What’s so special about Seawater?

Aquarium Chemistry

Water Quality: Nitrogen Cycle badmanstropicalfish.com (originally from

4 What do we mean by a “cycled” aquarium? A “cycled” aquarium is one that has an established population of the bacteria that convert ammonium to nitrite and nitrite to nitrate. A “cycled” aquarium is one that has an established population of the bacteria that convert ammonium to nitrite and nitrite to nitrate. Let’s take a closer look at each step. Let’s take a closer look at each step.

5 Step 1 – Ammonium NH 4 Ammonium is an ion that is fairly non-toxic to fish. However it easily changes to a highly toxic form, ammonia NH 3, which can stress and kill fish quickly. Ammonium is an ion that is fairly non-toxic to fish. However it easily changes to a highly toxic form, ammonia NH 3, which can stress and kill fish quickly. If the pH is acidic ( 7), the ammonium ion is quickly turned to ammonia, which is deadly for the fish. If the pH is acidic ( 7), the ammonium ion is quickly turned to ammonia, which is deadly for the fish.

6 Steps 2 and 3 – Nitrite (NO 2 - ) and Nitrate (NO 3 - ) Nitrite, like ammonia, is also very toxic to fish. Nitrite, like ammonia, is also very toxic to fish. Nitrate is less toxic in low to moderate concentrations, but becomes stressful as concentrations build up. Nitrate is less toxic in low to moderate concentrations, but becomes stressful as concentrations build up. The bacteria that do these steps of the cycle are aerobic. That means they need oxygen. The bacteria that do these steps of the cycle are aerobic. That means they need oxygen.

Water Quality: Nitrogen Cycle

Some aquaria are simple, some funky... Some aquaria are simple, some funky...

Some are big, but all the principles are the same Some are big, but all the principles are the same the Osaka Aquarium (seen here), boasts a tank of 1.4 million gallons and nearly 580 spp. the Osaka Aquarium (seen here), boasts a tank of 1.4 million gallons and nearly 580 spp.

Georgia Aquarium

Mystic Aquarium

New England Aquarium

Must maintain a tank ecology that mimics natural habitat. Must maintain a tank ecology that mimics natural habitat. Controlling water quality! Controlling water quality! managing the inflow and outflow of nutrients, managing the inflow and outflow of nutrients, management of waste (nitrogenous) management of waste (nitrogenous) beneficial bacteria populations. beneficial bacteria populations.

Aquarium Parts Tank Tank Filter Filter Gravel/substrate Gravel/substrate Pump Pump Aerator Aerator Reliable water supply Reliable water supply

Tanks High quality glass High quality glass -Plexiglass is expensive, but lighter Monteray Bay Aquarium

No one wants this much water on the carpet!! Plexiglass offers unique design options! Courtesy: Perigrine Plastics

Aquaria for research: St. Croix Waters Fishery

Filters – 3 (or 4) stages 1. Removes solids a) -small solids called “suspended solids” b) -larger ones called “flocs” 2. Provides substrate for nitrifiers 3. Binds up chemicals 4. Sometimes they can also kill all little critters

Gravel/Substrate Material for nesting Material for nesting Aesthetics Aesthetics Nitrification Nitrification “Live sand” “Live sand” Filtration Filtration

Gravel/Substrate

Gravel/Substrate PVC shavings! Activated Carbon

Media Filters Bead/Sand/Media filters all use water pressure to force water through some type of media. Bead/Sand/Media filters all use water pressure to force water through some type of media. Excellent filtering capacity, esp. for larger systems Excellent filtering capacity, esp. for larger systems More maintenance (media changing More maintenance (media changing backwashing, etc.) backwashing, etc.)

Mixed media filters

Gravity Filtration Trickle filters/Settling Chamber/Swirl Separators Trickle filters/Settling Chamber/Swirl Separators Good for nitrification and oxygenation. Good for nitrification and oxygenation. Prone to clogging if primary filtration inefficient. Prone to clogging if primary filtration inefficient.

Over 20 feet tall!

Biofilters Help to establish nitrogen cycle.Help to establish nitrogen cycle. Break down toxic fish wastes.Break down toxic fish wastes.

What really does the work?? What really does the work?? Bacteria!!

