Lithosphere and Groundwater

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

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

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

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

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.

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

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

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

Groundwater w Herbicides & Insecticides are used in “large quantities” by farmers- one billion pounds of active ingredient per year

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

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

Groundwater w in all of the other 50 states less than 5% tested high.

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

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

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

Pesticides and groundwater w most pesticides are synthetic organic compounds

Processes for loss from soil w volatilization w decomposition w retention by soil w transport by H2O

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

Ethylene dibromide w very soluble in water w not retained by soil w commonly found in ground water

Synthetic Organics w may be decomposed in different ways w many are broken down rapidly in sunlight

Some pesticides w react in water to form new compounds w fungicide Captan reacts rapidly with water to form a hamless product

Some chemicals w decompose very slowly and may persist for years w example - DDT

Organic Matter w is the most important soil particle in binding pesticide in the soil rather than going into the water

Primary transport w of pesticides through the soil is by percolation of water down

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)

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

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

Avoiding pesticides in h2o w alternative h2o sources w distilling h2o w ultraviolet light w activated carbon filter

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

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

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

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

Human Health Issues w Problems related to Nitrates w birth defects w cancer w migraines

Human Heath Issues w nervous system impairment w methomoglobinemia

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

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

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