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1) Hydrosphere (hidrosfera): all the water, in all the three physic states (solid, liquid

and gaseous), present in the Earth’s surface.

The Earth is the only planet in the Solar System that has liquid water, thanks to

its distance from the Sun and to its atmosphere. We have water in all the three

states:

❚ Solid water (snow and ice) is found in the poles, glaciers and permafrost.

❚ Liquid water is in the oceans, seas, rivers, lakes and underground water.

❚ Gaseous water (water vapour) is in the atmosphere.

*

Do you remember why atmosphere helps to have liquid water on Earth?

2) Salinity (salinidad): the concentration

of salts (the mass of salts by unit of volume)

in water. Its unit is grams per litre (g/L).

3) Salt water (agua salada): water in

seas and oceans has an average salinity of 35

g/L or more. This concentration of salts

makes it not drinking water (=not suitable for

cosumption).

4) Fresh water (agua dulce): water in

rivers, lakes, underground waters. Its salinity

is less than 5 g/L. Drinking water should be

less than 1 g/L.

By Peter Summerlin

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*75 % of the Earth’s surface is covered with water, but very few is available

(=disponible) for living things. Why?

Total available water:

100 % ………………….2,5 %

0,4 % …………………. X

X= 0,01 % of the total water

of the planet is available for

living things.

This 0,01 % is not evenly

(uniformemente,

equitativamente) available around

the planet.

*

1) Water is a molecule (molécula =

combinación de átomos) composed by

two atoms of hydrogen and one atom of

oxygen (H2O).

2) Pure water is colourless, odourless and

tasteless (incolora, inodora e insípida). Water

is the only substance that is present in

nature in all three states (gaseous, liquid and

solid); liquid at room temperature (20 ºC).

Boiling point = 100 ºC. Melting point = 0 ºC.

*

Can you correctly place in the picture the following items?

Boiling point: 100 ºC Melting point: 0 ºC

3) The density of water in the solid state is lower

than in the liquid state (the contrary to all the other

substances). **Thanks to this property, ice floats

on liquid water and aquatic life can continue to

exist under the ice in frozen lagoons and rivers or

in the Arctic.

4) Water is the universal solvent (disolvente

universal), because it can dissolve (disolver) many

substances. ** Living things use water to transport

dissolved substances. Example: nutrients are

transported in blood (sangre) or sap (savia). **

Aquatic animals can breath underwater because

water is a good solvent of oxygen.

*Lower (más baja)

Higher (más alta)

Water has a high heat capacity (elevado

calor específico), it means that it heats up

or cools down very slowly (because the

energy needed to change its temperature

by 1 ºC is very high). This property makes

water a good temperature regulator

(buen regulador térmico). Regions in the

coasts have more moderate temperatures

than regions in the interior. ** Living

things use this property to regulate their

own temperature. Example: when our

body temperature rises we sweat

(sudamos). This sweat (sudor) on our skin

evaporates using body temperature, this

way we manage to cool down.

*

Water participates in a high number of

biochemical reactions (like our metabolism).

High capacity of adhesion (between water

molecules). In this property are based three

other properties: 1) Capilarity (capilaridad;

water can move against gravity inside thin

tubes) **water and mineral salts travel from

the roots to the leaves of the plants, 2)

Incompressibility (incompresibilidad)

**hydrostatic skeleton of some invertebrates

(jellyfish) and 3) superficial tension **some

insects can walk on water.

*

*

Hydrostatic skeleton: water can’t compress

Superficial tension

Jellyfish

*

*El ciclo del agua o ciclo hidrológico es el conjunto de procesos que permiten al agua cambiar de estado y circular

entre la atmósfera y la superficie terrestre describiendo un movimiento cíclico.

Las fuentes de energía que actúan como motor de este proceso cíclico son el Sol y la fuerza de la gravedad.

•El Sol hace posibles los cambios de estado al

suministrar calor al agua. Así se produce la

evaporación del agua de los mares, océanos y de las

aguas superficiales continentales, que pone en

marcha el ciclo del agua.

•La fuerza de la gravedad provoca las

precipitaciones, que devuelven el agua a la

superficie terrestre. Esta fuerza también es la

responsable del movimiento del agua desde los

continentes hasta los océanos.

*1) Consumptive use: (uso consuntivo) when the water

we use is not returned to the water cycle.

Some examples of consumptive use:

1st) Agricultural use: 79 % of the total consumptive

use. It includes agriculture (agricultura) and raising

livestock (cría de ganado).

