AUTHOR=Gómez-Armesto Antía , Méndez-López Melissa , Parente-Sendín Andrea , Calvo-Portela Noemi , Pontevedra-Pombal Xabier , García-Rodeja Eduardo , Alonso-Vega Flora , Nóvoa-Muñoz Juan Carlos 

TITLE=Mercury Content and Pools in Complex Polycyclic Soils From a Mountainous Area in Galicia (NW Iberian Peninsula)

JOURNAL=Spanish Journal of Soil Science

VOLUME=Volume 13 - 2023

YEAR=2023

URL=https://www.frontierspartnerships.org/journals/spanish-journal-of-soil-science/articles/10.3389/sjss.2023.11192

DOI=10.3389/sjss.2023.11192

ISSN=2253-6574

ABSTRACT=Atmospheric mercury (Hg) usually tends to accumulate in the upper horizons of soils. However, the physico-chemical characteristics as well as specific pedogenetic processes of some soils, past climate changes or soil degradation processes, can lead to a redistribution of mercury through the soil profile. In this work, the presence and accumulation of mercury was studied in three deep polycyclic soils (FL, MF and FV soils) from a mountainous area in NW Iberia Peninsula. The highest total Hg values (HgT) were found in the organic matter-rich O and A horizons of FL and MF profiles (169 µg kg-1 and 139 µg kg-1, respectively) and in the illuvial horizon of RV (129.2 µg kg-1), being the last two those with the maximum Hg reservoirs found (29.3 and 29.0 mg m-2, respectively). Despite the highest Hg content and pools were found in the surface horizons, considerable Hg reservoirs were also observed in depths higher than 40-50 cm, indicating the importance of taking into account these soil layers when Hg pools are evaluated at a global scale. Based on the mass transfer coefficients, the contribution of the parent material to the Hg accumulation in most of the horizons was ruled out, thus being the pedogenetic processes responsible for the Hg redistribution observed along the soil profiles. Finally, by means of principal component analysis (PCA) and stepwise linear regression the main soil components involved in the Hg accumulation in each soil horizon were assessed. Organic matter and low stability Al-hummus complexes (PC1) showed a higher influence on the surface horizons, whereas reactive Al-Fe complexes and medium-high Al-hummus complexes (PC2) and crystalline Fe compounds and pHw (PC4) were more relevant in the Hg distribution observed in the deepest soil layers.