UV filtration UV filtration

Protein Skimmers/ Foam Fractionators Removal of excessive organics Removal of excessive organics -decreases B.O.D. and C.O.D. Increases flocculation Increases flocculation -decreases solids -decreases solids -increases water clarity -increases water clarity

Liquid Oxygen Facilitates higher densities Facilitates higher densities False security? False security? -increased density -increased solids -increased solids -may increase disease -may increase diseaseOzone Increases flocculation Increases flocculation Reduces disease outbreak Reduces disease outbreak -kills bateria, fungus, viruses viruses Expensive!! Expensive!!

Aeration Adds dissolved oxygen for specimen Adds dissolved oxygen for specimen Speeds up decomposition Speeds up decomposition Circulates water (air lift pump) Circulates water (air lift pump)

H 2 O molecule

One hydrogen H and two oxygen O atoms bonded by sharing electrons One hydrogen H and two oxygen O atoms bonded by sharing electrons Both H atoms make a positive side, O side is negative, so it is a: Polar molecule Both H atoms make a positive side, O side is negative, so it is a: Polar molecule

Hydrogen bonding Polarity means small negative charge at O end Polarity means small negative charge at O end Small positive charge at H end Small positive charge at H end Attraction between + and – ends of water molecules to each other or other ions Attraction between + and – ends of water molecules to each other or other ions Fig. 5.3

Hydrogen bonding: the result of polarity Hydrogen bonds are weaker than covalent bonds but still strong enough to result in: Hydrogen bonds are weaker than covalent bonds but still strong enough to result in: High surface tension High surface tension Cohesion and adhesion Cohesion and adhesion High solubility of chemical compounds in water High solubility of chemical compounds in water Solid, liquid, gas at Earth’s surface Solid, liquid, gas at Earth’s surface Unusual thermal properties Unusual thermal properties Unusual density Unusual density

Water molecules in different states of matter Fig. 5.5

Changes of state due to adding or subtracting heat Heat is energy of moving molecules Heat is energy of moving molecules Calorie is amount of heat needed to raise the temperature of 1 gram of water by 1 o C Calorie is amount of heat needed to raise the temperature of 1 gram of water by 1 o C Temperature is measurement of average kinetic energy Temperature is measurement of average kinetic energy

Unusual thermal properties of H 2 O H 2 O has high boiling point H 2 O has high boiling point H 2 O has high freezing point H 2 O has high freezing point Most H 2 O is in the form of water (liquid) on Earth’s surface (good for life) Most H 2 O is in the form of water (liquid) on Earth’s surface (good for life) High latent (hidden) heats of High latent (hidden) heats of Vaporization/condensation Vaporization/condensation Melting/freezing Melting/freezing Evaporation Evaporation

Fig. 5.6

Unusual thermal properties of H 2 O Water high heat capacity Water high heat capacity Which is the amount of heat required to raise the temperature of 1 gram of any substance 1 o C Which is the amount of heat required to raise the temperature of 1 gram of any substance 1 o C Water can take in/lose lots of heat without changing temperature much Water can take in/lose lots of heat without changing temperature much Rocks low heat capacity Rocks low heat capacity Rocks quickly change temperature as they gain/lose heat Rocks quickly change temperature as they gain/lose heat

Specific Heat Values Specific Heat Material(cal/g °C)(J/kg K) Aluminum Copper Iron Lead Brass Magnesium Zinc Styrofoam Air Water Ice

Global thermostatic effects Moderate temperature on Earth’s surface Moderate temperature on Earth’s surface Equatorial oceans (hot) don’t boil Equatorial oceans (hot) don’t boil Polar oceans (cold) don’t freeze solid Polar oceans (cold) don’t freeze solid Marine effect Marine effect Oceans moderate temperature changes day/night; different seasons Oceans moderate temperature changes day/night; different seasons Continental effect Continental effect Land areas have greater range of temperatures day/night and during different seasons Land areas have greater range of temperatures day/night and during different seasons

Density of Various Materials Materialg/cm 3 Aluminum2.7 Copper8.96 Iron7.87 Lead11.3 Brass8.4 Magnesium1.74 Zinc7.14 Lead11.3 Water1.00 Ice0.917

Density of water Density of water increases as temperature decreases Density of water increases as temperature decreases Density of ice is less than density of water Density of ice is less than density of water From 4 o C to 0 o C density of water decreases as temperature decreases From 4 o C to 0 o C density of water decreases as temperature decreases

Density of water Fig. 5.10

Where did Earth’s water come from? Where did Earth’s water come from? (MinuteEarth) Where did Earth’s water come from? A second opinion (NatGeo) A second opinion (NatGeo) A second opinion A second opinion

Ocean water composition

What are the differences?

