THE HUMAN IMPACT ON THE ENVIRONMENT
Causes of deforestation
Intensification of agriculture
forests cleared for land for agriculture > if same crop grown on same piece of land for many years > nutrients depleted & crumb structure of soil destroyed (> erosion) > soil longer can support life > desertification, if inorganic fertilizers, pesticides & insecticides are used > pollute water sources & destroy soil structure

Urbanisation
ppl: rural > urban areas for jobs & comfort > more demand of houses and other needs > deforestation, dispersal of domestic waste > not properly disposed > diseases & pollution, increase of automobiles > air pollution

Industrialization
Increase in pop > increase in industries to produce goods > more water, air and land pollution

Effects of deforestation
Eutrophication: natural waters enriched w/ nutrients (esp PO₄'s & NO₃'s) (soil erosion caused by deforestation, bad farming, overgrazing- hard layer of soil water runs off > rivers, (un)treated swage- waste materials, leaching of PO₄'s & NO₃'s) > microscopic plants (phytoplanktons & algae) multiply rapidly > algal bloom > H₂O green > O₂ deficient > die > too little surplus of plants to eat > planktons decompose > aerobic bacteria thrive, use O₂ > suffocation > die
reduce eutrophication: detergents w/ less PO₄'s, fertilizers that dont dissolve so easily, not letting animal wastes reach rivers, leave strip of land (wild ecosystem) next to water source (use nutrients), reduce arable farming (fertilizers), reduce factory farming (faeces & urine > rivers)
The water cycle (natural process through which water is circulated & purified)
-involves evaporation (due to heat and winds) & transpiration (& respiration) (H₂O enters atmosphere) > condensation (of H₂O vapour to form H₂O droplets) > precipitation (rains) > and drainage (run off )
-during precipitation water enters plants (photosynthesis) and oceans
-deforestation disrupts H₂O cycle equilibrium: tress removed > rainwater goes into soil, streams, rivers instead of returning to air as H₂O vapour (transpiration), prolonged showers > flooding , soil erosion > silt up rivers > flooding
-trees removed > less transpiration > air dry > drought > desertification
Local human populations: indigenous ppl forced out of homes, trees (sources) taken away
Gene pool: diversity of orgs reduced, deforestation > lost of habitat, shelter, food

POLLUTION
-addition of subs (pollutants) to environment which upsets natural balance
-air, water, terrestrial, radio-active, noise pollutants

Air pollution(almost all cause by burning fossil fuels) (smoke, particulates, oxides of N, CFCs, smog, CO, lead-cars)
troposphere-layer of air which supports life extended ~8km above earths surface

Sulphur dioxide (can be used as a insecticide, kills aphids)
Fossils fuels burn > SO₂, SO₂ readily combines w/ chemicals (H₂O > H₂SO₄, NH₃,) > quickly depostied
-can increase soil fertility if soil deficient in sulphates, but high conc harmful
-cause irritation of respiratory system, eye and damage epithelial lining of alveoli
-reduces growth of many plants (barley, wheat ,etc, lichens)(lichens consist of algal and fungal partner, of barren land the fungal phyphae forms the base and absorbed moistture in the air, moisture used by algal partner for photosynthesis, die > thin layer of humus > plants grow, pollution affects growth - pollution monitors)

Acid rain
SO₂ dissolves in water > sulphuric acid as rain, normal rain , pH ~5.6, acid rain pH 4-4.5
-coniferous plants damaged
-early symptom of acid rain = crown die-back, top of tree dies first
-lakes > acidic > affects uptake of calcium by crustaceans, w/o Ca > cant manufacture exoskeleton
-at low pH, more Al in sol > Al, toxic to many aquatic plant and fish
-acid rain falls on buildings > due to corrosive nature of acid, CaCO₃ might dissolve > buildings lose structure & lusture
-acid rain dissolve away many minerals in soil > leach away > eutrophication and less soil fertility

CO₂
-formed during respiration, burning of fossil fuels (combustion of coal, oil, gas, peat, and decomposition
-some CO₂ used in photosynthesis
large amt of CO₂: ₁excessive burning of fossil fuels [peat fires: fire a few feet underground > give out smoke] and ₂deforestation (removes tress which act as C reservoirs, inorganic C > organic C)
-contribute to greenhouse effect (warming of Earth by atmospheric gases like glass of a greenhouse), light rays form Sun (shot wavelength) reflected from Earths surface > heat waves (long wavelength) > trapped in atmospheres by CO₂, water vapour, hydrocarbons, methane, NO₂ and other CFCs, prevent heat form escaping Earths atmosphere, greenhouse effect: natural & heats Earth, too much > global temp ^ > meting of polar ice-caps > rise of sea levels

