Mans impact on the environment

3 impact of agriculture on ecosystem

1. deforestation

2. eutrophication

3. pollution

impact on ecosystem + lack of conservation =

1. affects environments

2. change the balance of ecosystem or disruption of ecological equilibrium

human activities which lead to negative impact on the ecosystem

1. agriculture

2. urban development

3. burning of fossil fuels

why deforest?

1. obtain wood for fuel

2. timber for construction

3. clear land for urban development

4. clear land for agriculture and cattle grazing

5. produce more food to support growing world population

harmful effects of deforestation

1. soil erosion

2. destruction of habitat plants and animals → extinction of plants and animals

3. loss of carbon sinks → speeding up global warming

4. low quality timber

5. some areas flood while other areas drought

solution to deforestation

1. reforestation (plant trees that has been cut off)

2. urban farming (vertical farming)

3. find alternatives for papers / recycle paper

what is the process of eutrophication?

1. untreated sewage / excessive use of fertilisers dumped into the water

2. excess nitrates and phosphates enrich water bodies with nutrients for algae

3. rapid growth of algae on water surface

4. prevents sunlight penetration into the water

5. death of submerged aquatic plants

6. plant dead bodies decomposed by bacteria

7. bacteria population increases and uses up dissolved oxygen (decomposition)

8. O2 depletion in water + drop in photosynthesis

9. biology equilibrium is disrupted and the population of producers and consumers falls greatly

solutions to eutrophication

1. proper sewage disposal and sewage treatment systems

2. use biodegradable washing detergent

3. minimal use of chemical fertilisers

what is a pollutant

a harmful substance which contaminates the environment and causes harm to living organism

what are the different types of air pollution

• sulfur dioxide

• carbon monoxide

• raw sewage

• inorganic waste (eg DDT)

source of sulphur dioxide

1. burning of fossil fuels

2. car exhaust

3. natural disasters

effects of sulphur dioxide

1. acid rain (h2SO4)

2. change in pH of soil and waterway

3. kills plants and aquatic life

4. irritates skin eyes and lungs when breathed in

5. aggravates diseases like asthma and bronchitis

6. corrodes metal and structures and erodes limestone in building and sculpture

how to control SO2 pollution

1. coal and petroleum are treated to remove sulfur

source of carbon monoxide pollution1

1. car exhaust

2. burning of fossil fuel

effects of CO pollution

1. competes with oxygen for binding to haemoglobin and reduces the capacity of blood to carry oxygen

2. colourless and odourless gas → an increase of carbon monoxide level in blood is undetectable and causes death

how to control CO pollution

1. catalytic converter to convert CO to CO2 before it is released into the atmosphere

raw sewage source

1. human and domestic waste

2. excessive use of fertilisers

3. industrial waste

4. detergent rich in phosphates

effects of raw sewage pollution

1. encourage eutrophication

2. increase bacteria population and decreases oxygen content in water

3. kills fish and aquatic organisms → high biological oxygen demand (BOD) → ecological disruption

4. microogrganisms present in sewage can cause diseases when water is consumed

how to control sewage

1. proper sewage treatment before disposal

2. minimal use of chemical fertilisers rich in phosphates and nitrates

3. use biodegradable washing detergent

source of inorganic waste

1, pesticide which contains chlorine used in crop protection

effects of inorganic waste pollution

1. pesticide molecules are non-biodegradable, small and insoluble → they accumulate in fat tissues of animals along food chains, reaching toxic levels in the consumers of higher trophic levels (bioaccumulation)

how to control inorganic waste

• ban the use of pesticides (inorganic)

• use biodegradable pesticides

• use biological control which uses the natural predator of pests to control its population

what does it mean to be non-biodegradable

it cannot be broken down by decomposers like bacteria

what are the pros and cons of DDT

pros: stable, wide-spectrum insecticides, very effective in killing pests and mosquitoes

cons: non-biodegradable, likely not to be soluble is water, stored in fatty tissues of organism to toxic levels

what is bioaccumulation

where a concentration of a non-biodegradable, toxic substance builds up in the tissues and is absorbed faster than it is removed

what is biomagnification

increase in the concentration of a substance up the food chain, because the substance is persistent and non-biodegradable

these persistent pollutants are transferred up the food chain faster than they are broken down or excreted

what is the difference between bioaccumulation and amplification

Bioaccumulation: Accumulation of toxic substances within a single  organism (e.g: fish)

Bioamplification: Accumulation of toxic substances along the food  chain (e.g: from shrimps to fish to seal to polar bear)

What is BOD?

Is a chemical procedure for determining how fast biological organisms  such as bacteria and algae use up  oxygen for decomposition of organic  matter in the body of water/\.

use of bod

Use to indicate level of water pollution.

High BOD = A large number of aerobic bacteria decomposing and using up lots  of oxygen. Thus dissolved oxygen level is low and this suggests a high level of  pollution in the sample of water.

oxygen concentration 50km downstream from point P returned to its original level but the number of fish are still much reduced. suggest 2 reasons for this

Fishes do not increased in number rapidly as they need time to reproduce.

Sources of food for the fish may also be lacking due to depletion of O2.