MY PRESENTATION

Aldave Mary Grace

HYDROSPHERE

HYDROSPHERE

The movement of water around, over, and through the

Earth is called the water cycle, a key process of the

hydrosphere.

A hydrosphere (from Greek ὕδωρ - hydor, "water" and

σφαῖρα - sphaira, "sphere") in physical geography

describes the combined mass of water found on,

under, and over the surface of a planet.

The total mass of the Earth's hydrosphere is about 1.4

× 1018 tonnes, which is about 0.023% of the Earth's

total mass. About 20 × 1012 tonnes of this is in the

Earth's atmosphere (the volume of one tonne of water

is approximately 1 cubic metre). Approximately 75% of

the Earth's surface, an area of some 361 million square

kilometres (139.5 million square miles), is covered by

ocean. The average salinity of the Earth's oceans is

about 35 grams of salt per kilogram of sea water

(35 ‰).[1]

The hydrosphere is often called the "water sphere" as it includes all the earth's water found in the oceans, glaciers, streams, lakes, the soil, groundwater, and in the air. The hydrosphere interacts with, and is influenced by, all the other earth spheres. The water of the hydrosphere is distributed among several different stores found in the other spheres. Water is held in oceans, lakes and streams at the surface of the earth. Water is found in vapor, liquid and solid states in the atmosphere. The biosphere serves as an interface between the spheres enabling water to move between the hydrosphere, lithosphere and atmosphere as is accomplished by plant transpiration. The hydrologic cycle traces the movement of water and energy between these various stores and spheres.

INTRODUCTION OF

HYDROSPHERE

A. PHYSICAL PROPERTIES OF WATER

We live on a planet that is dominated by water. More than 70% of the Earth's surface is covered with this simple molecule. Scientists estimate that the hydrosphere contains about 1.36 billion cubic kilometers of this substance mostly in the form of a liquid (water) that occupies topographic depressions on the Earth. The second most common form of the water molecule on our planet is ice. If all our planet's ice melted, sea-level would rise by about 70 meters.

Water is also essential for life. Water is the major constituent of almost all life forms. Most animals and plants contain more than 60% water by volume. Without water life would probably never have developed on our planet.

Water has a very simple atomic structure. This structure consists of two hydrogen atoms bonded to one oxygen atom (). The nature of the atomic structure of water causes its molecules to have unique electrochemical properties. The hydrogen side of the water molecule has a slight positive charge On the other side of the molecule a negative charge exists. This molecular polarity causes water to be a powerful solvent and is responsible for its strong surface tension (for more information on these two properties see the discussion below).

: The atomic structure of a water (or dihydrogen

monoxide) molecule consists of two hydrogen (H) atoms

joined to one oxygen (O) atom. The unique way in which

the hydrogen atoms are attached to the oxygen atom

causes one side of the molecule to have a negative

charge and the area in the opposite direction to have a

positive charge. The resulting polarity of charge causes

molecules of water to be attracted to each other forming

strong molecular bonds.

When the water molecule makes a physical

phase change its molecules arrange

themselves in distinctly different patterns .

The molecular arrangement taken by ice

(the solid form of the water molecule) leads

to an increase in volume and a decrease in

density. Expansion of the water molecule at

freezing allows ice to float on top of liquid

water.

Figure 8a-2: The three diagrams above illustrate the distinct arrangement patterns of water molecules as they change their physical state from ice to water to gas. Frozen water molecules arrange themselves in a particular highly organized rigid geometric pattern that causes the mass of water to expand and to decrease in density. The diagram above shows a slice through a mass of ice that is one molecule wide. In the liquid phase, water molecules arrange themselves into small groups of joined particles. The fact that these arrangements are small allows liquid water to move and flow. Water molecules in the form of a gas are highly charged with energy. This high energy state causes the molecules to be always moving reducing the likelihood of bonds between individual molecules from forming.

The following illustration shows how water molecules

are attracted to each other to create high surface

tension. This property can cause water to exist as

an extensive thin film over solid surfaces. In the

example above, the film is two layers of water

molecules thick.

