Acid rain and… the facts
www.acidrain.org.ca / Oxford Children´s Encyclopedia
What causes acid rain?
Acid rain is caused by air pollution. When fossil fuels such as coal and oil are burned, two gases, sulphur dioxide and nitrogen oxide, are released into the atmosphere. These two pollutants eventually react with the moisture in the air. When this polluted mixture falls onto the ground, it is called acid rain.
Rain measuring between 0 and 5 on the pH scale, is acidic therefore called ACID RAIN
Acid rain is harmful to the environment. It is hard to control because it may be blown by the wind, falling thousands of kilometers from where it was first formed. For example, much of the acid rain in Canada is caused by smoke from factories and power‐stations in the USA. The acid rain in Scandinavia may come from Britain.
What are the effects of acid rain?
Acid rain has many different effects. It has killed fish in the lakes of North America, Scandinavia, Scotland, and Wales. Vast areas of forest in northern and central Europe are dying because of it, while in many European cities statues and stone buildings are being eaten away by the acid. Acid rain corrodes metalwork such as steel bridges and railings; it also attacks some types of concrete. Even the water that we drink is slowly being polluted by acid rain.
What are the effects on trees and soil?
One of the most serious impacts of acid precipitation is on forests and soils. Great damage is done when sulphuric acid falls onto the earth as rain. Nutrients present in the soils are washed away. Aluminium also present in the soils is freed and this toxic element can be absorbed by the roots of trees. Thus, the trees starve to death because they have been deprived of their vital nutrients such as calcium and magnesium.
Acid rain is one of the most serious environmental problems of our time. It is a global problems that is gradually affecting our world.
How does acid rain effect lakes?
Lakes that have been acidified cannot support the same variety of life as healthy lakes. As a lake becomes more acidic, various types of fish disappear. Other effects of acidified lakes on fish include: decreased growth, inability to regulate their own body chemistry, reduced egg deposition, deformities in young fish and increased susceptibility to naturally occurring diseases.
Clean rain usually has a pH of 5.6. It is slightly acidic because of carbon dioxide which is naturally present in the atmosphere. Vinegar, by comparison, is very acidic and has a pH of 3.
What is pH?
This is a measure of how acidic or alkaline a substance is. (See a pH scale below). The initials pH stand for Potential of Hydrogen. Acids have pH values under 7, and alkalis have pH values over 7. If a substance has a pH value of 7. It is neutral‐neither acidic or alkaline.
Because the pH scale is logarithmic, a difference of one pH unit represents a tenfold, or ten times change. For example, the acidity of a sample with a pH of 5 is ten times greater than that of a sample with a pH of 6. A difference of 2 units, from 6 to 4, would mean that the acidity in one hundred times greater, and so on.
A difference of four units, from six to two, means that the acidity is
1. The ECOWAS COMMISSION has allocated own funds towards the cost of the Supply, Deployment & Installation of Network Equipment at the ECOWAS Commission Headquarters Data Centre, Abuja.
2. The ECOWAS Commission therefore invites sealed bids for the Supply, Deployment & Installation of Network Equipment at the ECOWAS Commission Headquarters Data Centre, Abuja described above in one lot.
3. The Bidding Document can be obtained at the Procurement Division, Directorate of General Administration, ECOWAS Commission, Plot 101, Yakubu Gowon Crescent, Asokoro District, Abuja, Nigeria, upon submission of a written request and payment of three hundred US Dollars (US$300.00) by Cash or Bank Draft made in favour of ECOWAS Commission, Abuja.
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5. Interested Bidders may obtain further information at the address below, during office hours: Monday to Friday from 9.00am (8.00am GMT+1) to 4.00pm (3.00pm GMT+1), ECOWAS Commission, Directorate of General Administration, Procurement Division, 1st Floor, Plot 101, Yakubu Gowon Crescent, Asokoro District, PMB 401 Abuja Nigeria.
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6. Bids shall be valid for a period of 120 (days) after Bid Opening and must be accompanied by a bid security of US$20,000.00 (Bank Guarantee or Insurance Bond).
7. Bids shall be delivered in sealed envelope and deposited in the ECOWAS Tender Box located Office of the Executive Assistant of Commissioner of Administration & Finance, fifth (5th) floor of the ECOWAS Commission Building, 101, Yakubu Gowon Crescent Asokoro District, P. M. B. 401, Abuja, Nigeria on or before November 7, 2013 at 11.30am (10.30am GMT+1) and clearly marked “International Competitive Bidding for the Production of ECOWAS Biometric Laissez Passer and Supply of Equipment” Do Not Open, Except in Presence of the Committee.
8. Bids will be opened in the presence of the bidders who wish to attend on November 7, 2013 at 12.00 noon (11.00am GMT+1), Room 523, Ecowas Commission, Abuja, Nigeria.
(The Economist, September 4th, 2013. Page 86. Adaptado.)
In “Bids will be opened in the presence of bidders who wish...” the relative pronoun may be replaced by
Read the following sentences:
I. Auditors have found risk detection too problematic to be
conducted.
II. Many companies are becoming aware of the need for
auditing.
III. All the firms that never audited do not see the need for it
now.
IV. Auditing has turned into a main issue in management
practice.
Indicate the sentences which are in line with the points raised in
Text 3
The words of Text I: output (line 26), mild (line 30), balance (line 37) and inventories (line 42) may be replaced, without change in meaning, respectively, by:
The phrasal verb “give up” is the same:
Which word is not plural?
Repórteres profissionais da área criminal, após os relatos dos moradores, começaram a fazer o rastreamento de crimes através da escuta de conversas de rádio entre os policiais.
Nessa história em quadrinhos, o garoto, dirigindo a carroça, argumenta com Patty que ela foi baleada e que, portanto, está eliminada da brincadeira.
The remark from the text on lines 93-94 – Remind them at all times that we are only assessing a certain type of work, not the whole person – implies that
Na frase das linhas 39-40 – The learner often seems to be disengaged or daydreaming. – o advérbio é utilizado para expressar ideia de
Na frase das linhas 82-83 – Allow learners to work in groups on projects where they have different roles which utilize their strengths. – os conectivos em destaque podem ser substituídos, respectivamente, por
A próxima questão se refere exclusivamente aos Parâmetros Curriculares Nacionais.
“Para que o processo de construção de significados de natureza sociointeracional seja possível, as pessoas utilizam três tipos de conhecimentos: conhecimento sistêmico, conhecimento de mundo e conhecimento da organização dos textos. Esses conhecimentos compõem a competência comunicativa do aluno e o preparam para o engajamento discursivo” (PCN, p. 29).
Assinale a alternativa, a partir de elementos adaptados dos PCN, que contém uma referência pertinente ao denominado conhecimento de mundo.
Esta questão reproduz o trecho de uma breve conversa. Assinale a alternativa que apresenta a palavra ou expressão que preenche a lacuna corretamente, levando em conta o contexto e o uso
da norma culta da língua.
“The scenary was really beautiful there.”
“Yes, the mountain was ____________flowers.”
In “The world dreamed. Braskem made it happen.” , there is a relation of _______________ between the sentences.
