Type Of Pollution On Land
Because we have covered the overview of the three main type of pollution – water pollution, air pollution and land pollution – in a previous article, in this article, we will be going in greater depth on land pollution.
Land pollution is defined as the degradation and degeneration of our land and its soil. With land pollution, not only is the ground and surrounding land affected, underground water supplies and other water bodies often get polluted eventually.
Land pollution is often a direct result of human activities, such as the indiscriminate dumping of waste materials like urban waste, industrial waste, human waste, mining waste and construction waste. In addition, practices like the indiscriminate use of insecticides and pesticides also lead to land pollution. Read more about the various human activities that cause land pollution.
The 2 Type of Pollution on Land
Nonetheless, regardless of the type of human activities that bring about land pollution, in general, there are two main type of pollution on land. Based on the definition of land pollution, ie. the degradation of land, land can be degraded when (i) the soil is contaminated with harmful substances, and (ii) when the soil loses the constituents that gives it its life-supporting capacity. These two type of pollution on land often take place together.
Below is an elaboration on these two type of pollution on land, and their effects.
Land pollution type 1: Soil Contamination
The contamination of soil – a form of soil degradation – is one type of pollution on land. This type of pollution on land refers to the introduction of foreign and harmful substances into soil, rendering it potentially harmful to the various forms of life that grow in it or come into contact with it.
Some examples of human activities that contaminate soil include the following:
- dumping of household, industrial or sewage waste at landfills, where the waste leeches harmful substances (e.g. engine oil, heavy metals) into the soil and contaminate it.
- excessive application of synthetic fertilizers and/or pesticides in agriculture, where toxic chemicals (e.g. dioxin, DDT) from these farming products leech into the soil and contaminate it.
- mining activities, where heavy metals, sulfuric acid and other toxic chemicals used in the mining process leeches from mining waste into the soil, contaminating it
- leakage of untreated sewage from underground sewage pipes into the surrounding soil
- the emission of acid-rain forming air pollutants (e.g. sulfur dioxide), as well as the extensive use of acid-forming nitrogen fertilizers, which increase the acid content of the contaminated soil
- improper irrigation practices that lead to soil salination (i.e. accumulation of free salts in soil that lead to soil degradation)
When there is contamination of soil with foreign (and often toxic) substances, substantial changes occur in the chemistry of the soil. These changes in turn affect the well-being of plants and animal life living in the soil, as well as the ecosystems that the soil supports.
In cases of serious soil contamination, entire populations of organisms (eg. plants, earthworms and other animals usually lower down in the food chains) that come into direct contact with the soil could be destroyed. This could in turn affect the animals higher up food chains. For example, the destruction of all the soil organisms and plants in a toxin-contaminated land area could mean that birds living in that ecosystem no longer have food. These birds would either have to search for new sources of food elsewhere, or risk starving to death.
In cases of less severe soil contamination, the organisms lower down the food chains (e.g. plants, earthworms, etc) may bio-accumulate the toxic substances in their bodies, and the effects of the toxins may bio-magnify in the higher order animals as you go higher up the food chains. For example, the effects of toxicity in birds that feed on the contaminated earthworms might be seen in the weakening of their egg shells, lowering of their productivity rates, etc.
Land pollution type 2: Loss of Original Constituents
The second type of pollution on land occurs when soil loses the original constituents that gives it its life-supporting capacity – a form of soil degradation. Some of the processes that bring about this type of pollution on land include soil erosion and desertification.
With soil erosion, topsoil is often removed (by actions of wind, water, ice, or simply gravity) at a rate faster than soil-forming processes are able to replace the soil. Although some degree of erosion is necessary in nature for healthy ecosystems, excessive erosion (often a result of human activities) is problematic. Erosion often leads to the loss of organic matter and nutrients from the soil, causing the land to lose its original soil structure and ability to support plant life. Crop yields from that piece of land may be substantially reduced. In other words, the quality of the soil has degraded.
In turn, desertification is the degradation of drylands – arid soil is rendered barren and becomes incapable of supporting plant life. Human factors like intense population growth in already fragile drylands can create immense pressures to produce sufficient food for the growing population in the area, as such excerbating problems of overgazing or overcultivation. Overgrazing and overcultivation then deplete the dryland of nutrients faster than they can be replenished – the dryland is stripped of its already limited nutrients. The loss of vegetation cover then increases the rate of soil erosion, which leads to further soil degradation in that dryland.
Relationship Between the 2 Type of Pollution on Land
Soil contamination and the loss of original constituents in the soil both bring about degradation of land, i.e. land pollution, and they often occur together (though not always).
Take the case of soil acidification. The acid content of the contaminated soil increases substantially as a result of excessive use of acid-forming nitrogen fertilizers or precipitation of acid rain over the contaminated land. The acidic soil increases the availability of manganese and aluminum in the soil, sometimes to toxic levels that can affect the growth of the plant roots.
At the same time, the acidic soil reduces the availability of soil calcium and magnesium, which are crucial for healthy plant growth. The acidic soil can also kill some of the bacteria fungi and earthworms in the soil, as such reducing the breakdown and release of nutrients from organic matter from the soil.
In other words, the original constitution of the contaminated soil has been altered, and the life-supporting ability of the soil has been greatly reduced or degraded.
Read related articles on land pollution:
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