How do humans pollute underground aquafers? What can be done to prevent it?

Question

How do landfills pollute aquafers? What else pollutes our underground water? If possible, provide sources, as I am doing this for a research paper.

Answer 1

Since you are doing a research paper, you will only be able to use my answer as a start.

Essentially the pollution of ground water occurs from what are called Point Sources and Non-Point Sources. These are pretty simple conceptually. Some are just a single place where the pollution happens and others where the pollution happens over large areas.

Some Point Sources are:
(1) Mines
(2) Injection Wells
(3) Factories or spill sites of specific location and generally large
(4) Landfill or waste storage dumps.

Some Non-Point Sources are:
(1) Farms with their chemicals
(2) Roadways where the oil and gasoline and tar migrate slowly and over large areas
(3) Home chemical use on lawns and gardens
(4) Air Pollution raining down on the land and becoming a water pollution item.
(5) Gas diffusion such as CO2 emissions getting into water or SO2.

The transport of pollution in the ground water aquifers is a complex and really poorly described phenomena. Water does travel under ground in defined streams as well as by general diffusive stream motion. Sometimes it enters and exits surface streams. Mammoth Cave in Kentucky is an underground stream system that is directly connected to the Green River adjacent to the cave system underground. In the cave this is called the New River.

The transport of pollution in an aquifer may be by direct flow, chemical diffusion, or by chemical process. The entry into ground water of one chemical may dislodge a chemical already present or may cause it to become immobile.

This fits tightly with water purification processes. The process of making hydrolic cements and mortar is at critical understanding here. If you take a modern water purification plant it generally is a 4 step process. This process may happen underground naturally or it may be reversed or interrupted by chemical additions. It can be accelerated underground by introduction of chemicals as well.

The process is this generally
(1) Chemical kill down to get out the biotic material by addition of a strong ion such as chlorine.
(2) The water is then settled with the introduction of a quick lime or calcium carbonate or calcium oxide to the water.
(3) The water is then filtered through a sand bed to create a cement or mortar to make an essentially insoluble precipitate in the water that attaches to the sand.
(4) The water is then filtered through a simple charcoal filter system to pick up volatile compounds and some other compounds.

This process removes pretty much anything except arsenic or too much salt.

Salt may be added at this point to reduce the "hardness" of the water.

This process needs to be looked at when water moves through the underground regions.

Also the oxidation of some items is rare underground but may be assisted.

Understanding the movement of water and thus pollution in the underground system is one of understanding the unique local structures. Water may move in any number of the 3 dimensions underground. The movement of pollutants may be inhibited by sedimentation or accelerated by erosion. The temperature of the water entering the area needs to be considered. Hot water relative to the ground temperature will cause solution of ions. Cold water will cause precipitation. Prolonged dry periods may cause extreme mobility when water reappears in a region.

Typically I would give you a lot of sources to look up. Since you are researching this, you should see this as a help of a general layout of where to look and some key words.

Answer 2

Any dirty water being dumped on the ground can soak into the ground and the aquifer below. The major source is rain water runoff from paved areas, but pit toilets, buried garbage and anything icky that can get washed into the ground by water is a potential source of contamination of aquifers.

Answer 3

Impossible to prevent but can reduce, the high income getting polluters must change their mind. After all the resources petroleum deposits, wild life trees, have used up the nature could answer it.