Acid Rain Research Project

Acid Rain Research Project
Acid Rain Research Project

Acid Rain Research Project

Part 1

Introduction

Acid rain is a popular

term for the atmospheric

deposition of acidified rain,

snow, sleet, hail, acidifying

gases and particles, as

well as acidified fog and

cloud water. The increased

acidity of these depositions,

primarily from the strong

acids, sulfuric and nitric, is

generated as a by-product

of the combustion of fossil

fuels containing sulfur or

nitrogen,

especially electrical utilities (power plants.) The heating of homes, electricity production, and driving vehicles all rely primarily on fossil fuel energy. When fossil fuels are combusted, acid-forming nitrogen and sulfur oxides are released to the atmosphere. These compounds are transformed chemically in the atmosphere, often traveling thousands of kilometers from their original source, and then fall out on land and water surfaces as acid rain. As a result, pollutants from power plants in New Jersey, Ohio or Michigan can impact forests, rivers or lakes in less developed parts of New Hampshire or Maine.

Acid rain was discovered in 1963 in North America at the Hubbard Brook Experimental Forest, in the White Mountains of New Hampshire at the initiation of the Hubbard Brook Ecosystem Study. The first sample of rain collected there had a pH of 3.7, some 80 times more acidic than unpolluted rain. Innovations for reducing fossil fuel emissions, such as scrubbers on the tall smoke stacks on power plants and factories, catalytic converters on automobiles, and use of low-sulfur coal, have been employed to reduce emissions of sulfur dioxide (SO2) and nitrogen oxides (NO x). As a result of increasing global economies, fossil fuel combustion is increasing around the world, with concomitant spread of acid rain, especially in areas such as China.

Precipitation chemistry

The source of the acids in the atmosphere is largely the result of the combustion of fossil fuels that produce waste by-products including gases such as oxides of sulfur and nitrogen. Oxidized sulfur and nitrogen gases are acid precursors in the

atmosphere. For example, SO2 reacts with water in the atmosphere to yield sulfuric acid:

SO2 + H2O + ?O2 = H2SO4

An analogous

reaction of

water with

nitrogen oxides,

symbolized as

NO x, yields

nitric acid

(HNO3).

Ammonia (NH3)

is a by-product

of some natural

processes, as

well as

agricultural

sources (e.g.,

application of nitrogen-containing fertilizers; emissions from intensive animal feedlots, such as decomposition of organic matter). In its dissolved form, ammonium (NH4+) contributes acidity to surface waters through the process of nitrification.

In addition to wet deposition (rain, snow, and fog), acidic deposition includes the deposition of dry, particulate, and gaseous acid precursors that become acidic in contact with water. This dry deposition is difficult to quantify and expensive to measure. Inferential methods indicate that dry deposition represents 20% to 80% of the total deposition of acids to the landscape, depending on factors such as location, season, and total rainfall.

Natural sources can

also contribute

additional acidity to

precipitation.

Natural emissions

can come from

wetlands and

geologic sources.

Major natural

sources of NO x

include lightning

and soil microbes.

Organic acidity may arise from freshwater wetlands and coastal marshes.

It is those natural sources that lead to the inference that pre-industrial precipitation in forested regions had a pH around 5.0. If true, then modern precipitation in the North and East is two to three times more acidic than pre-industrial.

The acidity of precipitation is still subject to misunderstanding. Even in pristine environments, precipitation pH is rarely controlled by the carbon dioxide (CO2) reaction that has an equilibrium pH of 5.6:

H2O + CO2 = H2CO3

Because of the many sources of acidity in precipitation, pH 5.6 is not the benchmark ‘normal’ pH against which the acidity of modern precipitation should be compared. Precipitation is a variable and complex mixture of particulates and solutes derived from local sources and long-range transport. For example, in arid or partly forested regions, dust from soil and bedrock typically neutralizes both the natural and human sources of acidity in precipitation, yielding a solution that may be quite basic (pH greater than 7). In the northeastern U.S. and eastern Canada, annual precipitation pH ranges from 4.3 in Pennsylvania, New York, and Ohio, to 4.8 in Maine and maritime Canada.