Reduce atmospheric CO₂ (cooperation necessary)
-less reliance of fossil fuels and more on renewable ones for power [solar, wind, nuclear, (oil)]
-more energy-saving measures
-more trees planted, afforestation, CO₂ > food
-ppl stop expecting standard of living to go on rising
-more speculative proposed solution (pumping CO₂ underground or down to ocean floor)

Air pollution: respiratory problems (carboxyhaemoglobin), heart disease, eye irritations, damage plants (less sunlight)
Ozone layer: ~25km up, where ozone reaches peak, filters UV radiation, CFCs (chlorofluorocarbons) react w/ ozone layer > reduce conc > holes > more UV radiation > cancer, affect climate, crops, marine plankton

Water pollution
Sewage
-dirty water form homes and industries
-contains (in)organic matter, if enter water sources w/o treatment > reduces O₂ levels (aerobic bact & solubilty of O₂ reduce as turbidity ^) & eutrophication, toxicity level > optimum condition > kills orgs, diseases (in faeces) spread

Oil
-industries, ships & accidents in sea > damage marine life and other terrestrial organisms (birds cant fly)

Factory refuse [toxic chemicals (Cu, Zn, Pb, Hg, cyanides), heated water]
-Cu: low conc > fish die, Hg: damages cell membranes, destroys enzymes, affects kidney, liver, brain>loss of sensation, coma, paralysis, Pb: brain damage
-heated water: orgs that are used to cool environment die

Land pollution
-due to dumping of waste and deposit, use of chemicals (pesticides)

Waste and deposits
-commercial activities > large vol of solid waste > dumped in pits > accumulates, domestic waste should be treated before dumped: decomposition of organic material in waste, can reduce vol & produce useful products (methane)
-industries: nuclear waste > mutations

Pesticides
-pest = organism which competes w/ man for food or space and is potentially dangerous
-pesticides = poisonous chemicals which kills pests [named after pest it kills, insecticides: insects, fungicides: moulds + fungi, rodenticides: rodents, herbicides: weeds]
-ideal pesiticide: ₁cheaper to manufacture w/ simple ingredients, ₂should not persist (breaks down to harmless subs, temp, no long term effect), ₃should not accumulate in organisms (prevents sick consumers), ₄should be specific
-most pesticides are not persistant (warfarin kills any rodents which eats it but is quickly broken down in rodents body)
-DDT- Dichloro Diphenyl Trichloroethane: persistant & not specific, helps control malaria, kills mosq, control lice, fleas, other carriers of diseases) and are accumulated along food chains > accumulates in fatty tissues > resistance > process of using DDT continues > amt of DDT builds up in high conc > kill larger org, DDT: prevents birds from building proper nests & cause infertility > egg shells thin > break when parents sit on them during incubation
pyrethrum-non-polluting insecticide, extracted from flower of species of chrysanthemum

Conservation
-preservation of endangered habitats or species as a result of pressure created by increasing human pop
-necessary to protect plants & animals > maintain a stable & balance ecosystem, if not > extinction > less biodiversity
-requires: preservation, management (of ecosystems), reclamation(habitat restoration), creation (habitat creation)
-for benefit of humans (economic reasons) & other org's
-involves: development of national parks & natural reserves, planned land use, legal protection of endangered species, commercial farming, breeding by zoos, removal of animals from threatened areas, control if introduced species, ecological study of threatened habitats, education

Recycling
-reusing of products or materials which would otherwise be thrown away [reusing original item or sending them back to factories > pulped or melted down > useful articles]
-saves natural resources and energy + $ in production
-reduces amt of rubbish > less pollution
-reduces extensive logging, energy & $, digesters can recycle used paper
Renewable resources-wood-replaced on the basis of plants & animals, yield sustainable (amt of yield = rate of prod.)
Non-renewable resources-minerals, iron and fuels, oil, coal-can't be replace, fixed quantity (biological fuels can replace fossil fuels, gasohol: from sugar cane waste to motor vehicle fuel, organic waste subs: converted to other fuels, methane, methanol, ethanol)

Reproduction in plants
Sexual reproduction in animals
Genetics
Cell Strcuture and Organisation
Enzymes
Animal and Plant Nutrition
Transport in Plants and Transpiration
Support, Movement and Locomotion
Transport in Man
Respiration
Excretion
Homeostasis
The Eye
Nervous System
Chemical Control of Plant Growth
The Use and Abuse of Drugs
Diversity of Organisms
Nutrient cycles and Ecology
Parasitism

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