1.5: humans & pollution Flashcards
pollution definition:
the addition of a substance or an agent to an environment by human activity, at a rate greater than that at which it can be rendered harmless by the environment, and which has an appreciable effect on the organisms in the environment.
the contamination of air, water or soil by substances that are harmful to living organisms.
pollution can occur naturally (ex. Through volcanic eruptions) or unnaturally (spilling of oil, disposal of industrial waste).
pollutant:
may be in the form of organic/inorganic substances, light, sound or heat energy or biological agents/invasive species and derive from a wide range of human activities including the combustion of fossil fuels.
major sources of pollution -
- combustion of fossil fuels
- domestic waste
- industrial waste
- agricultural waste
eg. of pollutants from combustion of fossil fuels -
Carbon dioxide -> Releases greenhouse gases which lead to climate change
Sulphur dioxide -> Acid decomposition which leads to tree and fish death, respiratory problems in humans (RPIH)
Nitrogen oxides -> Respiratory infections, eye irritation (EI), smog
Photochemical smog -> Secondary pollutants – damage to plants, RPIH, EI
Carbon monoxide -> Binds with haemoglobin in RBC’s instead of oxygen – can lead to death by suffocation
eg. of pollutants from domestic waste -
Organic waste (food and sewage) -> Eutrophication, waterborne diseases
Waste paper -> Volume fills up landfill sites, forests cut to produce it
Plastics -> Volume fills up landfill sites, derived from oil
Glass -> Energy required to manufacture it, can be recycled but most goes to landfills
Tins/cans -> Can be recycled but most goes into landfills
eg. of pollutants from industrial waste -
Heavy metals, fluorides -> Poisoning
Heat -> Reduces solubility of gases in water, so less oxygen so organisms may die
Lead -> Disabilities in children
Acids -> Corrosive
eg. of pollutants from agricultural waste -
Nitrates -> Eutrophication
Organic waste -> Eutrophication, disease spread
Pesticides -> Accumulate up food chains
forms of pollution -
- point source pollution
- non-point source pollution
point source pollution:
- release of pollutants from a single, clearly identifiable site (for e.g., a factory chimney, waste disposal pipe of a sewage works into a river).
- pollution that can be traced back to a single source or origin.
- it has a localised impact, so it is usually easier to manage.
- allows emission control.
- allows determination of responsibility and taking legal action and the polluter can be identified and prosecuted if necessary.
non-point source pollution:
- release of pollutants from numerous, widely dispersed origins (for e.g., gases from the exhaust systems of vehicles, chemicals spread on fields)
- pollution which cannot be traced back to a single source or origin.
- more difficult to identify and manage.
- hard to assign responsibility.
- the area affected may be large enough that it crosses borders, making regulation/control an issue that must be organised among several different governments or government branches.
primary & secondary pollutants:
primary pollutants – active on emission (carbon monoxide from the incomplete combustion of fossil fuels -> causes fatigue, headaches & can kill)
secondary pollutants – arising from primary pollutants undergoing physical or chemical change. (eg. photochemical smog)
persistent organic pollutants:
- organic compounds that do not break down in the environment through chemical, biological, and light processes. they remain active in the environment for a long time.
- they bioaccumulate in animal and human tissues and biomagnify in food chains and can cause significant harm.
- eg. pesticides, solvents, pharmaceuticals, and industrial chemicals.
biodegradable pollutants:
- decay or breakdown of pollution that occurs when microorganisms use an organic substance as a source of carbon and energy. the products are rendered harmless by natural processes and so cause no permanent harm.
- do not persist in the environment and break down quickly be either decomposer organisms or physical processes eg. light or heat.
- eg. soap, domestic sewage, degradable plastic bags
acute pollution:
- when large amounts of a pollutant are released, causing a lot of harm.
- pollution of significance which occurs suddenly and should take into account worst case discharge scenario from the facility.
- eg. Bhopal disaster of 1984 in India.
chronic pollution:
- results from the long-term release of a pollutant but in small amounts.
