sci

Chemistry

Chemical Reactions

Chemical reaction: a process that involves chemical change

• in a chemical reaction one or more pure substance(s) are changed into one or more new pure substances (reminder: elements and compounds are pure substances)

• this change is a chemical change (reminder: chemical bonds are broken or formed between atoms)

• example: iron + oxygen → rust

Chemical equation: uses chemical formulas to describe the atoms/molecules that reacted and those that are produced

• example: 2H₂ + O₂ → 2H₂O

  • plus sign (+) means “react with”

  • arrow (→) means “produces”

Reactants: atoms/molecules present before the chemical reaction takes place and are on the left side of the arrow in a chemical equation

Products: atoms/molecules present after the chemical reaction takes place and are on the right side of the arrow in chemical equation

Conservation of Mass and Atoms

Law of Conservation of Mass: “what goes in must come out”

• total mass of products equals total mass of reactants

• number of atoms of elements that are reactants must equal to the number of atoms of elements that are products

• atoms of elements are conserved in a chemical reaction

Writing and Balancing Chemical Equations

Word equation: hydrogen + oxygen → water

Skeleton equation: chemical formula is correct but the number of atoms of elements that are reactants do not equal the number of atoms of elements that are products

• in order to correct this we balance equations

Balanced equation: shows the number of each atom/molecule in the chemical reaction

Electrical Energy

Electrical energy: the energy of charged particles

A) Electrical energy has many applications.

What uses electrical energy?

• The human body

  • eg. moving your eyes to read relies on electrical signals in your muscle + nerve cells

  • eg. Electrical signals help maintain breathing and heart beat

• Technology

  • eg. touch-sensitive screens

  • robots

    • flexible plastic that replies to electrical signals

  • maglev trains

B) Many different types of energy can be transformed into electrical energy

• Energy is neither created or destroyed

• It is transformed from one kind of energy to another kind of energy

Types of energy

• Mechanical energy: The sum of kinetic energy and potential energy

• Kinetic energy: The energy of motion

• Potential energy: stored energy that a system has due to its position or condition

• Chemical energy: Energy stored in chemical bonds, and released when a chemical reaction occurs

  • eg. batteries store chemical energy

  • eg. Chemical energy stored in animals and plants is called biomass

  • eg. fossil fuels (coal, oil, natural gas) store chemical energy

• Solar energy: Energy carried by electromagnetic radiation given off by the Sun

  • Fossil fuels and biomass from the Sun’s energy being captured by plants and plant-like organisms

• Nuclear energy: Energy generated by forming new atoms

  • Nuclear fusion: New atoms are made as smaller atoms collide and fuse (occur in the Sun and stars)

  • Nuclear fission: New atoms are made by splitting larger atoms (carried out in reactors on Earth). Most of the energy is thermal energy, which is used to boil water into steam. Pressure from the moving steam turns turbines connected to generators

• Thermal energy: Energy due to the rapid motion of particles that make up an object; detected as heat

  • sources include nuclear reactions from Earth’s interior (geothermal energy), where steam and hot water form naturally

  • eg. Geysers, volcanoes, hot springs

C) Electrical energy is generated in different ways from different sources

• Most of the electrical energy in Canada is generated by transforming kinetic energy into electrical energy

• Source of kinetic energy may be moving water, wind, or moving steam produced by nuclear reactions or burning fossil fuels

Kinetic Energy to Electrical Energy: Generator System

Generator system: a system that transforms kinetic energy to electrical energy

Turbine: steam, water, or wind cause the turbine to spin

Shaft: As the turbine spins, the shaft spins

Generator: Kinetic energy of the spinning shaft is transformed into electrical energy inside the generator

Electric Potential Energy + Voltage

electrochemical cells: convert chemical energy into electrical energy

battery: a single electrochemical cell or a combination of electrochemical cells connected together

terminals: end points of an electrochemical cell/battery where connections are made

• Negative terminal: end where electrons accumulate

• Positive terminal: end that has lost electrons

Producing voltage

The two terminals in an electrochemical cell/battery are called electrodes

• the electrodes are in an electrolyte, which is a substance that conducts electricity

There are two groups of cells:

• Dry cells: electrolyte is a moist paste(used in flashlights and watches)

• Wet cells: electrolyte is a liquid(used in cars and motorcycles)

The amount of voltage that is produced in an electrochemical cell depends on the types of metal (electrodes) and electrolyte used.