Effects on surface water quality

Lake acidification begins with the deposition of the byproducts acid precipitation (SO4 and H ions) in terrestrial areas located adjacent to the water body. Hydrologic processes then move these chemicals through soil and bedrock where they can react with limestone and aluminum-containing silicate minerals. After

these chemical reactions, the leachate continues to travel until it reaches the lake. The acidity of the leachate entering lake is controlled by the chemical composition of the effected lake's surrounding soil and bedrock. If the soil and bedrock is rich

in limestone the acidity of the infiltrate can be reduced by the buffering action of calcium and magnesium compounds. Toxic aluminum (and some other toxic

heavy metals) can leach into the lake if the soil and bedrock is rich in aluminum-rich silicate minerals.

Surface water chemistry is a direct indicator of the potential deleterious effects of acidification on biotic integrity. Because surface water chemistry integrates the sum of processes upstream in a watershed, it is also an indicator of the indirect effects of watershed-scale impacts, such as nitrogen saturation, forest decline, or soil acidification.

Acid deposition degrades water quality by lowering pH levels (i.e., increasing acidity); decreasing acid-neutralizing capacity (ANC); and increasing aluminum concentrations. A recent survey in the Northeast concluded that 41 percent of lakes in the Adirondack region are still acidic or subject to short-term pulses in acidity associated with snowmelt or rain storms. In the Catskill region and New England as a whole, 15 percent of lakes exhibit these characteristics. Eighty-three percent of the impacted lakes are acidic due to acid deposition. The remaining 17 percent are probably acidic under natural conditions, but have been made more acidic by acid deposition. This survey presents a conservative estimate of lakes impaired by acid deposition. Data were collected from lakes that are one hectare

or larger and included only samples that were collected during the summer, when conditions are relatively less acidic.

Stream data from the Hubbard Brook Experimental Forest, New Hampshire (HBEF) reveal a number of long-term trends that are consistent with trends in lakes and streams across the Northeast. Specifically, the concentration of sulfate in streams at the HBEF declined 20 percent between 1963 and 1994. The pH of streams subsequently increased from 4.8 to 5.0. Although this represents an important improvement in water quality, streams at the HBEF remain acidic compared to background conditions, estimated to be above 6.0. Moreover, a lake or stream’s susceptibility to acid inputs – has not improved significantly at the HBEF over the past thirty years.

Acid Rain in Canada

The Long-Range Transport of Airborne Pollutants

On a daily basis, human activities -- industrial, agricultural and residential -- cause vast quantities of natural and synthetic chemicals to be emitted into the atmosphere. Once released, the substances are dispersed throughout the globe by air currents that know no boundaries -- provincial or international. This phenomenon is known as the long-range transboundary air pollution (LRTAP).

Over time, these emissions expose human beings, wildlife and resources to diverse quantities and mixtures of air pollutants. The resulting harm is difficult to evaluate, since it occurs over varying time frames and over vast areas having differing degrees of sensitivity. The reversibility of the damage is not yet well understood.

Some of the chemicals in the atmosphere are rendered harmless through exposure to sunlight, but others are extremely persistent, surviving and circulating around the earth for as long as months or years. They reach our water systems through dry or wet deposition.

Acid rain, one of the most publicized LRTAP phenomena, originated with emissions from coal-fired generators, non-ferrous metal smelters, petroleum refineries, iron and steel mills, pulp and paper mills, and from motor vehicle exhaust. The released sulphur dioxide and nitrogen oxides are converted to sulphuric and nitric acids in the atmosphere. These acids return to earth through wet sulphate and/or nitrate deposition (including rain, snow and fog).

In Canada, the major sources of sulphur dioxide emissions are non-ferrous metal smelters, followed by coal-fired generators. Motor vehicles and, to a lesser extent, coal-fired generators, are the major sources of nitrogen oxides. About half the wet sulphate deposition in eastern Canada is estimated to come from the United States, while about ten percent of the deposition in the northeastern United States comes from Canada.

The damage caused by acid rain deposition occurs in environments that cannot tolerate acidification. Many species of fish, insects, aquatic plants and bacteria develop reproduction difficulties. Some even die. The decline in the population of any of these aquatic organisms affects the food chain. Dwindling populations of insects and small aquatic plants and animals are especially serious because the entire food chain is affected.

