Environmental engineering

Environmental engineering is the application of science and engineering principles to improve the environment (air, water, and/or land resources), to provide healthy water, air, and land for human habitation and for other organisms, and to remediate polluted sites.

Environmental engineering involves water and air pollution control, recycling, waste disposal, and public health issues as well as a knowledge of environmental engineering law. It also includes studies on the environmental impact of proposed construction projects.

Environmental engineers conduct hazardous-waste management studies to evaluate the significance of such hazards, advise on treatment and containment, and develop regulations to prevent mishaps. Environmental engineers also design municipal water supply and industrial wastewater treatment systems as well as address local and worldwide environmental issues such as the effects of acid rain, global warming, ozone depletion, water pollution and air pollution from automobile exhausts and industrial sources.At many universities, Environmental Engineering programs follow either the Department of Civil Engineering or The Department of Chemical Engineering at Engineering faculties. Environmental "civil" engineers focus on hydrology, water resources management,bioremediation, and water treatment plant design. Environmental "chemical" engineers, on the other hand, focus on environmental chemistry, advanced air and water treatment technologies and separation processes.

Pollutants may be chemical, biological, thermal, radioactive, or even mechanical. Environmental engineering is a diverse field, which emphasizes several areas: process engineering, environmental chemistry, water and sewage treatment (sanitary engineering), waste reduction/management, and pollution prevention/cleanup.

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Deforestation

It is impossible to overstate the importance of humankind's clearing of the forests. The transformation of forested lands by human actions represents one of the great forces in global environmental change and one of the great drivers of biodiversity loss. The impact of people has been and continues to be profound. Forests are cleared, degraded and fragmented by timber harvest, conversion to agriculture, road-building, human-caused fire, and in myriad other ways. The effort to use and subdue the forest has been a constant theme in the transformation of the earth, in many societies, in many lands, and at most times. Deforestation has important implications for life on this planet.

Just think, originally, almost half of the United States, three-quarters of Canada, almost all of Europe, the plains of the Levant, and much of the rest of the world were forested. The forests have been mostly removed for fuel, building materials and to clear land for farming. The clearing of the forests has been one of the most historic and prodigious feats of humanity.

About one half of the forests that covered the Earth are gone. Each year, another 16 million hectares disappear. The World Resources Institute estimates that only about 22% of the world's (old growth) original forest cover remains "intact" - most of this is in three large areas: the Canadian and Alaskan boreal forest, the boreal forest of Russia, and the tropical forest of the northwestern Amazon Basin and the Guyana Shield (Guyana, Suriname, Venezuela, Columbia, etc.)

Today, forests cover more than one quarter of the world's total land area, excluding polar regions. Slightly more than 50% of the forests are found in the tropics and the rest are temperate and boreal (coniferous northern forest) zones.

For millennia, humankind has influenced the forests, although much of the impact has been relatively minor. Today, the impact is enormous. Deforestation is expanding and accelerating into the remaining areas of undisturbed forest, and the quality of the remaining forests is declining. Today we examine global patterns in deforestation, assess the human and ecological costs of forest loss, and discuss some of the steps that can help to rectify this alarming situation.

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Ozone exposure

A team of scientists says the risk of dying from respiratory problems is more than 30% greater in metropolitan areas with the highest ozone concentrations than areas where ozone levels were the lowest.

Ground-level ozone, along with particulate matter, is a major component of smog. Ozone is a naturally occurring gas most prevalent high in the atmosphere, where it protects against harmful ultraviolet rays of the sun. However, ozone at ground level is produced when exhaust from cars, power plants, and other sources reacts chemically in sunlight. According to the Environmental Protection Agency, ground-level ozone can irritate breathing, decrease lung function, inflame airways, and worsen lung conditions such as asthma and emphysema.

People who have chronic obstructive pulmonary disease (COPD) or certain other lung conditions often take their medications using devices called a metered dose inhaler (MDI) or a dry powder inhaler (DPI). If you have COPD, your doctor will prescribe the medication you need to use in an MDI or DPI.

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Plastic bag sideeffect

Every once in a while the government here passes out an order banning shop keepers from providing plastic bags to customers for carrying their purchases, with little lasting effect. Plastic bags are very popular with both retailers as well as consumers because they are cheap, strong, lightweight, functional, as well as a hygienic means of carrying food as well as other goods. Even though they are one of the modern conveniences that we seem to be unable to do without, they are responsible for causing pollution, killing wildlife, and using up the precious resources of the earth.

About a hundred billion plastic bags are used each year in the US alone. And then, when one considers the huge economies and populations of India, China, Europe, and other parts of the world, the numbers can be staggering. The problem is further exacerbated by the developed countries shipping off their plastic waste to developing countries like India.

Harmful effect of plastic bag:

Plastic bags litter the landscape. Once they are used, most plastic bags go into landfill, or rubbish tips. Each year more and more plastic bags are ending up littering the environment. Once they become litter, plastic bags find their way into our waterways, parks, beaches, and streets. And, if they are burned, they infuse the air with toxic fumes.

Plastic bags kill animals. About 100,000 animals such as dolphins, turtles whales, penguins are killed every year due to plastic bags. Many animals ingest plastic bags, mistaking them for food, and therefore die. And worse, the ingested plastic bag remains intact even after the death and decomposition of the animal. Thus, it lies around in the landscape where another victim may ingest it.

