Environmental Engineering Reference
In-Depth Information
Effects of Volcanoes
Although volcanoes are natural events, they still have an impact on people's health, the environment, and other
organisms. A variety of gases are released into the atmosphere during a volcanic eruption, and the effects vary,
depending on the amount released, the location, the wind pattern, the height of discharge, and other factors.
The most abundant gases released during an eruption include water vapor (H
2
O), carbon dioxide (CO
2
), and
sulfur dioxide (SO
2
). Other gases released include carbon monoxide (CO), helium (He), hydrogen (H
2
), hydro-
gen chloride (HCl), hydrogen sulfide (H
2
S), and hydrogen fluoride (HF).
Posing the potentially most harmful effects on organisms and the environment are
•
Hydrogen fluoride (HF
)
,
also called sewer gas, which can cause respiratory tract irritation, bone degen-
eration, and pulmonary edema in high concentrations. At lower concentrations, exposure can cause eye
irritation, diarrhea, dizziness, excitement, and staggering. When HF coats grass and animals then ingest
it, poisoning can occur, as can bone degeneration and even death. HF also contributes to acid rain.
•
Carbon dioxide (CO
2
)
has a density greater than that of air, so it sinks and can kill animals, people, and
plants. The CO
2
replaces the air, so asphyxiation can occur in areas with abundant CO
2
. This gas can
also collect in soils, which can affect the microbial population in the soil and nutrient intake by plants.
•
Sulfur dioxide (SO
2
)
can lead to acid rain, air pollution, and smog at a local level. On a global level, it
can lower surface temperatures and exacerbate depletion of the ozone layer. SO
2
also can harm human
health mainly by affecting the respiratory system and also irritating skin, eyes, nose, and throat.
•
Hydrogen chloride (HCl)
causes irritation of the eyes, throat, and respiratory system. It can lead to acid
rain because of its solubility in water, as well as to loss of ozone.
Atmospheric Effects of Volcanoes
Because these volcanic gases are released into the atmosphere, the effects can be dramatic:
• Ozone can be broken down when reactions occur with HCl or SO
2
. Fortunately, the ozone depletion di-
minishes once the gases are reduced in the atmosphere.
• Volcanic gases can contribute to global warming because CO
2
and water vapor trap and absorb solar en-
ergy, raising the temperature of the planet over time.
• The gases can contribute to the haze effect (smog), in which particulate matter in the atmosphere blocks
out solar radiation and ultimately can lower the mean global temperature.
These effects usually are not long-term when they occur because of volcanic activity, but they're exacerbated
by human activities that also release these gases into the atmosphere.
Solar Radiation, Intensity, and Seasons
Solar energy affects the entire dynamic of the planet, including climate, weather, biodiversity, and life's pro-
ductivity. The amount of solar energy the Earth receives depends on the tilt of Earth's axis, its rotation around
that axis, and its revolution around the Sun. One rotation equals one day, and a revolution equals a year.
Throughout the year, Earth has two
equinoxes,
times when day and night are equal. Toward the end of March,
the
vernal equinox
occurs, signifying the start of spring in the Northern Hemisphere and fall in the Southern
Hemisphere. The
autumnal equinox,
marking the beginning of fall in the Northern Hemisphere and spring in
the Southern Hemisphere, occurs at the end of September.
