The Dirt on Soil

The Case of the Illegal Dumpsite

a heterogeneous mixture of:• solids (minerals and organic matter)• liquid • gases that occurs on the land surface, occupies space, and is characterized by horizons, or layers.

Organisms found in Soil

Organic matter

Mole

Nematode

Earthworm

Amobea

Beetle Mite

What crimes involve soil?

Due to the widespread location of soil (earth), it can be used to associate people, objects, and scenes in numerous cases.

More biodiversity than any other medium on the planet

Nature of Soils(5 Soil Forming Factors)

Parent Material: Parent material is the material from which soils form. Soils form in

materials that have moved in from elsewhere.

Climate: Climate causes soils to vary. Weathering and leaching

patterns are determined by temperature and moisture amounts. Wind redistributes sand especially in dry regions.

Nature of Soils(5 Soil Forming Factors)

Biological Factors: Biological factors including plants, animals, and humans affect

soil formation. Plant roots open channels in the soil. Animals mix soils and form burrows. Humans can mix the soil intensely that the soil is considered parent material again.

Topography: Slope affects the moisture and temperature of soil.

Steep soils may erode and lose their topsoil as they form and consequently be thinner than level soils.

Time: Time for all the soil forming factors to interact with

the soil is a factor as well

TransferTwo main groups of analysis that scientists focus on in GEOFORENSICS---native and anthropogenic characteristics.

• Native characteristics can include soil chemical/physical properties such as mineral composition, particle size analysis, or the inclusion of unusual fossils.

• Anthropogenic characteristics can include chemical (TCE, PCE, Gasoline, MTBE etc.) or physical pollutants (metal shavings, glass, coal etc.) or combinations of each in the soil.

Locard’s Principle

How Do Soils Differ?

• Color

• Texture

You will be isolating color, size and texture during your field analysis

CSI Technician Data Qualitative and Quantitative

Field Analysis: Field analysis gives qualitative or semi-quantitative results.

Laboratory Analysis: Laboratory analysis gives quantitative results.

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Gas Chromatgraphy-Mass Spectroscopy

A GC-MS is a combination of a gas chromatograph and a mass spectrometer. • The gas chromatograph separates

molecules as they travel the length of the internal column. The column retains the molecules and then they come off the column as different times. This is called retention time

• Retention time allows the mass spectrometer to capture, ionize, accelerate, deflect, and detect the ionized molecules separately

What is a VOC?VOC stands for Volatile Organic Compounds.

VOCs are emitted as gas from certain products commonly used in the home, which in high quantities can pose serious health risks.

Products known to emit VOCs include:• Benzene (tobacco smoke, stored fuels, paint supplies,

and automobile emissions• cleaning supplies• Pesticides• building materials and furnishings• Office equipment• Perchloroethylene (dry cleaning)• Gasoline

Field Screening Tools you will will be using

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Universal indicator paperUniversal indicator papers have been impregnated with a mixture of several indicators. On contact with the sample solution they assume a particular color. A check against the color comparison table supplied allows the pH to be determined—reds indicate acid, green neutral, blues bases

Documenting the samples taken from the crime site

Place sample into sterile jar and label with location code

Place collect samples on ice—4 degrees C to prevent VOCs from evaporating

Chain of Custody form

Your Task as a CSI Technician

1. You will perform a visual inspection to determine which remaining sites contain grass, leaf matter, dirt and gravel.

2. You will confirm the location of the possible contamination site through the field analysis using the sorting sieve

3. Determine which of the remaining sites contain acidic and basic VOCs using a universal indicator paper

4. Collect soil sample for laboratory analysis using the CHAIN OF CUSTODY process

Proper Collection Technique

1. Wear Gloves2. Rinse sieve and

trowel after each sample sifting

3. Code/label the collection container

4. Complete a CHAIN OF CUSTODY form for each sample collected

Retain “washed” water in a field rinsate blank jar.

1.Write a hypothesis to solve the above scenario as it relates to finding the location of the weapon used to kill the victim?

2. How would you test you hypothesis?

REMEMBER … it is an IF and THEN statement

Let’s Go to the Crime Scene

Back in the CSI Crime Lab

Questions

1. What were the native characteristics of the soil where the contaminated soil was located?

2. What were the anthropogenic characteristics of the soil were the soil was located was located?

3. Can we definitely say that this analysis was from illegal dumping of toxic chemicals? If so, can we know who dumped it just from the analysis of the soil? What other evidence would we need?