1: Aquatic Intro & Hydrologic Cycle

solar energy

powers life on earth & drives the hydrologic cycle

“Goldilocks Zone”

earth is in this; distance from the sun is not too hot/cold, allows for liquid H₂O

liquid H₂O

the life-supporting molecule (unique)

respiration goal

make ATP

water

is densest at 4^oC (39.12^oF) and has a high specific heat

properties of water

arise mostly from its molecular structure; polar covalent bond produces “double” dipolar molecule, provides “double” dipolar moment; allows for extensive hydrogen bonding among molecules (each water molecule can H-bond to 4 other water molecules)

universal solvent

water; has excellent solvent properties — forms spheres of hydration around ions, polar compounds

nonpolar compounds

far less soluble in water because spheres of hydration cannot form

high latent heats of melting & evaporation

part of water properties; needs lots of E to change (ice → water, water → steam), all of which = high thermal stability (not up and down easily)

H₂O moderates

temperatures globally & locally (Hudson Bay, Canada ≈ UK latitudinally)

Gulf Stream

moderates temps

water is not

at highest density as a solid

water is most dense

at 4^oC

ice floats

because it is less dense than water

water distribution

more salt (saline) than fresh

freshwater is found

glaciers > ground > surface

surface water distribution

lakes > swamps > rivers/streams

phases of the hydrologic cycle

precipitation, evaporation, surface & groundwater runoff

each hydrologic phase involves

transport, temporary storage & change in physical state of water

precipitation

H₂O stored in atmosphere as water vapor for 9 days (short period of time); returns to earth via rain, snow, sleet, hail, & condensation

over oceans (net loss)

evaporation > precipitation

over land (net gain)

precipitation > evaporation

interception

included in precipitation; water clings to plants, other surfaces

surface runoff

included in precipitation; overland flow, surface detention, or depression storage

infiltration

precipitation → soil infiltrates becoming “subsurface water” or vadose water

vadose water

water in soil/above water table; moves vertically (percolation; via gravity) to water table o rflows laterally to nearest outlet or stream drainage channel

water from precipitation

may percolate to Water Table where permeable soils are saturated

H₂O below water table

ground water; can be stored months as soil moisture and 300+ years as ground water, accounts for stable base flow of many streams

interflow

ground water movement into & through overlying unsaturated soils

months

vadose zone storage

hundreds to thousands of years

ground water, zone of saturation

vadose flow (interflow) may be

subsurface storm flow or return flow

hydrologic cycle provides

water for intermittent streams (doesn’t flow year round) and base flow for permanent streams

evaporation (purifies, liquid to gas)

>80% precipitation returns to atmosphere through this; removes heat from surrounding

types of evaporation

transpiration, sublimation, evapotranspiration

transpiration

water moves from soil, through plant, then evaporates through leaf stomates

sublimation

solid to gas; water as snow + ice → atmospheric water w/o liquid phase

evapotranspiration

transfer H₂O from earth’s surface → atmosphere by sum of evaporation, sublimation, transpiration