Unit 10: How do the choices people make affect the environment?

Human Impact

A - Agriculture

H - Habitat loss/destruction

I - Invasive species

P - Pollution

P - Population (human)

O - Over-exploitation (factors endangering species)

Habitat loss

Occurs when a particular area transitions from a useable and stable environment to an unuseable habitat. a. This is caused by industrial activities, agriculture, aquaculture, mining, deforestation, and water extraction. i. Habitat fragmentation - the loss of large units of a specific habitat.

Invasive species:

A process in which an animal, microbe or plant moves into a new area in which they then parasitize or predate on the current residents, or hybridize amongst them, as well as compete for food and other resources. Invasive species can bring unfamiliar diseases with them and can disrupt crucial interactions. a. An example of an invasive species is the Brown Tree snake in Guam. This species is native to Australia, however, were accidentally brought to Guam, in which their arrival resulted in the extirpation of most resident bird species.

Pollution:

The discharge of toxic, synthetic chemicals and heavy metals into the environment. a. Many of these chemicals are natural, however, once they become too abundant, it can result in 'dead zones' i. For example, phosphorus and nitrogen are critical nutrients for plant growth, however, once they get too concentrated in water systems, the overabundance can lead to dead zones. [this process is known as eutrophication]

Population:

The exponential increase in the population has placed an immense strain on the resources (such as food, water, and other natural resources). The more people there are, the more land is required for settlements and agriculture ultimately resulting in more deforestation to make space for such necessities. This places stress on the biodiversity of the region.

Over-harvesting:

This includes targeted hunting, gathering or fishing of a particular species, however, also refers to the incidental harvesting such as 'by-catch' in ocean fisheries.

Bioaccumulation:

Bioaccumulation is the process in which certain substances - especially contaminants (such as heavy metals or pesticides) - accumulate and keep on accumulating in living organisms, continuously moving up the trophic levels over a period of time.

Discuss how human threats are harming biodiversity and leading to endangered species.

The main issue lies under the aspects of resource consumption, population growth, habitat conversion/urbanization, the introduction of invasive alien species, the over-exploitation of natural resources, and finally, environmental degradation. When referring to the increase in population, it applies to the fact that the more people there are, the more land is required for settlements and agriculture ultimately resulting in more deforestation to make space for such necessities. This places stress on the biodiversity of the region.

How much of the world's surface is used for agriculture:

In the year 2000, it was estimated that circa 37% of the Earth’s surface was appropriated for the agricultural industry. Now, That's a little more than 12 billion acres or about 35% of the total surface area of the earth.

Population growth rate

Population growth rate (r) is how fast a population changes in size over time. A positive growth rate means a population is increasing. A negative growth rate means it is decreasing. The two main factors affecting population growth are the birth rate (b) and death rate (d). Population growth may also be affected by people coming into the population from somewhere else (immigration, i) or leaving the population for another area (emigration, e). The formula for population growth takes all these factors into account.

Exponential Growth

Exponential growth occurs when the increase in a quantity is proportional to its current size, leading to growth that accelerates over time.

Invasive species:

An invasive species is an organism that is non-native (or alien) to a specific ecosystem in which its presence or introduction causes - or is likely to cause - environmental harm, economic harm, or even harm to the health of the other organisms or humans.

Endemic:

The ecological state of a species being unique to a defined geographic area. Organisms that are indigenous to an area are not endemic if they are also found elsewhere. (In simple terms, organisms that are only found in one area are known as Endemic). An example is, the tortoises of the Galapagos, as they are not found elsewhere.

Impacts of invasive species:

• Degrade wildlife habitat

• Outcompete native plant and animals

• Reduce biodiversity and cause the extinction of endangered species

• Cause economic damage – worldwide, the estimated damage from invasive species totals more than $1.4 trillion, this is 5% of the global economy

• Reduce crop quality and yield

• Reduce forage availability for grazing animals

• Increase wildfire hazard

• Interfere with regeneration of forests

• Increase soil erosion

• Threaten drinking water

• Impact recreational activities

Air Pollution -

Caused primarily due to excessive fuel combustion (such as transportation, cooking, and other industrial activities - like the burning of fossil fuels).

Water Pollution -

The causes of water pollution are from direct and indirect contaminant sources.

a. Direct contaminant sources = Domestic effluents and sewage, Industrial effluents, Agricultural effluents, Radioactive wastes, Thermal pollution, and Oil Pollution. [Ef luents refer to liquid waste that is sent out from factories or places where sewage is dealt with]

b. Indirect contaminant sources = Contaminants that enter the water supply from soils/groundwater systems and from the atmosphere via rain.

