BASIC COMPONENTS OF

THE ENVIRONMENT

The Atmosphere• The earth is surrounded by all kind of gases - Atmosphere. • Gives us air, water, heat, and protects us against harmful rays

of the sun and against meteorites. • A colorless, odorless, tasteless 'sea' of gases, water and fine

dust.• Made up of different layers with different qualities.• Consists of 78% nitrogen, 21% oxygen, 0.93 percent argon,

0.03 percent carbon dioxide and 0.04 percent of other gases.

• Troposphere– The layer where the weather happens.– Above this layer is the Stratosphere– In between them is the Ozone layer, that absorbs the

sun's harmful ultraviolet rays.– Above the Stratosphere is the Mesosphere,– the Thermosphere including the Ionosphere –– and the Exosphere. – The atmosphere measures about 500 miles (700km).

What does the Atmosphere consist of ?

• The atmosphere has at the upper side no clear boundary, because higher in the atmosphere, the layer becomes thinner and thinner.

• It constantly loses molecules of lighter gases such as helium and hydrogen. The further we get from the earth, the atmosphere is divided in thin layers, based on changes in the temperatureThe Troposphere

• The Troposphere is the lowest layer of the atmosphere and measures about 7 miles(12 km).

• Contains over 75 percent of all the atmosphere's gases and vast quantities of water and dust.

• As the sun heats the ground, it keeps this thick mixture churning. The weather is caused by these churnings of the mass.

• The troposphere is normally warmest at ground level and cools higher up where it reaches its upper boundary (the tropopause).

• The tropopause varies in height. At the equator it is at 11.2 miles(8 km)

• Stratosphere Extends from the tropopause up to its boundary (the Stratopause)31 miles(50 km) above the Earth's surface.19 percent of the atmosphere's gases and it contains little water vapour. Calmer layer; Movements of the gases are slow.A band of ozone gas, that absorbs harmful ultraviolet rays of the sun.Higher you get in the atmosphere, the warmer the air gets: Temperature rises from -76 ºF(-60 ºC) at the bottom to a maximum of about 5 ºF(10 ºC) at the stratopause.

• Mesosphere:Extends to its upper boundary (the Mesopause)At 50 miles(80 km) above the ground.Gases in the mesosphere are too thin to absorb much of the sun's heat. Temperatures in the mesosphere drop to -184 ºF(-120 ºC) at the mesopause.       

• Thermosphere:

Layer above the mesopause.Gases of the thermosphere absorb ultraviolet light from the sun. Because of this, the temperatures rise to 3,600 ºF (2,000 ºC) at the top. At a height of 430 miles (700 km) of the earth's surface.

• Ionosphere:

In the thermosphere, a separate layerA part of the thermosphere. Made of electrically charged gas particles (ionised). The particles get this electric charge by ultraviolet rays of the sun. Bounces radio signals, transmitted from the earth.

• Exosphere:

The outermost layer of the atmosphereExtends from 430 miles(700 km) to 500 miles(800 km) above the ground.

What influence does the Atmosphere have?

• The atmosphere is of vital importance for life on earth. Without atmosphere life would be impossible.

• It gives us air to breathe and protects us from meteorites and ultraviolet rays from the sun.

• The atmosphere absorbs so much heat that temperatures on earth are such that life is possible.

• The weather, that exists by constant circulation of water to water vapor, to rain to water.

• This cycle causes, together with the differences in temperature and circulation of air (wind), erosion of the earth's surface. By erosion the outside of the earth changes through the years.

Lithosphere

• The outer solid part of the earth, including the crust and uppermost mantle.• About 100 km thick.• Thickness is age dependent (older lithosphere is thicker).• Lithosphere below the crust is brittle enough at some locations to produce

earthquakes by Faulting.• Broken into Tectonic Plates.• Asthenosphere: Just under the lithosphere; the weaker, hotter, and deeper part of

the upper mantle. • The boundary between the lithosphere and the underlying asthenosphere

– A difference in response to stress– Lithosphere remains rigid for long periods of geologic time and deforms elastically and

through brittle failure,– Asthenosphere deforms viscously and accommodates strain through plastic

deformation.

