environmental chemistry

INTRODUCTION
Environmental chemistry is the scientific study of the chemical and biochemical phenomena that occur in natural places. Important general concepts from chemistry include understanding chemical reactions and equations, solutions, units, sampling, and analytical techniques.
ENVIRONMENTAL SEGMENT
ATMOSPHERE: Atmosphere protects the earth from cosmic radiation and helps in sustaining life on earth through Green –house effect. It also maintains heat balance of the earth. The atmosphere consists of a mixture of gases like nitrogen, oxygen, argon, carbon dioxide etc.
HYDROSPHERE: The hydrosphere include all types of water resources like lakes, streams, rivers, seas, oceans, ground water and minerals lying deep below the earth’s crust.
LITHOSPHERE: This is the rigid part of the earth e.g. soil. The soil consist of water, complex inorganic mixtures of silicates, carbonates and organic matter like polysaccharides, nucleotides, organo-phosphorus, organo-sulphur compounds, sugar etc.
BIOSPHERE: This consists of all living organisms and their interactions with other segments of the environment. It is divided into biotic and abiotic.
ATMOSPHERIC STRUCTURE
 The atmosphere can be broadly divided into four regions namely Troposphere, Stratosphere, Mesosphere and Thermosphere.
RADIATION BALANCE OF THE EARTH
The earth absorbs radiation s mainly in the visible region and emits radiations in the infra-red region.5.3% of this radiation is absorbs by the soil, 1.9% is absorbs by the marine and land vegetation, 27.8% is utilized for heating and evaporation of water and the remaining is reflected back.


GREEN HOUSE EFFECT
The earth is heated by sunlight. Earth radiates some of this heat back into space. Some gases like CO2, CH4, CFC, O3, N2O4, N2O2 in the lower atmosphere allow solar radiation to come in but these gases strongly absorbs the infrared radiations which the earth sends back as heat. The effect of radiation of thermal energy back to the earth is known as Green House effect. This Green House effect keeps our planet warm and helps in sustaining life on earth.
Recently, the concentration of green house gases is increasing constantly due to industrialization, deforestation an increased burning of fossil fuels, etc. This increase enhanced green house effect, leading to the over warming of the earth. This extra warming is called the Global Warming.
CONSEQUENCES OF GREEN HOUSE EFFECT
The surface water would evaporate faster than normal, creating drought.
Due to the warming of surface layer, biological productivity will decrease.
World’s food production can be affected by Global warming or Green House effect. This is due to the alterations in the pattern of weather leading to crop damage.
FORMATION AND DEPLETION OF OZONE LAYER
Formation of ozone layer: ozone is formed by photochemical reaction in the stratosphere:
O2 + hv   -------   O- + O-
O2  + O  -----------     O3

