ocean water

OCEAN WATER Spring 2014

Properties of Ocean Water Physical properties of ocean water

TemperatureDensityColor

Chemical Properties Determine its compositionEnable the ocean to dissolve other

substances

Properties of Ocean Water Composition of Ocean Water

Salts enter the ocean from rivers and streams

Gases enter the ocean from rivers, streams, & directly from the atmosphere

Elements in Ocean Water ○ 95.6% pure water ○ 75 chemical elements

6 most abundant: chlorine, sodium, magnesium, sulfur, calcium, & potassium

Properties of Ocean Water Dissolved Gases

3 most common○ Nitrogen○ Oxygen○ Carbon dioxide

Higher temperature= less dissolved gases Lower temperature= more dissolved gases Exchange of gases between the

atmosphere & the ocean is a constant thing

Properties of Ocean Water Salinity

The number of grams of dissolved solid per volume of liquid ○ Called salinity most dissolved solids are salts

78% of the dissolved salt in the ocean is NaCl (sodium chloride)

Increased by both evaporation & freezing Salinity varies by depth Because the ocean is constantly mixing the

average salinity is similar all over the globe

Properties of Ocean Water Temperature

Surface Temperture○ Movement of water throughout the ocean

thoroughly mixes the warmed surface water Distributes heat downward (100m – 300m)Temperature of this zone is relatively constant

○ Temperature decreases with increasing latitude Poles have colder surface temp than the middle

latitudes - Ice pack- floating layer of sea ice that covers the

surface of the ocean in both the Arctic & Antarctic during parts of the year

Properties of Ocean Water Temperature

Thermocline○ Zone of rapid temperature change ○ Exists because water near the surface that is

heated by the sun is less dense than the colder deeper water

○ Changing temperature or shifting currents may alter the depth or cause it to disappear completely

Properties of Ocean Water Density

Mass of a substance per unit of volume 2 factors affect the density of ocean water:

○ SalinityThe large amount of dissolved solids in ocean water

makes it more dense than fresh water ○ Temperature

Water becomes more dense as it get colder ***Affects density more than salinity

Properties of Ocean Water Color of Ocean Water

Color is determined by the way it absorbs or reflects sunlight

Only blue wavelengths tend to be reflected ○ Only the upper regions show color; the lower

region is in total darkness

Life in the Ocean Most marine organisms depend on 2

factors for their survival:Essential nutrients available in ocean waterSunlight

Life in the Ocean Ocean Chemistry & Marine Life

Animals & plants living in the ocean help maintain the chemical balance of ocean water

Nearly all life is regulated by the life processes of plants

Elements nitrogen, phosphorus, & silicon are critical nutrients for the growth of plants

Life in the Ocean Ocean Chemistry & Marine Life cont…

Marine plants & animals absorb & store the substances they need for life.

All of the elements necessary to marine life are consumed by marine plants & animals near the surface but released at great depths through decay

Upwelling- occurs when wind blows steadily parallel to the shore along a coastline, surface ocean water is moved farther offshore causing deep water to then move up

Life in the Ocean Sunlight & Marine Life

All marine plants & animals require sunlight in addition to the nutrients from water○ Plant growth is limited to the upper 100m of water

Plankton- free floating microscopic marine plants & animals ○ 2 main types of plankton

Phytoplankton- plants & other photosynthetic organismsZooplankton- non-photosynthetic animals

Nekton- eat plankton, forms of ocean life that swim Benthos- organisms that live on the ocean floor

Life in the Ocean Ocean Environments

2 general environments ○ Benthic- bottom

Divided into 5 zones ○ Pelagic- water

Divided into 2 zones ○ **The amount of sunlight, temperature, &

water pressure determine the distribution of marine life within these zones

Life in the Ocean Ocean Environments

Benthic Environments○ Intertidal zone- lies between low tide and high

tide lines Crabs, clams, mussels, sea anemones, & seaweed

live here○ Sublittoral zone- shallow & completely

submerged; located on the continental shelf; contains the largest number of benthosSea stars, brittle stars, & sea lilies

Life in the Ocean Ocean Environments

Benthic Environments○ Bathyal zone- starts at the continental slope &

ends at a depth of 4000mOctopuses, sea stars, & brachiopods Very little plant life

○ Abyssal zone- 4000m to 6000m of depthSponges, worms, & sea cucumbers No light at all

○ Hadal zone- inside ocean trenches; deeper than 6000m Virtually unexplored; life is sparse

Life in the Ocean Ocean Environments

Pelagic Zones○ Neritic zone- above continental shelves

Abundant sunlight, moderate temperatures, low pressure

Ideal for marine life Much of the seafood & fish that we eat lives here

○ Oceanic zone- extends into the deep ocean & open ocean waters beyond the continental shelfDivided into 4 zones based on depth

- Epipelagic ,Mesoplagic, bathypelgaic, abyssopelagic Marine life decreases with increasing depth

Ocean Resources Fresh Water from the Ocean

2 ways in which the need for fresh water can be met:○ Fresh water now available can be conserved

to avoid waste○ Amount of available fresh water can be

increased Can be done by finding a way to convert ocean water

to fresh water for a reasonable cost

Ocean Resources Fresh Water from the Oceans

Desalination- the removal of fresh water from salt water ○ Distillation- heating ocean water to remove the salt

Problem: evaporating liquid water requires a large amount of expensive heat energy

○ FreezingThe first ice crystals that form are free of saltChunks of ice can be melted & used as fresh water

○ Use of membranes (reverse osmosis) Allow water under high pressure to pass through while

blocking the dissolved salts

Ocean Resources Minerals from the Ocean

Nodules ○ Valuable source of manganese which is used making some types of

steel ○ Also contain iron, copper, nickel, & cobalt ○ Problem: expensive & difficult to retrieve

Minerals ○ Salt○ Magnesium○ Bromine

Petroleum is the most valuable mineral found beneath the ocean floor ○ Most comes from the continental shelves○ Productive offshore wells are located in the Gulf of Mexico, the North

Sea, the Persian Gulf, & off the coasts of California, Alaska, & Australia

Ocean Resources Food from the Ocean

Protein rich fish is an important part of the human diet

Aquaculture- farming of the ocean ○ Developing & raising species of marine

animals & plants that yield large amounts of food

○ Successful in growing catfish, salmon, oysters, & shrimp

Ocean Resources Ocean-Water Pollution

Oceans have been historically used as dumping grounds○ Garbage, sewage, nuclear wastes

Productive coastal waters are in the most danger