• 2 types of lithosphere:– Oceanic lithosphere, associated with Oceanic crust; Exists in the ocean

basins• About 50-100 km thick

– Continental lithosphere, associated with Continental crust• About 40 km to 200 km • Upper ~30 to ~50 km of typical continental lithosphere is Crust.

The Tectonic Plates of the Earth

A cut-away of the Earth

• Igneous rocks form from the cooling and crystallization of magma as it migrates closer to the Earth's surface.

• Extrusive igneous rocks• Intrusive igneous rocks

– Brought to the surface of the Earth by denudation and by a variety of tectonic processes.

• All rock types can be physically and chemically decomposed by a variety of surface processes collectively known as Weathering– Debris created by weathering, transported through the landscape by

erosional processes via streams, glaciers, wind, and gravity. – Debris is deposited as a permanent sediment– Compression, and chemical alteration over long periods of time:

Sedimentary rocks.

• Tectonic folding and Faulting exerts heat and pressure on both igneous and sedimentary rocks – Causes them to be altered physically or

chemically: Metamorphic rocks

Hydrosphere• The combined mass of water found on, under, and over the

surface of a planet.• >75% of the earth is covered with water bodies.• Oceans are rich source of Food, Minerals, Energy.• Only 1% of water available on Earth is fresh water, directly

useful for all human activity.• Precipitation, run-off, percolation, storage, evaporation,

transpiration, humidity and condensation form a water cycle in solid, liquid and vapour stages.

• Water bodies may be classified as– Rivers (Lotic system) – Lakes (Lentic system)

• River water transports and disperses all materials due to continuous flow and mixing. More oxygen is available in the top layers of water.

• Shallow waters (littoral zone) and open waters (limnetic zone) will have rooted plants or floating autotrophs (planktons), as plenty of sunshine is available.

• In the bottom layers, more nutrients (decaying organic matter) may be available, but without sunshine.

• Difference in temperature between upper layers Epilimnion and Hypolimnion may cause little vertical mixing even in stagnant lakes.

• Epilimnion, top-most layer in a thermally stratified lake– Warmer– Has a higher pH and dissolved oxygen concentration.– Being exposed at the surface, becomes turbulently mixed as a result

of surface wind-mixing. – Free to exchange dissolved gases (ie O2 and CO2) with the atmosphere.

– Receives the most light, so, contains the most phytoplankton.– Grow and reproduce; Absorb nutrients from the water– Die and sink into the Hypolimnion.

• Hypolimnion, the deeper layers

• Aquatic life depends upon the following factors:

– Depth of water and intensity of light penetration.– Dissolved oxygen and mineral salts– Temperature and solubility– Inorganic organic chemicals– Bottom deposits and water movement.

• Human activities causing pollution of water bodies

– Eutrophication of lakes– Silting of reservoirs– Submergence of lands– Depletion of water sources– Degradation of water quality.

Estuary• Estuaries are complex zones of river water mixing with sea. • A semi-enclosed coastal body of water with one or more rivers or streams flowing into it, and with a free

connection to the open sea• Estuaries are thus subject to both marine influences, such as tides, waves, and the influx of saline water;

and riverine influences, such as flows of fresh water and sediment.• Contain many biological niches within a small area; so associated with high biological diversity• Typically the tidal mouths of rivers • Characterized by sedimentation or silt carried in from terrestrial runoff and, frequently, from offshore. • Made up of brackish water• Bay, sound, fjord, firth, strait, etc

Mangrove

• Mangrove swamp or mangal. • Most specialised residents of mangrove forests are

– Mudskippers, fish that forage for food on land, and – Archer fish, fish that "spit" at insects and other small animals living in the

trees, knocking them into the water where they can be eaten. – Many fish, such as snappers, halfbeaks, and tarpon– Saltwater crocodile, American crocodile, Proboscis monkey, Crab-eating Frog– Very important buffer zones between land and sea– A natural defense against hurricane and tsunami damage in particular– The 2 famous and largest mangroves in India are along the Bay of Bengal.

• Sundarbans• Pichavaram

• Brackish seas– Baltic Sea (World’s largest pool of brackish water)– Black Sea– Caspian Sea (World’s largest lake)

• Brackish water lakes– Lake Charles in U.S.– Chilka Lake, Orissa, India

• Lochs• Coastal lagoons, marshes, and deltaS

– Kaliveli Lake, near Pondichery– Kerala Backwaters– Pulicat Lake, north of Chennai– Rann of Kutch

Do you know, what is meant by….