IMPORTANCE OF OZONE LAYER: The ozone layer acts as a protective shield for the existence of life on earth. It absorbs most of the harmful ultra-violet radiations coming from the sun and thereby protects lives from several radiation damage. In the absence of ozone layer, these ultra-violet radiations would cause swelling of skins, skin cancer, skin aging, dizziness, etc.
Depletion of ozone layer: Ozone layer is destroyed by its reaction with nitric oxide, chlorine, hydroxyl radical present in the atmosphere.
O3 + NO ---------- NO2 + O2
O3 + Cl ----------- O2 + CLF2
O3 + OH- --------- O2 + HOO-
Each atom of Cl can react with 105 molecules of ozone converting ozone into oxygen. This leads to the gradual thinning of ozone layer and ozone hole formation occurs.
SUBSTITUTES FOR CHLOROFLUROCARBONS (CFC’S)
CFC’S are ozone depleting substance (ODS) so their production and consumption must be stopped immediately.
Hydrochloroflurocarbons (HCFCs) and hydroflurocarbons (HCFs) are considered as ozone friendly substitutes for CFCs in the air –conditioning and refrigeration on the basis of some toxicity tests and environmental impacts.
POLLUTION
Pollution is the introduction of substances (or energy) by man into the environment liable to cause:
Hazards to human health,
Harm to living resources and ecological systems,
Damage to structures or amenity
Interference with legitimate uses of the environment.
POLLUTANT: This is a term used to describe a material which is present in excess of the natural concentration as a result of human activity and produces a bad effect upon the environment.
SOURCE: This is a term used to describe the material or activity (the system) which releases the pollutant.
RECEPTOR: This is something that is affected by the pollutant.
SINK: This is the store where the pollutant is received and stored for a long time.
AIR POLLUTION
Air pollution may be defined as the presence of one or more pollutants in the atmosphere in such quantities which might be injurious to human, plant or animal life or property. Every individual breathes approximately 20,000 times a day, inhaling about 15-22kg of air daily so air pollution is most crucial from the public health point of view.
CAUSES OF AIR POLLUTION: 
Carbon monoxide (CO): This arises from activities such as volcanic activity, natural gas and marsh gas emissions, electrical discharges in the atmosphere during storm, industrial operations. Carbon monoxide reduces the oxygen carrying-capacity of blood, as it attacks hemoglobin and displaces O2.
Fuel modification, Development of substitute fuels, Modification of engine design and Treatment of exhaust gases are efforts that have been directed towards controlling carbon monoxide emission from transportation section.
Oxides of nitrogen (NOX): NO2 is formed by photolytic reactions in the atmosphere. Oxides of nitrogen may also be formed fixation of nitrogen from organic matter present in the soil or from the atmosphere.
Sulphur dioxide (SO2): A mixture of SO2 and SO3 is commonly represented as SOx. This arises from activities such as volcanic activity, combustion of any sulphur-bearing materials in coal-fired power stations and refineries, transportation, smelting of sulphide ores in metallurgical operations.
Hydrocarbons: There are mainly three sources which emit hydrocarbons in the atmosphere. They are solvent evaporation, automobile exhausts and burning of wood, coal, oil and refuse.
Particulates: volcanic eruptions, wind and dust storms, salt spray etc. are natural sources of particulate constituents of the atmosphere.
ACID RAIN
Due to the reaction of rain water with atmospheric CO2, carbonic acid is produced which is responsible for pH of 5.6 to 5.7 of rain. This small acidity is sufficient to dissolve minerals in the earth’s crust and make them available to plant and animal life. The oxides of sulphur and nitrogen are converted into H2SO4 and HNO3 droplets by a series of chemical and photochemical reactions. The contribution of these acids in acid rain are mostly in H2SO4 > HNO3 > HCL order, e.g.
SO2  +  H2O  -----  H2SO4
4NO2 + 2H2O + O2 ------ 4HNO3
HCL (g) + H2O ----- HCL (aq)
Acid rains are likely to occur in areas of thick population and areas having large number of industries.
HARMFUL EFFECTS OF ACID RAINS
Acidification of soils leading to reduced forest productivity.
Damage to fresh-water life.
Cause irritation to eyes and mucus membrane; etc.
PHOCHEMICAL SMOG
This occurs as a result of the formation of aerosols that reduce visibility, generation of brown  hazy fumes that irritates the lungs and eyes, and which cause extensive damage to vegetation and rubber goods.
BIOLOGICAL OXYGEN DEMAND (BOD)
Biological oxygen demand is defined as the quantity of dissolved oxygen required by aerobic bacteria for the oxidation of organic matter under aerobic conditions. BOD approximates the amount of oxidizable organic matter present in the solution. When BOD is high, the dissolve oxygen becomes low hence, the greater the BOD, the greater the pollution. 

Worm ecology

They have bristles known as setae which are both sensing devices that can identify any soil vibrations and digging aids.the setae stick to dirt and the worm then contracts its body to force itself through soil.
The worm also secretesa mucus that helps it slide through dirt more quickly and can burrow dozens of feet below the surface.

Worm ecology

Food chain include cat -birds-worms-decomposed leaves-rainfall.
It belongs to the soil food web.
Its natural enemy include man,ants,mites,centipedes,nematodes,snakes,birds,flatworm,etc.
At night,the worm will stretch its body out to pull food back into its burrow.it keeps its back end anchored in the burrow so it can disappear quickly if a predator show up.

Worm ecology

Habitat is soil.
Physical factors that control its distribution pattern are soil,vegetation,rainfall,salinity and ph.
Biotic factors that control its population pattern are competition for food and water, predators

basic concept of cell thoery

1. all living tthings are made up of cell
2  all cells come from per existing cells
3  all cells contain the hereditary information necessary for regulating cell functions and transmitting information to the nenx generation

biochemistry

the cell is the functional basic unit of life because all living things are bulid up of cells.it is the buliding blocks of life