dear friend,
RSC= (CO32-+HCO3-) - (Ca2++ Mg2+)
can anybody explain how to calculate the residual sodium carbonate? it is appreciated if you could provide with an example calculation. also what is the unit of the parameter? moles/L or Eq/L?
we can get the carbonate and bicarbonate from alkalinity calculation. ( then we get carbonate as CaCO3 and bicarbonate as CaCO3) so then how to apply to the equation ( have to convert it to as HCO3 and as CO3)
Dear Saman,
The residual sodium carbonate (RSC) equals the sum of the bicarbonate and carbonate concentrations minus the sum of the calcium and magnesium ion concentrations, where the ions are expressed in meq/L.
• RSC index = [HCO3- + CO32-] − [Ca2+ + Mg2+]
• RSC should not be higher than 1.25 and preferably less than +0.5 for considering the water use for irrigation.
As RSC increases, much of the calcium and some magnesium are precipitated from the solution when water is applied to soil, increasing the sodium percentages and the rate of sorption of sodium on soil particles which increases the potential for a sodium hazard. Best wishes.
what is the RSC value of following CO3 =186mg/L ,HCO3=310mg/L,Ca=82mg/L Mg=42 mg/L
RSC index = HCO3/61 + CO3/30 – Ca/20 – Mg/12 (in case the ionic concentrations are measured in mg/l or ppm as salts)
In our region, RSC < 2.5 me/lt considered as safe for irrigation water with EC < 2 ds/m.
RSC = [HCO3- + CO32-] − [Ca2+ + Mg2+]
If RSC is more than 2.5 then excess of Carbonate ions linked with sodium and form sodium carbonate which further a threat to the soil structure and different Physical properties which later on affected both our water and land productivity.
The Residual Sodium Carbonate (RSC) is a measure of the potential for water to be corrosive or scale-forming in irrigation water. It is calculated using the concentrations of bicarbonate, carbonate, and calcium ions in the water. The formula for calculating RSC is as follows:
���=(��32−+���3−)−(��2++��2+)RSC=(CO32−+HCO3−)−(Ca2++Mg2+)
Here's how you can calculate RSC:
Determine the concentrations of ions:
��32−CO32− and ���3−HCO3− are the concentrations of carbonate and bicarbonate ions, usually given in milliequivalents per liter (meq/L) or milligrams per liter (mg/L).
��2+Ca2+ and ��2+Mg2+ are the concentrations of calcium and magnesium ions, also usually given in meq/L or mg/L.
Substitute the values into the formula: ���=(��32−+���3−)−(��2++��2+)RSC=(CO32−+HCO3−)−(Ca2++Mg2+)
Calculate the result:
If the value is positive, the water is considered potentially scale-forming.
If the value is negative, the water is considered potentially corrosive.
It's important to note that RSC is just one factor to consider when assessing the suitability of water for irrigation. Other factors such as the SAR (Sodium Adsorption Ratio) and EC (Electrical Conductivity) should also be taken into account for a comprehensive evaluation of water quality for irrigation purposes. Additionally, local guidelines or standards may provide specific thresholds for acceptable RSC levels in irrigation water.
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