• Cryosphere…???

• Pedosphere…??????

Biogeochemical Cycles

• Biogeochemical cycle or Nutrient cycle• A pathway by which a chemical element or molecule moves through both

biotic (biosphere) and abiotic (lithosphere, atmosphere, and hydrosphere) compartments of Earth.

• In effect, the element is recycled, • All the nutrients — C, H, O, N, S, P — used in ecosystems by living

organisms operate on a closed system; therefore, these chemicals are recycled.

• The nutrients are lost / replenished constantly such as in an open system.• The energy of an ecosystem occurs on an open system; the sun constantly

gives the planet energy in the form of light while it is eventually used and lost in the form of heat throughout the trophic levels of a food web.

• Reservoirs - the element is accumulated or held for a long period of time.

– Eg.: Coal deposits that are storing “C” for a long period of time.

• Exchange pools - Chemicals are held for only short periods of time

– Eg.:Plants and animals. – Utilize C to produce carbohydrates, fats, and proteins, which can then be used to build

their internal structures or to obtain energy. – Temporarily use C in their systems and then release it back into the air or surrounding

medium.

• Generally, reservoirs are abiotic factors whereas exchange pools are biotic factors.

• The amount of time that a chemical is held in one place is called its residence.

• The most well-known and important biogeochemical cycles, for example, include– Carbon cycle– Nitrogen cycle– Oxygen cycle– Phosphorus cycle– Sulfur cycle– Water cycle

• Many biogeochemical cycles that are currently being studied for the first time– Due to climate change and human impacts– The mercury cycle– The human-caused atrazine cycle.

CARBON CYCLE

• The biogeochemical cycle by which “C” is exchanged among the biosphere, lithosphere, hydrosphere, and atmosphere of the Earth.

• C cycle, usually thought of as 4 major reservoirs of C, interconnected by pathways of exchange. – The plants– The terrestrial biosphere: Fresh water systems and non-living organic

material, such as soil carbon.– The oceans: Dissolved inorganic C and living and non-living marine

biota,– The sediments including fossil fuels

CARBON CYCLE                                                                                                                                                                 

CARBON CYCLE                                                                                                                                                                 

• In the Atmosphere,• C exists in the atmosphere primarily as CO2.

• Approximately 0.04% on a molar basis, but increasing• Other gases containing C in atmosphere are methane and

chlorofluorocarbons.• Overall atmospheric concentration of these greenhouse gases

has been increasing• Trees convert CO2 into carbohydrates during photosynthesis,

releasing O2 in the process.

• Carbon is released into the atmosphere in several ways:– Through respiration performed by plants and animals - An exothermic

reaction; involves the breaking down of glucose into carbon dioxide and water.

– Through the decay of animal and plant matter – Fungi and bacteria break down the carbon compounds and convert C to carbon dioxide if oxygen is present, or methane if not.

– Through combustion of organic material which oxidizes the C it contains, producing carbon dioxide (and other things, like water vapor) – Burning fossil fuels

– At the surface of the oceans where the water becomes warmer, dissolved carbon dioxide is released back into the atmosphere.

– Volcanic eruptions and metamorphism release gases into the atmosphere. Volcanic gases are primarily water vapor, carbon dioxide and sulfur dioxide

• In the oceans….???

• Carbon footprint ?????• Global Carbon Project ?????

NITROGEN CYCLE• The biogeochemical cycle that describes the transformations of nitrogen

and nitrogen-containing compounds in nature.• A cycle which includes gaseous components.• The Processes of the nitrogen cycle:1. Nitrogen fixation

Conversion of N2

2. Assimilation3. Ammonification4. Nitrification5. Denitrification6. Anaerobic ammonium oxidation

• Nitrogen fixation – Conversion of N2

• Conversion of N2 from atmosphere into a form readily available to plants and hence to animals and humans

• 4 ways to convert N2 (atmospheric) into more chemically reactive forms:– Biological fixation: some symbiotic bacteria (associated with leguminous

plants) and some free-living bacteria are able to fix nitrogen as organic nitrogen. Mutualistic nitrogen fixing bacteria – Rhizobium in legume root nodules. These species are diazotrophs – Azotobacter

– Industrial N-fixation : Under great pressure, at 600 C, atmospheric N2 and H2 , combined to form NH3. In the Haber-Bosch process, N2 is converted together with H2 into NH3 which is used to make fertilizer and explosives.

