# Working with Concentrations

In water sample

–         1 gr/L = 1 part per thousand (ppth)

–         1 mg/L = 10-3 gr/L = 1 part per million (ppm)

–         1 µg/L = 10-6 gr/L = 1 part per billion (ppb)

–         1 ng/L = 10-9 g/L = 1 part per trillion (ppt)

–         1 pg/L = 10-12 g/L = 1 part per quadrillion (ppq)

In soil sample

–         1 gr/kg = 1 part per thousand (ppth)

–         1 mg/kg = 10-3 gr/kg = 1 part per million (ppm)

–         1 µg/kg = 10-6 gr/kg = 1 part per billion (ppb)

–         1 ng/kg = 10-9 g/kg = 1 part per trillion (ppt)

–         1 pg/kg = 10-12 g/kg = 1 part per quadrillion (ppq)

–         1 fg/kg = 10-15 g/kg = 1 part per quintillion

In air sample

–         Percent (parts per hundred) by volume (%v)

–         Parts per million by volume (ppmv)

–         Weight of pollutant per cubic meter of air (mg/m3, µg/m3, ng/m3, etc.)

–         Molecules of a pollutant gas per cubic centimeter of air (molecules/cc or molecules/cm3)

–         Moles of pollutant gas per liter of air (mol/L)

–         Partial pressure of pollutant gas

–         Mole fraction of pollutant gas

Reference

Eugene R. Weiner. Application of Environmental Aquatic Chemistry. A Practical Guide. Third edition. CRC Press