TY - JOUR
T1 - The role of Fe(III) in soil organic matter stabilization in two size fractions having opposite features
AU - Giannetta, Beatrice
AU - Zaccone, Claudio
AU - Plaza, César
AU - Siebecker, Matthew G.
AU - Rovira, Pere
AU - Vischetti, Costantino
AU - Sparks, Donald L.
N1 - Funding Information:
This research was partially supported by the Delaware Environmental Institute and by the Spanish Ministry of Economy and Competitiveness (grants AGL2013-48681 and AGL2016-75762 ).
Funding Information:
This research was partially supported by the Delaware Environmental Institute and by the Spanish Ministry of Economy and Competitiveness (grants AGL2013-48681 and AGL2016-75762).
Publisher Copyright:
© 2018 Elsevier B.V.
PY - 2019/2/25
Y1 - 2019/2/25
N2 - Soil organic matter (SOM) protection, stability and long-term accumulation are controlled by several factors, including sorption onto mineral surfaces. Iron (Fe) has been suggested as a key regulator of SOM stability, both in acidic conditions, where Fe(III) is soluble, and in near-neutral pH environments, where it precipitates as Fe(III) (hydr)oxides. The present study aimed to probe, by sorption/desorption experiments in which Fe was added to the system, the mechanisms controlling Fe(III)-mediated organic carbon (C) stabilization; fine silt and clay (FSi + Cl) and fine sand (FSa) SOM fractions of three soils under different land uses were tested. Fe(III) addition caused a decrease in the organic C remaining in solution after reaction, indicating an Fe-mediated organic C stabilization effect. This effect was two times larger for FSa than for FSi + Cl, the former fraction being characterized by both low specific surface area and high organic C content. The organic C retained in the solid phase after Fe-mediated stabilization has relatively low sensitivity to desorption. Moreover, attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy indicated that Fe-mediated organic C stabilization can be mainly ascribed to the formation of complexes between carbohydrate OH functional groups and Fe oxides. These results demonstrate that the binding of labile SOM compounds to Fe(III) contributes to its preservation, and that the mechanisms involved (flocculation vs. coating) depend on the size fractions.
AB - Soil organic matter (SOM) protection, stability and long-term accumulation are controlled by several factors, including sorption onto mineral surfaces. Iron (Fe) has been suggested as a key regulator of SOM stability, both in acidic conditions, where Fe(III) is soluble, and in near-neutral pH environments, where it precipitates as Fe(III) (hydr)oxides. The present study aimed to probe, by sorption/desorption experiments in which Fe was added to the system, the mechanisms controlling Fe(III)-mediated organic carbon (C) stabilization; fine silt and clay (FSi + Cl) and fine sand (FSa) SOM fractions of three soils under different land uses were tested. Fe(III) addition caused a decrease in the organic C remaining in solution after reaction, indicating an Fe-mediated organic C stabilization effect. This effect was two times larger for FSa than for FSi + Cl, the former fraction being characterized by both low specific surface area and high organic C content. The organic C retained in the solid phase after Fe-mediated stabilization has relatively low sensitivity to desorption. Moreover, attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy indicated that Fe-mediated organic C stabilization can be mainly ascribed to the formation of complexes between carbohydrate OH functional groups and Fe oxides. These results demonstrate that the binding of labile SOM compounds to Fe(III) contributes to its preservation, and that the mechanisms involved (flocculation vs. coating) depend on the size fractions.
KW - C cycle
KW - Coprecipitation
KW - Ferrihydrite
KW - Physical fractionation
KW - Sorption/desorption experiments
UR - http://www.scopus.com/inward/record.url?scp=85056157781&partnerID=8YFLogxK
U2 - 10.1016/j.scitotenv.2018.10.361
DO - 10.1016/j.scitotenv.2018.10.361
M3 - Article
C2 - 30759592
AN - SCOPUS:85056157781
SN - 0048-9697
VL - 653
SP - 667
EP - 674
JO - Science of the Total Environment
JF - Science of the Total Environment
ER -