Determination of boron isotopic variations in aquatic systems with negative thermal ionization mass spectrometry as a tracer for anthropogenic influences

Abstract

A technique for precise boron isotope ratio measurements with a high detection power has been developed by negative thermal ionization mass spectrometry (NTIMS). Relative standard deviations in the range of 0.03-0.3% have been obtained for the determination of the (11)B/(10)B isotope ratio using nanogram amounts of boron. Ba(OH)(2) has been applied as ionization promoter for the formation of negative thermal ions. By adding MgCl(2) better reproducibilities of the measurement have been achieved. A possible interference of BO(-)(2) ions at mass number 42 by CNO(-) could be excluded by the sample preparation technique used. Contrary to other NTI techniques no dependence of the measured isotope ratio on the boron amount used has been observed. Anthropogenic and natural saline influences in ground water have been successfully identified by boron isotope ratio determinations with this NTIMS method, due to the different isotopic composition of boron in natural and anthropogenic substances. In sewage, the boron isotope ratio is substantially influenced by washing powder, which contains low (11)B/(10)B ratios (expressed in delta(11)B values normalized to the standard reference material NIST SRM 951). In contaminated ground water, low delta(11)B values are normally correlated with high boron and high chloride concentrations. On the other hand, delta(11)B shifts to higher values in less contaminated samples. For ground water with saline influences, only the delta(11)B determination, and not the boron or chloride content, allowed the correct identification of this natural source of contamination.

Multi-isotope approach for the identification and characterisation of nitrate pollution sources in the Marano lagoon (Italy) and parts of its catchment area

“…90‰) natural range of б 11 B values (BARTH, 1993). Because B is widely used in industrial, agricultural, cosmetics, and household products, б 11 B is a useful tool for determining sources of pollutants including nitrate (EISENHUT et al, 1996;BARTH, 2000). The main industrial source of B to waters is sodium perborate (NaBO 3 ), which is used in laundry detergents (primarily as a bleaching agent) and in household cleaners; consequently, B is commonly found in household sewage.…”

“…Boron isotopes have been shown to be useful for identifying anthropogenic B sources in surface water and shallow groundwater systems: (i) municipal wastewater and sewage (BASSETT, 1990;VENGOSH et al, 1994VENGOSH et al, , 1999BASSETT et al, 1995;EISENHUT et al, 1996;VENGOSH, 1998;SEILER, 2005); (ii) irrigation return flows (BASSETT et al, 1995); (iii) fertilizer-affected irrigation waters from various agricultural settings (KOMOR, 1997); (iv) domestic solid waste deposit leachates from landfills (EISENHUT & HEUMANN, 1997;BARTH, 2000); (v) mixed agricultural sources dominated by animal waste (WIDORY et al, 2004); (vi) fly ash deposit leachates from a coal-fired power plant (DAVIDSON & BASSETT, 1993).…”

Isotopes for improved management of nitrate pollution in aqueous resources: review of surface water field studies

“…In addition, different processes control the isotopic composition of boron and nitrate (Seiler 2005). The δ 11 B values of sewage range from −7.7‰ to +12.9‰ (Bassett 1995;Eisenhut et al 1996;Gellenbeck 1994;Leenhouts et al 1998;Vengosh et al 1994Vengosh et al , 1999Widory et al 2004Widory et al , 2005. This range is overlapping with the one of the mineral fertilizers (ranging from +8‰ to +17‰; Chetelat and Gaillardet 2005;Komor 1997;Widory et al 2004).…”

Boron isotope ratio (δ11B) measurements in Water Framework Directive monitoring programs: comparison between double focusing sector field ICP and thermal ionization mass spectrometry

“…Boron isotopes have been successfully used for tracing sources of anthropogenic input into ground-and surface water, [1][2][3][4][5] rainwater and deposition, [6][7][8] freshwater lakes, 9 landfill percolates 10 and even anthropogenic emissions in the atmosphere.…”