What is the methodology for adding any contaminants of fixed concentration(100 ppm, 1000 ppm) to fixed amount of soil for leaching studies?
DEAR ARJUN
THE following illustrations will help you to get answer.
A measurement of 6 mg/kg is the same as 6 ppm or 6,000 ppb, which is equal to6,000 ug/kg. Concentrations of chemicals in water are typically measured in units of the mass of chemical (milligrams, mg or micrograms, ug) per volume of water (liter, L, l). ... Therefore, 1 g/ m3 = 1 mg/L = 1 ppm .
PPM = parts per million. PPM is a term used in chemistry to denote a very, very low concentration of a solution. One gram in 1000 ml is 1000 ppm and onethousandth of a gram (0.001g) in 1000 ml is one ppm. One thousanth of a gram isone milligram and 1000 ml is one liter, so that 1 ppm = 1 mg per liter = mg/Liter
A measurement of 6 mg/kg is the same as 6 ppm or 6,000 ppb, which is equal to6,000 ug/kg. Concentrations of chemicals in water are typically mea- sured in units of the mass of chemical (milligrams, mg or micrograms, ug) per volume of water (liter, L, l).
you should dry a soil sample, calculate the humidity at saturation and reintegrate the saturation with the solution you would like to to test. The volume depends on soil texture.
Another option to spike an uncontaminated soil is to mix it in air-dried condition with an apropriate amount of a contaminated soil. Thereby the particle size distribution of both soils shall be in the same range in order to enable the processing of a homogenious mixture and avoid segregation. This method produces not the exact desired concentration. But if a certain tolerance is fine for you, this method works quite well. In any case you should store a spiked soil for a sufficient time (equilibrium adjustment) before starting the subsequent experiments.
First you should measure Cr (52 g/mol) content of your soil(s). Then calculate the deficit amount to reach the targeted concentrations. If your soil contain no Cr (this is not possible) or you just want to add 100 and 1000 mg/kg Cr in this case the calculation whould be:
100 mg and 1000 mg Cr should be added to 1000 g soil. If you use K2Cr2O7 for this Cr addition the the required amounts of K2Cr2O7 ( 294,185 g/mole) are: 100*294.185/104 =282,87 mg/kg soil and 1000*294.185/104 =2828.7 mg/kg soil
1% = 10000 ppm, example take 1245 gm of soil, 1000 ppm will be 0.1% that is 0.1*(1/100)*1245 gm =1.245 gm chromium, total mixture will (1245 gm+1.245 gm) =1246.245 gm, Thank you.
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