Essential Water Quality Parameters and Their Role in Ecosystem Health

Table of Contents

• Introduction to Water Quality
• Categories of Water Quality
• Importance of Water Quality
• Indicators of Water Quality Analysis
• a. Physical parameters
• b. Chemical parameters
• c. Biological parameters
• Five core parameters of ambient water quality
• Freshwater pollution throughout the world
• Conclusion

Introduction to Water Quality

Water quality refers to the physical, chemical, and biological characteristics of water in relation to established standards. These standards are typically based on data obtained from the water treatment process and serve as benchmarks for evaluating water from various sources, such as surface water and groundwater.

Assessing water quality involves examining the physical, chemical, and biological attributes of water, considering both natural and human-induced factors, as well as its potential applications. The quality of water is a key indicator of ecosystem health, human safety in water use, and the extent of water pollution. It also helps determine the suitability of water for various purposes, including domestic use, drinking, aquatic life, irrigation, and industrial needs, which are critical when considering water supply options.

Categories of Water Quality

Water quality is typically classified into four categories:

1. Potable Water: Safe for drinking, with a pleasant taste, and suitable for domestic use.
2. Palatable Water: Aesthetically pleasing, though it may contain pollutants that are not harmful to human health.
3. Contaminated (Polluted) Water: Unsuitable for drinking or household use due to the presence of undesirable physical or chemical contaminants.
4. Infected Water: Water that has been contaminated by pathogenic microorganisms.

Importance of Water Quality

• Freshwater is critical for global dependency, despite constituting only 2.5% of the Earth's water resources, with around 70% of the planet covered by water.
• Out of this 2.5% freshwater, just 1.2% is accessible, while the majority is locked in glaciers and ice caps (68.7%) and groundwater (30.1%).
• Preserving freshwater is essential for protecting human health and aquatic ecosystems, which provide key resources such as drinking water, food, and recreational activities.
• Given the rising demand for water and limited freshwater availability, assessing and monitoring water quality is crucial for ensuring sustainable water supply for societal, economic, and conservation needs.
• Site-specific water quality assessments help trace the sources and pathways of harmful chemicals and contaminants, which are largely influenced by ecological, geological, and human activities.
• Identifying the sources of contamination is vital for reducing potential health risks and implementing effective water management strategies.

 

Indicators of Water Quality Analysis

Various parameters are used to assess the physical, chemical, and microbiological characteristics of water, as outlined below:

a. Physical parameters

• Physical indicators of water quality include temperature (Temp), electrical conductivity (EC), total suspended solids (TSS), total dissolved solids (TDS), turbidity, odor, color, clarity, and taste. 

b. Chemical parameters

• Chemical parameters include total hardness (TH), calcium hardness (CaH), magnesium hardness (MgH), chloride (Cl), chlorine residual, alkalinity, acidity, free CO2, dissolved oxygen (DO), biological oxygen demand (BOD), chemical oxygen demand (COD), toxic organic substances, and radioactive substances.

Here, the chemical parameters are further categorized as follows:

1. Cations

• Cations in water include calcium (Ca2+), magnesium (Mg2+), sodium (Na+), potassium (K+), and ammonium (NH4+) ions.

2. Anions 

• Anions in water consist of bicarbonate (HCO3–), carbonate (CO3–), chloride (Cl–), sulfate (SO42–), nitrate (NO3–), and fluoride (F–). 

3. Heavy metals 

• Heavy metals in water include iron (Fe), arsenic (As), zinc (Zn), aluminum (Al), manganese (Mn), cadmium (Cd), lead (Pb), copper (Cu), and nickel (Ni). 

c. Biological parameters

1. Microbiological parameters

• Biological indicators include bacteria (such as fecal coliform, Escherichia coli, Citrobacter species, Klebsiella pneumoniae, Staphylococcus aureus, Pseudomonas aeruginosa, Vibrio cholerae), as well as algae, viruses, and protozoa.

2. Benthic macroinvertebrates 

• Benthic macroinvertebrates, such as insects like mayflies (Ephemeroptera), stoneflies (Plecoptera), and caddisflies (Trichoptera), also known as EPT species, serve as biological indicators of surface water quality.

Five core parameters of ambient water quality

Sustainable Development Goal (SDG 6.3.2) assesses the percentage of water bodies that meet national ambient water quality standards. This is determined by evaluating five key parameters: 

• dissolved oxygen (DO) for surface water, 
• electrical conductivity (EC) for both surface and groundwater, 
• nitrogen (N) or nitrate (NO3–) for surface and groundwater, 
• phosphorus for surface water,
• pH for both surface and groundwater. 

These parameters provide valuable insights into the most common global stressors affecting water quality.

Freshwater pollution throughout the world

Water quality can be influenced by natural factors, but human activities have a much greater impact on most oceans, lakes, and rivers. Due to significant data gaps, both regionally and over time, accurately estimating the amount of contaminated freshwater and water bodies globally is highly challenging. Immediate action is needed to better understand the effects on water quality and to address the issues it poses worldwide.

Conclusion

Assessing water quality parameters before using water for drinking or other purposes is essential for minimizing public health risks and ensuring effective management strategies for public water supplies, industrial applications, and aquaculture.