Textbook Notes (369,137)
Canada (162,407)
Environment (171)
ENV100Y5 (131)
Chapter 3

Chapter 3.docx

10 Pages

Course Code
Monika Havelka

This preview shows pages 1,2 and half of page 3. Sign up to view the full 10 pages of the document.
Chapter 3: Earth’s Environmental Systems: • Consists of complex networks of interlinked systems • Between living and non-living System: is a network of relationships among parts, elements or components that interact with and influence one another through exchanges of energy, matter or information Types of systems – properties of boundaries: • Isolated system: neither energy nor matter can be exchanged across the boundaries • Closed system: energy can be exchanged across the boundaries, but matter cannot o Systems receive inputs and produce outputs of energy o Consequences:  Resources are finite and limited  There is no “away” to throw things to  “What goes around, comes around” - Principle of Environmental Unity • Open system: both matter and energy can be exchanged across the boundaries o System receive inputs of both energy and matter and produce outputs of both Sometimes cycles are affected by feedback loops: • Positive feedback: o Output from the system acts as an input that drives the system farther in the same direction – toward one extreme or another o Self-reinforcing, self-perpetuating o “vicious” cycle o Stabilizes the system o E.g. removal of soil by water or wind (erosion) • Negative feedback: o Output from the system acts as an input that moves the system in the opposite direction – stabilizing it or returning it to the starting point o Self-regulating, homeostatic o “equilibrium” cycle Systems show several basic properties: • Dynamic equilibrium – systems are constantly changing, interacting, balancing • Homeostasis – many systems tend to maintain stable internal conditions o Resistance: strength to remain constant o Resilience: some systems (not all) recover easily from disturbances • Emergent properties – system characteristics not evident in components on their own Complex systems have multiple subsystems: • Systems seldom have well-defined boundaries so deciding where one system ends and another begins can be difficult Environmental systems may be perceived in warious ways: • Major Earth spheres: o Geosphere: is the rock and sediment beneath our feet (uppermost layer – lithosphere) o Atmosphere: is composed of the air surrounding our planet o Hydrosphere: encompasses all water – salt or fresh, liquid, ice or vapour – in surface water bodies and glaciers near the underground  The subsystem that consists of the perennially frozen parts of the hydrosphere has its own name - crysophere o Biosphere: consists of all the planet’s living organisms o Arguing: anthrosphere/technospehre – encompasses the parts of the environment that are built or modified by humans for human use Ecosystem ecology: study of interactions among organisms and their physical environment as an integrated system • a way of looking at organisms and their interactions with the environment as an integrated system • focuses on functions, processes, fluxes (energy, nutrients), biogeochemical cycles, etc. • ecosystems are nested and hierarchical • ecosystems are dynamic • inputs, outputs, feedback loops, resistance & resilience, emergent properties • boundary between the biotic and abiotic components is often blurred • ecosystem stability: resistance and resilience • 4 main components: o abiotic env’t (water, soil minerals, atmospheric gases) o 1° producers o consumers o decomposers • species are not usually treated as separate units; functional role is what is important • abiotic components are of equal importance as biotic components (movement of nutrients & energy are focus of investigation) • human activities are often important (e.g. deposition of pollutants, harvesting of species, etc.) • ecosystems are nested and hierarchical, thus we can study them on a number of different spatial and temporal scales • spatial boundaries: o often indistinct boundary o organisms may move between aquatic & terrestrial environment; trees drop leaves into pond • temporal scale: o instantaneous o seasonal o successional o evolutionary history o geologic history • Energy flow in ecosystem: o ecosystem is an economy; energy is the currency o ecosystems based on autotrophs o autotrophs transform energy from sunlight or inorganic compounds into chemical energy stored in sugars o energy converted by primary producers: growth, maintenance (respiration), reproduction  Net Primary Productivity (NPP) = Gross Primary Productivity(GPP) - respiration by autotrophs  NPP = energy available to consumers & decomposers • terrestrial ecosystems: max NPP in wet tropics • marine ecosystems: max NPP along coastlines Limit to productivity in aquatic ecosystem: o coastlines more productive than open ocean o depth of photic zone; nutrients o Systems and cycles consist of interconnected reservoirs: • Acycle is: o a system of two or more connected reservoirs, in which material (or energy) is transferred in a cyclical fashion. o a way of understanding and modeling where substances come from, where they go, where they “reside” in the Earth system, and how they are transferred and transformed. • Matter is endlessly recycled through environmental systems, changing form as it goes. • Energy comes into the Earth system, cycles around, is used and degraded, and then exits the system. Biogeochemical Cycle: • Nutrients moving ecosystems • Travel through atmosphere, hydrosphere, geosphere and from one organism to another in dynamic equilibrium • Reservoir: a location where materials in a cycle remain for a period of time before moving to another reservoir o Residence time: average time the material remains in the reservoir o If Sources = Sinks: Steady State • Flux: movement of material/energy among reservoir o amount of material transferred, described in terms of mass or volume per unit of time o Fluxes are controlled by rates of transfer processes and capacities of reservoirs • Sources: a reservoir that releases more material than it takes in • Source: where the flux is coming from o gives out more than it takes in • Sink: where the fl
More Less
Unlock Document

Only pages 1,2 and half of page 3 are available for preview. Some parts have been intentionally blurred.

Unlock Document
You're Reading a Preview

Unlock to view full version

Unlock Document

Log In


Join OneClass

Access over 10 million pages of study
documents for 1.3 million courses.

Sign up

Join to view


By registering, I agree to the Terms and Privacy Policies
Already have an account?
Just a few more details

So we can recommend you notes for your school.

Reset Password

Please enter below the email address you registered with and we will send you a link to reset your password.

Add your courses

Get notes from the top students in your class.