PROGRAMS AND PLANS--Changes in selected parameter names in WATSTORE October 3, 1978 QUALITY OF WATER BRANCH TECHNICAL MEMORANDUM NO. 79.02 Subject: PROGRAMS AND PLANS--Changes in selected parameter names in WATSTORE The Quality of Water Branch has been working closely with EPA since 1972 to develop standard parameter terminology for water- quality determinations that indicates the physical phase sampled and the analytical procedures used. Basic agreement with EPA on chemical determinations was reached several years ago but the new terminology was not incorporated into the STORET system and, therefore, we delayed its introduction in WATSTORE. Because of the increased need for a clear indication of whether all or only part of a constituent associated with the solids in a water-quality sample is determined by a chemical analysis, the Geological Survey has decided to implement the new terminology in WATSTORE in accordance with the plans described herein. Note that the use of the new terminology requires no change in parameter code numbers; only the names that describe certain parameters will be affected. The physical phase refers to the phase in which a constituent of interest occurs in the sample. The most common phases are "dissolved", "suspended", and "bottom material". For chemical determinations, the only aspect of the analytical procedure that is addressed is the treatment, which controls the completeness of the determination with respect to measuring all of a constituent in the sample or only part of it. For the purpose of parameter definition, "all" is defined as equal to or greater than 95 percent. The terms defined below will become part of the standard water- quality terminology of the Water Resources Division beginning with data reports for water year 1978. These terms have been used in the 1978 Water-Quality Laboratory Services Catalog (p. 138) and will be in the revised TWRI Book 5, Chapter Al. They are further explained in the attached diagram. Dissolved.--That material in a representative water sample which passes through a 0.45 um membrane filter. This is a convenient operational definition used by Federal agencies that collect water data. Determinations of "dissolved" constituents are made on subsamples of the filtrate. It is recognized that certain kinds of samples cannot be filtered; to provide for this, procedures that are considered equivalent to filtering through a 0.45 um membrane filter will be identified and announced at a later date. (Because some water samples contain colloidal material that can pass through a 0.45 um filter, analysis of samples for geochemical equilibrium studies may require filtering through a filter of smaller pore size. Data derived from such samples will require special identification when stored or retrieved. Instructions for such storage will be issued in the near future). Suspended, recoverable.--The amount of a given constituent that is in solution after the part of a representative water-suspended sediment sample that is retained on a 0.45 um membrane filter has been digested by a method (usually using a dilute acid solution) that results in dissolution of only readily soluble substances. Complete dissolution of all the particulate matter is not achieved by the digestion treatment and thus the determination represents something less than the "total" amount (that is, less than 95 percent) of the constituent present in the sample. To achieve comparability of analytical data, equivalent digestion procedures would be required of all laboratories performing such analyses because different digestion procedures are likely to produce different analytical results. Determinations of "suspended, recoverable constituents are made either by analyzing portions of the material collected on the filter or, more commonly, by difference, based on determinations of (l) dissolved and (2) total recoverable concentrations of the constituent. Suspended, total.--The total amount of a given constituent in the part of a representative water-suspended sediment sample that is retained on a 0.45um membrane filter. This term is used only when the analytical procedure assures measurement of at least 95 percent of the constituent determined. A knowledge of the expected form of the constituent in the sample, as well as the analytical methodology used, is required to determine when the results should be reported as "suspended, total". Determinations of "suspended, total" constituents are made either by analyzing portions of the material collected on the filter or, more commonly, by difference, based on determinations of (l) dissolved and (2) total concentrations of the constituent. Total, recoverable.--The amount of a given constituent that is in solution after a representative water-suspended sediment sample has been digested by a method (usually using a dilute acid solution) that results in dissolution of only readily soluble substances. Complete dissolution of all particulate matter is not achieved by the digestion treatment and thus the determination represents something less than the "total" amount (that is less than 95 percent) of the constituent present in the dissolved and suspended phases of the sample. To achieve comparability of analytical data, equivalent digestion procedures would be required of all laboratories performing such analyses because different digestion procedures are likely to produce different analytical results. Total.--The total amount of a given constituent in a representative water-suspended sediment sample regardless of the constituent's physical or chemical form. This term is used only when the analytical procedure assures measurement of at least 95 percent of the constituent present. in both the dissolved and suspended phases of the sample. A knowledge of the expected form of the constituent in the sample as well as the analytical methodology used is required to judge when the results should be reported as "total". (Note that the word "total" does double duty here indicating both that the sample consists of a water-suspended sediment mixture and that the analytical method determines all of the constituent in the sample. Recoverable from bottom material.--The amount of a given constituent that is in solution after a representative sample of bottom material has been digested by a method (usually using an acid or mixture of acids) that results in dissolution of only readily soluble substances. Complete dissolution of all bottom material is not achieved by the digestion treatment and thus the determination represents less than the total amount (that is, less than 95 percent) of the constituent in the sample. To achieve comparability of analytical data, equivalent digestion procedures would be required of all laboratories performing such analyses because different digestion procedures are likely to produce different analytical results. Total in bottom material.--The total amount of a given constituent in a representative sample of bottom material. This term is used only when the analytical procedure assures measurement of at least 95 percent of the constituent determined. A knowledge of the expected form of the constituent in the sample, as well as the analytical methodology used, is required to judge when the results should be reported as "total in bottom material". For some parameter codes, the new terminology will be inconsistent with terminology used by EPA for those same parameter codes. We believe that our choice of terminology, which is based on the analytical methods used by USGS and EPA to acquire the data that are associated with those codes, is correct and in conformance with our agreement. We expect that no inconsistency will occur between the two agencies in the association of a particular parameter code number with a particular analytical method. It should be noted that our use of a term that refers to a sample containing particulate matter implies that the original sample was representative of the bottom material or of the water-suspended sediment mixture that was sampled. Use of the new terminology and definitions will be mandatory beginning with data for water year 1978. On or about October 1, 1978, column headings produced by tabling program A534 will be changed to reflect the new terminology. At about the same time, the list of parameter codes that can be obtained through program K321 will be revised to incorporate the new terminology. To facilitate consistency in use of the old terminology in data reports for water years prior to 1978, parallel tabling programs will be available for a limited period of time. Information on retrieval procedures and on the exact time schedule for program changes will be forthcoming from the Automatic Data Section. R. J. Pickering Chief, Quality of Water Branch Attachment WRD Distribution: A, B, S, FO, PO