Soil transportation, fate and exposure of chemicals

Question 1

Characteristics of residual soil?

Answer 1

• Underlying bedrock is the parent material.
• Soil made in the same area and composition is similar with the bedrock.
• It is usually less fertile and we have less information regarding it.

Question 2

Characteristics of transported soil?

Answer 2

• Parent material is different and depends on the source of rock.
• Soil was transported so composition is different than the bedrock and is a mixture of various components.
• It is usually more fertile and is more studied than the residual soil.

Question 3

Main types of transported soil?

Answer 3

Gravity
Glaciers
Water
Wind

Question 4

Examples under gravity transportation?

Answer 4

Colluvial deposits -> talus

Question 5

Examples under glacier transportation?

Answer 5

Glacial deposits -> Eskers, drumlins

Question 6

Examples under water transportation?

Answer 6

Fresh water:
streams -> alluvial deposits
lakes -> lacustrine deposits

Sea water:
marine deposits -> marine clay and marl

Question 7

Examples under wind deposits?

Answer 7

Aeoline deposits -> loess and sand dunes

Question 8

What happens to chemical when they enter the environment? (Many examples)

Answer 8

o Degrade chemically, photochemically or biologically
o Drift into the soil or to water body
o Be adsorbed to the soil or to the sediment
o Retail in solid material and accumulate in soil or organisms
o Vaporise to the atmosphere

Question 9

The transformation of chemicals depend on what environmental conditions?

Answer 9

o Temperature, pH, sunlight intensity, microbial activity, etc.
o Air and water exchange, sorption/desorption, etc.

• Lipophilicity of chemicals – ability of chemical to dissolve in fats, oils, etc.

Question 10

Properties of Chemicals? (3)

Answer 10

• Water Solubility:
- Tendency of chemical to transfer from water to air, soil, and organisms.

• Dissolving better in organic solvents than in water:

• Tendency to move into organic phases (soluble in fat, etc.).
• Lipophilic chemicals can be accumulated in an organism.

• Volatility:
- Tendency of chemical to vaporize with high vapor pressure and low water solubility.

Question 11

What is sorption?

Answer 11

Stickiness of chemical with soil and
sediment, depends on the soil type and organic content.

Sticky soils such as clay has higher sorption
capacity.
o Absorption – soak up inside the
surface.
o Adsorption – hold molecules as a thin
film on the outside surface.

Question 12

What is desportion?

Answer 12

Detachment of chemicals from

soil particles.

Question 13

Small soil/sediment size particles do what?

Answer 13

They attract more chemicals. Small molecule size chemicals can easily accumulate in soil and organisms.

Question 14

Water soluble chemicals can?

Answer 14

Travel through soil pores to ground and surface water

Question 15

Particles age and temperature?

Answer 15

Aged and low temperature decrease release of chemical in water body through soil.

Question 16

Organic matter of soil makes the soil retain?

Answer 16

More chemicals

Question 17

Environmental degradation and chemicals relate how?

Answer 17

Resistant chemicals to environmental degradation are typically harmful in nature.
Slow degradation leads to accumulation.

Question 18

What is abiotic degradation?

Answer 18

Abiotic Degradation - that of chemicals without microbes.

o Hydrolysis – breaking chemical bonds by addition of water.
o Oxidation – breaking chemical bonds by addition of oxygen.
o Oxidation helps in the process of photolysis.

Question 19

What is biotic degradation?

Answer 19

Biotic Degradation – that of chemicals with microbes.

o Leads to mineralization of chemicals to water, carbon dioxide, etc.

Question 20

What is mineralization?

Answer 20

Complete conversion of chemicals to their simplest
naturally occurring fragments.
Increasing microbial activity increases potential of chemical degradation.

Question 21

Finnish Context for Toxic Transportation in Soil?

Answer 21

Chemical and biological processes are slow due to cold.

Physical processes such as sorption, degradation, evaporation, bioaccumulation are slow due to cold.

Active organic layer is low in soil and amount of nutrient is low in soil.

Humic content (due to dissolved organic material) is high in water aiding sorption of chemicals.

Question 22

What are the water structures for soil interaction?

Answer 22

Littoral zone (producers like plants)
Limnetic zone (producers like algea)
Profundal zone (mixture of aerobic and anaerobic
producers such as green photosynthetic bacteria)
Benthic zone (with sulfur reducing bacteria)

Question 23

Presence of low nutrient content in the water can do what?

Answer 23

In case of low nutrient in the water, the microbes will grow in the surface (where there is carbon dioxide from atmosphere and light).

Same is the case of microbes based on the availability of oxygen (more on surface and less on deeper water)

Question 24

What is eutrophication?

Answer 24

Excess amount of nutrients in water body.

Major causes:
➢ Through organic matter (such as sewage waste)
➢ Through inorganic matter (such as nitrogen and phosphorous)

Question 25

How does the eutrophication starts?

Answer 25

Algae and cyanobacteria get energy
-> carbon from sunlight and carbon dioxide from the surface

Cyanobacteria also fixes atmosphere nitrogen adding up more nutrient in the water body system

Phosphorous is the required nutrient now – a small pollution can thus trigger eutrophication

Question 26

Water solubility, a chemical property what does it mean?

Answer 26

Determines the tendency for chemicals to move or

transfer from water to air, soil, and organisms.

Question 27

Chemicals that dissolve better in organic solvents than in water has?

Answer 27

Tendency to Move into Organic Phases (lipophilic = fatsoluble).
Lipophilic chemicals can be accumulated in an organism.

Question 28

What does bioaccumulation means?

Answer 28

Refers to the accumulation of substances, such as pesticides, or other chemicals in an organism.

Question 29

When does bioaccumulation occurs?

Answer 29

When an organism absorbs a substance at a rate greater than that at which the substance is lost.

Question 30

What is volatility?

Answer 30

Volatility is the tendency of a substance to vaporize = to get in the air.
It is directly related to a substance’s vapor pressure.

Question 31

The evaporation of a chemical from water depends on its volatility and its water solubility as well. However, If the substance is totally water soluble then?

Answer 31

It will not easily evaporate from water although it’s

vapor pressure is high.

Question 32

Soil sorption is highly dependent of?

Answer 32

Soil type and particularly soil organic content.

Generally, soils higher in clay and organic matter have a higher ‘sorption capacity´.

Question 33

Chemicals are usually attached to the smallest or largest particle size fraction?

Answer 33

Smallest!

Question 34

How does planarity affect sorption?

Answer 34

Planar compounds sorb more tightly and may reach more narrow spaces.
Planar compounds are more tightly bound and nonplanar compounds.

Question 35

Why is molecular size important?

Answer 35

Because the larger ones cannot bioaccumulate and thus cannot by pass the cell membrane easily.

Question 36

How does chemicals react if temperature is pretty low?

Answer 36

Decreases the fraction of chemicals that can be released to the water phase.
Evaporation is smaller.
Also bioaccumulation decreases.

Question 37

Why is chemical degradation important?

Answer 37

In ideal situation chemicals are degraded to nontoxic products such as carbon dioxide, water, and minerals
(mineralization).

Question 38

If the chemical is easily degradable, it may

Answer 38

not have significant impact on the environment.

Question 39

If the chemical degrades slowly,

Answer 39

it can spread broadly and accumulate in soil or in biological organisms.