• most electrochemical cells produce 1.5V or 2V

Electric Potential Energy

• energy is the ability to do work

• electric energy can do work

  • *when unlike charges are moved farther apart, they gain electric potential energy

• electric energy that is stored is potential energy (electric potential energy: the electrical energy stored in an electrochemical cell)

• electric energy that is moving is kinetic energy

Electric Potential Difference

Voltage: the amount of electric potential energy per coulomb of charge

Volt(V): unit of measure for voltage

Voltmeter: measures voltage vetween two locations of charge separation

The actual electric potential energy is the product of both the voltage and the amount of charge: Energy = Voltage * Charge

Electric Current

Electric circuit: a complete pathway that allows electrons to flow

Energy around a circuit

In a circuit:

1. Chemical energy in the battery separates positive and negative charges and gives electrons on the negative terminal electric potential energy.

2. Electrons move across the wire as they are repelled by the negative terminal and attracted to the positive terminal.

3. Potential energy is transformed into other forms of energy when it passes through a load (eg. in buzzers, it is transformed into sound energy).

Circuit Components

Main components of a circuit:

1. Source: where the electrical energy comes from (electrochemical cell or battery)

2. Conductor: the wire through which electric current flows

3. Load: a device that converts electrical energy into other forms of energy

   1. examples: light bulbs, heaters, radios

   2. as electrons pass through a load, they lose energy as electrical energy is converted to another type of energy

   3. a load resists (hinders) the flow of current

      1. electrons in the current collide with atoms that make up the load, or with each other

      2. collisions interfere with the flow of current

4. Switch: a device that can turn the circuit on or off by closing or opening the circuit

   1. controls the flow of current

Circuit diagram: a diagram that uses symbols to represent different components of an electric circuit.

Electrons are so pushy

• all electrons have a negative charge

  • this means electrons repel/push each other

• electrons in every part of a circuit are “pushing” each other, so when a circuit is closed, the load works immediately

Current electricity

• when a battery is connected to a complete circuit it causes electrons to move

• moving electrical charges form an electric current

Current electricity: the continuous flow of charge in a complete circuit

• chemical energy from a source (cell or battery) causes charges to move through a conductor (wires), carrying energy to an electrical device (cellphone)

• The moving charges are called an electric current

Current: the measure of flow

electric current: the amount of charge passing a point in a conductor every second

Symbol for current: I

• measured in amperes (A)

  • one coulomb of charge passing a given point per second

Ammeter: a device used to measure the current in a circuit

Modelling the flow of current

A) Negative terminal repels the negative charges already in the conductor

Positive terminal attracts the negative charges already in the conductor

Electrons move along the conducting wires; electrons from the electrochemical cell move into the conductor

B) As the electrons pass through the load, they transfer some of their energy to the load

The electrons then leave the load and return to the electrochemical cell

C) Electrons enter the electrochemical cell; combine with positive ions to become neutral

Over time: fewer electrons at negative terminal; fewer positive ions at positive terminal

Chemical energy can carry more electrons up, keeping the number of separated charges equal

Resistance and Ohm’s Law

Resistance and the Flow of Electrons

Resistance: the property of a material that slows down the flow of electrons and converts electrical energy into other forms of energy

• measured in ohms (Ω)

Resistor: an electrical component that has a specific resistance - prevents flames or sparks

Factors that affect the amount of resistance in a material:

• length of the material the current passes through (longer = more resistance)

• the cross-sectional area is inversely proportional to the resistance (thinner = more resistance)

• Type of material the current passes through (material’s resistivity)

Resistance and Current

Voltage is directly proportional to current:

• if you increase the voltage connected to a circuit, the current will also increase

Resistance and current are inversely proportional

• if you increase the resistance in a circuit, the current will decrease

Short Circuit

Short circuit: a circuit with a resistance that is too low, making the current so high that it is dangerous

