water and its unique properties

Question 1

define hydrosphere

Answer 1

refers to all groundwater present on above or below earth’s surface (oceans ,seas , lakes ,river)

Question 2

facts about water

Answer 2

1) water exist on earth over a wide temperature range
2) it takes a lot of heat to evaporate liquid water (effective cooling medium )
3) a high surface tension and high wetting ability
4) dissolves a variety of compounds (carries dissolved nutrients and remove dissolved waste product )
5) liquid water expands rather than contracts on freezing - therefore ice water floats

Question 3

the hydrological cycle

Answer 3

refers to the circulation of water between atmosphere ,land and the oceans - driven by the sun

Question 4

summary of the hydrological cycle

Answer 4

1) water evaporates from lakes, rivers and oceans
2) transpiration - is the loss of water vapour from pores
(stomata) in the leaves of plants
3) when the temperatures fall - water vapour condeses forming clouds or fogs
4) condensation - the conversion of water vapour into droplets of liquid water ; this occurs because cool air holds less water than warm air .
5) precipitation - any form of water resulting from condensed atmospheric water vapour being returned to Earth’s surface under gravity
6) interception - precipitation that collects on leaves and stems of plants - will reach the ground

Question 5

residence time

Answer 5

average time that a water molecule spends in any part of the hydrological cycle

Question 6

Runoff

Answer 6

the visible flow of water in rivers , creeks and lakes at the water stored in the basin drains out

Question 7

infiltration

Answer 7

the process whereby water enters soil and porous rocks

Question 8

percolation

Answer 8

the downward movement of water through soil or porous rock

Question 9

groundwater

Answer 9

water that occurs below Earth’s surface where it fills up pores and cracks within rocks and sediments

Question 10

aquifer

Answer 10

a layer of rock or sediment saturated with groundwater

Question 11

water table

Answer 11

upper most surface of aquifer

Question 12

surface runoff

Answer 12

water from precipitation that flows on the surface - occurs because the amount of water falling is greater than the rate of infiltration of the ground-Surface runoff erodes and transports soil. It dissolves and transports nutrients as well as undesired substances within and between ecosystem

Question 13

what does the hydrological cycle help with ?

Answer 13

The hydrological cycle is a cycle ofnatural renewal and purification of earth’s water resources. Evaporation and precipitation act as a distillation process, removing impurities dissolved in water. Water flowing through streams and in aquifers is also filtered and purified by various processes, both chemical and biological

Question 14

causes of water scarcity

Answer 14

1) uneven distribution - Canada - abundant water whilst highly populated region lack water
2) the lack of economic means to create adequate water collection and storage infrastructure
3) available water - polluted
4) unsustainable use of aquifers

Question 15

surface water

Answer 15

Surface water-Precipitation that does not infiltrate the ground or return to the atmosphere by evaporation, but collects in ponds,lakes, streams and rivers. In other areas much surface water is lost since it ends up in the sea

Question 16

strategies for increasing freshwater availability

Answer 16

being dams across rivers to divert surface water

2) using ground water (pumped through bore holes and pumping stations )
3) desalination

Question 17

recharge area/zone

Answer 17

The area of land through which water passes into the aquifer. It is the areathat replenishes the aquifer

Question 18

the unsustainable water extraction ;

Answer 18

1) can cause lowering of water table - more difficult to extract water
2) contamination of water through salt -water intrusion
3) Subsidence(downward movement of the overlying rock) can occur since water extraction can result in compression of the aquifer material particularly if it is clay or s

Question 19

desalination

Answer 19

the removal of salt from sea water or from salty groundwater- distillation or from salty groundwater

Question 20

distillation

Answer 20

the heating of saltwater until the water evaporates. This leaves the salts behind. Water vapour is condensed forming pure water. used in united arab Emirates - very costly

Question 21

reverse osmosis

Answer 21

involves pumping seawater at high pressures through semi-permeable membranes that allow water molecules to pass through but do not allow the passage of dissolved salts.

