EAOS 111 Properties of Seawater, Marine Data & Ingredients for Life

Potential Energy

Stored in a system. Examples include chemical, nuclear, and gravitational.

Kinetic Energy

Expressed in Motion. Examples include radiant, electrical, and sound.

Why does light attenuate in the ocean?

Molecules, compounds, dust particles, and droplets all scatter light. Water absorbs energy from light and turns it into heat.

Photic Zone

40-600 m, but commonly 100 m. Where the sea has light and heat. All marine photosynthesis occurs in this zone. Marine life and food webs are concentrated here, and atmosphere-hydrosphere interactions dominate.

Secchi Disk

A thirty cm disk, often with an x on it, lowered into the water until it can no longer be seen, describes turbidity.

Visibility

The distance things can readily be identified under water.

Adaptations to Light

Transparency, coloring, mirroring, iridescence, luminescence, florescence, and camouflage.

Dangers of UV Radiation

Sunburn, skin cancer, immune issues, cataracts.

Why does New Zealand have such high summer UV levels?

Orbital ellipse, ozone, and clear air.

Forms of Oxygen

O atomic oxygen, O₂ oxygen gas or diatomic oxygen, and O₃ ozone gas or triatomic oxygen.

Oxygen in the Atmosphere

Oxygen molecules dissociate after absorbing a UV photon whose wavelength is less and 240 nm, the atomic oxygen radicals combine with other O₂ molecules to create ozone. Ozone molecules absorb UV light between 200 and 310 nm and dissociate into a molecule of O₂ and an oxygen atom. This is a continuing process, ending when an oxygen atom recombines with an ozone molecule to make two O₂ molecules.

Ozone Depletion and Destruction

Free-radical catalysts permanently destroy O₃ (such as OH^-, NO^-, Cl^-, and Br^-). All occur naturally but most atmospheric chlorine and bromine is produced by people with chlorofluorocarbons (CFCs), which come from refrigerants, fire-extinguishers, and propellants. A single chlorine ion can continue to destroy the ozone for years until it settles out of the stratosphere or is tied up in another molecule.

Ozone Hole

In the Antarctic spring, strong westerly winds circulate around the pole and pile up cold stratospheric clouds over the south pole, over 50% of ozone depletion occurs in this area and at this time (chemical reactions at extreme cold, sunlight), the ozone hole was growing in space and time from the 1980s through the 2000s.

Montreal Protocol on Substances that Deplete the Oxone Layer

A protocol agreed on by 24 countries and the European Economic Community on 16 September 1987, with the aim of phasing out the production of compounds that deplete the ozone in the stratosphere, placing trade sanctions on non-signatories that did not comply.

Light

Electromagnetic radiation which travels through air as well as through a vacuum and is scattered and absorbed by water.

Sound

Shock or pressure waves which travel through air but do not travel in a vacuum, travels through water much farther than light.

Speed of Sound in Water

About 1500 m/s, due to the proximity of molecules being closer together and better able to transfer energy between one another.

The SOFAR Channel

Sound waves travel until they hit something or dissipate. Sound waves travelling near the thermocline, however, bend up and down and are refracted back towards the minimum speed zone.. This means that sound waves, especially low frequency sound waves, in this Sound Fixing and Ranging Channel can travel many km without dissipating, possibly around the whole world.

SONAR- Sound Navigation and Ranging

People use machines for echolocation, to find things, fishing, and mapping the seafloor.

Measuring Seawater Parameters

Special machines such as CTD, RBR, and Sonde. Collecting water samples for lab work to study nutrients, plankton, and chlorophyll. Huge amounts of data are collected on one field trip because they are expensive and dangerous.

Life on Earth is Based on Sunlight

Solar energy fuels photosynthesizers like plankton, producing organic matter. Organic matter fuels other organisms, life has become very efficient at using sunlight.

Deep Sea Ecosystems

Where there is no light, organisms rely on marine snow and whale-fall, organic matter exported from the surface, and underwater landslides (mass-wasting events) rapidly transporting material to great depths, which is really just photosynthesis at a distance.

Hydrothermal Vent Ecosystems

Energy gained from chemo-autotrophy is higher than that gained from organic matter that reaches the seafloor (because there’s not much organic matter that reaches the sea floor), founding rich and diverse ecosystems.

Anoxic Photosynthesis

Photosynthesis occurring in anoxic environments, with the use of other molecules like iron or sulfide.

Atmospheric Thermodynamic Equilibrium

Feedbacks between life and its environment lead to a habitable planet.