Environmental Change (cont’d); Matter Cycling

ENST1001A, Week 614 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)