water pollution

LEARNING OBJECTIVES

By the end of this lesson you should be able to:

• Describe water pollution
• Explain the types of water pollution
• Explain about different water contaminants
• Explain different methods of control of water pollution

Water is crucial to life. We use water for drinking, cooking, washing, and other different human activities. Two-thirds of the surface of the earth is water, yet we are facing water scarcity to date. With the continued increase in population and pollution, water demand has increased as the number of stable water decreases. Water pollution refers to the contamination of water bodies, normally as a result of the activities of humans. Water bodies include oceans, seas, rivers, lakes, groundwater, and aquifers. Water pollution occurs upon the introduction of pollutants into the natural environment. For example, the release of inadequately treated wastewater into water bodies can result in the degradation of aquatic ecosystems. This can result in public health problems for people and animals downstream. They may use this polluted river water for drinking, bathing by humans, or irrigation.

TYPES OF WATER POLLUTION

There are two major types of water pollution - surface water pollution, and groundwater pollution. 

Surface water pollution

This refers to the pollution that contaminates water found on the surface of the earth. It includes the pollution of lakes, rivers, and oceans. A subset of this type of pollution is marine pollution. The major path of entry of contaminants to the sea is through the rivers. For example, industrial wastes and discharged sewage in rivers pour into the ocean. The ocean may become contaminated through liquid chemicals or through debris.

Groundwater pollution

This is the pollution of water that is found below the surface of the earth. Surface water and groundwater interact. Groundwater pollution is not classified as surface water pollution because groundwater aquifers are prone to contamination from sources that do not directly affect surface water bodies. Major causes of groundwater contamination include the presence of naturally occurring contaminants, commercial and industrial leaks, fertilizers leaching, and sewage.

CATEGORIES OF POLLUTION SOURCES

Groundwater and surface water have been studies and managed separately even though they are interrelated. Surface water seeps through the soil thus becoming groundwater. Groundwater can also feed sources of surface water. Sources of surface water pollution are mainly grouped into two based on their origin.

Point sources

Contamination of a waterway from a single, identifiable source like a ditch is called point source water pollution. Examples of sources falling in this category include sewage treatment plant discharges and city storm drain.

Non-point sources

Diffuse contamination that does not originate from a single source is called non-point source pollution. This type of pollution is mainly the cumulative effect of little amounts of contaminants gathered from different sources in an area. For example, leaching of nitrogen compounds from fertilized agricultural lands.

CONTAMINANTS AND THEIR SOURCES

The specific contaminants that result in water pollution include a wide range of chemicals, physical changes like elevated temperatures, and pathogens.  While many of the chemicals that are regulated occur naturally (calcium, iron, sodium, manganese, etc.) concentration determines what is a natural water component, and what is a contaminant. Higher concentrations of naturally occurring substances may have a negative effect on aquatic flora and fauna.

Pathogens

Pathogens are disease-causing microorganisms. They can produce waterborne diseases in either animal or human hosts. High pathogen levels may be a result of inadequately treated sewage release or pit latrines.

Organic and inorganic contaminants

Organic water pollutants include: detergents, disinfection by-products like chloroform, petroleum hydrocarbons like diesel fuel and lubricants, insecticides, and herbicides.

Inorganic water pollutants include: acidity resulting from industrial discharges, ammonia from food processing waste, chemical waste from industries, and fertilizers containing phosphates and nitrates.

CONTROL OF WATER POLLUTION

The following are some of the major methods of control of water pollution:

• Municipal wastewater treatment. Centralized sewage treatment plants should be used to treat water before releasing it. This helps to remove pollutants in water and reduce water pollution.
• On-site sanitation. Businesses and households that are not served by a treatment plant should have a septic tank to pre-treat wastewater before releasing it. This reduces groundwater pollution.
• Industrial wastewater management. Industries should treat their wastewater to remove contaminants.
• Agricultural wastewater treatment. Agricultural wastewater is normally contaminated with chemicals used in the farm like insecticides and herbicides. This water should be treated before release to reduce water pollution.
• Erosion and sediment control. Soil and sediments from farms, construction, or mining sites may pollute water when carried by water. Proper measures should be put in place to reduce water contamination. The use of sediment basins, silt fences, and mulching can help reduce water contamination from soil and sediments.

HOW CAN WE HELP TO REDUCE WATER POLLUTION?

It is our responsibility to reduce water pollution. Below is a list of things you can do to help reduce water pollution:

• Avoid disposing of household cleaning agents and chemicals down the sink or toilet. Follow the recommended disposal protocol of chemicals.
• Avoid pouring oil, fat, or grease down the sink.
• Avoid flushing drugs down the toilet. Follow the proper disposal recommendations.
• Minimize the use of inorganic fertilizers, pesticides, herbicides, and insecticides.
• Avoid dumping plastic wastes in waterways.