Environmental impacts

Páginas: 6 (1442 palabras) Publicado: 16 de septiembre de 2012
FIRST ASSIGNMENT - Environmental impacts

Ignacio Romero Gómez

One of the aim of life-cycle assessment, is to try to have a product perspective in order to consider environmental issues referred to the production process.
For the porpouse of obtening a good assessment of any kind of product, which starts from a raw material and finishes when it is useless, is necessary to look at theimpact assessments. These impacts assessments are divided into three main levels: Characterisation, Normalisation and Weighting.
The first level is about the environmental impacts which may cause the product to the environment with emissions and waste, and also the negative effects to the living beings. There are three kinds of categories depending on the importance of the impact:
• Global• Local
• Regional

On this assignment, we focus on global and local impacts.

Greenhouse effect

The first global impact is greenhouse effect, as we know; the Earth has a natural temperature control system. Certain atmospheric gases are critical to this system and are known as greenhouse gases. Some of the solar radiation is absorbed by the atmosphere but most is absorbed by the land andoceans. The Earth's surface becomes warm and as a result emits infrared radiation. The greenhouse gases trap the infrared radiation, so the atmosphere becomes warmer, so a negative and dangerous effects is that the poles may melt, with all its consequences.
Naturally occurring greenhouse gases include water vapour, carbon dioxide, ozone, methane and nitrous oxide, and together create a naturalgreenhouse effect.
However, human activities are causing greenhouse gas levels in the atmosphere to increase. As we can see on the single diagram 1.1, the main human activities are deforestation; CFCs, used as refrigerants, propellants; nuclear factories; some farming practices and land-use changes increase the levels of methane and nitrous oxide; and petrol engines, that are in the transportation weuse normally in our daylife.

Diagram 1.1
Human activities that make worse the greenhouse effect

Ozone depletion

First of all we need to know the importance of the ozone layer, which is a belt of naturally occurring ozone gas that serves as a shield from the harmful ultraviolet B radiation emitted by the sun.
Ozone is a highly reactive molecule that contains three oxygen atoms. It isconstantly being formed and broken down in the stratosphere.

Today, there is widespread concern that the ozone layer is deteriorating due to the release of pollution containing the chemicals chlorine and bromine.
Chlorofluorocarbons (CFCs), chemicals found mainly in spray aerosols heavily used by industrialized nations for much of the past 50 years, are the primary culprits in ozone layerbreakdown. When CFCs reach the upper atmosphere, they are exposed to ultraviolet rays, which cause them to break down into substances that include chlorine. The chlorine reacts with the oxygen atoms in ozone and destroys the ozone molecule. Based on the circular graphic 2.1, we can assess the importance of the human on the source of chlorine at the stratospheric (82%).
Such deterioration allows largeamounts of ultraviolet B rays to reach Earth, which can cause skin cancer and cataracts in humans and harm animals as well. Extra ultraviolet B radiation reaching Earth also inhibits the reproductive cycle of phytoplankton that make up the bottom rung of the food chain. Biologists fear that reductions in phytoplankton populations will in turn lower the populations of other animals.

Graphic2.1
It shows the proportion of chlorine due to human

Acidification

The first regional impact we are talking about is acidification, which is commonly associated with atmospheric pollution..

The main envarionmental effect is acid rain, this phenomenon occurs when some gases react in the atmosphere with water, oxygen, and other chemicals to form various acidic compounds. Sunlight...
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