Lithosphere and Groundwater

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Lithosphere and Groundwater
Original Power Point Created by Linda
Rist Modified by Georgia Agricultural Curriculum
Office June 2002
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Lithosphere

• solid rocky crust of the earth
• rocks on the surface are classified in 3 types
• igneous-cooled, molten rock, granite

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Lithosphere

• Sedimentary- sediments deposited in water and
  later made solid.
• Metamorphic-Igneous and sedimentary rocks changed
  by hear /or pressure Ex marble, slate

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Groundwater

• groundwater- water occurring beneath the surface
• used mostly as well water
• most occurs within lithosphere
• water table- the surface of ground water in a well

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Groundwater

• point in the ground that is completely saturated
  with water.
• Water fills all spaces between soil and rock
  particles. (pores)

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Groundwater

• Porosity- portion of the ground that contains
  spaces or voids. The total porosity of the
  material and size and continuity determine the
  volume of groundwater that is held available.

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Groundwater

• U.S. gets 1/2 of our drinking water from
  groundwater

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Groundwater

• Groundwater pollution
• 1988- EPA published a report
• 46 pesticides found in groundwater in 26 states
• only 9 were in concentrations higher than health
  advisory levels

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Groundwater

• World Health Organization (WHO) each year 1/2
  million people are poisoned by pesticides

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Groundwater

• Herbicides Insecticides are used in large
  quantities by farmers- one billion pounds of
  active ingredient per year

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Groundwater

• Nitrates- EPA standard of no more than 10mg/liter
  of Nitrate Nitrogen in groundwater used for
  drinking.
• More than 21 of samples contained more than 10mg
  per liter in Kansas and Rhode Island

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Groundwater

• 10-19 were in excess in California, Arizona,
  Oklahoma, and New York
• 5-9 were in excess in Colorado, South Dakota,
  Nebraska, Texas, Minnesota, Iowa, Illinois,
  Pennsylvania, Maryland, and Delaware

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Groundwater

• in all of the other 50 states less than 5 tested
  high.

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Controlling Groundwater pollution

• 1990 National Fertilizer and Environment Research
  Center set up 20 demo sites to control pesticide
  and nitrate pollution.

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Problems of greatest concern

• metallic impurities in phosphoric acid fertilizer
• gypsum pond leakage
• treatment of contaminated soil
• reducing pollution from liquids rinsed from
  application equipment

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Problems of greatest concern

• microbial techniques for waste treatment
• nitrate inhibitors for area
• techniques for sampling and testing groundwater
• developing better containments for chemigation
  and fertigation

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Pesticides and groundwater

• most pesticides are synthetic organic compounds

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Processes for loss from soil

• volatilization
• decomposition
• retention by soil
• transport by H2O

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Fumigants

• relatively volatile
• vaporize at low temperature and move as gases
  through the soil
• Ethylene dibromide - used for nematode control

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Ethylene dibromide

• very soluble in water
• not retained by soil
• commonly found in ground water

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Synthetic Organics

• may be decomposed in different ways
• many are broken down rapidly in sunlight

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Some pesticides

• react in water to form new compounds
• fungicide Captan reacts rapidly with water to
  form a hamless product

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Some chemicals

• decompose very slowly and may persist for years
• example - DDT

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Organic Matter

• is the most important soil particle in binding
  pesticide in the soil rather than going into the
  water

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Primary transport

• of pesticides through the soil is by percolation
  of water down

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Health Advisory Concentrations

• each of two animals is treated with a range of
  doses of the pesticide
• maximum dosage that produces no adverse effects
  in the more sensitive of the two species is
  divided by a safety factor (100)

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Concentrations

• for a substance for which a safety factor of 100
  has been used
• a 22 pound child would have to drink 26 gallons
  of water with the health advisory concentration
  per day every day

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Continued

• to ingest an amount of pesticide equivalent to
  the max daily intake that produced no observable
  effect in the test animal of the same average
  weight

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Avoiding pesticides in h2o

• alternative h2o sources
• distilling h2o
• ultraviolet light
• activated carbon filter

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Nitrates and groundwater

• mostly from plant fertilizers
• introduction of legumes (alfalfa)
• plants that take Nitrogen from the air and put it
  into the soil

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Nitrates and groundwater

• commercial fertilizers are used to supplement
  naturally occurring nutrients
• production of ag crops has increased due to the
  use of fertilizers

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Nitrates and groundwater

• plants absorb only part of each nutrient present
  in the soil
• as the concentration of nutrients in the soil
  increases, of total amount absorbed decreases
• greater residues are left in the soil

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Nitrates and groundwater

• most chemical ions of fertilizers are bonded to
  and retained by the soil
• Nitrogen is not

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Human Health Issues

• Problems related to Nitrates
• birth defects
• cancer
• migraines

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Human Heath Issues

• nervous system impairment
• methomoglobinemia

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Methomoglobinemia

• type of anemia
• hemoglobin carried Nitrogen instead of Oxygen to
  the body cells
• common cause of infant deaths

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Groundwater use

• over drafts
• when more water is removed than is replaced by
  water from the surface
• 57 of water resource regions have over drafts

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Groundwater use

• water table is falling in these areas
• most serious over draft is at the Ogallala
  Aquifer
• nations largest
• under parts of 8 states