Environmental Chemistry

Grade 9

Pollution

The introduction or presence of potentially harmful substances to an environment

Pollutant

The substance of pollution

Pollutants enters land via

Pesticide on crop to control pests (run-off), dumps, un-recycled matter, litter

Pollutants enter water via

Liquid wastes (sewage, oil, etc.) can be released into waterways

Pollutants enters air via

Gases and aerosolized particles are released into the atmosphere

How do organisms receive pollutants?

Via two ways, absorption and ingestion

Absorption

A chemical substance passes through a membrane (eg. cell wall, roots, skin)

Ingestion

A chemical substance that has been directly consumed by an organism (drinking, breathing, eating)

What are the different kinds of pesticides?

Herbicides, insecticides, and fungicides

Herbicide

Chemical products that kill plants

Selective Herbicides

Only kills certain species of plants (e.g. Killex)

Non-selective Herbicides

Kills ALL plants (e.g. Roundup- carcinogenic)

Insecticide

Substances that kills insects and/or invertebrates (no spinal column)

Fungicide

Chemical substances that kills mushroom and other fungi (e.g. Mefenoxam)

Persistant Pollutants

Waste/pollution that doesn’t biodegrade easily or at all in the environment

What does this diagram show?

Bioaccumulation

Bioaccumulation

The increase concentration in ONE organism as time passes, there will be more pollutant as the organism grows

What does this diagram show

Biomagnification

Biomagnification

The increase in concentration up the food chain (micro plastics)

Examples of persistent pollutants

• Plastics

• Mercury

• Lead

• CFC (found in old fridges)

• PCB

• DDT

Organic (nutrients)

Chemical products rich in carbon and hydrogen in the same molecule

Carbohydrates

Provides energy to cells (e.g. sugars, starches, grains)

Protein

Builds up and repairs structures

Lipids (fats)

Stockage of unused energy, good for long-term energy

Inorganic Nutrients

Other necessary and important chemicals (e.g. fertilizer)

Macrominerals

Elements we need more of (e.g. Ca, P, Mg, Na)

Trace Elements

Elements we need less of (e.g. Cu, Zn, Fe, I)

Fertilizers

Contains phosphorus, potassium and nitrogen which helps plants grow, it tries to mimic the nitrogen cycle (N conversions)

Explain the soil in this diagram

The concentration of nitrogen in the soil is low, but the plants concentrate minerals in their structures (we eat plants)

Algal bloom

When there is too much phosphorus and/or nitrogen which causes algae growth on the surface of the water. It blocks sunlight, reduces turbidity, and kills plants and fish (Low oxygen and biodiversity)

What does the pH scale tell us?

It tells us how acidic or how basic a solution or fluid is

What is neutral on the pH scale?

7

How do the numbers on the pH scale work?

The numbers are logarithmic, the difference between each number is a change by a factor of 10

Neutralization

When an acid and base are mixed

Indicators

A chemical that changes colour at different pH levels

Bases (alkaline)

Based on concentration of OH- (e.g. NaOH, drain cleaner, bleach)

Acids

Based on the concentration of H+ (e.g. lemons, vinegar, hydrochloric acid, etc.)

Natural Indicators

Some plants have natural indicators and change colours (e.g. hydrangea, red cabbage- Dasia Taylor)

How does air carry pollutants?

Circumpolar winds carry pollutants/pollution from industrial areas to areas 100s of kilometers away (winds move clockwise)

How do clouds carry pollution?

Precipitation brings down water and dissolved pollutants from the clouds

How does soil carry pollutants?

More porous soil can absorb water and dissolved pollutants as they pass through, less porous/impenetrable soil stops/redirects the flow

How does water carry pollutants?

Toxins dissipate and get diluted (diffusion) and can be concentrated in collection zones (e.g. lakes)

What does landfills have to have?

Landfills must always have an impermeable layer/dam to prevent toxins/pollutants from leaching into the waterways

Biomediation

Using organisms to fix an environmental problem (e.g. a bacteria that cleans up spills)

Biodegradation

Things that can chemically and physically break down and decompose on their own (typically good and sustainable)

Acid precipitation

Rain, hail or snow with a pH less than 7

What do emissions from fossil fuels and water form?

• Carboxyl acid(s)

• Nitric and nitrous acids

• Sulphuric acid

What happens when pH goes down?

Crops go down, plants die and harvest goes down

What pH levels affect fish?

7- Good

~4.5-5.5- Meh (reproductive difficulties)

<4.5- Dead

What are the different ways to neutralize acid precipitation?

Liming, scrubbers, catalytic converters

Liming

When calcium carbonate (basic) is added to acidified bodies of water, neutralizes pH, not preventative, temporary solution, exothermic reaction (can cause unwanted temperature changes)

Scrubbers

Passing harmful gases through a mixture contain calcium carbonate to “filter”/neutralize them before they reach the atmosphere

Catalytic Converters

A honey comb coated with a catalyst such as platinum for combustions (leads to a complete combustion before exhaust is released)

LD50

The amount of any substance that would kill 50% of people

Acute toxicity

When it only takes one exposure of small dose to have serious effects

Chronic toxicity

The substance builds up overtime and has bad effects (bioaccumulation)

ppm

Parts per million, 1/1 000 000 particles of the solution contain the toxin or [] of 1mg/1kg

ppb

Parts per billion, 1/1 000 000 000 particles contain the toxin or [] 1mewg/1 kg