2nd) Domestic use: (uso doméstico) around 12 % of the

total consumptive use. Personal hygiene, drinking,

cooking, domestic and urban cleaning.

3rd) Industrial use: In Spain, it represents 9 % of the

total consumptive use. Industry uses water as raw

material (materia prima), as a machine refrigerant or for

cleaning.

*

2) Non-consumptive use: (uso no consuntivo)

when the water we use is returned to the water cycle

without significant alterations (sin alteraciones

significativas o importantes).

Examples of non-consumptive uses:

1) Recreational activities (aquatic sports that do

not pollute the water, pools, water parks).

2) Transport (by ship)

3) Production of hydroelectric energy

*Some actions for a sustainable use (uso sostenible) of water:

In agriculture: change to drip irrigation (riego por goteo), increase irrigation

taxes (impuestos), reuse of wastewater (aguas residuales) for irrigation and water

(regar) plants in the evening to avoid evaporation.

At home: install devices to save tap water (instalar aparatos para ahorrar agua

del grifo), adjust the cost of water to its value, in gardening use plant species

adapted to the climate, fill completely the washing machine and the dishwasher

and use short cycles, close the tap while brushing your teeth or washing your

hands, take a shower instead of a bath, repair water leaks (fugas de agua), etc.

In industry: recycle the water used as refrigerant, reuse water in close circuits.

*Water pollution (contaminación del agua): is the alteration in

the composition of water that makes it inadequate for its intended

use (inadecuada para el uso al que se destina).

Pollution in oceans and seas: polluted rivers are the main

source (son la fuente principal) of pollutants and plastic debris

(desechos plásticos). Also oil slicks (mareas negras) due to oil

spills from petroleum maritime transport.

* Pollution of surface water; the main sources come from its

consumptive use:

1) Pollution from agriculture and livestock farming. Soil (el suelo) is

polluted by herbicides, pesticides and fertilisers used in agriculture and

by the large quantity of organic waste from livestock (ganado).

Afterwards, runoffs (aguas de escorrentía) or the infiltration make this

pollution reach surface waters and aquifers.

*2) Domestic pollution.

Wastewater is the water

polluted by domestic use. It

contains a lot of organic matter

(materia orgánica) and

detergents. When they reach

surface waters eutrophication

(eutrofización) happens. Some

organisms grow very quickly

with the excess of organic

matter and consume all the

oxygen available in water (some

algae and microorganisms). This

causes the death of many other

living things in the area.

*

3) Industrial pollution. Surface and groundwater can also be polluted

by industrial and mining discharges (por vertidos industriales o

mineros). Many toxic metals end up polluting water. Besides, the hot

water coming from the refrigeration of machines can be returned to

rivers killing many living things.

*Many people in developing countries (países en vías de desarrollo)

don’t have access to good quality water; they often drink water from the

same places where wastewater is discharged. This is the cause of

serious diseases, such as cholera (cólera) and typhoid fever (fiebre

tifoidea).

Other diseases are

indirectly caused by unsafe

water, such as malaria.

The larvae of the Anopheles

mosquito (the one that

transmits the disease) grow

in stagnant water (agua

estancada).

*

Polluted water also

causes diseases in

developed countries

(países desarrollados).

The accumulation of

heavy metals (metales

pesados) and other

pollutants in rivers,

aquifers, seas and

oceans can cause brain

damage (daños

cerebrales), damage to

other organs or even

death.

Fresh water in nature

Water treatment plant

(= planta potabilizadora) Wastewater treatment plant

(= planta depuradora)

Water for human

consumption

*In developed countries, drinking water does not come directly from the natural environment.

First, it is cleaned up and processed in water treatment plants. Then, after human use, it is also

treated before returning it to nature (to avoid eutrophication and pollution with detergents and other

chemical products) in wastewater treatment plants.

Agua en el medio natural

Agua para consumo humano

Estación de tratamiento

de agua potable

(= planta potabilizadora)

Estación depuradora

de aguas residuales

(= planta depuradora)

*

*(Ampliación)

In the following slides you should only study the definitions of drinking

water treatment and wastewater treatment.

Notice that the last step in the water treatment plants is disinfection

(desinfección), this is when chlorine is normally added (en ese momento es

cuando se añade el cloro)

If you are curious you can read how these water treatment plants work,

you can find these slides translated to make it easier for you.

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