Example: If there wasn’t a load (light bulb) to resist the flow of current, the current would be so large that the conductor would get very hot and start a fire

Ohm’s Law

electrical resistance: ratio of the voltage to the current

Ohm (Ω): unit of measurement for resistance

Ohm’s Law: Voltage (V) = Current (I) * Resistance (R)

• voltage = volts (V)

• resistance = ohms (Ω)

• current = amps (A)

Converting prefixes

milli(m) represents 1/1000

kilo(k) represents 1000

mega(M) represents 1,000,000

Series and Parallel Circuits

Circuits can be connected in two ways:

1. Series: a circuit that has only one path for current to travel (ex. Christmas lights)

2. Parallel: a circuit that has more than one path for current to travel (ex. house lights)

Charges with one path to follow (series circuit)

• electrons must travel through all components of the circuit

  • if one part of a circuit is not connected (eg. a switch is open), all electrons are blocked and the current stops

Voltage and current in a series circuit

• in an electric circuit, the charge that leaves a battery “loses” all its voltage before it returns to the battery

• each load in a series circuit loses a portion of the total voltage supplied by the battery

• in a series circuit, the total voltage of the circuit = sum of the voltages lost on the loads

• the current in each part of a series circuit is equal

Current - I₁=I₂=I₃ (same throughout)

Voltage - V_total=V₁+V₂+V₃

Resistors in Series

• resistors placed in series increase the total resistance of the circuit

• If you increase the total resistance of the circuit, the total current throughout the circuit decreases

More than one way to go (parallel circuit)

• a closed pathway that has several different paths for electrons to travel in order to return to the battery

Voltage + Current in a Parallel Circuit

• In an electric circuit, the charge that leaves a battery “loses” all its voltage before it returns to the battery

• since the pathways of a parallel circuit all connect at the same location, the voltage lost on each of these pathways is identical

• loads that are in parallel have the same voltage

Junction point: where a circuit divides into multiple paths, or where multiple paths join

• no current is created or destroyed, it is only split into different pathways

• current entering must divide among the possible paths

• the amount of current through each of these pathways is dependent on the resistance of the path

• the total current entering a junction point must equal the sum of the current leaving the junction point

Current - I_total=I₁+I₂+I₃

Voltage - V₁=V₂=V₃

Resistors in Parallel:

• when you place a resistor in parallel with another resistor, you create another pathway so the total resistance must decrease (there are more paths for the electrons to flow so less backup)

• more current will travel through a path of lower resistance than a path of higher resistance

The Power of Electricity

A matter of time and energy

Power: the rate of change in energy

• The rate at which work is done or energy is transformed

• Watt (W) is the unit for measuring power

• 1W = 1J/Sec

• Joule (J) is a measurement of the energy

A device that can transform one form of energy into another form in a shorter period of time has more power.

Electrical power: the rate at which electrical energy is used by a load

• load: an appliance (washing machine, TV)

Phantom load: Electrical energy a device uses when it is turned off (eg. stand-by mode on TVs)

• appliances in stand-by mode are actually “on” and have phantom loads

• phantom loads account for about 900kWh of energy/year

Calculating Electrical Power

Power(P) = Voltage(V) * Current (I)

To calculate power in Watts use the following units of measurement:

• Voltage = Volts (V)

• Current = Amps (A)

A larger unit for energy

Kilowatt-hour (kW*h): a larger unit of energy

1.0 kilowatt-hour = 1.0 kilowatt * 1.0 hour

To calculate energy in kilowatt-hours (kW*h) use the following units of measurements:

• Power = kilowatts (kW)

  • 1kW = 1000W

• Time = hours (h)

  • 1h = 3600s

Energy calculation:

    energy(Joules) = power(watts) * time(hours)

Paying for electricity

• Smart meter: An electrical energy meter that measures how energy use changes in a building over the course of the day

• The power company charges a fixed amount of money for every kilowatt-hour of electrical energy used

Renewable energy sources

• an energy source that is available on a continuous basis

  • eg. sunlight, wind, river flow, tides and waves, geothermal sources, biomass

• provide alternative options for generating electrical energy

  • examples in BC: Bennett Dam, Bear Mountain Wind Park, The Klemtu Small-scale Hydro and Solar Project