Plastic bags are non-biodegradable. And one of the worst environmental effects of plastic bags is that they are non-biodegradable. The decomposition of plastic bags takes about 1000 years.

Petroleum is required to produce plastic bags. As it is, petroleum products are diminishing and getting more expensive by the day, since we have been using this non-renewable resource increasingly. Petroleum is vital for our modern way of life. It is necessary for our energy requirements – for our factories, transport, heating, lighting, and so on. Without viable alternative sources of energy yet on the horizon, if the supply of petroleum were to be turned off, it would lead to practically the whole world grinding to a halt. Surely, this precious resource should not be wasted on producing plastic bags, should it?

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Air pollution cleaned by fog

While it hassles commuters, morning mist removes a lot of airborne particles which are hazardous for people with respiratory health problems. The water droplets inside morning fog are of just the right size to collect and hold onto tiny air pollutant particles floating in the air. Once the fog settles back to the ground, it takes the air pollution particles with it.

A dreary, foggy morning may wreak havoc on your morning commute. But now, scientists reveal that not all thick, foggy air is bad. Some of it may be helping to clean up our polluted skies.

Commuting to work in the morning is already a long trek for Emilie Lorditch. But add in a blanket of thick, dense fog, and the drive worsens. "It can be really scary," she says.

Atmospheric chemists say poor visibility and traffic tie-ups have given fog a bad rap. Now, new research shows fog is actually good at clearing up something bad -- dust and dirt particles in the air.

Different kinds of fog appear across the country. But, the kind responsible for air pollution cleanup is called radiation fog. It occurs mostly in the morning.

"Radiation fog forms when the atmosphere is very stable and the skies are clear," Collett says. "And so the ground tends to radiate heat away to the sky."

On a clear night, heat from the ground radiates into space, leaving cool air just above the ground. Once the air reaches a specific temperature, water droplets form, surrounding pollution particles and creating radiation fog. When the sun comes up, it evaporates the water droplets, cleaning the particles out of the air, and leaving dirt and dust on the ground.

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Atmospheric pollution

Although atmospheric pollution can have natural sources, for example volcanic eruptions, the term is usually used to refer to the gaseous by-products of man-made processes such as energy production, waste incineration, transport, deforestation and agriculture. During the last 200 years, mankind has begun to significantly alter the composition of the atmosphere through pollution. Although air is still made up mostly of oxygen and nitrogen, mankind, through its pollution, has increased the levels of many trace gases, and in some cases, released completely new gases to the atmosphere. Some of these trace gases, present in elevated concentrations, can be harmful to both humans and the environment.

Air pollution can result in poor air quality, both in cities and the countryside. Some air pollutants make people sick, causing breathing problems and increasing the likelihood of cancer. Others are harmful to plants, animals, and the ecosystems in which they live. Some air pollutants return to Earth in the form of acid rain, which corrodes statues and buildings, damages crops and forests, and makes lakes and streams unsuitable for fish and other plant and animal life.

Man-made air pollution is also changing the Earth's atmosphere so that it lets in more harmful radiation from the Sun. Although we have now banned products which can harm the Earth's ozone layer, ozone holes over Antarctica and the Arctic still form every year. At the same time, mankind is releasing more greenhouse gases to the atmosphere, preventing heat from escaping back into space and leading to a rise in global average temperatures. Global warming will raise sea levels and change climates all over the world. Some places will become hotter and drier, others wetter. The incidence of severe storms and flooding is likely to increase. Global warming will also affect food supply and increase the spread of tropical disease.

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Asia pollution

The grey, sulphur-laden skies overlying parts of Asia have a bright side — they reflect sunlight back into space, moderating temperatures on the ground. Scientists are now exploring how and where pollution from power plants could offset, for a time, the greenhouse warming of the carbon dioxide they emit.

A new modelling study doubles as a thought experiment in how pollution controls and global warming could interact in China and India, which are projected to account for 80% of new coal-fired power in the coming years. If new power plants were to operate without controlling pollution such as sulphur dioxide (SO2) and nitrogen oxides (NOX), the study finds, the resulting haze would reflect enough sunlight to overpower the warming effect of CO2 and exert local cooling.

But this effect would not be felt uniformly across the globe and would last only a few decades. In the long run, CO2 would always prevail, and the world could experience a rapid warming effect if the skies were cleaned up decades down the road.

The study, which is under review at Atmospheric Chemistry and Physics, builds on a well-established idea. Global temperatures were relatively stable in the decades leading up to the 1970s, even as fossil-fuel consumption shot up. Then industrialized countries began curbing SO2 and NOX to reduce acid rain and protect public health — and temperatures increased rapidly. The latest work, led by Drew Shindell at NASA's Goddard Institute for Space Studies in New York, looks at how the climate effects of air pollutants and greenhouse gases could play out over time and geography.

The study analysed a suite of scenarios for the years 2000 to 2080, mixing annual rates of power-plant growth from 5% to 10% with various controls on SO2 and NOX pollution. SO2 is a precursor to sulphate aerosols and dominates the cooling effect, which varies depending on when plants adopt pollution controls. The sooner controls are put in place, the sooner the warming potential of CO2 kicks in.

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