HOW CAN WE ASSESS HUMAN IMPACT?Text 2.2: 68 - 84

Agenda1. Demo – If Earth Were an Apple2. Primer – United Nations Environment

Programme3. Assessing Impacts on Ecosystems

Assessing Soils Assessing Water Quality Assessing Organisms

4. Inquiry & Demo – Bioaccumulation5. STSE – Increasing Biodiversity in Your

Community

Learning Goal

By the end of the class I can Determine a method for assessing human

impact on the environment.

Demo - If the World Was an Apple…

Why Do We Assess the Impacts?

To provide leadership and encourage partnerships in caring for the environment by inspiring, informing, and enabling nations and peoples to improve the quality of life without compromising that of future generations.

How Do We Assess the Impacts?

We need to find ways of assessing effects of human impact on soils, water, and organisms.

Helps us to find ways to prevent harm to the ecosystem.

Helps us find ways to improve the health of ecosystems that have been damaged by human activities.

How Do We Assess Soils? Soil is a loose covering on the ground containing a

mixture of organic matter, minerals, and moisture. To assess soil quality we look at three components

1) Soil profile, 2) Soil type, 3) Acidity

• Each main soil type supports different varieties of plants, with loam being preferred for agriculture.

• Most plants prefer a neutral pH environment = optimal pH zone

How Do Humans Impact Soils? Soil erosion – the loss of

soil when water or wind washes or blows it away caused by overgrazing, ploughing, tilling, and intensive agriculture.

Crop rotation is a practice that helps reduce nutrient loss by planting a different crop in a particular field each year.

Plants such as soybeans, peas, lentils, alfalfa have a symbiotic relationship with nitrogen-fixing bacteria in their nodules.

How Do Humans Impact Water Quality?

Healthy aquatic ecosystems are full of organisms

Types and quantities of species present in the water can indicate the state of water quality. i.e. beaches closed in summer

Different organisms prefer different conditions

Dissolved Oxygen (mg/L)

Aquatic Organisms

8 Large # of diverse species thrive6 Mayflies, stoneflies, & beetles start to

disappear.4 Freshwater shrimps, midge larvae, and

worms can survive2 Midge larvae and some worms can survive.

Dissolved Oxygen –

measurements give the

level of oxygen present in

water

Biological oxygen

demand (BOD) –

measures how quickly

oxygen is used up by

micro-organisms in a given

body of water

How Do Humans Impact Water Quality?

As acidity increases diversity of plants and animals decrease.

Neutral = best e.g. fish die if the water’s pH falls to 4.5

Run-off from fields, storm sewers, gardens, and roads carry high levels of nutrients can cause overload.

Overload = Eutrophication is the addition of nutrients to an aquatic ecosystem causing increased plant growth of plants such as algae.

How Do Humans Impact on Organisms?

Pesticides are chemicals that kill unwanted organisms, usually ones that attack crops and reduce yield.

Some last a long time in the environment i.e. heavy metals, DDT

Bioaccumulation – gradual build-up of a substance in an organism’s body.

Biomagnifiction – toxin becomes more and more concentrated each link in the food chain as one animal eats many contaminated animals.

Demo - Bioaccumulation

We will simulate how bioaccumulation happens with a tropic level.

Select 14 volunteers 8 zooplankton 4 large fish 2 eagles

Inquiry – Impact of Bioaccumulation?

1. Use the following website to determine three types of bioaccumulation and fill in the chart.

2. Research one type of Persistent Bioaccumulative, Persistent Organic Pollutant or Toxic Pollutant

3. Describe how it affects the organism.

http://www.eoearth.org/article/bioaccumulation

STSE – Increasing Biodiversity in Your Community

In groups of 3-4 complete the STSE A15 p.g. 81