Properties Of Pollutants Flashcards
What do the properties of pollutant determine?
- the length of time it may cause a problem
- the level of harm it may cause
- where and how far it might travel
What is it important to understand properties?
They can help to anticipate what might happen and even prevent them from
Explain state of matter as a pollutant property
Whether a pollutant is a solid, liquid or gas affects its ability to be dispersed by moving water or water
what are solid pollutants more likely to do?
Be deposited close to the source
What are gas pollutants more likely to do?
They are easily transported in the atmosphere- can go further than solids
What are the different forms of energy that pollutants can be?
Noise, Heat, Ionising radiation, light
What impact does the energy form have as a pollutant property?
It has a wide variation of impacts because of the way energy behaves
How can density be an important property of pollutants?
The density will effect dispersal
Why does the density of a pollutant affect its dispersal?
Denser materials require more kinetic energy to keep them suspended so are more likely to be deposited close to the source
Name a high density pollutant
Lead dust
What impact can the density of pollutants that are gases have?
Some gases are denser than air, this means they settle close to the round if there is insufficient wind
Example of an incident where there was a high density gas pollutant involved
Hydrogen cyanide was released in Bhopal, India in 1984
It remained very close to the source
What is persistence/ how is it a property of pollutants?
It is a measure of the length of time that a pollutant remains in the environment before it chemically breaks down (degrades)
How can the persistence be measured?
As the time it takes for half a pollutant to break down
The measurement of time for pollutant to degrade is also known as what?
The environmental half life
What is the measurement of the time taken for pollutants to degrade also known as?
The environmental half-life
Why is the environmental half-life not a precise measurement?
Because the rate of breakdown can be affected by environmental conditions
E.g. light, temp, oxygen levels, PH, presence of bacteria
Give 2 examples of high persistence pollutants
-CFCs
- organochlorine insecticides e.g. DDT
Give 2 examples of low persistence pollutants
- sewage
- Pyrethroid insecticides
How can the types of degradation be categorised?
By the features that cause the break down
What are the 3 types of degradation and what is each caused by ?
Biodegradation: caused by living organisms (usually bacteria)
Photodegradation: caused by light
Thermal degradation: caused by heat
What is the toxicity of a pollutant?
A measure of how poisonous a substances is to a living organism
How does the toxicity of pollutants cause harm usually?
By damage to proteins- especially the inhibition of enzyme action
Give 4 examples of toxic pollutants
-carbon monoxide
-lead
-acids
-cyanide
Explain why carbon monoxide is a toxic pollutant
It prevents blood from carrying oxygen (or CO2 to leave the body) by binding to Hb in red blood cells
Explain why lead is a toxic pollutant
It inhibits enzyme action in nerve cells
Explain Acids as toxic pollutants
They inhibit protein action by changing the molecular shape- e.g. active site of an enzyme
Explain why cyanide is a toxic pollutant
It inhibits enzymes involved in aerobic respiration
Specificity is a property of what property?
Toxicity
Why is specificity used to describe toxic pollutants?
Because there are variations in toxicity to different groups of organism
(Specific toxins are more toxic to some groups than others)
What does it mean if a pollutant is non-specific?
They have similar toxicities to all groups
Example of a toxic pollutant that is also specific
Pyrethroid insecticides have a high toxicity to insects, but a low toxicity to mammals meaning it is relatively safe for them to be used by humans in areas where there is livestock
However they also have a high toxicity to fish so shouldn’t be used near rivers or fish farms
Explain reactivity as a pollutant property
The reactivity can affect the severity of the pollution caused- either increasing or reducing problems caused by
Name a pollutant with a low reactivity and what it does as a pollutant
CFCs have a low reactivity except in the presence of UV light
They are relatively stable in the troposphere but in the stratosphere they are broken down and thats where they release chlorine
Name 3 pollutants with high reactivities and what they do as a pollutant
NOx, Ozone and Hydrocarbons
They react with each other to produce PANS which are more toxic
What 2 things could a reactive pollutant do?
- degrade rapidly e.g. sewage
- react with other substances to create secondary pollutants e.g photochemical smog
What is a primary pollutant?
One that is released by human activities
What is a secondary pollutant?
One produced by chemical reactions between one or more primary pollutants and/or non-pollutants
Explain adsorption as a property of pollutants
-some pollutants can stick to the surface of materials
- this can immobilise them so they cant cause pollution
- it is possible they can be released later and cause problems after a period of time
- there presence may then not be obvious
What kind of material surfaces can pollutants get stuck to if they have adsorption as a property?