(B). THE HYDROLOGIC CYCLE

The hydrologic cycle is a conceptual

model that describes the storage and

movement of water between the biosphere,

atmosphere, lithosphere, and the

hydrosphere .Water on this planet can be

stored in any one of the following reservoirs:

atmosphere, oceans, lakes, rivers, soils,

glaciers, snowfields, and groundwater.

Water moves from one reservoir to another by way of processes like evaporation, condensation, precipitation, deposition, runoff, infiltration, sublimation, transpiration, melting, and groundwater flow. The oceans supply most of the evaporated water found in the atmosphere. Of this evaporated water, only 91% of it is returned to the ocean basins by way of precipitation. The remaining 9% is transported to areas over landmasses where climatological factors induce the formation of precipitation. The resulting imbalance between rates of evaporation and precipitation over land and ocean is corrected by runoff and groundwater flow to the oceans.

The planetary water supply is dominated by the oceans .Approximately 97% of all the water on the Earth is in the oceans. The other 3% is held as freshwater in glaciers and icecaps, groundwater, lakes, soil, the atmosphere, and within life.

Water is continually cycled between its various reservoirs. This cycling occurs through the processes of evaporation, condensation, precipitation, deposition, runoff, infiltration, sublimation, transpiration, melting, and groundwater flow, describes the ty[ical residence times of water in the major reservoirs. On average water is renewed in rivers once every 16 days. Water in the atmosphere is completely replaced once every 8 days. Slower rates of replacement occur in large lakes, glaciers, ocean bodies and groundwater. Replacement in these reservoirs can take from hundreds to thousands of years. Some of these resources (especially groundwater) are being used by humans at rates that far exceed their renewal times. This type of resource use is making this type of water effectively nonrenewable.

(C). ATMOSPHERIC HUMIDITY

The term humidity describes the fact that the atmosphere can contain water vapor. The amount of humidity found in air varies because of a number of factors. Two important factors are evaporationand condensation. At the water/atmosphere interface over our planet's oceans large amounts of liquid water are evaporated into atmospheric water vapor. This process is mainly caused by absorption of solar radiation and the subsequent generation of heat at the ocean's surface. In our atmosphere, water vapor is converted back into liquid form when air masses lose heat energy and cool. This process is responsible for the development of most clouds and also produces the rain that falls to the Earth's surface.

The most commonly used measure of humidity is

relative humidity. Relative humidity can be simply

defined as the amount of water in the air relative to

the saturation amount the air can hold at a given

temperature multiplied by 100. Air with a relative

humidity of 50% contains a half of the water vapor it

could hold at a particular temperature.,illustrates

the concept of relative humidity.

The following illustration describes how relative humidity changes in a parcel of air with an increase in air temperature. At 10° Celsius, a parcel of dry air weighing one kilogram can hold a maximum of 7.76 grams of water vapor .In this state, the parcel of air would be at saturation and its relative humidity would be 100%. Increasing the temperature of this parcel, without adding or removing any water, would increase its ability to hold water vapor. According to, a 10 degree Celsius rise in temperature would increase the saturation mixing ratio of this parcel of air to 14.85 grams. Since no water has been added or removed, the actual amount of water in the parcel would remain 7.76 grams. This quantity is known as the mixing ratio. Dividing the mixing ratio by the saturation mixing ratio and then multiplying this number by 100 determines the relative humidity of the parcel of air (7.76/14.85 x 100 = 52%). At a temperature of 20°Celsius, relative humidity would be 52%. Raising the temperature of the parcel of air by another 10° Celsius would again lower its relative humidity. In this state, the actual mixing ratio would still be 7.76 grams, while the saturation mixing ratio would increase to 27.69 grams. Relative humidity would drop to 28% at a temperature of 30° Celsius (7.76/27.69 x 100 = 28%).

(D). CONDENSATION, FREEZING, AND DEPOSITION

We have learned that water is available on the

Earth in the following three forms: vapor; liquid; and

solid. The process of water moving from one of

these forms to another is called a phase or state

change. In the atmosphere, three processes act to

create water droplets or ice crystals. These three

processes are:

Condensation - water moving from a vapor to a

liquid state.

