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Environmental Chemistry C Focus on Soil Lin Wozniewksi [email protected] Safety Students must wear: Closed shoes Slacks or skirts that come to the ankles Sleeved Shirt (if wearing a lab apron) Lab coat or lab apron

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Environmental chemistry c l.jpg

Environmental Chemistry C

Focus on Soil

Lin Wozniewksi

[email protected]


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Safety

  • Students must wear:

    • Closed shoes

    • Slacks or skirts that come to the ankles

    • Sleeved Shirt (if wearing a lab apron)

    • Lab coat or lab apron

    • Indirect vent or unvented chemical splash proof goggles. No impact glasses or visorgogs are permitted


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Students can bring

  • Calculator

  • 1 sheet of paper on which anything is acceptable

  • A writing instrument


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Supervisors will provide

  • The instruments

  • The materials to test

  • Any calibration curves necessary

  • Any other testing materials necessary

  • Instructions on how to use instrumentation or test kits.


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Soil Nutrients

pH

Fertilizers

Effects of soil Temperature

Difference between sand, silt, & clay

What plants need

Porosity, water retention, & permeability

Contaminants

Remediation

Impacts of over fertilization

Main Focus


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Main Focus

  • Gas Spectrogram retention times

  • Mass Spec

  • Dilutions, unit conversions & Stoichiometric calculations

  • How to prepare students

  • Resources


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3 Main classes of nutrients

Absolutely necessary

Nitrogen

Phosphorous

Potash

Vital

Calcium

Magnesium

Sulfur

Trace

Iron, Manganese, Zinc, Boron, Copper, Molybdenum

Chlorine, Silicon, Nickel, Cobalt

Soil Nutrients


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Soil Testing

  • Test kits are available at local garden centers and Sears costing from ~$3-5. Often enough material for several tests are included

  • Numbers are not usually given, just very low, low, optimum, and above.

  • Even professional soil testers will give not only the numbers (which will vary from laboratory to laboratory and hence are unreliable) will also give the results in terms of very low, low, optimum, high.


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pH

  • Many plants need a slightly acidic soil

  • The natural pH of most water is about 6 because of the carbon dioxide dissolved in it.

  • Some flowers like hydrangeas have different colored flowers in different pH soils

  • Many plants produce natural indicators that change colors in different pH’s


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Calcium and Magnesium

  • Both Calcium and Magnesium are vital to proper plant growth

  • Neither are tested for in a standard NPK soil test kit

  • Can be tested for by testing a digested sample


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Remediation

  • To raise the pH of acidic soils (below pH 5.8), add lime (limestone)

  • To lower the pH of basic soils (above pH 8.3) that do not contain free carbonate, add sulfur.

  • Since limestone is a combination of calcium and magnesium carbonate, it can be added to increase the carbonate level if necessary.


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Fertilizers

  • NPK Fertilizers are only concerned with the 3 Absolutely Necessary ingredients

    • Nitrogen in the form of Ammonia (NH3) and Nitrate (NO3-)

    • Phosphorous (Usually in the form P2O5)

    • Potash (K+) (Usually as K2O)

  • The numbers on the bag tell the weights of each ingredient, in that order

  • There are lots of different fertilizers for various purposes



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Effect of Temperature

  • Water has a very high specific heat because of the hydrogen bonding

  • This means it can store a lot of heat in the bonds

  • Moist soil will not warm up as fast as dry soil

  • Dry soil will not cool down as fast as wet soil

  • Most plants prefer an optimal temperature for maximum growth-they will not grow properly if too hot or too cold


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What Plants Need

  • The Nitrogen is used for green leaves

  • The Phosphorus is used for strength and the root system

  • The Potash is used for fruits.

  • Most plants need a neutral pH around 6-6.5

  • Plants need balanced nutrition and not just NPK fertilizers


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Fertilizer Good or Bad

  • A good fertilization plan can be more beneficial for the environment than no fertilization

  • A properly applied fertilization program will promote plant growth which will prevent soil erosion

  • Proper fertilization means only applying what is necessary and not over applying


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Pollutant or Contaminant?

  • It is a pollutant if it is supposed to be there, but the substance is present in higher quantity than it should be.

    • Fertilizers, some ions, etc.

    • Sometimes metals are thought of as contaminants, but many soils contain arsenic and mercury naturally

  • It is a contaminant if it is not supposed to be there at all

    • Plastics


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Pollutants

  • Are metals pollutants or trace nutrients?

    • It depends on the concentrations

    • Some copper, iron, etc. are necessary for plant development.

  • Plants take the metal ions up in their structure and can be used to bio-remediate area, but then the plants can not be used for food.


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Remediation

  • Remediation depends on source and size of problem

  • Soil bacteria will digest many petroleum spills if the spill is not large scale or buried deeply

  • Underground storage tank leaks often have to be dug out so bacteria can get to petroleum

  • Clay will retain heavy metal contamination for long periods

  • Plants can be used to bio remediate soil

  • Chemical reactions can be used for some remediation

  • Electrokinetic remediation using acetic acid has achieved some success


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Source of Pollutant/Contaminant

  • Point Source – Used to be the biggest source of pollution. This would be a single plant, a chemical spill, a single farmer, etc. Legislation has almost eliminated this type of pollution

  • Non Point Source – Now the biggest source of pollution. This would be petroleum products dripping off of vehicles, road salt, fertilizer from residential areas, etc. This is much harder to control


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Mass Spec

  • Most questions will either be

    • Match the picture

    • Determine the weight of some part

    • Determine the relative abundance of some part

  • Graphs have

    • the mass of the components that the mass spectrometer has broken the compound up into on the x-axis

    • The relative abundance on the y-axis


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GC Spectrograms

  • Used to separate components of a mixture

  • The further right a peak is, the longer it is retained in the column

  • This is usually because it has a higher affinity for the stationary phase

  • Or it has a lower affinity for the mobile phase

  • The higher the peak is, the higher the concentration of that particular component of the mixture


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Preparation of Soil Samples

  • Normally to test for metal ions, the soils must be refluxed in concentrated nitric acid for about 24 hours to remove the metals to be tested for

  • Then the liquid is diluted.