• Non-renewable energy source: an energy source that is non-replaceable in a human lifetime

  • eg. coal, natural gas, uranium (nuclear reactions)

Sustainable energy system: A sustainable way of perceiving, producing, and using energy

• Ensuring that the extraction, production and use of energy have limited impacts on environmental and human health

• less reliance on nonrenewable sources

• ensuring the availability of renewable and reliable energy sources for current and future generations

• providing access to affordable energy for Earth’s entire population

First Peoples Ecosystem Based Management (EBM)

• Respect and Responsibility - making decisions that respect the natural world; responsible use of resources

• Intergenerational Knowledge - listening to Elders and sharing knowledge between generations

• Balance and Interconnectedness - balance makes sure future generations are considered; interconnectedness takes many relationships with an ecosystem into consideration

• Giving and Receiving - giving thanks for natural resources recognizes their value; benefits or resources are shared in a community

Earth System

We are all connected

• the interaction between earth’s four spheres (hydrosphere, lithosphere, atmosphere, biosphere)

• The idea of interconnectedness is at the heart of what it is to be First Peoples

  • similar ideas have been developing among other societies since the modern environmental movement(1970)

  • Canadian Inuit leader Sheila Watt-Cloutier made a petition before the U.S. Senate in 2004 about the threat of climate change on Inuit and the Arctic environment

At any time, matter occupies one of Earth’s four spheres (systems):

They are the “geosphere” (land), “hydrosphere” (water), “biosphere” (living things), and “atmosphere” (air)

Earth’s spheres are interconnected (interact with and affect each other in different ways)

The Hydrosphere

The hydrosphere encompasses all forms of water in the Earth’s environment

This includes the oceans; all water found on the Earth’s surface such as lakes, rivers, snow and glaciers; water under the Earth’s surface and water vapour found in the atmosphere

Water continuously cycles through ecosystems by 3 processes:

• evaporation, condensation, precipitation

The Geosphere (Lithosphere)

The geosphere contains all the solid, rocky land of the planet’s surface (crust), the semi-solid land underneath the crust(mantle), and planet(core)

Major Landforms

The lithosphere includes various landforms such as mountains and valleys, as well as rocks, minerals and soil

The lithosphere is constantly being shaped by external forces such as sun, wind, ice, water and chemical changes

The Atmosphere

The gaseous part of Earth

The upper portion of the atmosphere protects the organisms of the biosphere from the sun’s ultraviolet radiation. It also absorbs and emits heat

Sun Energy

Solar energy that reaches Earth is absorbed and reflected by Earth’s atmosphere and Earth’s surface.

Solar energy heats Earth’s surface unevenly and global winds help redistribute thermal energy around Earth.

Ocean currents also redistribute thermal energy around Earth.

Solar energy enters the biosphere through photosynthesis and cellular respiration.

The amount of solar energy that reaches different regions of Earth varies so it heats Earth’s surface unevenly

• Earth is spherical

• Solar energy strikes the Earth at different angles

• Receives more direct solar energy at lower latitudes (Mexico)

• Therefore, atmosphere heats up unevenly

• Lower latitudes become warmer

• Earth’s curved surface affects the concentration of light and warming at different parts of its surface

• Solar energy that reaches Earth is absorbed and reflected by Earth’s atmosphere and Earth’s surface

The Greenhouse Effect

• the greenhouse effect moderates Earth’s temperature.

• the average global temperature would be -18C if greenhouse gases were not naturally in the atmosphere

• solar energy passes through the clear atmosphere

• most solar energy is absorbed by Earth’s surface and warms it

• some solar energy is reflected by Earth and the atmosphere

• energy is emitted from Earth’s surfaces

• some of the energy passes through the atmosphere, and some is absorbed and re-emitted in all directions by greenhouse gas molecules. the effect of this is to warm Earth’s surface and the lower atmosphere

Global winds and ocean currents

Earth’s major wind systems result from:

• Convection currents

  • warm air near Earth’s surface rises and cools

  • cool air is denser and sinks, creating wind that moves warm and cool air around Earth