Question 22

osmosis

Answer 22

Osmosis–the movement of water from a region of high-water concentration (low solute concentration) to a region of lower-water concentration (higher solute concentration) across a semi-permeable membrane.It is a passive process that occurs naturally and does not require an external energy source

Question 23

disadvantages of reverse osmosis

Answer 23

Reverse osmosis can result in the seawater in the vicinity becoming more saline. The membranes used for reverse osmosis are expensive and can easily be damaged by pollution such as floating oil patches

Question 24

efficient use of water resources

Answer 24

Water saving crop irrigation systems➢Treatment and reuse of wastewater➢Early detection and repair of leaks➢Realistic pricing of water➢More efficient appliances that use water

Question 25

name the two local aquifers

Answer 25

the mean sea level aquifer and the perched aquifer.

Question 26

the mean sea level aquifer

Answer 26

his is present in the pores of lower coralline limestone and globigerina limestone at sea level. Seawater also penetrates into these pores, but the less dense freshwater ‘floats’on the denser saltwater. The mean sea level is lens shaped and is thickest in the central regions of the island- y loses some of its freshwater through discharge into the sea at the coastal zone.

Question 27

collected from;

Answer 27

underground gallaries - ta’Kandja

Question 28

overuse of this aquifer

Answer 28

y loses some of its freshwater through discharge into the sea at the coastal zone.

Question 29

The perched aquifer

Answer 29

formed above the clay - impermeable - water collects on top of it -y loses some of its freshwater through discharge into the sea at the coastal zone.

Question 30

spring water

Answer 30

The perched aquifer is the source of the few freshwater springs present on the island-ut many have been diverted to reservoirs built by farmers.Only the names remain (Ghajn Zejtuna, Ghajn Dwieli etc.).

Question 31

local rare freshwater species

Answer 31

the endemic Maltese freshwater crab

Question 32

Sea water is an excellent medium for supporting life:

Answer 32

1) contains dissolved oxygen and carbon dioxide
2) has a high specific capacity - stable environment
3) allows light penetration - photosynthesis

Question 33

the marine biome is made up of 2 main habitats:

Answer 33

the pelagic environment (water itself )
benthic environment (seabed )

Question 34

a biome

Answer 34

a biome is a major ecological habitat)

Question 35

marine zones can be distinguished ;

Answer 35

• The coastal zone is closest to land, extending from the coastline to the end of the continental shelf. This is the shallow seabed surrounding a continent
• The water tends to be sunlit, warm and rich in nutrients

Question 36

the open sea is divided into zones

Answer 36

the upper zone - photic zone - enough light penetration for photosynthesis - up to 200m deep- the light penetration depends on the water clarity and angle of incidence - poor in nutrients

• the bathyal zone -insufficient for photosynthesis- low amounts of dissolved oxygen -zooplankton and various species live here

the abyssal zone -1500m deep and more - completely dark and cold- rich in nutrients due to debris

Question 37

aquatic producers

Answer 37

algae and plants

Question 38

oceanic circulation

Answer 38

driven by temperature changes and density(warm water is less dense than cold ) and prevailing winds which are ultimately powered by the sun

Question 39

what do ocean currents transport?

Answer 39

warm water from equatorial region towards towards the poles whilst colder water flows from the poles to the tropics.

Question 40

what is oceanic circulation responsible for ?

Answer 40

transportation of heat , salt and nutrients, dissolved gases and living organism

Question 41

ocean temperature change with

Answer 41

depth and latitude

Question 42

the thermocline

Answer 42

Below the mixed surface waters, there is a thin layer of water where the temperature falls rapidly.

Question 43

density difference

Answer 43

prevents mixing between the surface waters and deep water - thermocline acts as a lid

Question 44

upwelling zones

Answer 44

deep water returns here - strong currents -water - up to surface again full of nutrients important for primary productivity

Question 45

tides

Answer 45

a periodic rise and fall of sea level caused by the gravitational pull exerted on earth by moon and sun

Question 46

moon’s gravity

Answer 46

ocean bulge out in the direction of moon and on the other side too - earth pilled towards the moon

Question 47

the sun’s gravity

Answer 47

whether the tides are strong or weak depends on the sun’s position and moon relative to earth

Question 48

when are the strongest spring tides

Answer 48

when earth , sun,and moon are in line with each other

Question 49

weakest spring tides

Answer 49

when moon and sun are perpendicular

Question 50

tidal range -

Answer 50

the different water levels on different days

Question 51

tidal range in Malta

Answer 51

small

Question 52

canada

Answer 52

exceeds 15 m

Question 53

in france

Answer 53

generate electricity - early stages of development

- suitable sites are limited , corrosion and expensive but might become a realistic operation in uk