ENVIRONMENTAL CHEMISTERY:

Introduction

Environmental chemistry is a major route through which we learn about the Earth’s natural processes as well as
humanity’s impacts on the planet. This is one of the reasons why environmental chemists are well-positioned to
help humanity solve some of our toughest challenges related to energy, health, food, and natural resources, many of
which are related to humanity’s impacts on the planet. Environmental chemists monitor what is in the air, water,
and soil to study how chemicals enter the environment, what affects they have, and how human activity affects the
environment. They monitor the source and extent of pollution and contamination, especially compounds that affect
human health, and they promote sustainability, conservation, and protection. As concerns about geochemistry and
the natural environment increase, environmental chemists also study the processes that affect chemicals in the
environment. Gases emitted by a pine forest may create a mist when mixed with car exhaust, for example. In other
instances, the environment may have effects on chemicals that can be toxic. Environmental chemists examine the
ways both chemicals and the environment are changed by interacting. In the service of monitoring those impacts,
environmental chemists can work everywhere. Their jobs can take them from the upper recesses of the Earth’s
atmosphere to the depths of the oceans, from the ice in the North Pole, to the dirt near a shuttered factory, to the
dust in someone’s home, from the top of a coal-burning power plant’s smokestack to a leather tannery in India, to a
site where old electronics are dumped in Nigeria. These are but a few of the places where environmental chemists
have either taken samples in person or found a way to capture samples that they have then analyzed to learn more
about our world. Environmental chemists have a skill that is valued in today’s labor market, according to the U.S.
Bureau of Labor Statistics. The bureau expects job opportunities for environmental scientists to grow 19% between
2010 and 2020. Environmental chemists are in demand in industry, government, and academia, as well as by
contract labs and consulting groups. They can be involved in analytical testing or new product development in the
lab, or work with users of chemicals in the field, and safety and regulatory issues in an office. As a result, companies
in a variety of industries are placing greater emphasis on compliance and environmental processes. Government
agencies such as the U.S. Departments of Agriculture and Defense and the U.S. Environmental Protection Agency, as
well as agencies at the state and sometimes local level, hire chemists for environmental work. In addition,
waste management companies and consulting firms employ such chemists as consultants, sometimes
related to remediation work. Opportunities are expected to grow in contract labs and consulting, because
businesses are increasingly outsourcing this work. Colleges and universities are hiring more environmental
chemists to serve as instructors and educators as they establish programs in environmental chemistry.
The environment consists of four segments that is given below:
a. Atmosphere
It is a cover a gases which extends to height of about 600km from the earth surface. It protects the life on
the earth from the harmful radiation of sunlight. The main sphere of atmosphere from earth surface are as
fallows:
 Troposphere: from 0 to 16 km from earth surface and it contains O2,N2 etc gases.
 Hydrosphere Stratosphere: from 16 to 50 km from the earth surface. It contains O 2 + ,NO + etc.
 Mesosphere : from 50 to 80 km from earth surface and it contains O 2 + , O + .
 Thermosphere: from 85 to 600 km from earth surface.
b. Hydrosphere
It is part of environment which contains water in the form of sea, ocean, rivers, ponds etc. about 70% of
surface of earth is covered with water.
c. Lithosphere
It is a solid components of earth consisting of soil, rock, mountains etc. about 30% of the surface of earth is
covered by lithosphere.
d. Biosphere
This denotes the realm of living organisms and their inter actions with environment ,hydrosphere and
lithosphere. Both the biosphere and environment are influenced considerably by each other.

Air pollution

fig 1: air pollution

The composition of the atmosphere and atmospheric structure contains three different types of components and that’s why air is never found clear in nature. These components are released in atmosphere due to natural and manmade activities the natural activities like volcanic activity vegetable decay forest fires etc. and the manmade activities like gases , mists, particulates aerosols etc. resulting from the chemical and biological processes used by man. The latter are present in air. The addition of undesirable materials into the atmosphere either by natural or manmade activity on the earth which adversely effect the quantity of air and hence disturb the dynamic equilibrium in the atmosphere is called air pollution. Or in other words addition of unnecessary material into the atmosphere and their environment is called air pollution.

Despite public awareness and relentless media coverage, Kathmandu’s air quality has    worsened in the past two years. But public outrage does not seem to translate into action to    clean up the air.

A road-widening spree, earthquake destruction and delays in fixing streets dug up to replace water mains has turned the Valley into a dust bowl. There has also been a 25% increase in the number of vehicles on the roads.

 In Nepal, 35,000 people die annually due to illnesses caused by polluted air. Average life expectancy is reduced by at least four years in the worst-affected areas like Kathmandu Valley, Chitwan and other parts of the Terai. 

“Air pollution is a silent killer and while it is difficult to quantify its heath impact, hospitalisation due to serious respiratory diseases has increased sharply in recent years,” says chest specialist Raju Pangeni at HAMS Hospital in Kathmandu. “It is now causing heart attacks, kidney diseases, osteoporosis and dementia. Air pollution is more dangerous than smoking cigarettes”. Out of 122 countries, Kathmandu is the seventh polluted capital of the world in terms of pollution.       

fig 2: air pollution in different country

Air pollutions

Undesirable materials like different gases particulate in atmosphere are called air pollutions.

  1. Gases: CO ,CO2 ,SOx ,hydrocarbon.
  2. Particulates: dust , smoke  and O3.

Air pollutions also divided into two  types that is given below:

  • Primary air pollutions
  • Secondary air pollutions

SOx – The mixture of SO2 and SO3 are denoted by SOx Sources of SOx : The main source of sulfur dioxide in the air is industrial activity that processes materials that contain sulfur, eg the generation of electricity from coal, oil or gas that contains sulfur. Some mineral ores also contain sulfur, and sulfur dioxide is released when they are processed.

