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Examples of soil pollution

Themes: What is soil pollution | Examples of soil pollution | Cleaning up soil pollution | Quiz

Pesticide application using a Tractor Mounted Sprayer. Where used responsibly, as here, pesticides are beneficial. Innapropriate use can lead to pollution. Image credit: Defra, Crown Copyright. Some soil pollution can occur naturally. In the course of soil formation some rocks containing undesirable amounts of particular elements will weather and breakdown and pass these elements on to the soil where they enter the domain of plant roots. Plants can take up these in abnormal quantities and while the plant may survive, animals foraging on them may become sick or die and humans can also be affected. There are many examples worldwide where either excessive amounts of particular elements in soil have created health problems in a particular region

By far the biggest danger from pollutants is, however, man-made and can be traced back to emissions from industry in the last two hundred years, the huge increase in domestic waste in the last few decades, especially sewage sludge and its disposal to land, and the increased used of pesticides and fertilisers on farm crops. These are now recognised as potentially damaging to land and hence are a matter of concern in the drive to maintain the quality of our soil. The early contamination of land from mining and smelting, with waste being distributed around the land by air and water, has left an unwanted inheritance. For example, lead, nickel, copper and zinc mining has left major pollution in some parts of the world. In recent years the processes of nuclear fission in relation to the testing of atomic bombs and the nuclear power stations have provided a legacy of radionuclides, for example radium and caesium, which have contaminated some soils.

Sewage sludge is waste derived mainly from households and industry that is in the process of undergoing treatment prior to its disposal. The variety of sources that make up sewage sludge means that it varies in its composition but can contain a wide variety of undesirable elements. Some of these elements have been passed to the land in the last decades as sewage sludge was seen as a potential fertiliser and spread on the land. The sludge contains significant amounts of nitrogen, phosphorus and other nutrients and because of this has been considered as a potentially valuable source of fertiliser. Furthermore, because of its content of organic matter it was seen as a useful soil conditioner but it also contains a range of metals some of which in the past have been present in large amounts. In recent years as the potential harm of sewage sludge to land came to be recognised, so more care has been exercised in ensuring that the content of heavy metals of sewage sludge applied to land is reduced. Similar awareness now exists in relation to the possibilities of adding pathogens to soils from sewage sludge.

Themes: What is soil pollution | Examples of soil pollution | Cleaning up soil pollution | Quiz