WATER CYCLE

How are groundwater and surface water connected?

Percolation and Seepage

Groundwater pollution (also called groundwater contamination) occurs when pollutants are released to the ground and make their way down into groundwater.

It can also occur naturally due to the presence of a minor and unwanted constituent, contaminant or impurity in the groundwater, in which case it is more likely referred to as contamination rather than pollution.

The pollutant creates a contaminant plume within an aquifer. Movement of water and dispersion within the aquifer spreads the pollutant over a wider area.

Its advancing boundary, often called a plume edge, can intersect with groundwater wells or daylight into surface water such as seeps and spring, making the water supplies unsafe for humans and wildlife.

The movement of the plume, called a plume front, may be analyzed through a hydrological transport model or groundwater model.

Analysis of groundwater pollution may focus on soil characteristics and site geology, hydrogeology, hydrology, and the nature of the contaminants.

Pollution can occur from on-site sanitation systems, landfills, effluent from wastewater treatment plants, leaking sewers, petrol stations or from over application of fertilizers in agriculture.

Pollution (or contamination) can also occur from naturally occurring contaminants, such as arsenic or fluoride.

Using polluted groundwater causes hazards to public health through poisoning or the spread of disease.

Earth = the natural filter

Groundwater pollution

• Very cold, no bacterial breakdown

• Very slow water movement: recharge can take 100’s or 1000’s of years

• Pollutants can stick to rocks in aquifer and pollute new water

What Pollutes Groundwater?

Natural SourcesSome substances found naturally in rocks or soils, such as iron, manganese, arsenic, chlorides, fluorides, sulfates, or radio nuclides, can become dissolved in ground water.

•Septic Systems – faulty privies , drainage systems,•Improper Disposal of Hazardous Waste•Landfills - lechates•Releases and Spills from Stored tanks•Chemicals and Petroleum Products•Injection Wells/Floor Drains•Surface Impoundments•Sewers and Other Pipelines•Pesticide and Fertilizer Use•Improperly Constructed Wells•Improperly Abandoned Wells•Mining Activities•hazardous waste - deep well injection•leaky underground storage tanks

How can we protect groundwater?• Prevention is the key…

– Monitor aquifers & landfills– Requirements for old fuel tanks

• Leak detection system– Stricter regulations on toxic waste disposal

• Above-ground storage of toxic waste