.69 a 87.89 a 142.58 a
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As concentration (mg/kg) As concentration (mg/kg) As concentration (mg/kg) As concentration (mg/kg) As concentration (mg/kg) As concentration (mg/kg)
Acacia albida Acacia albida Acacia albida Acacia luederitzii Acacia luederitzii Acacia luederitzii
Shoots Roots Shoot/root ratio Shoots Roots Shoot/root ratio
Mine tailings Shoot/root ratio Shoot/root ratio
-Myco 269.9262 809.7785 0.33 177.2 628.3 0.28
Myco 196.1901 738.0484 0.27 98.6 394.9 0.25
Mine Tailings 10 Fly Ash Mine Tailings 10 Fly Ash Mine Tailings 10 Fly Ash
-Myco 444.53 727.0971 0.61 160.2 204.4 0.78
Myco 374.72 683.5953 0.55 138.3 178.9 0.77
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Heavy metals concentrations
Table 4. Heavy metal concentrations in shoot and
roots of Acacia luederitzii grown in mine
tailings as affected by fly-ash amendment and
mycorrhizal inoculation at 12 weeks after
planting.
As As Shoot/Root Ratio Cu Cu Shoot/Root Ratio Mn Mn Shoot/Root Ratio Ni Ni Shoot/Root Ratio Pb Pb Shoot/Root Ratio Zn Zn Shoot/Root Ratio
Shoots Roots Shoot/Root Ratio Shoots Roots Shoot/Root Ratio Shoots Roots Shoot/Root Ratio Shoots Roots Shoot/Root Ratio Shoots Roots Shoot/Root Ratio Shoots Roots Shoot/Root Ratio
Mine tailings Mine tailings Shoot/Root Ratio Shoot/Root Ratio Shoot/Root Ratio Shoot/Root Ratio Shoot/Root Ratio Shoot/Root Ratio
-Myco 239.44 596.10 0.40 445.90 1212.2 0.37 19.40 52.37 0.37 93.11 265.1 0.35 322.8 918.6 0.35 24.70 70.31 0.35
Myco 128.31 365.19 0.35 256.76 759.25 0.34 15.39 46.64 0.33 54.88 173.3 0.32 167.5 562.15 0.30 14.31 46.42 0.31
Mine Tailings 10 Fly Ash Mine Tailings 10 Fly Ash Mine Tailings 10 Fly Ash Mine Tailings 10 Fly Ash Mine Tailings 10 Fly Ash
-Myco 160.25 204.44 0.78 157.27 226.40 0.69 130.54 162.06 0.81 30.54 123.6 0.25 240.0 312.83 0.77 29.43 47.79 0.62
Myco 138.27 178.85 0.77 15.52 61.69 0.25 47.74 35.24 1.35 2.82 10.5 0.27 290.0 287.76 1.01 15.52 12.53 1.24
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Soil Properties
Fig. 3. Soil pH and EC as influenced by fly ash
amendments and mycorrhiza inoculation after crop
cultivation.
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Heavy Metal Availability
Fig. 4. Water soluble fractions of different
heavy metals.