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Flashcards in Land Pollution (T4) Deck (6):

Define pollution..

They addition of any substance or form of energy to the environment at a rate faster than the environment can accommodate it by dispersion, breakdown, recycling or storage in some harmless form.


List three key examples of land pollution..

- farming
- deforestation
- human sewage and waste


How can farming damage the environment?

As a by-product of using pesticides and herbicides, some food chains can be damaged, often because pesticides tend to kill insects indiscriminately, as opposed to targeting a specific organism. Similarly, herbicides kill all weeds , including some beneficial food sources for animals and insects. This creates gaps in the food chain as once part of the food chain is wiped out, this can cause all sorts of problems up the chain - in the long run affecting humans too.

Fields that are intensively farmed often contain only one single crop species. This is called a mono-culture and means that the field cannot support the ecosystem it once did, so species have to find another habitat.

Improper disposal of farmland waste can accumulate and leach into nearby land, reducing its fertility and biodiversity. Wild plants often need poor soils to flourish and are out competed by weed species such as nettles and docks if the fertility of the land is too high.

The use of chemicals can have adverse effects on animals. In battery and intensive farming (eg: the farming of hens or the rearing of white veal calves) a large amount of veterinary intervention is needed to keep the animals healthy until slaughter. Also the indiscriminate use of antibiotics can in turn lead to super bugs which are resistant to the medication and can be passed onto humans.


What is deforestation?

The loss of whole habitats (not just trees).

It mainly occurs due to the demand for timber and new farming lands.


What are the main effects of deforestation on the environment?

A decrease in available water: fewer trees means less transpiration and photosynthesis, thus the water cycle is affected. The flow of water through a plant (the transpiration stream) is critical to producing water vapour in the atmosphere.

Soil erosion: soil exposed due to deforestation dries out under the sun and can be blown away by winds or washed away by rain.

Flooding: it can cause serious flooding as rainwater runs off the exposed soil rather than soaking into the ground.

Climate change: as the forests and their associated flora are removed, a greater amount of carbon dioxide is released into the atmosphere, disrupting the balance of atmospheric gases. Carbon dioxide is a greenhouse gas and the major contributor to global warming.


Explain how human sewage and waste can damage the environment...

Pollution by sewage is generally caused by poorly maintained sewage pipes and the accumulation of large amounts of waste.

The above is common in developing countries, but when floods occur (eg, New Orleans after hurricane Katrina) even countries with advanced sewage systems are affected.

Most bulky waste from the household goes to landfill sites which are carefully monitored in developing countries but still not free from poisonous chemicals. Construction and demolition debris from heavy industry is often poured into landfill which can cause asbestos and other harmful chemicals to spread into the surrounding environment.

Even common household items can contain poisonous metals, for example some smoke alarms contain radioactive americium.

Polluted liquids can ooze out into neighbouring land, which can in turn pollute local water sources.

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