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Students will learn to: <br>- evaluate the effects of <br>u2022 water pollution by sewage and by inorganic waste <br>u2022 pollution due to insecticides including bioaccumulation up food chains and impact on top carnivores <br>- outline the roles of microorganisms in sewage treatment as an example of environmental biotechnology <br>- discuss reasons for conservation of species with reference to the maintenance of biodiversity and how this is done, e.g. management of fisheries and management of timber production
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Lesson Objectives (f) evaluate the effects of ▪ water pollution by sewage and by inorganic waste ▪ pollution due to insecticides including bioaccumulation up food chains and impact on top carnivores
Lesson objectives: Water pollution 1. Sewage 2. Inorganic waste 3. Fertilizers 4. Pesticides 5. Insecticides 6. Herbicides ◼ FI SH iP
Sewage Untreated sewage is a good source of food for bacteria When sewage is discharged into rivers and lakes, bacteria grows and multiply depleting the O2in the water Organisms die due to lack of O2 Anaerobic bacteria break down organic wastes releasing foul-smelling gases e.g. hydrogen sulphide and ammonia Bacteria causing cholera and typhoid if present in untreated sewage may cause an epidemic if it gets into drinking water in wells 1. 2. 3. 4. 5.
Inorganic wastes ◼ Dumping of waste products e.g. mercury, arsenic into rivers and streams ◼ Minamata Disease (mercury poisoning)
Fertilisers ◼ Fertilisers not absorbed by crops may be washed away by rainwater into the nearby lakes and rivers ◼ Since fertilisers contain phosphates and nitrates, they promote the growth of algae and plants (eutrophication) ◼ Submerged plants and animals die due to lack of sunlight. The dead bodies of algae and water plants are decomposed by bacteria. Bacteria grow and multiply rapidly, using up the O2in the water ◼ Other organisms e.g. fish die due to lack of O2
Insecticides ◼ used to kill insects ◼ Non-biodegradable insecticides e.g. DDT (i.e. cannot be broken down by bacteria) can remain in the soil or water for many years ◼ Insecticides may be carried by rainwater into streams, rivers and lakes ◼ In high concentrations, they may poison fish or animals that take in the polluted water or feed on the contaminated fish ◼ Leads to bioaccumulation (the process by which the concentrations of some toxic chemicals gradually increase in living tissue, such as in plants, fish, or people as they breathe contaminated air, drink contaminated water, or eat contaminated food)
Bioaccumulation DDT (dichlorodiphenyltrichloroethane) • insoluble in water • not excreted but stored in fatty tissues of organisms • cannot be broken down by organisms • accumulates in the bodies of consumers • organisms feeding at higher levels in a food chain can accumulate huge amounts of DDT from eating their prey • DDT may not be poisonous to large organisms in small amounts but may be harmful in larger amounts • Eventually the conc. of DDT accumulates to the extent that the top consumers suffer toxic effects due to bioaccumulation
Bioaccumulation w a t e rz 0 . 0 4 o o p l a n k t o n p p m s m a l l f i s h 0 . 5 p p m l a r g e f i s h 2 p p m b i r d s 2 5 p p m phytoplankton
Herbicides ◼ substances used to kill weeds ◼ contain dioxin which when washed into streams and rivers pollutes the water supply ◼ Causes miscarriages in pregnant women, physical and mental abnormalities in children and increase the risk of cancer
Pesticides ◼ Used to kill pests that destroy crops ◼ Includes herbicides and insecticides Advantages ◼ Healthier crops ◼ Higher yield of crops ◼ Socio-economic factors (more crops; more income for farmers) Disadvantages ◼ Expensive ◼ Pests may develop resistance against the pesticide ◼ Useful organisms may be killed ◼ Non-biodegradable pesticides cause pollution and bioaccumulation
Bioindicators Definition An organism and/or biological process whose change in numbers, structure or function points to changes in the integrity or quality of the environment ◼ e.g. fish are usually the 1storganisms to die when lakes and rivers become polluted ◼ e.g. presence of tubifex worms in polluted water due to their tolerance for different O2levels ◼ e.g. growth of lichens greatly reduced in areas with high levels of sulfur dioxide (SO2)
TYS questions 7a(ii) Explain how water may be polluted by agricultural practices. [7] [N99 2B 7a(ii)] 8) Explain the effects that sewage can have on rivers and seas. [3] [N2005 2B 8 Or]