How Acid Rain Affects Water Quality

The effects of acid deposition on water quality, although complicated and variable, have been well documented. Impacts from these acidic compounds in the atmosphere can occur directly, by deposition on the water surface, or indirectly, by contact with one or more components of the terrestrial ecosystem before reaching any aquatic system. The interactions of acid deposition with the terrestrial ecosystem, including vegetation, soil, and bedrock, result in chemical alterations of

the waters

draining these

watersheds,

eventually

altering

conditions in the

lakes

downstream.

The extent of

chemical

alteration

resulting from

acidic deposition

depends largely

on the type and

quantity of the

soils and the

nature of the

bedrock

material in the

watershed, as

well as on the amount and duration of the precipitation. Watersheds with soils and bedrock containing substantial quantities of carbonate-containing materials, such as limestone and calcite, are less affected by acidic deposition because of the high acid-neutralizing capacity derived from the dissolution of this carbonate material. Thousands of lakes in Canada, however, lie on the Precambrian Shield. This vast expanse of bedrock possesses few limestone-type materials and, consequently, has only a limited ability to neutralize acidic deposition. Consequently, lakes and rivers in these areas generally show acidification effects, including

decreasing pH levels and increasing concentrations of sulphate and certain metals such as aluminum and manganese.

The map below shows the potential of soils and bedrock to reduce the acidity of acid rain. Red shaded areas, almost half of Canada's area, are most sensitive to the effects of acid rain.

Acid Rain in China

Beijing: China, the world's largest consumer

of coal, is paying a heavy price for its rapid

development, with 258 of its cities

experiencing acid rains due to excessive

emission of sulphur dioxide, causing health

hazards and damage to buildings and scenic

spots, according to official statistics.

The study of the changing weather pattern in

Xiamen in the southeastern part of Fujian

province, regarded as one of the best places

to live or visit in China, shows that the city is witnessing continuous acid rains, staining its centuries-old colonial buildings and the world's biggest Buddhist statue.

"Official statistics show every drop of rain in Xiamen in the first half of 2010 was acidic, recording pH levels of less than 5.6 (neutral is 7)," Zhuang Mazhan, chief engineer at Xiamen's Environmental Monitoring Central Station said. "The acid rain is leaving buildings with yellowish signs of corrosion... and is slowly turning the leafy island yellow. It's making the city much less attractive," he told state-run 'China Daily'. "Leshan Giant Buddha, which has stood in southwest China for more than 1,000 years, has also been badly affected. Its nose is turning black, hair curls have fallen from its head and its reddish body is becoming a charred grey colour," the daily said.

The 71-metre high and 28-metre wide statue, which was carved out of a cliff during Tang Dynasty (AD 618-907), had survived floods and earthquakes, but it was now at a greater risk from the man-made threat, it said.

Xiamen is not alone and according to the latest annual quality report published by the Chinese Ministry of Environmental Protection, 258 cities and counties recorded acid rainfall in 2009. For 112 of them, at least one in every two precipitations was acidic.

In fact, the areas suffering from acid rain are actually expanding, with some already reporting increased acidity, the daily quoted an internal study commissioned by the ministry with Tsinghua University as saying.

Monitoring stations in the Pan-Bohai Bay area in northeast China have recorded the highest frequency and acidity of acid rains in 15 years, the study said.

The coastal city of Dalian in Liaoning province, also a popular summer resort, reported an acid rain frequency of 51.6 per cent in 2007.

Acid rain is a by-product of burning coal and fossil fuels. Combustion releases sulfur

dioxide (SO2) and nitrogen oxides into the air, which bond with water and oxygen molecules and then fall as sulfuric and nitric acid.

China, which consumes over three billion tonnes of coal per annum, is also the third largest acid rain region, after Europe and North America.

A 2005 report found that 28 per cent of the country's territory, mostly south of the Yangtze River was affected by acid rain.

Studies say that the acid rainfall is also increasing along the west coast of the Taiwan Straits, around Chengdu and Chongqing in southwest China and throughout the Pan-Beibu Gulf Economic Zone in the south.

All these regions are expected to become the country's next growth engines thanks to booming heavy industries, such as petrochemicals, energy, metallurgy and equipment manufacturing, Tsinghua study said.

The "sad findings" of the study suggest the country has failed to curb environmental deterioration despite huge anti-pollution efforts, Wei Fusheng, an academician at the Chinese Academy of Engineering, said, echoing the growing public complaints about worsening air quality in many major cities.

Last month, Beijing's municipal government announced it had hit its target of 266 "blue-sky days" in 2010 ahead of schedule.

