Iron stocks of buried Podzols: Endogenic iron deficits and potential exogenic enrichment in the Maashorst region, SE Netherlands

• Podzolization depends on endogenic and exogenic iron pools.
• Iron stocks exceed potentially available quantity of immobile iron from weathering.
• An exogenic iron source is required for explaining observed iron deficits.
• Potential influx sources are aerosol, aeolian and micrometeoritic dust.
• A contributing factor in immobile and active iron dynamics in podzols

Podzolation is the dominant soil forming process in chemical poor sandy soils. It is well studied how iron concentrations of podzols are effected by translocation of active iron from eluvial to illuvial horizons and leaching to the aquifer. Iron stocks of Podzols, in contrasts, have not been widely studied for comparison purposes of individual soil horizons or between soils. In this study we provide an analysis of the iron stocks for two buried Podzols developed in Late-Glacial aeolian coversands. Chemical analyses of the active and immobile iron fractions in each of the horizons in both profiles show that more iron has been involved in the podzolation process, than the amount which can be derived by chemical weathering of minerals in the overlying soil horizons. This deficit in endogenic iron therefore requires exogenic enrichment to explain the observed iron concentrations during podzolation. The contribution of exogenic iron was studied using micrometeorites as a proxy for atmospheric deposition. These particles of cosmic origins are part of a continuous flux of iron-rich materials into the Earth's atmosphere and they are deposited over time on every square meter of land surface. Their extraction from ectorganic F horizon of initial Podzols helped illustrate that atmospheric deposition in the form of aerosol and aeolian (e.g. Sahara) dust, micrometeorites and other hydrolysable particles are a relevant iron contribution in soil development. The requisite active iron for podzolation can therefore be derived from chemical weathering of atmospheric iron sources in the acidic soil environment.