Soil Analysis

Question 1

soil

Answer 1

degraded material that lies on Earth’s surface

Question 2

natural soil examples

Answer 2

• rocks
• minerals
• vegetation
• animal matter

Question 3

natural soil range

Answer 3

can range from 100% inorganic to 100% organic

Question 4

100% inorganic soil

Answer 4

sand

Question 5

100% organic soil

Answer 5

peat

Question 6

artificial/manufactured soil

Answer 6

• glass
• paint
• cinders

Question 7

soil forensic importance

Answer 7

• easily transferred/transported/unnoticed
• class evidence
• exclusion/inclusion of known samples to questioned sample

Question 8

where soil samples can be found

Answer 8

• boots
• shovels
• tires
• wildlife

Question 9

crimes where soil evidence could be useful

Answer 9

• murder
• abduction
• rape
• burglary
• hit & run

Question 10

variations in soil crime scene

Answer 10

if the soil is indistinguishable for miles surrounding the crime scene, it will have limited value in associating soil found on the suspect with that particular site

Question 11

collection of soil

Answer 11

collected at various intervals within a 100-yard radius of the crime scene, as well as the site of the crime, for comparison to the questioned soil

Question 12

how to collect soil of the body & objects

Answer 12

• must not be removed
• each object should be individually wrapped in paper & transmitted to the laboratory

Question 13

soil collection for standard/reference samples

Answer 13

• only a tablespoon or two of the top layer of soil is collected, placed in individual plastic containers, & labeled according to location
• dry out samples

Question 14

how is soil analyzed?

Answer 14

• color comparisons
• soil texture & structure
• microscopic examination for debris
• geologically for rocks & minerals
• density gradient tube technique

Question 15

munsell soil color chart

Answer 15

• typically soil samples are uniformly dried & compared using standardized colors
• 1,100 distinguishable colors
• colors darker when wet

Question 16

color of soil with low levels of organic matter

Answer 16

lighter

Question 17

color of soil with high levels of organic matter

Answer 17

darker

Question 18

low power magnification microscopic examination of soil

Answer 18

investigates presence of contaminants, plants, & animal debris

Question 19

high power magnification microscopic examination of soil

Answer 19

• can classify rocks & minerals
• 1000s of minerals

Question 20

high power magnification of 1000s of minerals

Answer 20

• 20 commonly observed in soils (4-5 found together)
• distinguished by polarized light microscopy

Question 21

which is the largest: sand, silt, clay

Answer 21

sand

Question 22

which is the smallest: sand, silt, clay

Answer 22

clay

Question 23

sand size

Answer 23

2.00-0.05 mm

Question 24

silt size

Answer 24

0.05-0.002 mm

Question 25

clay size

Answer 25

< 0.002 mm

Question 26

how to separate sand, silt, and clay

Answer 26

- sieves - water separation

Question 27

density gradient tubes

Answer 27

- these tubes are typically filled w/ layers of liquids that have different densities - when soil is added to the density gradient tube, its particles will sink to the portion of the tube that has a density of equal value

Question 28

ideal soil pH

Answer 28

5.5-8 is ideal pH range for plant growth

Question 29

Differential Thermal Analysis

Answer 29

- DTA - as soil is heated, reactions happen to physical state or chemical reaction

Question 30

DTA reaction types

Answer 30

exothermic or endothermic

Question 31

exothermic

Answer 31

reaction with the release of heat

Question 32

endothermic

Answer 32

reaction with the absorption of heat

Question 33

Thermogravimetric Analysis

Answer 33

- TGA - monitor weight change as soil is heated at a constant rate

Question 34

what is caused by an exothermic reaction?

Answer 34

loss of weight

Question 35

Cation Exchange Capacity

Answer 35

- CEC - negatively charged conditioner particles hold & store positively charged cations - plant roots exchange hydrogen cations for essential nutrients it cannot produce for itself - co-insides with soil textures

Question 36

what type of evidence is soil?

Answer 36

class evidence