However, the usual thick smog and the smell of smoke during winter - when the Central heating system is fired up - made some citizens doubt the accuracy of the capital's air quality ratings, the daily said.

Similarly, in the Yangtze River and Pearl River deltas, more hazy days are recorded every year.

"That shows the existing monitoring and assessment systems for the country's environmental quality have their defects," Wei said, adding that nitrogen oxides and other pollutants are still left out when it comes to emissions control.

Chinese officials say that the government is aggressively pursuing its promises made in late 2009 to cut the intensity of carbon dioxide emissions per unit of GDP in 2020 by 40 to 45 per cent, compared with 2005 levels.

China is also committed to increasing the share of non-fossil fuels in primary energy consumption to around 15 per cent to have 40 million more hectares of forest by 2020. Despite the Chinese government's pledge to rely more on renewable energy sources, Wang Xianzheng, President of the China National Coal Association, recently projected that the annual coal consumption will reach 3.8 billion tonnes by 2015, an increase of 800 million tonnes compared to 2009.

Part 2

After research of to become a chemist, I found the Ph.D. Program Information of Carton University.

To graduate as a Ph.D. , students are required four to five years study to complete the Ph.D. degree program. According to the official information:

A research thesis defended before an examination board which includes an external examiner (11.0 credits)

A comprehensive examination in chemistry. The format of this examination depends on the field of chemistry in which the student is conducting his/her research. At Carleton University this normally consists of two parts:

a research proposal examination and

a research topic presentation. Consult the recent calendar or the Director/Associate Director for details. Students who fail to complete the comprehensive examination by the end of their third year in the graduate school will be deregistered from the program. (No credit, Pass or Fail)

Two credits of graduate courses (made up of any combination of 0.5 credit and 0.25 credit courses).

CHEM 5801 (1.0 credit)

CHEM 5802 (1.0 credit)

Carleton University also provides the employment opportunities for chemistry students. It requires students should hold at least an MSc in Chemistry, or related field, and demonstrate teaching competence in a relevant area, preferably at the university level. Priority will be given to candidates holding a PhD. For first and second year courses priority will be given to those with experience teaching large classes.

Part 3

Nowadays, we are facing all kinds of environment problems on the Earth, acid rain is one of them. When the ph level of rain is lower than 5.5, it is defined as acid rain. Acid rain can acidize the soil and water body; restrain all the plants and hydrophyte grow, and also influence the entire habits system around it. According to the article I found that about the effect of acid rain in Canada and China, there are some irreversible damage caused by acid rain: a huge area of natural forest became feeble and died; many lakes in Canada was started polluting by acid rain, if we don’t take steps to stop the pollution, we will be drinking poisonous water after 10years.

Most of the acid compounds were formed in the combustion of fossil fuels to generate electricity and provide transport. Coal is the important energy source to generate electricity, but it contains sulfur, it will produce harmful gas such as SO2 during the combustion. There are two kinds of sulfur, inorganic and organic sulfur in the coal. Most inorganic sulfur in the form of minerals, mainly pyrite is (FeS2). Biolog ist’s use of microbial desulfurization, the divalent iron into trivalent iron, and the elemental sulfur turns into sulfuric acid. This is one way to remove the inorganic sulfur in the coal, so that it will produce less SO2. The way that government is solving the problem is deal with the emissions. They moved factories away from where people live to the best of their ability. It’s still hard to figure out the pattern of the acid float with the atmosphere and settle on the ground. The way that I think most possible is to find a new clean and high efficiency energy source. This method is costing a great amount of money and time to the success.

Therefore, the development of technology is the most important and related to the future of the world. Although this is a hardship that challenge all human, I trust that those problems must be solved in 10 years After that, there will be new troubles in front of us, we won’t shrink back, that’s how we progress in all human history.

Bibliography

Acid rain https://www.360docs.net/doc/2318839136.html,/view/article/149814/

Acid rains make life hard in 258 Chinese

itieshttps://www.360docs.net/doc/2318839136.html,/article/world/acid-rains-make-life-hard-in-258-chinese-cities-79213

The Long-Range Transport of Airborne Pollutants

http://www.ec.gc.ca/eau-water/default.asp?lang=En&n=FDF30C16-Carleton University, Department of Chemistry

http://www5.carleton.ca/chemistry/

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