3.4.1 Pollution: properties of pollutants Flashcards
what states of matter can pollutants be?
solid
liquid
gas
What does state of matter affect?
the ability for the pollutant to be dispersed by moving water or air
What is usually the case with the dispersal of solid pollutants?
usually deposited close to the source
What is usually the case with the dispersal of gases?
transported easily in the atmosphere
What are the different energy forms of of pollutants?
Noise
Heat
Ionising radiation
light
What is the general behaviour of different energy forms?
Widley varying impacts due to the way energy behaves
How will density affect dispersal of pollutants?
Denser materials will require more kinetic energy to keep suspended (more likely to be deposited close to source
What is an example of a high density pollutant?
Lead dust
How does density of Gases affect dispersal?
Some gases are denser than air and settle close to the ground if there is insufficient wind to disperse them
What is an example of a disaster involving dense gases?
Hydrogen cyanide Bhopal India 1984
What is persistence?
measure of the length of time a pollutant remains in the environment before it breaks down chemically (degrades)
What is one of the main ways persistence can be measured?
Half-life
What is half-life?
the amount of time it takes for half the pollutant to breakdown
What conditions can affect the rate of breakdown?
light
temperature
oxygen levels
pH
presence of bacteria
What are some pollutants with a high persistence?
CFCs
Organochlorine insecticides (DDT)
What pollutants have a low persistence?
Sewage
Pyrethroid insecticides
What are the three types of degradation?
Biodegradation
Photodegradation
Thermal degradation
What is biodegradation?
caused by living organisms/ bacteria
What is photodegradation?
caused by light
What is thermal degradation?
caused by heat
What is toxicity?
a measure of how poisonous a substance it to living organisms
How do most toxic substances cause harm?
by damaging proteins, especially enzymes meaning cells may malfunction
What do toxins have varying levels of which can affect target species?
specificity
What is specificity?
some substances are more or less toxic to certain organisms
What is an example of specificity?
insecticides have a high toxicity to insects but low to mammals
How is Lead toxic?
inhibits enzyme action in nerve cells and can affect the brain, kidneys and bones
Why was Lead toxicity a problem for humans?
Lead was present in paint until 1992 and people may be at risk of exposure when removing old paint during renovations
What can reactivity affect?
Severity of pollution increasing or reducing the problems caused
How reactive are CFCs?
Low reactivity unless exposed to UV light
What is the stability of CFCs like?
Relatively stable in troposphere but broken down in stratosphere and releases chlorine
What is the reactivity of NOx, ozone and Hydrocarbons?
High
What more harmful pollutant is created when NOx, ozone and hydrocarbons create?
react with each other to produce PANS which are more toxic
What are PANS?
secondary pollutants formed by the photochemical reaction of hydrocarbons with nitrogen oxides in the atmosphere
Wat is a reactive pollutant that degrades rapidly?
Sewage
What is an example of a pollutant that reacts with other substances to produce secondary pollutants?
NOx to create acid rain and photochemical smog
What is Adsorption?
when pollutants become attached to the surface of materials such as soil particles or aquatic sediments
What can adsorption do to pollutants?
immobilize them so they cant cause pollution problems
What is the problem with pollutants that have been absorbed?
they may be released later to cause problems after a period of time when their presence was not obvious
what is an example of pollutants being released for an absorbed store?
disturbance of lake sediments by storms releasing phosphates or PCBs
What does water soluble mean?
it dissolves into water
What are the characteristics of water soluble pollutants?
tend to be less harmful
can excrete them from our body (urine)
don’t tend to bioaccumulate
What does lipid soluble mean?
Dissolves into fats (lipids)
What are the characteristics of lipid soluble pollutants?
tend to be more toxic
cannot be expelled from our body
continuous exposure causes bioaccumulation
What is an example of a lipo-soluble pollutant?
mercury
What is bioaccumulation?
when the concentration of a pollutant builds up overtime in the body if regular exposure occurs
as concentration increases so does toxicity
What is biomagnification?
occurs when pollutants increase in concentration through the trophic levels (food chain)
What must occur for biomagnification to take place?
bioaccumulation
pollutant must be soluble in lipids
what is synergism?
involves 2 or more pollutants where their effects interact to create a different effect (usually more serious)
what is important to remember with synergism?
pollutants themselves do not interact to produce a new pollutant (secondary pollution) it is their effects that interact
What is an example of synergism?
Tropospheric Ozone damages leaf cuticles which enables sulphur dioxide to cause more damage to newly exposed living cells
What is a mutagen?
agents which cause changes in the chemical structure of DNA by damaging chromosomes by rearrangement of DNA structure (mutation)
Where does the Gonadic effect occur?
Cells in ovaries and testes
What is the Gonadic effect?
mutation in egg, sperm cells or embryo that may cause a birth abnormality in offspring
Where does the Somatic effect occur?
general body cells
What is the Somatic effect?
mutation in body cell may make it behave abnormally as damaged DNA cannot control normal cell function
Why is singular cell death not an issue?
as can be replaced by division of healthy cells
What are some serious consequences of DNA mutations that are not killed?
Cancer
What is cancer?
uncontrollable cell division which produces a tumour
What are some examples of mutagenic pollutants?
ionizing radiation
UV light
chlorinated organic substances (PCBs, dioxins)
cadmium
asbestos
What is carcinogenic action?
Mutagens that cause cancer
What does cell manipulation by carcinogens cause?
mass of tissue called a tumour
How can a tumour cause health problems?
by preventing normal tissue function
What are Teratogens?
cause birth abnormalities by preventing normal gene expression
What do Teratogens not do?
do not change DNA structure but inhibit function of proteins and enzymes that DNA would normally control
Can teratogen abnormalities be inherited?
no because DNA structure is not affected
What are some examples of Teratogenic pollutants?
mercury
Herbicide 2,4,5T (no longer used)
What is pollutant mobility?
ability of pollutant to move dependant on its properties (state of matter, density and solubility in water)
What are more mobile pollutants likely to do?
Travel greater distances and affect larger areas
What might reduce severity of mobile pollutants?
Dilution
How mobile is lead dust?
high density of atmospheric dust cause most particles to be deposited near source
What is the mobility of smoke particles?
Very mobile
easily washed from atmosphere by rain or settle if relatively stable
smaller particles settle more slowly
What is the mobility of Sulphur dioxide gas?
Very mobile
soluble in water and easily removed from atmosphere by rain
usually moves 250km from source
What is the mobility of CFCs?
Chemically stable
low water solubility so remain in atmosphere for a long time
disperse throughout whole atmosphere
