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Lecture 4 - Dmitri - Pollution, Pollutants and Environmental Toxicology, 24-25/10
Terms in this set (34)
Because the burning of coal polluted the environment, the white coloured moth was more easily seen by other animals and so it disappeared in industrial areas and gave way to the dark-coloured moth.
SO2 as a pollutant
The peak of production of SO2 was in the late 60s, but due to increased environmental awareness and the introduction of legislation to clean up the air - Clean Air Act 1956 - the production of SO2 has almost dropped twice.
Pollution - def.
"Pollution" shall mean the direct or indirect introduction, as a result of human activity, of substances, vibration, heat or noise into the air, water or land which may be harmful to human health or the quality of the environment, result in damage to material property, or impair or interfere with amenities and other legitimate uses of the environment.
"Contamination" is being used for situations where a released substance is present in the environment without any obvious harm, in contrast to "pollution" where harmful effects are apparent.
Possible problems with contamination definition - if a chemical substance didn't show any harm, it could be just a matter of time and a matter of quantity. So this term is being used less and less nowadays.
Exert harmful effects in the form in which they have been released into the environment
E.g. CO2, CO, SO2, NOx's etc.
Products of chemical reactions occurring in the environment, usually between less harmful precursors.
E.g. - O3 - formed in the atmosphere under sun radiation during reactions of HC's with NOx's
E.g. - Acid rains. We release SO2 and NOx's which mix with water/vapour. Those oxides are reduced to form acid rains.
Bioacculumulation and Biomagnification
Some substances, which are normally considered as safe for animals may cause severe harmful effects if they are persistent in the environment and have a tendency for accumulation
Side effects of aldrin and dieldrin
Convulsions and other nervous system effects, and can cause kidney damage
Side effects of cadmium
Damages lungs and kidney, also causes bones to become fragile
Side effects of Mercury
Causes hallucinations, manic-depressive psychosis, increased irritability, muscular terrors, irreversible brain damage
Classification of pollutants
(1) according to source (e.g. industrial pollution)
(2) according to the media affected (e.g. air pollution)
(3) according to nature of the pollutant (e.g. heavy metal pollution)
(i) a source of pollutants
(ii) the pollutants themselves
(iii) the transport medium (water, air, etc..)
(iv) the target (or receptor) , which includes ecosystems, individual organisms and structures.
Energy related sources
- sulphur oxides - if the feed contains S
- particulates - from 1-10 macrom. When burning solid particles like coal and also the heavy residuals of petrol(?)
- nitrogen oxides and hydrocarbons
- carbon monoxide
- Carbon dioxide - large
(see lecture 6)
- pesticides - largely controlled
- nitrates and phosphates
- heavy metals
Very wide range of pollution
- domestic waste
Global distillation of pollutants
(1) At low latitudes, evaporation of pollutants exceeds deposition
(2) Pollutants are transported by the atmosphere and oceans
(3)At high latitudes, deposition of pollutants exceeds evaporation
(4) Pollutants enter the polar food web and accumulate in biota
Toxicology (from greek - poisonous)
A branch of biology and medicine concerned with the study of the adverse effects of chemicals on living organisms. It is the study of symptoms, mechanisms, treatments and detection of poisoning, especially the poisoning of people
Interdisciplinary science concerned with the study of natural and anthropogenic pollutants and their impacts on living organisms and ecological systems.
Concerns oil spillages and pesticides.
DDT - dichlorodiphenyltrichloroethane
Used to control malaria (kill insects). Saved about 5x10^7 lives.
1945-1960 - DDT was mostly used then. More insecticides were discovered in result. Dieldrin, Lindane, Chlordane, etc. Massive insect-control projects were undertaken as well - Dutch elm disease, Fire ant, etc. Production peaked around the beginning of the 60's.
DDT after Silent Spring
Exposed the effects of DDT. They were able to observe the change in the biology of falcons and connect that to pesticides. EDF petitions the Federal court to force action on control of pesticides. EPA is created to control pesticides.
Looking back on DDT use
(1) It turned out to be persistent in the environment.
(2) Bioaccumulation and biomagnification in the food chain
(3) Not toxic to humans, but no necessarily safe for other organisms.
(4) Long term use leads to development of DDT resistance in insects
Explain the transfer of energy from primary produces (plants) to complex consumers. Normally, the levels of feeding are referred to as trophic levels. Ex: plants -> insects -> birds -> fox.
An increase in the concentration of a chemical in a biological organisms over time, compared to its concentration in the environment. Obv, components accumulate in living things when they are taken up faster than they are broken down or excreted. Understanding the dynamic process of accumulation is important in protecting human beings and other organisms from the adverse effects of chemical exposure, and it has become a critical consideration in the regulation of chemicals.
Reasons for bioaccumulation and biomagnification
1) Stability of the chemical in different fluids, such as water or fat.
2) Solubility of a chemical in water or fat.
For example, if a chemical is more easily soluble in fat, it will affect more severely. If it is soluble in water, it is more easily cleaned away from organisms.
At the time of pesticides, there were no tests for this, but then the Hansch index was designed.
A process that results in the accumulation of a chemical in an organism at higher levels than are found in its food. It occurs when a chemical becomes more and more concentrates as it moves up through a food chain - the dietary links between single-celled plants and increasingly larger animal species.
Ration b/w the concentration when a substance X is dissolved in octanol (roughly represents fats) and in water. Logarithmic scale.
The higher the value of the coefficient, the higher the probability the chemical will be in the organic phase in a organism and it is more likely to accumulate and magnify.
E.g. Atrazine is not as dangerous as it is not that stable with a factor of 2.6.
Indices of toxicity
LC50 - Lethal concentration that kills 50% of a population
LD50 -Lethal dose that kills 50% of a population
EC50 - Effective concentration that causes 50% of an observable response, e.g. reduction in growth rate or reproduction rate
NOEL - No observable effect limit
A standard method of testing lab animals is dose-response.
- LD50 - lethal dose; amount of toxicant to kill half the population
- ED50 - effective dose; scientists may be interested in non-lethal health effects
- Threshold dose - rather than a linear response, responses occur above a certain dose.
- Dose-response curves can be U-shaped, J-shaped or inverted U
- Individuals vary in their response to toxicants
- Type of exposure may vary response
- The interaction of multiple toxicants
Produced at high temperatures from air when things are burned.
People have been burning fire for ages. It wasn't a problem until it finally became one.
An example of how pollution by fine particulate carbon (from burning coal) changed the environment is the change in the colour of moths.
Acid rains. Produced when there is sulphur in the thing we are burning