Analytical developments in the measurements of boron, nitrate and phosphate isotopes

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Aggarwal, J.; Sheppard, D.; van der Raaij, R.W. 1997 Analytical developments in the measurements of boron, nitrate and phosphate isotopes. Lower Hutt: Institute of Geological & Nuclear Sciences. Institute of Geological & Nuclear Sciences science report 97/34 [7] p.

Abstract: A study has been initiated using a suite of different isotopes in an attempt to be able to fingerprint and determine the source of contaminants into groundwater systems. Three different isotope systems have been examined, viz. B isotopes, O and N isotopes in nitrates and O isotopes in phosphates. B isotopes have the potential to identify not only seawater in groundwaters, but also boron bearing detergents commonly found in effluents (Barth et al., in press). Studies on phosphates have been used to show the discharge of sewage and fertilisers into groundwaters (Lance, 1977; Hill and Sawhney, 1981), but no studies have been carried out on the use of O isotopes in phosphates to distinguish between these two sources. Combination of N and O isotopes in nitrates have been used in a number of studies to identify sewage and fertiliser components in groundwaters e.g. Aravena et al., 1993; Wassenaar, 1995. Identification of sewage and fertiliser components in these systems is complicated by fractionation of N isotopes during denitrification processes which increases the delta15N of the nitrate dissolved in water, as shown by Komor and Anderson (1993). The measurement of the O isotopes in nitrate assists in recognising such processes. The aim of this study is to develop appropriate techniques to enable these isotope measurements to be carried out with sufficient precision to enable contaminant sources to be identified. (auth)