Natural variations in stable boron isotopes ( B) as tracers in terrestrial ecosystems.

For many years after the discovery of the two stable isotopes of boron (B,B) in 1920 they were not used as tracers in the soil-plant system due to analytical constraints. However, with the advent of inductively coupled plasma mass spectrometry in the early 1980s, it became possible to measure precisely the natural variations of the B isotopes in biological systems. Nevertheless, up to the present time there is very little information in the literature on B variations in soils, plants, fertilizers and foodstuffs. Therefore, information on the potential of B as a tracer of B dynamics in natural- and agro-ecosystems remains limited. The relative abundance of the boron isotope ( B) in soils, plants and nutrient sources, and applications of variations in the natural abundance of B as a tracer of anthropogenic sources of nitrate contamination of water and the provenance of agricultural products are reviewed.