TM96-11 Changes in reporting of gross alpha and gross beta results

The National Water Quality Laboratory (NWQL) has been reporting gross alpha results in micrograms per liter (µg/L) and micrograms per gram (µg/g) based on a natural uranium curve and in picocuries per liter (pCi/L) and picocuries per gram (pCi/g) based on a Th-230 curve. The gross beta results have been reported in pCi/L and pCi/g based on a Cs-137 curve and in pCi/L and pCi/g based on an Sr-90/Y-90 curve. The Techniques of Water-Resources Investigations of the U.S. Geological Survey (L.L. Thatcher and others, 1977, Book 5, Part A5) lists, under Residue method R-1120-76: Gross alpha, suspended and dissolved, based on a natural uranium curve (µg/L) Gross beta, suspended and dissolved, based on a cesium-137 curve (pCi/L) Gross beta, suspended and dissolved, based on a strontium-90/yttrium-90 curve (pCi/L) In 1988 gross alpha results were added, suspended and dissolved, based on a thorium-230 curve (pCi/L). It was also during this year that the high solids method was added for gross alpha samples that exceeded 250 mg/L total dissolved solids (TDS). In 1993, the NWQL discontinued the acceptance of raw unacidified samples for radiochemical analysis. Gross alpha and gross beta, suspended, on field-filtered samples, were then reported in pCi/g, under Schedule 165.