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Environmental Change
(cont’d); Matter Cycling
ENST1001A, Week 6
14 October, 2011
New readings: Textbook Chapter 4
Catching up: leftovers
from last lecture
(slides deleted since
they’re in the files from
week 4)
Matter (Chapter 4)
has mass
takes up space
“what things are made of”
elements, atoms, molecules
law of conservation of matter
Biogeochemical cycles
matter moving through the ecosphere
recall: energy flows; matter moving too
of all the naturally occurring chemical
elements, about 30 are required for life
nutrients (macro- and micro-)
cycled continuously through ecosphere
Figure 4.1 Generalized model of biogeochemical cycle
Some really key cycles:
nitrogen
phosphorus
sulphur
carbon
water
Phosphorus (P)
See text Figure 4.2
Sulphur
See text fig 4.3
Nitrogen
See text fig 4.4
C
See text fig 4.7
See text fig 4.6
Hydrological Cycle
water also necessary for life
many unique properties
common in all three phases
high molecular attraction --> tension
high heat capacity
universal solvent
density: solid LESS dense
See Text Figure 4.8
Water availability
very unequal distribution on Earth
varying availability
Canada relatively rich, although most is ice
regionally large potential deficits
large demand from southern neighbours
Available Water
easiest to access/use:
surface freshwater
Groundwater
See text Figure 4.9
Precipitation
also highly variable
regional patterns (see Figure 4.10) -> why?
Air pressure & winds
need to bring back energy for a minute
energy + air -> air masses, winds
Convection systems
•
cool air will descend, and will flow towards areas of
lower pressure
•
Precipitation often occurs in low pressure zones
•
as warm air rises, it cools, and can become
supersaturated, resulting in precipitation
Implications...
strong tendency of air movement -> global air
circulation patterns
strong influence on climate
combines with processes that govern water
cycle
-> strong influence on other processes, soil
formation, plant growth, ... (recall last week)
Back to water...
of course, these air masses also carry water
evaporation
air masses move
precipitation
Clouds
air can get supersaturated = too much water in
vapour form -> condensation
condensation nuclei -> droplets
at first, droplets too small to fall; large
numbers of droplets or ice crystals -> clouds
kept up by upward movements of air
Remote sensing of
clouds...
satellites have “long” been used to study
weather and climate
important tool to monitor development and
track of storms, fronts, ...
Which brings us back
to...
soils
vegetation
Humans and BGC
Cycles
“Some of the most notable environmental
crises today result from humans disrupting the
natural flow of biogeochemical cycles”
discuss
Examples
Eutrophication (text Figure 4.13)
acid deposition (text Figures 4.15-4.16, 4.18)
greenhouse gases (TBC)