- persistent release of a pollutant at low concentrations resulting in adverse effects on animal or human body with symptoms that develop slowly, due to long and continuous exposure to low concentrations of a hazardous substance. such symptoms do not usually subside when the exposure stops.
- it is serious because it often goes undetected for a long time, it is usually more difficult to clean it up and it often spreads widely.
- eg. Beijing’s poor air quality is an example of chronic air pollution.
measurements of pollution -
direct measurements: record the amount of a pollutant in water, the air or soil.
indirect measurements: record changes in an abiotic or biotic factor which are the result of the pollutants.
pollution management strategies:
- Alter human activity
- Controlling release of pollutant
- Clean-up and restoration of damaged systems
alter human activity:
alter human activity that leads to the production of the pollutant in the first place, by promoting alternative technologies, lifestyle, and values through:
- campaigns
- education
- community groups
- government legislation
- economic incentives/disincentives
controlling release of pollutant:
when the activity/production is not completely stopped, strategies can be applied at the level of regulating or preventing the release of pollutants by:
- legislating & regulating standards of emission
- developing/applying technologies for extracting pollutant from emissions
clean-up and restoration of damaged systems:
where both the above levels of management have failed, strategies may be introduced to recover damaged ecosystems by:
- extracting and removing pollutant from ecosystem
- replanting/restocking lost or depleted populations and communities.
DDT:
was developed as the first of the modern synthetic insecticides in the 1940s.
initially used to combat insect-borne human diseases (such as malaria) and for insect control in crop and livestock production, institutions, homes, and gardens.
quick success led to the development of resistance by many insect pest species.
DDT is an eg of a persistent organic pollutant that is extremely hydrophilic and strongly absorbed by soil.
banned after the publish ofSilent Springby Rachel Carson.
advantages of DDT -
- non-toxic
- highly persistent giving long lasting effect
- safe if used properly
- alternatives are not as effective
- banning of DDT = increase in malaria and resurgence of mosquitos
- DDT significantly reduces malaria death. eg. Ecuador (1993-1995) – increase of DDT = 61% reduction in malaria
disadvantages of DDT -
- loss and degradation of soil
- would affect other wildlife
- lead to premature birth, low birth weight and abnormal mental development of infants
- alternative methods of pest control exist
- significant ecological effects
- effects of accumulation in human tissue are not fully known
eutrophication:
increased amounts of nitrogen and/or phosphorus are carried into streams, lakes and groundwater causing nutrient enrichment. this lead to rapid growth of algae, accumulation of dead organic matter, high rate of decomposition and lack of oxygen.
role of positive feedback -
- increase in inputs of nutrients (nitrates and phosphates) which enter the lake
- increase in algae productivity in the lake
- massive increase in algae
- increase in dead organic matter due to increase in decomposer as there are more algae for food
- higher rate of decomposition as the decomposers respiration
- increase in oxygen demand but decline in oxygen level
- death of organisms
management strategies to restore a eutrophic lake -
add aerators to the lake (to maintain survival of species);
remove aquatic plants during their growing period;
dredge the mud from the bottom of the lake to remove nutrients;
add aluminium or iron salts to flocculate the phosphates andsuspended particles;
introduce species of fish which consume algae;
reintroduction of native species of plants and animals
evaluation of above management strategies -
aerators are expensive to operate;aerators do not reduce the pollution problem, so must beused continuously
aquatic plants which have been removed from the lake transferthe nutrient overload to another ecosystem;
mud pumped from the lake transfers nutrient overload toanother ecosystem
flocs must be removed as aluminium is toxic
system diagram showing impacts of pollutants -
inputs of the process or activity, which includeenergy and other resources consumed andraw materials and chemicals used
step-by-step process flows
decision points (e.g., on alternate methods)
process outputs, which include products orservices, air emissions, noise, odor, radiation,wastewater discharges, solid waste, and hazardouswastes.