  • Most of the ions are not colored and therefore need a reagent that when combined with the metal ions will be colored so the solution can be put in a colorimeter.

  • Since this is time consuming and dangerous, it may be advantageous to “fake” the materials to be tested for.


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Preparation of Test Materials

  • Food coloring makes an extremely good coloring agent.

    • If dilute enough, students would be hard pressed with the naked eye to tell the difference between a liter of water with a drop of red food coloring and an iron(III) solution with phenanthrolene added

    • Students would have a tough time telling with the naked eye the difference between a solution of copper(II) ion and a dilute solution of water and blue food coloring.

  • Black food coloring makes an extremely good base to hide other colors in.


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Basic Types of Soil

  • Sand – Largest particles – virtually no organic material - try to form a 1” ball of moist soil in your hand & if it feels gritty & won’t stay together it is a sandy soil

  • Silt – Smaller particles, more organic material – considered most fertile - less gritty ball than sand, more gritty than clay, ball crumbles

  • Clay –Smallest particles - if the 1” ball feels smooth, plastic, requires lots of pressure to form, stays together well & forms ribbons between your fingers, it is clay soil


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Other Soil types

  • Loam –made of some sand, silt, and clay - if the 1” ball feels partially smooth, partially gritty & forms a ball that easily crumbles it is loamy soil

  • Peat Soil – dead plant material – very acidic

  • Chalky Soil – has a large number of stones and is very alkaline


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Porosity

  • A measure of the void spaces in the soil as a percentage of the soil

  • Porosity = void volume/soil volume

  • Sandy soil ~.43-.36

  • Clay soil ~ .58-.51

  • Seems counterintuitive

  • Example

    • If 1 m3 of soil is actually .7 m3 of soil and .3 m3 of air and water

    • Porosity = .3 m3/1 m3 = .3 (sandy soil)


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How to Measure Porosity

  • Easiest method is to measure a volume of the soil

  • Measure an amount of water

  • Pour water into soil and collect that which runs through

  • Pour volume = Original volume of water – volume collected


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Permeability

  • The ability of the soil to transmit fluids

  • In other words how quickly the water can flow through the soil


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How to Measure Permeability

  • Take a sample of soil .1 meter deep in a sieve or container with a drain

  • Take a volume of water

  • Time how long it takes for the water to come out the bottom of the container


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Water Retention

  • Related to particle size, porosity, and permeability

  • Defined as water content as a function of matric pressure

  • A centrifuge is preferred to measure matric pressure

  • Often measured at the pore size in porosity measurements


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Impacts of Over fertilization

  • The main impact of over fertilization is the runoff into streams and rivers

  • The runoff into the streams and rivers causes unnatural algae blooms

  • Algae blooms take dissolved oxygen out of the bodies of water

  • When the dissolved oxygen is taken out of the water, fish and macro invertebrates die

  • Then you also have the problem of over production of fertilizer at plants with the associated environmental costs


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Calculations-Dilutions

  • Many fertilizers are liquids

  • They are sold in concentrated forms and require dilutions before use

  • Students should be able to do calculations involving dilutions


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Calculations-Unit Conversions

  • Parts per notation is a measure of concentration

  • Students need to be able to convert from one type of concentration to another

  • pph = parts per hundred = %

  • ppm = parts per million = 1/1,000,000 = 1X10-6


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Stoichiometry

  • Many contaminating heavy metals can be oxidized to remediate.

  • Oxides of most metals are insoluble in water and therefore removed from ecosystem

  • Oxidation can be by means of air injection or injection of strong oxidizer like ozone or permanganate

  • Some petroleum products are thermally burned


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How To Prepare Students

  • Practice

    • In teams

    • With soil test kits

    • With instruments

    • With calibration curves

    • Doing unit conversions, etc

  • Make notes


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How to Prepare Students

  • Have students research

    • Fertilizers

    • Plant nutrients

    • Environmental effects

    • Trace nutrients

    • Chromotography


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Resources

  • Nutrient depleation http://www.youngevity.ca/misc/mineral_depletion.php

  • Activity - http://www-tc.pbs.org/saf/1301/teaching/teach2.pdf

  • With Acid Rain http://www.eurekalert.org/pub_releases/2004-03/uom-ars032604.php#

  • Tomato Plant nutrient requirements http://www.wikihow.com/Grow-a-Tomato-Plant

  • Reading Fertilizer Labels http://www.wikihow.com/Read-a-Fertilizer-Label


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Resources

  • Effects of nutrient deficiency on plants http://www.uga.edu/vegetable/home.html

  • Soil Testing http://www.lowes.com/lowes/lkn?action=howTo&p=LawnGarden/soiltest.html

  • Soil Test Kits http://www.shopping.com/xDN-garden--soil_testing_kits-price_range_10_20

  • Fertilizer Numbers http://www.agroservicesinternational.com/index.html


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Rescources

  • Instrument labs

    http://education.ti.com/educationportal/activityexchange/activity_list.do?cid=us

    Source for all sorts of mass spectra & GC

    http://riodb01.ibase.aist.go.jp/sdbs/cgi-bin/cre_index.cgi

    http://webbook.nist.gov/chemistry/name-ser.html

  • Soil in General

    http://techalive.mtu.edu/meec/module06/Porosity.htm

    http://mypage.iu.edu/~lwoz/socrime/index.htm


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Questions?

  • Thank You


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