• Coriolis effect - a change in the direction of moving air, water or other objects due to Earth’s rotation

• When air temperature changes, weather occurs

• solar energy enters the biosphere through photosynthesis and cellular respiration

Ocean currents also move thermal energy around Earth

• surface currents are created by wind

• five major sets of surface currents (one in each main ocean basin)

• warm currents: move heat (warm water from the equator) toward the poles (higher, colder latitudes)

• cold currents: bring cold water from colder, higher latitudes to tropical regions

The Biosphere

Biotic and abiotic components of the environment

Energy flow between trophic levels

The biotic elements include all microorganisms, plants and animals on, above, or under the earth (found throughout all the other spheres)

All life exists in the biosphere

Biodiversity - large variety of organisms

    often an indicator of the health of the ecosystem

The biosphere cannot survive without elements from all the other spheres

Plants and animals need water from the hydrosphere, minerals from the lithosphere and gases from the atmosphere

The air, water, and land provide homes for all the various forms of life

All living things dependent on non-living things for energy, water, and space; living things use nutrients and decomposers recycle nutrients into inorganic material that can form part of the soil

The environment contains all the factors that surround and influence the biotic and abiotic things within it

The environment is our surroundings

Each living thing within the biosphere inhabits and interacts with the things that surround them

An ecosystem is a smaller function within the environment. It is the unique interaction between the living and non-living elements. An ecosystem is a community functioning together as one unit.

Abiotic components of an ecosystem support the life functions of the biotic components of an ecosystem

Biotic and Abiotic Parts

Biotic parts: living parts of an environment

Abiotic parts: non-living parts of an environment

Biotic and abiotic parts of the environment are connected through the ways in which they interact with one another

Biotic and Abiotic Interactions

Organisms within communities constantly interact to obtain resources such as food, water, sunlight or habitat

Every organism has a special role within an ecosystem

Natural processes move matter in cycles from the biotic and abiotic parts of the environment

An ecosystem has abiotic components such as oxygen, water, nutrients, light and soil that interact with biotic components such as plants, animals and microorganisms

• oxygen for cellular respiration

• water for survival

• nutrients are chemicals that are required for plant and animal growth (ex. nitrogen, phosphorus)

• light is required for photosynthesis

• soil anchors plants, absorbs and holds water, provides nutrients for plants and supports many species of small organisms

Food chain

Interactions are needed to provide a constant flow of energy to sustain the biosphere

Food chain: a model that describes how food energy is passed from one living thing to another

everything stems from the sun

Energy flows from producers(plants) to primary consumers(herbivores) to secondary and tertiary consumers(carnivores)

each step in a food chain is called a trophic level

Energy pyramids

Energy pyramids model how energy is lost at each trophic level of a food chain - food energy is lost to obtain food/digest food, repair tissues, move, heat, etc.

Energy is lost for survival

only 10% of food energy can be passed from consumer to consumer

Producers: living things that make their own food to get energy they need to live (becomes energy source)

• usually through photosynthesis by plants and single-celled organisms

Decomposition - breaking down of dead organic material

• by decomposers

  • ex. bacteria, fungi

  • living things that break down dead material to get energy they need

Food Web

A model of feeding relationships shows a network of interacting and overlapping food chains

A change in the number of one organism could affect several food chains in the food web

All organisms in an ecosystem are connected and depend on each other for survival

Why are there limits to the length of a food chain?

Most of the energy transferred from one organism to another is lost to the environment as unusable heat

Some energy has already been used to support life functions (growth, cellular respiration)

Some energy is stored in wastes that are excreted

Less and less energy is available to each organism in the food chain

Consumers: living things that eat producers or other consumers to get energy they need

Herbivores: primary consumers that eat plants

Carnivores: secondary consumers that eat primary consumers

Omnivores: eat both plants and animals - interconnectedness food chains form a food web

Detrivores: eat bodies of small dead organisms/plant matter, and animal wastes

Photosynthesis and Cellular Respiration

Photosynthesis and cellular respiration balance each other

Each process makes the raw materials that the other processes needs to store or release energy:

• photosynthesis stores energy; cellular respiration releases energy

• photosynthesis uses carbon dioxide and water, and produces glucose and oxygen

• cellular respiration uses glucose and oxygen, and produces carbon dioxide and water

The Hydrosphere

The Water Cycle

All water on Earth continuously cycles through ecosystems by the interaction of three main processes in the water cycle:

• evaporation: heat from the Sun causes water at Earth’s surface to evaporate

• condensation: as warm air rises, it cools and condenses, forming clouds

• precipitation: water falls back to Earth’s surface when it rains or snows

Water moves over Earth’s surface (“run off”) and moves downhill back into the ocean water due to gravity

Water moves through the biosphere by transpiration

Transpiration: process by which water is absorbed by the roots of plants, carried through plant and lost as water vapour through small pores in leaves

A small portion of the water in the hydrosphere is fresh

• ex. precipitation, rivers, streams, groundwater, frozen glaciers

Ninety-seven percent of Earth’s water is salty = oceans

• ocean currents also redistribute thermal energy and nutrients around Earth

• surface currents are created by wind

Grand Ocean Conveyer Belt

The great ocean conveyer belt is a massive system of deep-water currents that moves deep water, thermal energy, and nutrients around Earth

Movement of these currents is based on the differences between the temperature and salt content of water:

• cold water is more dense than warm water

  • cold water sinks and displaces the warm water

• saltier water is more dense than less salty water

  • saltier water sinks and displaces less salty water

The great ocean conveyor belt also moves nutrients, such as nitrogen and phosphorus, around the ocean

Surface water that sinks does not have many nutrients

After the water sinks, bacteria in deep water break down organic material and return nutrients to the water

When the deep water returns to the surface, it has a high concentration of nutrients

Water Pollution

Water pollution - any physical, biological or chemical change in water quality that has an adverse effect on organisms or that makes water unsuitable for desired uses

Synthetic(human-made) chemicals and pollutants enter the environment in air, water and soil

Decomposers cannot break them down through the biodegradation process so they stay in the environment for a long time

Two types of sources of pollution:

Point Sources and Non Point Sources

Point Sources:

Examples: factories, power plants, sewage treatment plants, oil wells

Easy to monitor and regulate

Non-point sources

Examples: run-off from farms, lawns, construction sites, logging areas, roads, parking lots

Difficult to monitor, regulate and treat since pollution is periodic

Bioaccumulation

Bioaccumulation is the gradual build up of these chemicals/pollutants in cells and tissues of organisms

Accumulation = chemical taken up and stored faster than it is broken down and excreted

• via food intake, skin contact or respiration

The process by which pollutants collect in the cells and tissues of organisms

These chemicals can harm organism:

• birth defect and affect body systems

• ex. red tide (algae toxins taken in by clams, human shellfish PCBs and orcas, raptors)

Biomagnification vs. Bioremediation

Biomagnification is the increase in concentration of pollutants in tissues of organisms that are at successively higher levels in a food chain or food web

Bioremediation is a method that uses living organisms to help clean up chemical pollution naturally

• ex. some microorganisms naturally feed on chemicals and reduce them to non-toxic compounds

• ex. plants can act as stabilizers, reducing wind, water erosion that could spread the contaminants

Nutrient Cycles

Nutrients are chemicals required for growth and other life processes

• Carbon, oxygen, hydrogen, nitrogen and phosphorus

There are sources, stores and sinks for each nutrient

Nutrients flow in and out of stores in nutrient cycles

Without interference, generally the amount of nutrients flowing into a store equals the amount of nutrients flowing out (balanced)

Carbon stores

Carbon atoms are a fundamental unit in cells of all living things

Carbon can be stored in many different locations:

Short-term storage:

• aquatic and terrestrial organisms

• CO₂ in the atmosphere

• top layers of the ocean

Long-term sotrage:

• middle and lower ocean layers

• coal, oil and gas deposits in land and ocean sediments (carbon stored in the decomposing remains of organisms buried deep in the ground transforms into these carbon-rich fossil fuels - coal, oil, natural gas)

Carbon Cycle

• carbon dioxide gas moves from the atmosphere into the biosphere through photosynthesis and cellular respiration

• carbon dioxide also moves back to the atmosphere when organisms die and decompose

• carbon enters the geosphere when the remains of organisms are trapped under sediment layers

Human Activities: upsetting the balance

Human activities can upset the natural balance of nutrient cycles.

