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Lithosphere and Groundwater
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Lithosphere w solid rocky crust of the earth w rocks on the surface are classified in 3 types w igneous-cooled, molten rock, granite
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Lithosphere w Sedimentary- sediments deposited in water and later made solid. w Metamorphic-Igneous and sedimentary rocks changed by hear &/or pressure Ex: marble, slate
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Groundwater w groundwater- water occurring beneath the surface w used mostly as well water w most occurs within lithosphere w water table- the surface of ground water in a well
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Groundwater w point in the ground that is completely saturated with water. w Water fills all spaces between soil and rock particles. (pores)
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Groundwater w 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 w U.S. gets 1/2 of our drinking water from groundwater
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Groundwater w Groundwater pollution w 1988- EPA published a report w 46 pesticides found in groundwater in 26 states w only 9 were in concentrations higher than health advisory levels
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Groundwater w World Health Organization (WHO) each year 1/2 million people are poisoned by pesticides
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Groundwater w Herbicides & Insecticides are used in “large quantities” by farmers- one billion pounds of active ingredient per year
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Groundwater w Nitrates- EPA standard of no more than 10mg/liter of Nitrate Nitrogen in groundwater used for drinking. w More than 21% of samples contained more than 10mg per liter in Kansas and Rhode Island
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Groundwater w 10-19% were in excess in California, Arizona, Oklahoma, and New York w 5-9% were in excess in Colorado, South Dakota, Nebraska, Texas, Minnesota, Iowa, Illinois, Pennsylvania, Maryland, and Delaware
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Groundwater w in all of the other 50 states less than 5% tested high.
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Controlling Groundwater pollution w 1990 National Fertilizer and Environment Research Center set up 20 demo sites to control pesticide and nitrate pollution. w Pierre, South Dakota Cone Ag Service
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Problems of greatest concern w metallic impurities in phosphoric acid fertilizer w gypsum pond leakage w treatment of contaminated soil w reducing pollution from liquids rinsed from application equipment
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Problems of greatest concern w microbial techniques for waste treatment w nitrate inhibitors for area w techniques for sampling and testing groundwater w developing better containments for chemigation and fertigation
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Pesticides and groundwater w most pesticides are synthetic organic compounds
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Processes for loss from soil w volatilization w decomposition w retention by soil w transport by H2O
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Fumigants w relatively volatile w vaporize at low temperature and move as gases through the soil w Ethylene dibromide - used for nematode control
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Ethylene dibromide w very soluble in water w not retained by soil w commonly found in ground water
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Synthetic Organics w may be decomposed in different ways w many are broken down rapidly in sunlight
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Some pesticides w react in water to form new compounds w fungicide Captan reacts rapidly with water to form a hamless product
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Some chemicals w decompose very slowly and may persist for years w example - DDT
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Organic Matter w is the most important soil particle in binding pesticide in the soil rather than going into the water
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Primary transport w of pesticides through the soil is by percolation of water down
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Health Advisory Concentrations w each of two animals is treated with a range of doses of the pesticide w 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 w for a substance for which a safety factor of 100 has been used w 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 w 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 w alternative h2o sources w distilling h2o w ultraviolet light w activated carbon filter
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Nitrates and groundwater w mostly from plant fertilizers w introduction of legumes (alfalfa) w plants that take Nitrogen from the air and put it into the soil
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Nitrates and groundwater w commercial fertilizers are used to supplement naturally occurring nutrients w production of ag crops has increased due to the use of fertilizers
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Nitrates and groundwater w plants absorb only part of each nutrient present in the soil w as the concentration of nutrients in the soil increases, % of total amount absorbed decreases w greater residues are left in the soil
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Nitrates and groundwater w most chemical ions of fertilizers are bonded to and retained by the soil w Nitrogen is not
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Human Health Issues w Problems related to Nitrates w birth defects w cancer w migraines
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Human Heath Issues w nervous system impairment w methomoglobinemia
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Methomoglobinemia w type of anemia w hemoglobin carried Nitrogen instead of Oxygen to the body cells w common cause of infant deaths
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Groundwater use w over drafts w when more water is removed than is replaced by water from the surface w 57% of water resource regions have over drafts
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Groundwater use w water table is falling in these areas w most serious over draft is at the Ogallala Aquifer w nations largest w under parts of 8 states
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