"Concentration standard deviation of soluble ammonium {soluble_NH4+ CAS 14798-03-9} per unit volume of the atmosphere [aerosol <1um phase] by filtration, water leaching"@en . . "SDN:P01::AEC059SD" . "The square root of the average of the squares of deviations about the mean of a set of values of the specified measurement."@en . .