10 Questions
What is the term for the residue of TSS and TDS after heating to dryness for a defined period of time and at a specific temperature?
Fixed solids
What is the unit of measurement for electrical conductivity in S.I. units?
milliSiemens/m (mS/m)
What is the typical conductivity of seawater?
5 S/m
What is the formula to estimate the TDS value of water from its electrical conductivity?
TDS (mg/L) ≅ EC (dS/m) × (0.64)
What is the pH range for natural water?
5-10
What is the primary factor that determines the presence of specific aquatic species in a water body?
Salinity
What is the unit of measurement for salinity?
Parts per thousand
Which of the following fish species can tolerate saltwater after they smolt?
Salmon and trout
What is the term for the suspended solids that are retained on the top of the filter?
Total suspended solids
What is the classification for water with a TDS of 5000 mg/L?
Freshwater
Study Notes
Salinity
- Salinity is the total concentration of all ions and dissolved salts in a given volume of water.
- It determines the presence of aquatic animals in a water body.
- Expressed in parts per thousand by weight (ppt), e.g., 1 gram of salt in 1000 grams of water is 1 g/kg or 1 ppt.
- Salinity ranges from 0 ppt in fresh water to 35 ppt in the open ocean.
- Optimum salinity ranges for culture ponds: 0.01-1 ppt for freshwater species and 20-35 ppt for brackish water species.
Solids in Water
- Solids in water consist of suspended solids (retained on a filter) and dissolved solids (pass through a filter).
- The residue left after evaporation is called total dissolved solids (TDS).
- Total solid (TS) = Total dissolved solid (TDS) + Total suspended solid (TSS).
Classification of Water by TDS
- Freshwater: 5000 mg/L TDS.
Solids Measurement
- Fixed solids: residue left after heating to dryness for a defined period at a specific temperature.
- Volatile solids: solids lost on ignition (heating to 550°C).
- Formulas for calculating total solids, total dissolved solids, and total suspended solids.
Electrical Conductivity (EC)
- Measures the ability of a solution to carry or conduct an electrical current.
- Increases with the concentration of ions in solution.
- Units: micromhos/cm (U.S.), milliSiemens/m (mS/m), or deciSiemens/m (dS/m).
- EC can be used to estimate TDS value of water.
Water pH
- Defined as the negative logarithm of the hydrogen ion concentration.
- Measures hydrogen ion activity or acidity/alkalinity, ranging from 0-14.
- Natural water pH range: 5-10.
- Optimum water pH range in aquaculture: 6.5-9.
Learn about salinity, its measurement, and its impact on aquatic life. Understand how salinity affects the presence of species in a water body and its range in different types of water. Test your knowledge of salinity and its significance in aquatic ecosystems.
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