Land clearing, agriculture, urban expansion, mining industry, motorized transportation, and burning fossil fuels can all increase the levels of nutrients by reintroducing carbon from stores and from reducing plants that can absorb and convert CO₂

Extra carbon dioxide in the air traps heat in the atmosphere leading to global warming and global climate change

Global Warming and Global Climate Change

Carbon dioxide is a greenhouse gas (Absorb solar energy in Earth’s atmosphere)

Extra carbon dioxide in the air traps heat in the atmosphere leading to global warming and climate change

Global warming; an increase in the average temperature of Earth’s surface

Global climate change: a long-term change in Earth’s climate

Can be caused by natural factors of human activity

Natural: natural variations in greenhouse gases, changes in ocean atmospheric circulation, changes in Earth’s orbit

Human Activity: increase in greenhouse gases due to burning of fossil fuels

Effects of Excess Carbon in the Carbon Cycle

Earth’s surface temperature: increased by between 0.56C and 0.92C in the past 100 years

This “small” change can greatly affect conditions:

1. Warmer temperature

   1. land and sea ice melts

      1. sea level rises

         1. coastal flooding occurs

   2. warmer seawater absorbs more CO₂

      1. seawater becomes more acidic

         1. coral reefs and other ecosystems are harmed

   3. extreme weather events increase

      1. more frequent heat waves

         1. human illness and fatalities occur

Melting sea and land ice has led to destruction of habitats for polar organisms, increased local flooding, and release of methane gas (a greenhouse gas) from melting permafrost

Rising sea level:

• some islands have gone underwater

• salt water gets into the drinking water supply

• coastal flooding and destruction of wetlands

Changing ocean chemistry:

• ocean becomes more acidic because it absorbs more carbon dioxide from the air

• an acidic and warming ocean can destroy coral reefs and corals themselves (acidity dissolves the organisms’ shells)

Naturally occurring greenhouse gases

Greenhouse gases can also be released into the atmosphere from human activities

• Carbon dioxide: Released when fossil fuels(oil, natural gas, coal) are burned

• Nitrous oxide: Enters the atmosphere when fertilizer is applied to crops

• Methane: Released in large amounts by herds of cattle → farting

Nitrogen Cycle

• nitrogen is very important in the structure of DNA and proteins

• nitrogen is stored in oceans, lakes, marshes and soil

• largest store of nitrogen is in the atmosphere in the form N₂ (unusable form)

  • nitrogen fixation - processes that make this nitrogen available to plants (part of nitrogen cycle)

Nitrogen is cycled through interactions between living and non-living things

Nitrogen Fixation

Nitrogen is a nutrient that cells need to build proteins

Nitrogen makes up 78% of air, but organisms cannot use this form of nitrogen

Nitrogen-fixing bacteria in soil and water change nitrogen into forms that plants can use

Nitrogen fixation is the conversion of N₂ gas into compounds usable by plants

• lightning(in the atmosphere) provides the energy for N₂ gas to react with O₂ gas to form nitrogen containing compounds that enters through rain

Nitrification

Nitrification occurs when certain nitrifying bacteria convert ammonium(NH₄⁺) into nitrate(NO₃^-)

Takes place in two stages:

1. Ammonium → nitrite (NO₂^-)

2. Nitrite → nitrate

Nitrates enter plant roots through the process of uptake

• herbivores then eat plants and use nitrogen

Nitrogen Cycling

• Denitrification - nitrates are converted back to N₂ by denitrifying bacteria (released into atmosphere)

• volcanic eruptions

• nitrogen dissolves in water, enters waterways, & washes into lakes & oceans & settle in sediments - through gravity

• nitrogen trapped in rocks

  • gets seeped into soil → layers + rocks → gets trapped in deep layers

Human Influences

1. Using fertilizer(contains nitrates) in agricultural practices increases the concentration of nitrogen in soil

• excess nitrogen is washed away, or leaches(when nutrients/chemicals flow into waterways) into the waterways

