A Two‐Fold Increase of Phosphorus in Alpine Ice Over the Twentieth Century: Contributions From Dust, Primary Biogenic Emissions, Coal Burning, and Pig Iron Production

Abstract

AbstractPhosphorus (P) is a key nutrient for many organisms but its global atmospheric budget is largely unconstrained. Estimates of major emissions sources such as fossil‐fuel combustion range from ∼0.02 to 1.1 Tg yr−1, and primary biogenic emissions range from 0.16 to 1.0 Tg yr−1. Here we used detailed measurements of phosphorus in Alpine ice cores extracted from the Col du Dôme (CDD) glacier located near the Mont Blanc summit and atmospheric model simulations to evaluate changes in western European emissions from pre‐industrial (PI) to modern times. The ice‐core records show that P concentrations during the PI were about 0.9 ng g−1, of which one third was of crustal origin and two thirds the result of primary biogenic emissions. Concentrations were higher throughout the 20th century, reaching 2.5 ng g−1 in the 1980s. Analysis of source tracers measured in the same ice, commodity productions statistics, and other information suggest that the increase in P throughout the 20th century was caused by enhanced emissions from natural and anthropogenic sources. Coal burning and steel industry represented the main anthropogenic sources during the first and second half of the century, respectively. After 1950, the increase in P was also caused by enhanced dust emissions, with increased biogenic emissions caused by recent changes of use‐land also contributing. These findings provide important constraints on the atmospheric P budget at the scale of western Europe during the recent centuries.