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 , 4.18) greenhouse gases (TBC)