Three Common Indicators in Water Quality Monitoring

Writer： admin Time：2024-07-09 13:35:20 Browse：445℃

Water quality parameter analysis is categorized into three main groups: organic chemical indicators, inorganic chemical indicators, and physical property indicators. Different water quality parameters can indicate various water quality issues. Professional sensors are capable of accurately monitoring parameter data. Today, we will provide a brief analysis of several common parameter indicators in water quality analysis.

Organic chemical indicators

01 Dissolved oxygen (DO)

This refers to the molecular state dissolved in water. The content of dissolved oxygen in water is influenced by factors such as atmospheric pressure, water temperature, and salt content. A decrease in atmospheric pressure, an increase in water temperature, and an increase in salt content will lead to a decrease in dissolved oxygen content.

02 Chemical oxygen demand (COD)

This refers to the amount of oxidant consumed by oxidizing reducing substances in water. It reflects the degree of pollution of water by reducing substances such as organic matter and inorganic substances.

03 Permanganate Index, Oxygen Demand (CODMn)

This is a common indicator reflecting the pollution of organic and inorganic oxidizable substances in water bodies. It reflects the amount of inorganic and organic matter suspended and dissolved in water that can be oxidized by potassium permanganate.

04 Biochemical Oxygen Demand (BOD)

This refers to the amount of dissolved oxygen consumed by aerobic microorganisms in the biochemical oxidation process of organic matter in water. BOD is a comprehensive indicator reflecting the degree of organic pollution in water bodies.

05 Total Phosphorus (TP)

Total phosphorus is the main indicator for controlling eutrophication of water bodies. It is measured by the total amount of various forms of phosphorus in water that can be oxidized into phosphate by strong oxidizing substances.

06 Ammonia nitrogen (NH3-N)

This refers to nitrogen in the form of free ammonia NH3 and ionic ammonia NH4+ in water. When the ammonia nitrogen content is high, it is toxic to fish and can have varying degrees of harm to the human body.

07 Total nitrogen (TN)

This refers to the total amount of various forms of inorganic and organic nitrogen in water. It is often used to indicate the degree of nutrient pollution in water.

08 Total organic carbon (TOC)

This is a comprehensive indicator of the total amount of organic matter in water bodies expressed in terms of carbon content.

09 Total oxygen demand (TOD)

It refers to the amount of oxygen required for the oxidation of organic matter in water during combustion. TOD can only reflect the amount of oxygen required for almost all organic matter to become CO2, H2O, NO, SO2 after combustion. It is closer to the theoretical oxygen demand value than BOD and COD.

Inorganic Chemical Indicators

01 Hardness

Hardness was originally used to indicate the degree of soap foaming in water. Nowadays, chemical methods are used to convert the content of Ca and Mg ions in water into the corresponding amount of CaCO3 to calculate the hardness value, which is expressed in mg/L.

02 pH Value

The pH value indicates the strength of acidity and alkalinity in water, expressed as the negative logarithm of the activity of hydrogen ions in the solution. pH represents the most basic property of water. It can control the dissociation degree of weak acids and weak bases in water, reduce the toxicity of chlorides, ammonia, hydrogen sulfide, etc., and prevent the release of heavy metals in sediments. It affects changes in water quality, the growth and decline of biological reproduction, corrosiveness, water treatment effects, etc.

03 Conductivity

The conductivity of water is related to the amount of inorganic acids, alkalis, and salts it contains. This indicator is often used to infer the total concentration or salt content of ions in water. Different types of water have different conductivity.

04 Oxidation Reduction Potential

Oxidation reduction potential is the comprehensive result of the oxidation-reduction reaction between various oxidizing substances and reducing substances in water. The redox potential of the water body must be measured on site.

Physical Property Indicators

01 Turbidity 

Turbidity is the degree of obstruction caused by suspended matter in the water to the transmission of light. When the water contains suspended matter such as silt, clay, organic matter, inorganic matter, plankton, and microorganisms, it can scatter or absorb light, and the turbidity is large.

02 Transparency 

Transparency refers to the clarity of the water sample. Clean water is transparent. Transparency is the opposite of turbidity. The more suspended matter and colloidal particles in the water, the lower its transparency.

03 TSS
TSS is solid pollutants in the water that mainly exist in the form of suspended, colloidal, and dissolved states. Suspended solid pollutants are usually called suspended matter, which refers to impurities, inorganic matter such as silt, organic matter, and plankton produced by the decay of plants and animals.