Water is ?
▶ Water is an odourless, tasteless, colourless liquid at ambient temperature and formed by a combination of hydrogen and oxygen
(H2O). Water has always been an essential element of life on the earth, Plant, animals and human beings all require water for
their daily needs
▶ It is estimated that there are about 1.4 billion ㎦ of water on the Earth with 97 percent of sea water, 3 percent of fresh water.
For fresh water 68.7 percent of them exist as glaciers in the north and south poles or as polar ice caps in alpine regions; 30.1
percent of them as underground water; 0.9 percent of soil moisture and air humidity; 0.3 percent of surface water in rivers and
▶ Therefore the water which 6 billion people all over the world can use is only limited to the 0.3 percent of fresh water in rivers and
lakes. In other words, we are using precious and rare water that only takes 0.0075percent of all the water on the Earth.
| • Fresh water
|| • Sea Water|
o Icecaps and Glaciers : The frozen oceans the poles.
o Surface water : Lakes, Swamps, Rivers.
o Other water : Rain, Snow, etc
※ Recycle Water : Sewage, wastewater reusing
o Surface sea water
o Deep sea water
▶ Fresh water has a low density of salinity; it contains less than 1,000mg of salts in 1ℓ of water.
▶ Classified by density of salinity(based on TDS)
• Sea Water : about 10,000~50,000 mg/ℓ
• Brackish Water : about 1,000~10,000 mg/ℓ
• Fresh Water : less than 1,000 mg/ℓ
▶ Current world status of water
- 6 billion populations all over the world are using 54 percent of all the water resources
- 1/3 of world population is suffering from severe water insufficiency
• Year 2025
- Demand for water is expected to increase 40 percent more than that of 1995 worldwide.
- 2/3 of all the countries on the Earth will lack of water within 25 years.
• reasons of water supply insufficiency
- Radical increase in demand of water with population growth
- contaminated water resource by pollusion
- Environmental changes such as El Nino and La Nina
※ Recycle Water
• Reclaimed water refers to recycled wastewater treated to improve its quality to be used again for everyday use or for
• It is expected to be used for washing, sprinkling, irrigating in industries
▶Sea water is water from a sea or ocean. On average, seawater in the world's oceans has a salinity of about 3.5%, or 35 parts
per thousand (also expressed 35‰ or 35 ppt). This means that every 1 kg of seawater has approximately 35 grams of dissolved
salts (mostly, but not entirely, the ions of sodium chloride: Na+, Cl-).
▶The average density of sea water at the surface of the ocean is 1.025 g/ml; sea water is denser than fresh water (which reaches
a maximum density of 1.000 g/ml at a temperature of 4°C) because of the added weight of the salts and electrostriction.
The freezing point of sea water decreases with increasing salinity and is about -2°C (28.4°F) at 35 parts per thousand.
• The characteristics of sea water
- pH : about 8.1
- Density : 1.02~1.04 g/cm²
- Sea water TDS : 35,000 mg/ℓ ~ 45,000mg/ℓ
- High specific heat, heat capacity, surface tension
- High boiling and melting points
- Dissolves substances well
• Major elements of Seawater
- Pure water (96.5%)
- Minerals (3.5%) : Chloride and Sodium ion (85%), the rest(15%)
※ law of the regular salinity ratio : concentration of salt elements varies by region but the composite ratio is constant.
♦ Salinnity of Seawater
• Salinity is the number of grams of inorganic salts dissolved in a kilogram of salt water (Expressed as part per thousand, g/kg,
permil; ‰). On average, seawater in the world's oceans has a salinity of ~3.5%.
This means that for every 1 liter (1000mL) of seawater there are 35 grams of salts dissolved in it
(Red Sea 40‰, Mediterranean Sea 38‰).
• Directly estimating the salinity is technically difficult, therefore measuring the amount of Chloride and putting the number in the
following formula is used instead.
Deep sea water
▶ Deep sea water exists under 200m of the sea where sunlight does not reach. Derelicts or germs do not exist in that part of the
sea water; it keeps stable low temperature all the year round. It is matured sea water which has rich boundaries of nutritious salts
that are essential for sea plants' growth.
▶ Deep sea water is characterized by low temperature, cleanliness, safety, rich nutritions, maturation that fully explain the
usefulness of this sea resource. With the help of its source of energy, sunlight, deep sea water is created among the circulating
system in nature and revolves repeatedly. Absolutely it is one of the tremendous pure resources.
||Korean East sea
||1.52 ~ 1.9
(14.5 ~ 23.1)
|8.1 ~ 9.8
(16.1 ~ 24.9)
|8.2 ~ 10.7|
(24.3 ~ 28.0)
|7.19 ~ 7.90
(8.16 ~ 8.20)
|7.8 ~ 7.9
(8.1 ~ 8.3)
|7.45 ~ 7.64|
(8.05 ~ 8.35)
||33.72 ~ 33.94
(32.5 ~ 33.0)
|34.3 ~ 34.4
(33.7 ~ 34.8)
|34.37 ~ 34.29|
(34.33 ~ 35.05)
||9.13 ~ 9.47
(7.79 ~ 8.9)
|4.1 ~ 4.8
(6.4 ~ 9.5)
|1.24 ~ 1.45 |
(6.87 ~ 7.28)
|depth of water