Groundwater Geochemistry in the Alisadr, Hamedan, Western Iran

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Groundwater Geochemistry in the Alisadr,Hamedan,
Western Iran
Aida Asgary NDSU Geol 628 Geochemistry 2010
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Why Groundwater Quality is Important

• In arid and semi-arid regions, agriculture is
  limited by the availibility of suitable
  irrigation water.
• Groundwater is the main source of irrigation and
  drinking in these areas.

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Study Area

• Climate of study area is semi-arid.
• The area is characterized by predominance of
  metamorphic rocks (sedimentary rocks)
• Groundwater has been used for drinking,
  agricultural and domestic purposes.
• Hydrogeochemical investigation was carried out in
  Alisadr area to identify groundwater
  geochemistry and its suitability for irrigation
  purposes.

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Study Area
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Fifty nine samples were selected.The
results show that major cations in order to
their concentrations are Ca, Mg2,Na,and
K.Among anions Co32-, Hco3, Cl-, and No3- have
the highest concentrations.Besed on dominant
cations and anions water types were found.
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Groundwater Quality, WHO Standards

• World Health Organization Standards
• Based on WHOs drinking water standards, limit
  for No3 in drinking water is 50 mg/l.
• Concentration of No3 in 15 of the samples were
  above the standards.
• High values of NO3 are results of agricultural
  activities.

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Groundwater Quality, Total Hardness

• Hard water is the water that contains high levels
  of dissolved calcium, magnesium.
• Hardness 2.5(mg Ca/L) 4.1(mg Mg/L)
• The greater the amount of dissolved minerals in
  the water, the harder it is.
• mg/L Degree of Hardness. 0 - 75 Soft, 75 - 150
  Moderately Hard, 150 - 300 Hard, 300 and up Very
  Hard

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Groundwater Quality, Total Hardness

• Ways in which total hardness and water quality
  are connected are
• Household plumbing.
• Decrease in cleaning ability.
• Water heaters can become less efficient.
• Most of the water samples were in the categoray
  of hard and very hardwater.

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Groundwater Quality, SAR

• The sodicity hazard of water is described by
  Sodium Adsorption Ratio ( SAR).
• High concentrations of Na are undesirable in
  water because Na is adsorbed in to the soil
  cation exchange sites, causing soil accumulations
  to disperse, reducing its permeability.

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Groundwater Quality, SAR

• SARNa/(Camg/2)0.5

Areas with high SAR, special management with
salinity control may be required, only plants
with good salt tolerance should be selected.
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The Origin of Species

• Compositional relations among dissolved species
  can reveal the origin of species and the process
  that generated the observed water compositions.
• Possitive correlations indicates common resource.

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The Origin of Species

• Negative correlation between Ca and HCO3 shows
  that Calcite (CaCO3) can not be the source of Ca.
• Calcium and So4 ions in groundwater are provided
  mostly by the dissolution of Gypsum(CaSO42H2O)
• There is a strong correlation between Na and Cl
  that may explain the dissolution of halite(NaCl)
  in water can be the source.
• Dissolution of Anorthite (CaAl2Si2O8) also can
  contribute to Ca ions in groundwater.

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Inverse Modeling

• Inverse modeling is used to estimate sets of
  minerals and gases that account for the
  differences in composition between the solutions.
  At least two solution is needed, but we can add
  as many as we want.
• Inverse modeling can be used to predict the
  changes that may occur in concentration of
  elements in the flowpath, by indicating whether a
  mineral will disolve or precipitate.

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Inverse Modeling

• Hypothesis
• In this study correlation ratios were used to
  demonstrate possible origin of species, can
  inverse modeling provide the same results?

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Inverse Modeling

• 5 water solution were chosen.
• Water solutions show increase in concentration of
  elements, with emphasizes on elements that cause
  quality problems for water.

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Inverse Modeling

• 
  INVERSE_MODELING 1
• -solutions
  1 5
• 
  -uncertainty 0.5 0.5
• -phases
• Gypsum
• Calcite
• Anorthite
• Halite
• -balances
• pH
  0.2 0.2
• -tolerance
  1e-010
• -mineral_water
  true

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Results of Inverse Modeling

• Positive mole transfers show dissolution of a
  mineral, and negative mole transfers shows
  precipitation of a mineral

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• 1.
• Phase Mole Transfers Minimum
  Maximum
• Gypsum 9.770e-004 0.000e000
  0.000e000 CaSO42H2O
• Calcite -3.565e-004 0.000e000
  0.000e000 CaCO3
• Anorthite 3.840e-005 0.000e000
  0.000e000 CaAl2Si2O8
• Halite 1.797e-003
  0.000e000 0.000e000 NaCl
•  2.
• Phase Mole Transfers Minimum
  Maximum
• Calcite -3.565e-004
  0.000e000 0.000e000 CaCO3
• Anorthite 3.840e-005 0.000e000
  0.000e000 CaAl2Si2O8
• Halite 1.796e-003
  0.000e000 0.000e000 NaCl
•   3.
• Phase Mole Transfers Minimum
  Maximum
• Gypsum 9.770e-004 0.000e000
  0.000e000 CaSO42H2O
• Anorthite 1.336e-005 0.000e000
  0.000e000 CaAl2Si2O8
• Halite 1.797e-003
  0.000e000 0.000e000 NaC
•  
•  4.

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Results of Inverse Modeling

• Results indicates the dissolution of gypsum,
  anorthite and halite and precipitation od
  calcite.
• Based on the results origin of species are found,
  and they support the results in the article.

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Thank You