Water Pollution

Causes of Water Pollution

Water pollution can originate from various sources, which can be broadly categorized into point sources and non-point sources.

Point Sources

Point sources refer to identifiable and localized sources of pollution, such as:

• Industrial Discharges: Factories may release pollutants directly into water bodies. For example, chemical plants might discharge hazardous substances like heavy metals.
• Sewage Treatment Plants: These facilities treat wastewater but sometimes release untreated or inadequately treated water into rivers and oceans.

Non-Point Sources

Non-point sources are diffuse and harder to trace, including:

• Agricultural Runoff: Pesticides, fertilizers, and animal waste from farms can wash into water bodies during rainfall.
• Urban Runoff: Stormwater from cities can carry oil, chemicals, and debris into lakes and rivers.

Effects of Water Pollution

The effects of water pollution are extensive and can be categorized into ecological, human health, and economic impacts.

Ecological Impacts

• Loss of Biodiversity: Pollutants can kill aquatic plants and animals, reducing biodiversity.
• Eutrophication: Excess nutrients can lead to algal blooms, depleting oxygen and harming aquatic life.

Human Health Impacts

• Waterborne Diseases: Polluted water can cause diseases such as cholera, hepatitis, and typhoid.
• Toxicity: Consumption of contaminated water can lead to chronic health issues like cancer and neurological disorders.

Economic Impacts

• Fishing Industry: Pollution can reduce fish populations, affecting livelihoods.
• Tourism: Polluted water bodies can deter tourists, impacting local economies.

Management Strategies

Altering human activity

• Legislation and policies to promote eco-friendly fertilizers and limit the use of chemical fertilizers and pesticides
• Limit the use of water and reuse greywater
• Opt for a sustainable irrigation method
• Use biological control for pests
• Use of rainwater harvesting systems

Controlling the release of pollutants

• Developing technologies to extract pollutants from water storage
• Developing voluntary campaigns for clean water storage
• Buffer Zones: Establishing vegetation buffers along waterways to filter runoff.

Clean-up and restoration

• Cleaning up pollutants from water storage (example: Dredging)
• Restocking lost or depleted populations
• Bioremediation - using microorganisms to break down pollutants.

Accumulation of plastic in Marine Environments

A major problem faced by our marine environments is the buildup of plastic waste in oceans and seas due to inadequate disposal and degradation processes - accumulation of plastic.

Sources:

• Land-based: Mismanaged waste, urban runoff, and storm drains.
• Ocean-based: Fishing nets, shipping, and maritime activities.

Types of Plastic:

• Macroplastics: Large items like bottles and bags.
• Microplastics: Tiny particles resulting from the breakdown of larger plastics.

Impacts:

• Wildlife: Entanglement and ingestion harm marine animals.
• Ecosystems: Plastics transport invasive species and release toxic chemicals.
• Food Chains: Microplastics enter the food web, affecting human health.

Eutrophication

Eutrophication is the process by which water bodies, for example: lakes, become overly enriched with nutrients causing a high amount of algal bloom leading to loss of aquatic life. Eutrophication is primarily caused by excessive use of fertilizers. When fertilizers used in nearby agricultural lands enter water bodies, they increase the concentration of nitrates and phosphates in the water. Algaes consume these nutrients, leading to population growth and extensive algal blooms. Such algal blooms restrict the flow of oxygen to lower layers of the water body, ultimately causing loss of aquatic life in the water body.

Causes:

1. Agricultural Runoff: Fertilizers containing nitrates and phosphates.
2. Sewage Discharge: Nutrient-rich wastewater.
3. Industrial Effluents: Nutrients from factories and treatment plants.

Impacts on Ecosystems:

1. Oxygen Depletion: The decomposition of algae consumes oxygen, causing hypoxia or anoxia.
2. Loss of Biodiversity: Fish and aquatic organisms die due to low oxygen levels.
3. Habitat Degradation: Dense algal mats block sunlight, disrupting photosynthesis.

Eutrophication Management Strategies

• Reducing Nutrient Inputs:
  • Use of organic fertilizers and controlled application.
  • Improved sewage treatment to remove nutrients.
• Buffer Zones: Planting vegetation along waterways to absorb runoff nutrients.
• Aeration: Adding oxygen to water bodies using pumps or fountains.
• Chemical Treatments: Using algaecides or phosphorous binders to reduce algae growth (caution needed to avoid further harm).

Water Quality

Water quality is a measure of the physical, chemical, and biological characteristics of water to determine its suitability for various uses (e.g., drinking, recreation, agriculture). It is important to measure water quality to implement management strategies and prioritize critical water bodies for conservation. It can be assessed by measuring dissolved oxygen, pH, turbidity, total dissolved solids (TDS) and concentration of nitrates.

Biochemical Oxygen Demand (BOD)

BOD measures the amount of organic matter in a water sample. It can indicate if a particular part of a water body is polluted with organic matter or not.

Organisms use oxygen in respiration. The faster their rate of respiration, the more oxygen they use. So, BOD indirectly determines the amount of organic matter and its respiration rate. The lower the BOD, the lesser amount of organic matter meaning that less oxygen is being removed from the water.

Following is the procedure for BOD:

• Take a sample of water
• Measure oxygen level
• Place the sample in a dark place in an air-tight container for 5 days (recommended for the temperature to be 20 degrees celsius)
• After 5 days, re-measure the oxygen level
• BOD is the difference between the two oxygen levels

Assessment:

• High BOD indicates pollution from organic waste (e.g., sewage, agricultural runoff).
• Low BOD reflects clean water with minimal organic contamination.