– Combustion of fossil fuels : automobile engines and thermal power plants, which release various nitrogen oxides (NOx).

– Other processes : Additionally, the formation of NO from N2 and O2 due to photons and especially lightning, are important for atmospheric chemistry

• Assimilation– Plants absorb nitrate or ammonium ions from the soil– Nitrate is absorbed - First reduced to nitrite ions– Ammonium ions for incorporation into amino acids, nucleic acids, and chlorophyll.

• Ammonification / Mineralization– When a plant dies, an animal dies, or an animal expels waste, the initial form of nitrogen

is organic.– Bacteria or fungi convert organic nitrogen within the remains back into NH4, a process

called ammonification

• Nitrification– Conversion of ammonia to nitrates, performed primarily by soil-living bacteria and other

nitrifying bacteria.– Oxidation of NH3 is performed by bacteria (Nitrosomonas), which converts ammonia to

nitrites (NO2-)

• Denitrification– The reduction of nitrates back into the largely inert nitrogen gas (N2)

– Performed by bacterial species such as Pseudomonas and Clostridium in anaerobic conditions.

OXYGEN CYCLE

• The biogeochemical cycle that describes the movement of oxygen within and between its three main reservoirs: the atmosphere (air), the biosphere (living things), and the lithosphere (Earth's crust).

• The main driving factor of the oxygen cycle is photosynthesis

PHOSPHORUS CYCLE

• Describes the movement of phosphorus through the lithosphere, hydrosphere, and biosphere.

• Atmosphere does not play a significant role in the movements of phosphorus,

• Because phosphorus and phosphorus-based compounds are usually solids at the typical ranges of temperature and pressure found on Earth.

SULPHUR CYCLE

• One of the constituents of many proteins, vitamins and hormones

• The essential steps of the sulfur cycle are:– Mineralization of organic sulfur to the inorganic form, H2S

– Oxidation of sulfide and elemental S and related compounds to SO42–

– Reduction of sulfate to sulfide.– Microbial immobilization of the sulfur compounds and subsequent

incorporation into the organic form of sulfur.

• Assimilative sulfate reduction in which SO42– is reduced to

organic sulfhydryl (thiol) groups (R–SH) by plants, fungi and various prokaryotes.

• Desulfuration in which organic molecules containing sulfur can be desulfurated, producing H2S gas

• Oxidation of hydrogen sulfide produces elemental sulfur; Done by the photosynthetic green and purple sulfur bacteria

• Oxidation of elemental sulfur by sulfur oxidizers produces sulfate.

• Dissimilative sulfur reduction in which elemental sulfur can be reduced to hydrogen sulfide.

WATER CYCLE

• The Hydrologic cycle• Continuous movement of water on, above,

and below the surface of the Earth.• Changes states among liquid, vapor, and ice at

various places in the water cycle.

• The sun drives the water cycle.• Evapotranspiration: Water transpired from plants

and evaporated from the soil.• Precipitation: Rain, snow, hail, fog drip, graupel and

sleet• Snowmelt: Snowpacks can thaw and melt, and the

melted water flows over land as snowmelt.• Surface runoff: Flow on the ground; This includes

both surface runoff and channel runoff• Groundwater and Freshwater

• Infiltration: Much of the surface runoff soaks into the ground– Infiltration deep into the ground and replenishes aquifers -

store huge amounts of freshwater for long periods of time.

• Canopy interception: Precipitation, intercepted by plant foliage and eventually evaporates back to the atmosphere rather than falling to the ground.

• Subsurface Flow: Flow of water underground, in the vadose zone and aquifers– May return to the surface (eg. as a spring / pumping) or– Eventually seep into the oceans.

