Measuring Water Quality (DP IB Environmental Systems & Societies (ESS))

Measuring Water Quality

• To directly test the quality of aquatic ecosystems, various parameters can be measured and analysed. 

Water testing is conveniently carried out in the field using digital probes

Some of the different water quality parameters that can be used are:

   1. pH

• pH measures the acidity or alkalinity of water

• pH impacts the survival, growth, and reproduction of aquatic organisms

• Unusual pH levels can indicate pollution, acidification, or other environmental changes

   2. Temperature

• Temperature measures the degree of heat or coldness of water

• Temperature affects the metabolic rates, behaviour, and distribution of aquatic organisms

• Abnormal temperature fluctuations can stress or harm aquatic life

   3. Dissolved Oxygen (DO)

• Dissolved oxygen measures the amount of oxygen dissolved in water

• Adequate oxygen levels are crucial for the survival of aquatic organisms

• Low dissolved oxygen can lead to hypoxia, suffocating or killing aquatic life

   4. Suspended Solids (Turbidity)

• Turbidity refers to the level of suspended solids, such as sediment, organic matter, or algae, in water

• High turbidity reduces water clarity, light penetration, and can disrupt aquatic habitats

• Turbidity measurements provide insights into sedimentation, erosion, and overall water quality

   5. Metals

• Testing for metals, such as mercury, lead, cadmium, or arsenic, assesses contamination levels

• Metals can accumulate in aquatic organisms, posing risks to their health and ecosystem integrity

• Monitoring metal concentrations helps identify pollution sources and evaluate potential ecological impacts

   6. Nitrates and Phosphates

• Measuring nitrates and phosphates assesses nutrient pollution in water

• High nutrient levels can lead to eutrophication, harmful algal blooms, and oxygen depletion

• Monitoring nutrient concentrations helps manage nutrient inputs and prevent water quality degradation

• These parameters provide valuable information about the health and condition of aquatic ecosystems

  • Most of these parameters can be measured using standard water testing kits

  • The measurements obtained using these kits can be compared to standardised charts, colour charts, or tables that feature known samples

  • For example, when analysing water for nitrates, uncontaminated water typically contains less than 5 mg dm⁻³, whilst polluted water may contain 5–15 mg dm⁻³

  • It is crucial to compare readings from various locations, such as upstream and downstream of a sewage outlet or factory, to assess any potential impacts on the ecosystem

Photo by Tarek Badr on Unsplash 

Measuring water pollution parameters near factory outlets is vital to assessing the impact on ecosystems

• Monitoring and analysing these parameters at regular intervals help scientists, environmental agencies, and policymakers understand the overall water quality, identify potential issues, and implement appropriate management strategies to protect and restore aquatic ecosystems