Salinity : Total amount of solid material dissolved in water- Typical salinity is 3.5% or 35 Typical salinity is 3.5% or 35 ‰ or parts per thousand (ppt) = grams of salt per kilogram of water g/Kg\ ‰ or parts per thousand (ppt) = grams of salt per kilogram of water g/Kg\ Six elements make up 99% of dissolved solids in seawater Six elements make up 99% of dissolved solids in seawater Fig. 5.12

Measuring salinity Can be measured by specific gravity, electrical conductivity or by refraction of light Can be measured by specific gravity, electrical conductivity or by refraction of light We will measure with a refractometer in parts of salt per thousand of water (the unit being ppt or ) We will measure with a refractometer in parts of salt per thousand of water (the unit being ppt or ‰)

Salinity variations Open ocean salinity 33 to 38 Coastal areas salinity varies more widely, especially in estuaries Open ocean salinity 33 to 38 ‰ Coastal areas salinity varies more widely, especially in estuaries What factors would cause salinity to vary? What factors would cause salinity to vary?

Processes that add/subtract water from oceans Precipitation (rain or snow) Precipitation (rain or snow) Runoff (river flow) Runoff (river flow) Melting icebergs Melting icebergs Melting sea ice Melting sea ice Evaporation Evaporation Formation of sea ice Formation of sea ice Salinity decreases through: Salinity increases through:

Deep ocean variation of salinity Surface ocean salinity is variable Surface ocean salinity is variable Deeper ocean salinity is nearly the same (polar source regions for deeper ocean water) Deeper ocean salinity is nearly the same (polar source regions for deeper ocean water) Halocline, rapid change of salinity with depth Halocline, rapid change of salinity with depth

Salinity versus depth Fig. 5.22

Hydrologic cycle describes recycling of water near Earth’s surface Fig. 5.15

Surface ocean variation of salinity Fig. 5.21

Surface ocean variation of salinity Polar regions : salinity lower, lots of rain/snow and runoff Polar regions : salinity lower, lots of rain/snow and runoff Mid-latitudes : salinity higher, high rate of evaporation Mid-latitudes : salinity higher, high rate of evaporation Equator : salinity lower, lots of rain Equator : salinity lower, lots of rain Thus, salinity at surface varies primarily with latitude

Density of seawater Ocean layered according to density Ocean layered according to density to g/cm 3 surface seawater to g/cm 3 surface seawater Density seawater controlled by temperature and salinity Density seawater controlled by temperature and salinity Salinity greatest influence on density in polar oceans Salinity greatest influence on density in polar oceans Polar ocean is isothermal Polar ocean is isothermal

Salinity versus depth Fig. 5.22

Our ocean is layered due to density differences at depth Pycnocline, abrupt change of density with depth Pycnocline, abrupt change of density with depth Thermocline, abrupt change of temperature with depth Thermocline, abrupt change of temperature with depth Halocline, abrupt change of salinity with depth Halocline, abrupt change of salinity with depth High latitude oceans High latitude oceans Isothermal Isopycnal

Fig. 5.23

Sound and light of seawater Due to density, the speed of sound in salt water is 1500 m/sec Due to density, the speed of sound in salt water is 1500 m/sec As opposed to 340 m/sec in air As opposed to 340 m/sec in air The index of refraction of light in water is 1.33, as you increase the salinity, you increase the index The index of refraction of light in water is 1.33, as you increase the salinity, you increase the index

Ocean pH

Residence time and steady state Fig. 5.16

Fig Carbonate buffering

Carbon emissions and poor little ocean critters Carbon dioxide is a natural by-product of combustion. Carbon dioxide is a natural by-product of combustion. In low pH water, organisms cannot form calcium carbonate shells. In low pH water, organisms cannot form calcium carbonate shells.

What do the data show?

Can you drink seawater?

No, it will make your cells plasmolyze and you will die. But we now can remove salt from seawater No, it will make your cells plasmolyze and you will die. But we now can remove salt from seawater Or can we?

Can you drink seawater? No, it will make your cells plasmolyze and you will die. But we now can remove salt from seawater No, it will make your cells plasmolyze and you will die. But we now can remove salt from seawater Or can we? Distillation--most common process Distillation--most common process Electrolysis Electrolysis Reverse osmosis Reverse osmosis Freeze separation Freeze separation

Trapped on a desert island? what do you do?

Fig. 5.24