Freezing - water moving from a liquid to a solid

state.

Deposition - water moving from a vapor to a solid

state

(E). CLOUD FORMATION PROCESSES

Condensation or deposition of water

above the Earth's surface creates clouds. In

general, clouds develop in any air mass that

becomes saturated (relative humidity

becomes 100%). Saturation can occur by

way of atmospheric mechanisms that cause

the temperature of an air mass to be cooled

to its dew point or frost point. The

following mechanisms or processes can

achieve this outcome causing clouds to

develop:

). Orographic uplift occurs when air

is forced to rise because of the

physical presence of elevated land. As

the parcel rises it cools as a result of

adiabatic expansion at a rate of

approximately 10° Celsius per 1000

meters until saturation. The

development of clouds and resulting

heavy quantities of precipitation along

the west coast of Canada are mainly

due to this process.

(2). Convectional lifting is associated with surface

heating of the air at the ground surface. If enough

heating occurs, the mass of air becomes warmer

and lighter than the air in the surrounding

environment, and just like a hot air balloon it begins

to rise, expand, and cool. When sufficient cooling

has taken place saturation occurs forming clouds.

This process is active in the interior of continents

and near the equator forming cumulus clouds and

or cumulonimbus clouds (thunderstorms). The

rain that is associated with the development of

thunderstorm clouds is delivered in large amounts

over short periods of time in extremely localized

areas.

(3). Convergence or frontal lifting takes place

when two masses of air come together. In most

cases, the two air masses have different

temperature and moisture characteristics. Oneof

the air masses is usually warm and moist, while the

other is cold and dry. The leading edge of the latter

air mass acts as an inclined wall or front causing

the moist warm air to be lifted. Of course the lifting

causes the warm moist air mass to cool due to

expansion resulting in saturation. This cloud

formation mechanism is common at the mid-

latitudes where cyclones form along the polar

front and near the equator where the trade winds

meet at the intertropical convergence zone.

(4). Radiative cooling occurs when

the Sun is no longer supplying the

ground and overlying air with energy

derived from solar insolation (e.g.,

night). Instead, the surface of the

Earth now begins to lose energy in the

form of longwave radiation which

causes the ground and air above it to

cool. The clouds that result from this

type of cooling take the form of surface

fog.

WATER POLLUTION

INTRODUCTION

Comprising over 70% of the Earth�s surface, water is undoubtedly the most precious natural resource that exists on our planet. Without the seemingly invaluable compound comprised of hydrogen and oxygen, life on Earth would be non-existent: it is essential for everything on our planet to grow and prosper. Although we as humans recognize this fact, we disregard it by polluting our rivers, lakes, and oceans. Subsequently, we are slowly but surely harming our planet to the point where organisms are dying at a very alarming rate. In addition to innocent organisms dying off, our drinking water has become greatly affected as is our ability to use water for recreational purposes. In order to combat water pollution, we must understand the problems and become part of the solution.

POINT AND NONPOINT SOURCES According to the American

College Dictionary, pollution is defined as: �to make foul or

unclean; dirty.� Water pollution occurs when a body of water is

adversely affected due to the addition of large amounts of materials

to the water. When it is unfit for its intended use, water is considered

polluted. Two types of water pollutants exist; point source and

nonpoint source. Point sources of pollution occur when harmful

substances are emitted directly into a body of water. The Exxon

Valdez oil spill best illustrates a point source water pollution. A

nonpoint source delivers pollutants indirectly through environmental

changes. An example of this type of water pollution is when fertilizer

from a field is carried into a stream by rain, in the form of run-off

which in turn effects aquatic life. The technology exists for point

sources of pollution to be monitored and regulated, although political

factors may complicate matters. Nonpoint sources are much more

difficult to control. Pollution arising from nonpoint

sources accounts for a majority of the contaminants in streams and

lakes.

