Theboron cycle is thebiogeochemical cycle ofboron through theatmosphere,lithosphere,biosphere, andhydrosphere.[1][2]
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Boron in the atmosphere is derived from soil dusts, volcanic emissions, forest fires,evaporation ofboric acid from seawater,biomass emissions, andsea spray.[1]Sea saltaerosols are the largest flux to the atmosphere. On land, boron cycles through the biosphere by rockweathering, and wet and dry deposition from the atmosphere.[1][2]
The marine biosphere circulates a large reservoir of boron. Dissolved boron is delivered to the ocean by river transport,wet deposition, submarinegroundwater discharge, andhydrothermal vents.[1][2] Boron is lost from the oceans in emissions from the ocean surface, deposition of organic materials and sediments (mostlycarbonates), and thesubduction of ocean sediment.[1]
The boron cycle has been significantly impacted by human activity. Majoranthropogenic fluxes are coal mining andcombustion, oil production, emissions from industrial factories,biofuels, landfills, and mining and processing of boron ores.[1][2] Anthropogenic boron fluxes to the hydrosphere and atmosphere have increased[1] and anthropogenic fluxes now exceed the natural boron fluxes.[1]
