| Contents Notes |
As part of a multidisciplinary study of Chesapeake Bay, the National Bureau of Standards (NBS) was asked to develop the techniques and procedures necessary to measure trace and toxic element concentrations within the water column throughout the length of Chesapeake Bay. The Inorganic Analytical Research Division of the Center for Analytical Chemistry at NBS has completed the analysis for selected elements (Cd, Ce, Co, Cr, Cu, Fe, Mn, Mo, Ni, Pb. Sc, Sn, Th, U, and Zn), including some elements at concentrations consistently below one picogram per milliliter (part per trillion). The characterization of Chesapeake Bay can be divided into five major phases. The first included the development and construction of a sampling system for the trace metallic elements dissolved in water and a filtration system for collecting the particulate elemental component. The second phase consisted of sampling chemical stabilization by acidification and storage of the samples in the field. The total complement of 102 samples was obtained, filtered, acidified and stabilized. There were also 51 replicate bottom samples obtained and frozen for archival use. A series of over 30 blanks was also prepared and integrated with the 102 water samples to be analyzed. The third major phase of activity consisted of the chemical separation and preparation of samples for the analytical instrumental methods. The chemical separation/sample preparation stage of this work has been described in the literature for both instrumental techniques. The fourth major phase consisted of the instrumental analysis of the samples for the trace elements. The total number of elemental concentrations resulting from the analyses of the contracted elements exceeded 3000 and involved several thousand more unreported analyses totaling over 5000 separate determinations. The fifth major phase involved data reduction and evaluation of the statistical significance of the blank. The blanks were statistically modeled for each element, and the blank and uncertainty of the blanks were applied to the data. The concentrations were adjusted uniformly to at least the 95 percent confidence limit. |