CAUSES OF POLLUTION Many causes of pollution including sewage and fertilizers contain

nutrients such as nitrates and phosphates. In excess levels, nutrients over stimulate the growth of aquatic plants and algae. Excessive growth of these types of organisms consequently clogs our waterways, use up dissolved oxygen as they decompose, and block light to deeper waters. This, in turn, proves very harmful to aquatic organisms as it affects the respiration ability or fish and other invertebrates that reside in water.

Pollution is also caused when silt and other suspended solids, such as soil, washoff plowed fields, construction and logging sites, urban areas, and eroded river banks when it rains. Under natural conditions, lakes, rivers, and other water bodies undergo Eutrophication, an aging process that slowly fills in the water body with sediment and organic matter. When these sediments enter various bodies of water, fish respirationbecomes impaired, plant productivity and water depth become reduced, and aquatic organisms and their environments become suffocated. Pollution in the form of organic material enters waterways in many different forms as sewage, as leaves and grass clippings, or as runoff from livestock feedlots and pastures. When natural bacteria and protozoan in the water break down this organic material, they begin to use up the oxygen dissolved in the water. Many types of fish and bottom-dwelling animals cannot survive when levels of dissolved oxygen drop below two to five parts per million. When this occurs, it kills aquatic organisms in large numbers which leads to disruptions in the food chain.

Polluted River in the United

Kingdom The pollution of rivers and

streams with chemical contaminants

has become one of the most crutial

environmental problems within the

20th century. Waterborne chemical

pollution entering rivers and streams

cause tramendous amounts of

destruction.

Pathogens are another type of pollution that

prove very harmful. They can cause many

illnesses that range from typhoid and

dysentery to minor respiratory and skin

diseases. Pathogens include such

organisms as bacteria, viruses, and

protozoan. These pollutants enter

waterways through untreated sewage,

storm drains, septic tanks, runoff from

farms, and particularly boats that dump

sewage. Though microscopic, these

pollutants have a tremendous effect

evidenced by their ability to cause sickness.

CLASSIFYING WATER

POLLUTION

The major sources of water pollution can be classified as municipal, industrial, and agricultural. Municipal water pollution consists of waste water from homes and commercial establishments. For many years, the main goal of treating municipal wastewater was simply to reduce its content of suspended solids, oxygen-demanding materials, dissolved inorganic compounds, and harmful bacteria. In recent years, however, more stress has been placed on improving means of disposal of the solid residues from the municipal treatment processes. The basic methods of treating municipal wastewater fall into three stages: primary treatment, including grit removal, screening, grinding, and sedimentation; secondary treatment, which entails oxidation of dissolved organic matter by means of using biologically active sludge, which is then filtered off; and tertiary treatment, in which advanced biological methods of nitrogen removal and chemical and physical methods such as granular filtration and activated carbon absorption are employed. The handling and disposal of solid residues can account for 25 to 50 percent of the capital and operational costs of a treatment plant. The characteristics of industrial waste waters can differ considerably both within and among industries. The impact of industrial discharges depends not only on their collective characteristics, such as biochemical oxygen demand and the amount of suspended solids, but also on their content of specific inorganic and organic substances. Three options are available in controlling industrial wastewater. Control can take place at the point of generation in the plant; wastewater can be pretreated for discharge to municipal treatment sources; or wastewater can be treated completely at the plant and either reused or discharged directly into receiving waters.

Wastewater Treatment Raw sewage includes waste

from sinks, toilets, and industrial processes. Treatment

of the sewage is required before it can be safely buried,

used, or released back into local water systems. In a

treatment plant, the waste is passed through a series of

screens, chambers, and chemical processes to reduce

its bulk and toxicity. The three general phases of

treatment are primary, secondary, and tertiary. During

primary treatment, a large percentage of the suspended

solids and inorganic material is removed from the

sewage. The focus of secondary treatment is reducing

organic material by accelerating natural biological

processes. Tertiary treatment is necessary when the

water will be reused; 99 percent of solids are removed

and various chemical processes are used to ensure the

water is as free from impurity as possible.