Distribution of boron in the environment

Abstract

The findings of a study to identify and quantify the orders of magnitude for major reservoirs and flows of boron (B) in the environment are outlined. The orders of magnitude for B reservoirs and flows arising through natural processes, such as the hydrological cycle and volcanism, are compared with those arising from anthropogenic activities, such as coal combustion and the extraction and use of borates for commercial purposes. The major stores and reservoirs for B have been identified, in order of magnitude, as the continental and oceanic crusts (10¹⁸ kg B), the oceans (10¹⁵ kg B), groundwater (10¹¹ kg B), ice (10¹¹ kg B), coal deposits (10¹⁰ kg B), commercial borate deposits (10¹⁰ kg B), biomass (10¹⁰ kg B), and surface waters (10⁸ kg B). The largest flows of B in the environment arise from the movement of B into the atmosphere from oceans, at between 1.3 * 10⁹ kg and 4.5 * 10⁹ kg B per annum. Other hydrological flows are also important. Drainage from soil systems into groundwaters and surface waters accounts for between 4.3 * 10⁸ kg and 1.3 * 10⁹ kg B per annum. B mining and volcanic eruptions represent the next most significant B flows, accounting for approx 4.0 * 10⁸ kg and 3.0 * 10⁸ kg B, respectively.