Understanding Pollution Sources, Types, and Impacts
Sources of Pollution
According to their origin, there are several sources that determine the type of contamination: natural and artificial (or man-made).
Natural Sources of Pollution
Natural sources encompass pollutant emissions generated by the activity of the biosphere, hydrosphere, and geosphere:
- Volcanic eruptions: Contribute sulfur compounds and a large number of particles to the atmosphere.
- Forest fires: Occur naturally and emit high concentrations of CO2, smoke, and dust.
- Living activities: Include electrical discharges during storms, leading to the formation of nitrogen oxides that oxidize atmospheric nitrogen. Sea salt particles are emitted into the air by strong winds, transferring particles from arid regions to other areas.
Artificial Sources of Pollution
Artificial sources stem primarily from human actions, mainly from fossil fuel use (coal, etc.) in homes, transport, industry, agriculture, and livestock farming.
Types of Pollutants
Air pollutants are considered to be chemicals and forms of energy that, at certain concentrations, can cause discomfort, damage, or risks to people or ecosystems. The residence time is the length of time a pollutant can stay in the atmosphere.
Forms of Energy as Pollutants
The second major group of pollutants consists of forms of energy, divided into three types:
- Ionizing radiation: A series of particles or electromagnetic waves that can ionize atoms of matter, directly altering their function and structure. When absorbed by living beings, it may cause birth defects or cancer.
- Non-ionizing radiation: Waves that do not alter the structure of matter and do not cause the ionization of atoms. The effects depend on the intensity of the electromagnetic field and the time of exposure, and can include nervous system or hormonal disorders.
- Noise: A special type of atmospheric pollution with a major impact on the population.
Emission Characteristics
Emission characteristics are determined by the nature of the pollutant (gas or particles). When the temperature of a gas emission is higher than the average, the gas rises, facilitating its dispersion.
Atmospheric Conditions
Atmospheric conditions determine the state and movement of air masses, determining their stability or instability and the spread of pollutants.
- Air temperature and variations with height (lapse rate): Determine the movement of air masses and can lead to temperature inversions, hindering dispersion.
- Winds: Elements that disperse pollutants, depending on their direction, speed, and turbulence.
- Precipitation: Has a washing effect on the atmosphere, dragging pollutants to the ground. Storms favor this process.
Geographical and Topographical Characteristics
Geographical and topographical features influence the origin of winds that carry pollutants or cause their accumulation.
Coastal Areas
Sea breeze systems cause daytime contaminants to move inland, while at night, pollutants move towards the sea in a cyclical motion.
Mountain Areas
Presence of Plant Mass
Decreases the amount of air pollution by slowing the wind speed, facilitating the deposition of particles. The vegetation absorbs CO2 for photosynthesis, acting as a carbon sink.
Presence of Urban Centers
Influences the movement of air masses, decreasing or slowing their speed and forming turbulence. The heat island effect occurs, where the temperature inside the city is higher than the periphery due to the heat produced by combustion in vehicles. This brings out the urban breeze, a cyclic circulation of cold air masses from the periphery. These factors contribute to hindering the spread of contaminants, promoting their concentration and causing the formation of an urban pollution dome, increased by anticyclonic situations and removable by the arrival of cold fronts that bring wind and rain to the city.