Pollution is the process of making land, water, air, or other parts of the environment dirty and not safe or suitable to use. This can be done through the introduction of a contaminant into a natural environment, but the contaminant does not need to be tangible. Things as simple as light, sound, and temperature can be considered pollutants when introduced artificially into an environment.
Land Pollution
Land can become polluted by household garbage and by industrial waste. Commercial or industrial waste is a significant portion of solid waste. Much of it is classified as non-hazardous, such as construction material (wood, concrete, bricks, glass, etc.) and medical waste (bandages, surgical gloves, surgical instruments, discarded needles, etc.). Hazardous waste is any liquid, solid, or sludge waste that contains properties that are dangerous or potentially harmful to human health or the environment. Industries generate hazardous waste from mining, petroleum refining, pesticide manufacturing, and other chemical production. Households generate hazardous waste as well, including paints and solvents, motor oil, fluorescent lights, aerosol cans, and ammunition.
Water Pollution
Water pollution happens when chemicals or dangerous foreign substances are introduced to water, including chemicals, sewage, pesticides, and fertilizers from agricultural runoff, or metals like lead or mercury from industrial runoff.
According to the United Nations, 783 million people do not have access to clean water and around 2.5 billion do not have access to adequate sanitation. Adequate sanitation helps to keep sewage and other contaminants from entering the water supply.
About 80% of pollution in the marine environment comes from the land through sources like runoff. Water pollution can also severely affect marine life. Warming water can also be harmful. The artificial warming of water is called thermal pollution. It can happen when a factory or power plant that is using water to cool its operations ends up discharging hot water. This makes the water hold less oxygen, which can kill fish and wildlife. The sudden change of temperature in the body of water can also kill fish.
Nutrient pollution, also called eutrophication, is another type of water pollution. It is when nutrients, such as nitrogen are added into bodies of water. The nutrient works like fertilizer and makes algae grow at excessive rates. The algae block light from other plants. The plants die and their decomposition leads to less oxygen in the water. Less oxygen in the water kills aquatic animals.
Air Pollution
The air
we breathe has a very exact chemical composition; 99% of it is made up of
nitrogen, oxygen, water vapor, and inert gases. Air pollution occurs when
things that are not normally there are added to the air. A common type of air
pollution happens when people release particles into the air from burning
fuels. This pollution looks like soot, containing millions of tiny particles,
floating in the air.
Another common type of air pollution is dangerous
gases, such as sulfur dioxide, carbon monoxide, nitrogen oxides, and chemical
vapours. These can take part in further chemical reactions once they are in the
atmosphere, creating acid rain and smog. Other sources of air pollution can
come from within buildings, such as secondhand smoke.
Finally,
air pollution can take the form of greenhouse gases, such as carbon dioxide or
sulfur dioxide, which are warming the planet through the greenhouse effect. The greenhouse effect is when gases absorb
the infrared radiation that is released from the Earth, preventing the heat
from escaping. This is a natural process that keeps our atmosphere warm. If too
many gases are introduced into the atmosphere, though, more heat is trapped and
this can make the planet artificially warm.
Air pollution kills millions of people each
year. If the pollutant is highly toxic, the effects on health can be widespread
and severe. An irritant (e.g., particulates less than 10 micrometers) may cause
respiratory illnesses, cardiovascular disease, and increases in asthma. The
very young, the old, and those with vulnerable immune systems are most at risk
from air pollution. The air pollutant may be carcinogenic (e.g., some volatile
organic compounds) or biologically active (e.g., some viruses), or radioactive
(e.g., radon). Other air pollutants like carbon dioxide have an indirect impact
on human health through climate change.
Noise Pollution
Even
though humans cannot see or smell noise pollution, it still affects the
environment. Noise pollution happens when the sound coming from planes,
industry or other sources reaches harmful levels. Research
has shown that there are
direct links between noise and health, including stress-related illnesses, high
blood pressure, speech
interference, and hearing loss.
Underwater noise pollution coming from ships has been shown to upset whales' navigation systems and kill other species that depend on the natural underwater world. Noise also makes wild species communicate louder, which can shorten their lifespan.
Light Pollution
Most people cannot imagine
living without the modern convenience of electric lights. For the natural
world, though, lights have changed the way that days and nights work. Some
consequences of light pollution are:
- Some
birds sing at unnatural hours in the presence of artificial light.
- Scientists
have determined that long artificial days can affect migration schedules,
as they allow for longer feeding times.
- Streetlights
can confuse newly hatched sea turtles that rely on starlight
reflecting off the waves to guide them from the beach to the ocean. They
often head in the wrong direction.
- Light
pollution, called sky glow, also makes it difficult for astronomers, both
professional and amateur, to properly see the stars.
- Plant
flowering and developmental patterns can be entirely disrupted by
artificial light.
- Light
pollution could also be making smog worse by destroying nitrate radicals
that help the dispersion of smog.
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