Effects of SOx

Sulfur dioxide affects the respiratory system, particularly lung function, and can irritate the eyes. Sulfur dioxide irritates the respiratory tract and increases the risk of tract infections. It causes coughing, mucus secretion and aggravates conditions such as asthma and chronic bronchitis.

Remedy of SOx

  • improved efficiency of conversion of fuel to electricity (this would reduce pollutant emissions per unit of electricity generated);
  • shift to nuclear generation as rapidly as possible since no sulfur oxide (or particulate) is emitted from nuclear plants;
  • shift fossil fuel plants to lower sulfur fuels;

NOx – The mixture of NO and NO2

The formation of NO and NO2 is given below:

Concentration of NOx

The concentration is depends upon the sunlight and traffic density. Its maximum level in busy city is 1 to 2 and o.5 ppm respectively.

Effect of NOx

NO2  is more dangerous then the NO and affect the respiratory system and damages the lungs and it also affect the marble building and metallic structure.

Remedy of NOx

Fuel burn out is completed at a relatively low temperature excess air. Under this condition NO is not formed.

Carbon monoxide

Sources: volcanic action ,natural gas emission ,electrical discharge during storm , seed germination , marsh gas production etc.

The chemical reaction is given below:

  1. modifications of internal combustion engines to reduce the amounts of pollutions formed during fuel combustion.
  2. Development of pollution free power sources to replace the internal combustion engine.
  3. Development of exhaust system reactors and develop the substitute fuels for gasoline.

Hydrocarbon HC

Sources of HC are petroleum 55% coal 3.3% and wood 2.2 %.

Effects of HC

If the concentration of HC rises to atmosphere 500 to 1000ppm they have carcinogenic effects to lungs and causes cancer.

Remedy of HC

They are remove by the chemical and photochemical reaction.

Particulates

small solid particulates and liquid droplets are known as the particulates. The sources of particulates are volcanic eruption blowing dust. They are two types of particulates:

  • Inorganic particulates: oxides of metal metallic halide, combustion of fuels asbestos dust sulphuric dust etc.
  • Organic particulates: it contains polycyclic aromatic hydrocarbons ,dust ,smoke or shoot etc.

It causes damage of lungs due to their ability to penetrate into the deep air passage. And it also damage the soil building , accelerate corrosion of the materials. It also effect the change in climate. To decrease that type of the problem different type of remedy is using that is gravity setting chamber, filters, scrubbers etc.

Disastrous Effects of Air pollution

  1. Respiratory and heart problems

The effects of air pollution are alarming. They are known to create several respiratory and heart conditions along with Cancer, among other threats to the body. Several million are known to have died due to direct or indirect effects of Air pollution. Children in areas exposed to air pollutants  are said to commonly suffer from pneumonia and asthma.

     2. Global warming

Another direct effect is the immediate alterations that the world is witnessing due to global warming With increased temperatures worldwide, increase in sea levels and melting of ice from colder regions and icebergs, displacement and loss of habitat have already signaled an impending disaster if actions for preservation and normalization aren’t undertaken soon.

Global warming is one of the greatest challenges of 21st century Scientist estimate that the earths average temperature is increasing by 0.05 degree celcius, changing regional climates could affects forests ,crops , fields and water supplies, the increased temperature would lead to glaciers and polar ice caps and the level of sea may rise  there by flooding the coastal lands and change the climate radically.

Removal of global warming:

  • Reduction in CFC production.
  • Development of environment compatible technologies.
  • Recovering green house from the atmosphere.

3. Acid rain

The falling rain water reacts with these oxides to form a mixture of sulphuric acid and nitric acid and water. This known as acid rain. Its ph value is less than 5.7. the chemical reaction is given below:

Eutrophication

Eutrophication is a condition where a high amount of nitrogen present in some pollutants gets developed on sea’s surface and turns itself into algae and adversely affect fish, plants and animal species. The green colored algae that are present on lakes and ponds is due to the presence of this chemical only.

5. Effect on wildlife

Just like humans, animals also face some devastating effects of air pollution. Toxic chemicals present in the air can force wildlife species to move to a new place and change their habitat. The toxic pollutants deposit over the surface of the water and can also affect sea animals.

6.  Depletion of the Ozone layer

Ozone exists in the Earth’s stratosphere and is responsible for protecting humans from harmful ultraviolet (UV) rays. Earth’s ozone layer is depleting due to the presence of chlorofluorocarbons, hydro chlorofluorocarbons in the atmosphere. As the ozone layer will go thin, it will emit harmful rays back on earth and can cause skin and eye related problems. UV rays also have the capability to affect crops.

Solutions For Air Pollution

1. Use public mode of transportation

Encourage people to use more and more public modes of transportation to reduce pollution. Also, try to make use of carpooling. If you and your colleagues come from the same locality and have same timings you can explore this option to save energy and money.

2. Conserve energy

Switch off fans and lights when you are going out. A large number of fossil fuels are burnt to produce electricity. You can save the environment from degradation by reducing the number of fossil fuels to be burned.

3. Understand the concept of Reduce, Reuse and Recycle

Do not throw away items that are of no use to you. In-fact reuse them for some other purpose. For e.g. you can use old jars to store cereals or pulses.

4. Emphasis on clean energy resources

Clean energy technologies like solar, wind and geothermal are on high these days. Governments of various countries have been providing grants to consumers who are interested in installing solar panels for their home. This will go a long way to curb air pollution.

5. Use energy efficient devices

CFL lights consume less electricity as against their counterparts. They live longer, consume less electricity, lower electricity bills and also help you to reduce pollution by consuming less energy.

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