Soil Pollution -

Refers to the incorporation of unwanted chemicals within the soil due to human activities. (Eg. Insecticides and pesticides)

Effects of pollution on human health:

Higher risk of asthma and other respiratory diseases. Pollution has a serious toxicological impact on human health

Other effects of pollution:

(1) Environmental degradation

(2) Human health is majorly influenced

(3) Climate change

(4) Depletion of the Ozone Layer

(5) Infertile land

Link between fossil fuels and and acid rain affecting trees:

Power plants emit the majority of sulfur dioxide as well as large quantities of nitrogen dioxides when they burn fossil fuels - such as coal - to produce electricity. Additionally, the exhaust from means of transportation leads to large emissions of nitrogen oxides and sulfur dioxides. These pollutants lead to the formation of Acid Rain. (Acid rain a combination of waste gases - sulfur dioxide and nitrogen oxide - that mixes with the atmospheric water).

Eutrophication

Eutrophication is a process that takes place in a body of water (such as a river or a lake) when too many nutrients are added to the system.

Steps:

1. Excess nutrients enter waterways (Eg. Fertilizes are into the waterways by rain or irrigation).

2. The nutrients promote plant growth (in particular, the growth of Algae)

3. An ‘algal bloom’ occurs.

4. This bloom obscures light from the plants.

5. Oxygen levels drop as plants can no longer photosynthesize (due to the lack of sunlight).

6. The Algae dies which is then decomposed by bacteria.

7. The decomposition leads to increased biological oxygen demand.

8. The water becomes hypoxic - meaning that it is deprived of adequate oxygen.

9. Due to the lack of oxygen, fish, macroinvertebrates, and other aquatic life forms die

Sewage

If untreated sewage gets into rivers, micro-organisms decompose it. They dramatically increase in number and use oxygen from the water for aerobic respiration. As a result there is less oxygen dissolved in water, so aquatic organisms such as fish and insects may be unable to survive.

Nitrate fertilisers

These are soluble, and when sprayed on crops they can be easily washed into waterways, this is called leaching. The process can be outlined as follows:

1. increased nitrates in the water increase the growth of algae and plants

2. the algae form a bloom over the water surface, preventing sunlight reaching other water plants

3. these plants die because they are unable to carry out photosynthesis without light

4. microbes such as bacteria increase in number as they decompose the dead plants, using and reducing the oxygen content in the water during respiration as they do so

5. the low oxygen levels can cause aquatic insects and fish to suffocate, and eventually the lake may be left completely lifeless

How do pollutants lead to biomagnification:

Biomagnification refers to the tendency of pollutants to concentrate as they move from one trophic level to the next. The higher the organism is in the food chain, the higher the concentration of the contaminant or substance is.

List the greenhouse gases:

1. Carbon Dioxide (Emissions are caused by fossil fuel combustions, deforestation, as well as the production of cement)

2. Methane - a potent gas. (Emissions are due to fossil fuel productions, agriculture - in particular, cows/livestock farming, landfills, as well as the melting of the permafrost)

3. Nitrous Oxide (Emitted subsequent the use of fertilizer applications and the burning of fossil fuels)

4. Water vapor

5. ChloroFluoroCarbons (CFC’s) (The most common reasons as to why CFCs are emitted are due to refrigerants)

Explain how the greenhouse gas effect may lead to climate change:

The greenhouse effect is a natural process, moreover, is crucial to maintaining the habitability of the Earth, however, as a consequence of the anthropogenic error (human disturbance/destruction) there has been an increase in the concentration of atmospheric Carbon Dioxide (as evident in the ‘Keelings Curve’) and other potent greenhouse gases resulting in an Enhanced Greenhouse Effect.

Due to the greenhouse effect, the atmosphere traps heat that radiates from the earth towards space. The gases allow sunlight and heat to pass through, however, blocks the heat from escaping, leading to an increase in the mean temperature. Analyze data and predict the effects of climate change. The ‘Keelings Curve’ illustrates that the Atmospheric Carbon Dioxide levels have been increasing over time.

Conservation:

Attempts to protect and preserve biodiversity. Attempts to prevent the extinction or endangerment of species.

In-situ conservation:

This type of conservation takes place in the natural habitat of species that need conservation. (Eg. National parks and wildlife sanctuaries).

An advantage of this type of conservation - Helps in recovering populations in the surroundings wherein they have developed their distinct features.

A disadvantage of this type of conservation - The conditions that initially threatened the organisms to the extent that they required conservation may still be present in the area.

Ex-situ conservation:

This type of conservation strives to conserve species outside their natural habitats. (Eg. Zoological parks and botanical gardens).

An advantage of this type of conservation - Helps in recovering populations or preventing their extinction under stimulated conditions that closely resemble their natural habitats.

A disadvantage of this type of conservation - The species can never return back to their natural habitat.

Ecological footprint:

The ecological footprint measures the amount of biologically productive land and water areas an individual, city, country, or region uses to produce the resources that it consumes or and the amount it uses to absorb the wastes that are generated.

NGO:

Non-Governmental Organization.

Any non-profit or voluntary citizens’ group which has been organized on a local, national or international level.

Examples include the Red Crescent, WWF, and Greenpeace.

IGO:

Intergovernmental Organization.

An entity that has been created by a treaty involving two or more nations.

Examples include the United Nations, the World Bank as well as the European Union.