• Vadose zone / unsaturated zone– The portion of Earth between the land surface and the zone of

saturation

• Evaporation: Transformation of water from liquid to gas phases as it moves from the ground or bodies of water into the overlying atmosphere. – Solar radiation– Implicitly includes transpiration from plants, though

together they are specifically referred to as evapotranspiration

• Sublimation:– State change directly from solid water (snow or

ice) to water vapor• Advection:

– Movement of water — in solid, liquid, or vapor states — through the atmosphere.

• Condensation: – Transformation of water vapor to liquid water

droplets in the air, producing clouds and fog• Transpiration:

– Release of water vapor from plants into air.

Average reservoir residence times

Internal structure of the Earth

• Consists of several layers.• Three main layers

– Core– Mantle– Crust.

• The Crust• Covers the mantle• Earth's hard outer shell - surface on which we are

live• Much thinner• Oceanic crust

– 6-11 km thick– Consists of heavy rocks, like basalt.– Basalt has a dark, fine and gritty volcanic structure.– Formed out of liquid lava, which cools off quickly.

• Continental crust.– About 30 km thick.– Mainly made up of light material like granite.

The Mantle• Above the core• Begins about 10 km below the oceanic crust and

about 30 km below the continental crust.• Separates inner mantle and the outer mantle.• About 2,900 km thick• Nearly 80% of the Earth's total volume.

Inner Mantle:• Between 300 km and 2,890 km below the

earth’s surface.• Average temperature is 3000ºC• Rock is still solid because of the high

pressures. • Consists of sulphides and oxides of silicon and

magnesium.

Outer Mantle:• Thinner than the inner mantle.• Found between 10 km) and 300 km below the surface of the

earth. • Still , two different layers.

– Bottom layer is tough liquid rock• Silicates of iron and magnesium.• Temperature between 1400ºC) and 3000ºC

– Upper layer• Same material but is stiffer.

Influence of the Mantle• Earth, hotter inside – heat current flows from the core to

the crust - Convection current• Current cools as it comes close to surface of earth.• Rising of the current decreases and goes into horizontal

direction along the bottom of the crust. • When the current cools down more, the convection current

descends again and goes to the inner earth.• Temperature increases and the current rises again. This

goes on and on. • When the current comes at a weaker part of the crust, for

example at a volcano, magma comes above the earth's surface.

• Convection current along the bottom of the crust causes the moving of the tectonic plates - Plate tectonics

• Bumping of two tectonic plates causes an earthquake

The Core• Inner part of the earth is the core• About 2,900 km below the earth's surface• A dense ball of the elements iron and nickel.• Two layers, the inner core and the outer core.• Inner core - solid and 1,250 km thick.

– Pressures great - Temperatures there reach 6700ºF (3700ºC).

• Outer core is so hot that the metal is always molten, • Outer core - 2,200 km thick.

– Because the earth rotates, the outer core spins around the inner core and that causes the earth's magnetism.

• What does the core consist of?• Inner core:

It is 3,200 - 3,960 miles (5,150-6,370 km) below the earth's surface and mainly consists of iron, nickel and some lighter elements (probably sulphur, carbon, oxygen, silicon and potassium. The temperature in the inner core is about 9032 - 10832 ºF (5000-6000 ºC). Because of the high pressure, the core is solid. The average density of the core is about 15g/cm³.

• Outer core: The outer core is at 1,800 - 3,200 miles (2,890-5,150 km) below the earth's surface. The outer core is liquid and mainly consists of iron, some nickel and about 10% sulphur and oxygen. The temperature in the outer core is about 7200 - 9032 ºF (4000-5000ºC). The density of the outer core is between the 10g/cm³ and 12,3g/cm³. The outer core and inner core together cause the earth's magnetism.

• What Influence does the Core have? • Because the core is so hot, it radiates a natural heat to the

upper layers. Because of this a current of heat comes into being. Those are also known as the convection currents. The convection currents cause the movement of the tectonic plates. This movement is called plate tectonics. The outer core and the inner core together cause the earth's magnetism. Because the earth rotates, the outer core spins, the inner core doesn't spin because it's solid. This gives a kind of dynamo effect and causes the earth's magnetism. Magnetism has been used by sailors to find their way on earth for thousands and thousands of years. Magnetism also influences electro-particles outside the atmosphere of the earth, up to more than 37,000 miles (60,000 km) into space