title: Measurement of boron isotope ratios in groundwater studies.
abstract: Boron is present at low levels in groundwater and rainfall in the UK, ranging between 2 and 200 ng ml-1. A sensitive technique has been developed using inductively coupled plasma mass spectrometry (ICP-MS) to measure boron isotope ratios at low concentrations with a precision (Sr) of between 0.1 and 0.2%. Samples were evaporated to increase elemental boron concentrations to 200 ng ml-1 and interfering matrix elements were removed by an adapted cation-exchange separation procedure. The validity of measuring boron isotopic ratios by ICP-MS at this concentration level is discussed in relation the theoretical instrument precision attainable based on counting statistics. Using the developed procedure it is possible to use ICP-MS to establish a reliable database documenting the natural variation in boron isotope compositions in aquifers and rain water in the UK. Preliminary results demonstrate a trend in boron isotopic compositions with increasing boron concentration. The method may be used to evaluate possible levels of boron pollution from anthropogenic inputs into natural aqueous systems.
authors.affiliation: Geology Department, Royal Holloway College, University of London, Egham, Surrey, UK.
authors.forename: N C
authors.initials: NC
authors.lastname: Porteous
authors.forename: J N
authors.initials: JN
authors.lastname: Walsh
authors.forename: K E
authors.initials: KE
authors.lastname: Jarvis
mesh_terms: D001895:Boron / Q000032:analysis*; D007554:Isotopes; D013058:Mass Spectrometry; D014881:Water Supply / Q000032:analysis*
chemical_list: D007554:Isotopes; D001895:Boron