-soil particles
-aquatic sediments
Example of Adsorption as a property being an issue
Lake sediments being disturbed by storms so releasing phosphates or PCBs as a result
What does it mean if a pollutant is soluble in water?
-substances are more easily dispersed in water bodies
- this can reduce the concentration or mean they affect larger areas
Name a pollutant that is water soluble
Nitrates
What are lipids and what are they insoluble in?
-organic compounds that are fatty acids or derivatives of fatty acids
-they are insoluble in water
What does it mean if a pollutant is lipid soluble?
-The substances can dissolve in lipids
What can happen if a pollutant is lipid-soluble?
- it could pass through the phospholipid cell membrane and be stored in oil or fat deposits in the cell
Name 2 examples of lipid-soluble pollutants
-mercury
-DDT
What is Bioaccumulation?
The process by which the amount of a substance within an organism increases
The original dose may have been too small to be toxic but they may build up to eventually reach toxic levels
What kind of pollutants are often involved in Bioaccumulation and how?
The long-term ingestion of small doses of a liposoluble pollutant
Why are liposoluble pollutants more likely to bio-accumulate than water soluble pollutants?
Liposoluble are more likely because they may be stored in lipids whereas water soluble ones tend to be excreted from the body more easily
Explain how Biomagnification occurs
-substances that bioaccumulate may become more concentrated along the food chain
- they become progressively more concentrated into a smaller biomass with each trophic level
-organisms in later trophic levels tend to have longer lives so build up even higher concentrations from food intake
What type of organisms are most susceptible to biomagnification and why?
-endotherms (warm-blooded)
-they have a higher food intake because they have higher metabolic rates, are more likely to ingest more pollutant
What is synergism?
In pollution it involves two or more where their effects interact to create a different, usually more serious, effect
Why is synergism different to a secondary pollutant?
The pollutants themselves don’t interact to produce a new pollutant, which is what happens in a secondary pollutant, the effects interact and cause a different effect
Give an example of synergism in pollution
Ozone damages the leaf cuticle which means sulphur dioxide is able to cause more damage because there is more newly exposed living cells
Explain mutagenic action as a property of pollutants
-some pollutants are mutagens
-mutagens are agents that cause chemical changes to DNA structure
-these changes are known as mutations
How can mutagens chemically change DNA?
By damaging the chromosomes and rearranging the DNA structure
Name 3 different impacts of mutagens
-gonadic effects
-somatic effects
-carcinogenic action
Gonadic effects caused by mutagenic action impact what kind of cells in the body?
Cells in the ovaries or testes
Somatic effects caused by mutagenic action impact which cells in the body?
General body cells
What are the gonadic effects of mutagens?
-A mutation in an egg or sperm cell or in an embryo
- they may cause a birth abnormality in the offspring produced
What are the somatic effects of mutagens?
-it may cause a body cell to act abnormally because the DNA is damaged
-this means DNA cant control normal cell function
-individual cells death isn’t a problem-replaced by healthy cell division
-serious effect is uncontrollable cell division that can cause a tumor- if the cells with DNA mutations aren’t killed
Name 5 examples of mutagenic pollutants
-Ionising radiation
-UV light
-Chlorinated organic substances e.g. PCBs,dioxins
-Cadmium
-Asbestos
What are carcinogens?
Mutagens that cause cancer
How do carcinogens cause cancer?
-cell multiplication caused by a carcinogen produces a mass of tissue called a tumour
-the tumour may eventually cause health problems by preventing normal tissue function
Explain teratogenic action as a property of pollutants
-teratogens cause birth abnormalities by preventing normal gene expression
-the birth abnormality cannot be inherited by future generations because the DNA structure is not effected
Why is teratogenic action different to mutagenic?
It doesnt change the DNA structure but it does inhibit the function of proteins and enzymes DNA usually controls
Name an example of a teratogenic pollutant
Mercury
Explain mobility as a property of pollutants
The ability of a pollutant to more in the environment, but it depends on other properties like the state of matter,density and solubility in water
What are more mobile pollutants likely to do?
- travel greater distances
-affect larger areas
-dilution however may reduce the severity of the effect
Explain the mobility of Lead dust
The high density of atmospheric lead dust causes most particles to be deposited close to the source
Explain the mobility of CFCs
CFCs are chemically stable and have a low solubility in water
They remain in the atmosphere for a long time and disperse throughout the whole atmosphere