  • this promotes huge growth in aquatic algae called algae blooms

  • algae blooms use up all CO₂ and O₂ and block sunlight, killing many aquatic organisms

  • algae blooms can also produce neurotoxins that poison animals

2. Burning fossil fuels (factories and vehicles) releases gaseous nitrogen oxides

3. Clearing forests by burning releases trapped nitrogen into atmosphere which increases acid precipitation

The Phosphorus Cycle

Phosphorus is a nutrient essential for the growth and development of organisms

It is cycled through interactions between living and non-living things

Weathering

Phosphorus is stored in the geosphere

Natural weathering processes release phosphorus from rocks

a) Chemical weathering, via acid precipitation

b) Physical weathering, including wind, water and freezing

Phosphorus is then absorbed by soil and plants, which are then eaten by animals

Decomposers breaks down animal waste and dead organisms which returns phosphorus to the soil and water

Human Impacts on Phosphorus

• fertilizer use (run-off can lead to algal blooms that block the sunlight from reaching organisms in the deep waters (organisms die))

• mining

• household cleaners/detergents

all produce excess phosphorus that leaches and runs-off into different systems

Nutrient Cycles and Biodiversity

Any significant changes to any of these nutrients (C, N, or P) can greatly affect biodiversity

• slight temperature fluctuations caused by global warming and changes in water levels can drastically change ecosystems

• increased levels of nitrogen can allow certain plant species to outcompete other species, decreasing resources for every species in the food webs

• *Earth’s spheres are interconnected so any change in one will greatly impact all the others

Sustainability

Sustainability - the ability of an ecosystem to continue to exist indefinitely by recycling their materials

Sustainability ensures balanced systems now and for the future

• natural ecosystems are sustainable as long as they have a continued and constant source of energy

• Ecosystem services are the benefits that organisms receive from the environment and its resources

• ex. food production(crops), water supply(wells), raw supply(fossil fuels), climate regulations(regulation of greenhouse gas) gas supply(regulation of carbon dioxide or oxygen), etc.

• we must use these services without reducing the health of the ecosystem (any change to one part will disrupt the entire ecosystem, making it unbalanced)

• Sustainable practices provide economic opportunities while maintaining biodiversity(a variety of organisms) and ecosystem health.

• Sustainable earth requires that society’s demand on nature is in balance with nature’s ability to meet that demand.

How can Individuals Make a Difference?

• Make proper choices as a consumer

• Volunteer, take public transit, recycle, use solar power

• Vote in favour of parties that promote a healthy Earth

• Join science-minded advocacy groups

• Employ smart growth - strategy focussed on concentrating growth in the centre of a city, rather than in outlying areas

  • Homes and businesses are intermixed

  • Green spaces are preserved

  • Enhances public transportation

How can our actions promote sustainability?

Inquiring individuals can make a difference. Responsible decision making and choices can lead to sustainable practices that benefit all life.

Promoting Sustainability:

Dark Sky Preserve & Small Scale Solar Projects Dark Sky Preserve: A park dedicated to reducing the effects of artificial lighting on the nighttime environment.

Helps protect wildlife in the park that rely on darkness to forage for food, mate, or migrate

McDonald Park in Abbotsford, B.C. is a Dark Sky Preserve

Small scale and community solar projects can help reduce the use of fossil fuels

Grand Forks Aquatic Centre in Grand Forks, B.C. uses 18 solar panels to heat pool water and hot tubs

The Scia’new First Nation on Beecher Bay in East Sooke, B.C. are building a sustainable housing development

Development includes ecologically sustainable technologies (geothermal heating system to provide heat to homes; removed trees will be used to make fireplace mantels)

Negative Influences

Land use, resource use, habitat loss, habitat fragmentation, deforestation, soil degradation, agricultural practices, contamination, overexploitation, extinction, etc.

Better resource management practices are required

Bias

Being scientifically literate involves being able to recognize and evaluate bias in information

• Bias: A judgment that is based on a person’s knowledge, understanding, and beliefs

• choice of photo can also indicate bias