What would happen if you put a dry sponge under a trickling

faucet?

The sponge would absorb the water until at a certain point

water would start to drip from it. You could say that the

sponge had a water capacity:

It could hold so much water before it couldn’t hold any

more and the water started dripping out.

Heat capacity is similar. Heat capacity is how much heat an

object can absorb before it increases in temperature.

The mass of an object influences its heat capacity (like a large sponge can hold more water than a smaller sponge), and so does the material itself.

Think of putting a piece of wood under a faucet. How would this compare to the sponge?

The water would begin to drip out sooner, right? It wouldn’t have much water capacity compared to a sponge.

Similarly, different types of substances have different capacities for absorbing heat.

Specific HeatSpecific heat is how much heat energy a single gram of material must absorb before it increases 1°C. Each material has its own specific heat. The higher a material’s specific heat, the more heat it must absorb before it increases in temperature.

Experimental Setup

Specific Heat

Specific heat can be calculated by the following equation:

c = q/(m• ΔT)where c is the specific heat capacity of the material, q is the quantity of heat transferred to or from the object, m is the mass of the object, and ΔT is the resulting temperature change of the object.

ORq = c • m• ΔT

Dissolved Oxygen

Oxygen is a soluble gas!O2

O2O2O2

O2

O2

O2 O2

Oxygen in water usually enters the water from the air at the surface, where it slowly dissolves. The oxygen then diffuses in the water, very slowly-about 300,000 times more slowly than it does in air.

Oxygen: Easy come, easy go!

Photosynthesis Respiration

O2

O2

• What’s going on here…?

Sunrise Noon SunsetMidnight Midnight

Dis

solv

ed

Oxy

gen

Daily Aquatic Oxygen Cycle

0

1

2

3

4

Oxygen Can Diffuse into or out of the Water Column

The air is 21% oxygen

Water holds much less than 1%O2

O2

O2

O2

O2

O2

O2

O2

O2

O2

O2

O2

O2

O2O2

O2

O2

O2O2

O2

Hmmm… How do you think oxygen might get into the

water from the air? What kinds of factors might affect the amount

of oxygen in the water? Do you think the temperature of water can

affect the amount of oxygen in it? If so, how? Would you predict warm water to have more

oxygen or less than cold water?

SaturationThe warmer water is, the less DO it can hold.

100% DO Saturation

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101214161820

0 5 10 15 20 25 30 35

Temperature (C)

100

% S

atur

atio

n Le

vel

When water has all the oxygen it can hold, it is considered 100% saturated with DO.Any excess oxygen evaporates!

Why does it matter?For mg/L (or ppm): • 0-2 mg/L: not enough oxygen to support most animals • 2-4 mg/L: only a few kinds of fish and insects can

survive • 4-7 mg/L: good for most kinds of pond animals • 7-11 mg/L: very good for most stream fish

For percent saturation: • Below 60%: poor quality, bacteria may be using up DO • 60-79%: acceptable for most stream animals • 80-125%: excellent for most stream animals • 125% or more: too high

Instream Dissolved OxygenSALMONID WATERS - Dissolved Oxygen

B. Other life stages 8 No production impairment6 Slight production impairment5 Moderate production impairment4 Severe production impairment 3 Limit to avoid acute mortality

A. Embryo and larval stages 11 No production impairment 9 Slight production impairment 8 Moderate production impairment 7 Severe production impairment 6 Limit to avoid acute mortality

C. Invertebrates 8 No production impairment 5 Moderate production impairment 4 Limit to avoid acute mortality

Other Water Temperature Effects

Stratification of layers of water in summer

Ice cover as water cools to freezing

Growth and survival of aquatic organisms