Conservation - the protection and preservation of natural resources in the environment
Lesson Objectives (g) outline the roles of microbes in sewage disposal as an example of environmental biotechnology (h) discuss reasons for conservation of species with reference to the maintenance of biodiversity, management of fisheries and management of timber production
Terms to familiarise ◼ Renewable resources - Resources that are able to be replaced or replenished, either by the earth's natural processes or by human action ◼ Non-renewable resources
Reasons for Conservation 1. To prevent extinction of plant and animal species 2. Maintaining a stable & balanced ecosystem (prevents disruption of natural cycles e.g. carbon & water cycles and prevents global warming) 3. Maintain a large gene pool. Many wild plants and animals possess favourable genes. By cross- breeding the different varieties of wild plants and animals, we can improve agricultural produce, gaining a better yield of milk or produce plants with better resistance to diseases and drought 4. Conservation of marine life (source of food)
The Need 5. To maintain biodiversity. Tropical rainforests house a large number of species of animals and plants. Many tropical plants are of great economic importance as they are sources of raw materials for industries, medicinal drugs, natural insecticides and food. 6. Of scientific value (we learn from studying wildlife) 7. Preserves natural scenery and wildlife for appreciation. It maintains natural resources for outdoor recreational activities e.g. fishing, hiking and skiing
Conservation measures on two fronts 1. Indirectly through human population control, and reducing/eliminating pollution 2. Directly through conserving natural resources Through a) legislation (laws) b) education c) 3Rs (reduce, reuse, recycle)
Environmental Biotechnology Definition The use of biological science to provide environmentally friendly solutions to reduce pollution and keep the environment clean e.g. use of decomposers in sewage treatment
Sewage treatment 1. Sewage from households are drained into settling tanks, and then sedimentation tanks. In these tanks, the heavier sandy materials in the sewage settle to the bottom of the tank and are removed 2. In the aeration tank, bacteria is mixed with the sewage. The bacteria secrete enzymes to digest the solid organic waste in the sewage into harmless soluble substances and CO2. Bacteria also feed on the digested products 3. The liquid that is generated from this bacterial digestion is filtered and disease-causing microorganisms are removed before the filtrate is discharged into the rivers or seas. The digested solid that remains after filtration is called sludge 4. Anaerobic bacteria break down organic matter in the sludge in anaerobic sludge digesters 5. Sludge is removed from the tank, dried and used as fertilisers
Conservation of forests 1. Prevent indiscriminate logging 2. Legislation of laws to regulate rate and selective logging of trees OR the prohibition of human activities that harm the ecosystem 3. Planting of new seedlings to replace the ones cut down (reforestation) 4. Government designate land as forest reserves. Laws that prohibit tree felling, hunting and other human activities that might harm the forest ecosystem protect these forest reserves. Forestry departments to enforce forest conservation laws with regular checks and research to improve the quality of forests and make the forest more productive e.g. control insects and diseases that harm them
Conservation of fishing grounds 1. Banning drift nets (indiscriminately trap all forms of sea life) 2. Using nets with a certain mesh size (hole size) so that young fish are not caught 3. Regulating the size of ships allowed into fishing grounds 4. Limiting the period of fishing in fishing grounds 5. Banning the harvesting of endangered species; 6. Encouraging the raising of these fish in hatcheries and releasing them into fishing grounds where fish populations are decreasing
Conserving wildlife ◼ Establishing protected areas for wildlife e.g. Serengeti National Park in Tanzania ◼ Captive breeding or breeding endangered species of animals in zoos and wildlife parks, and releasing them to the wild later e.g. the golden tamarin was re-established in the wild in this way ◼ Farming wildlife for human use as well as to replenish their numbers in the wild, e.g. farming crocodiles, iguanas and butterflies
TYS questions 7(b) Explain why the following are recycled: i) household water ii) paper (c) Suggest the problems which may arise when household water is recycled. [2] [3] [N99 2B 7b,c]
