TY - JOUR
T1 - Fe(III) Photoreduction Producing Feaq 2+ in Oxic Freshwater Sediment
AU - Lueder, Ulf
AU - Jørgensen, Bo Barker
AU - Kappler, Andreas
AU - Schmidt, Caroline
PY - 2020
Y1 - 2020
N2 - Iron(III) (Fe(III)) photoreduction plays an important role in Fe cycling and Fe(II) bioavailability in the upper ocean. Although well described for water columns, it is currently unknown to what extent light impacts the production of dissolved Fe(II) (Fe2+) in aquatic sediments. We performed high-resolution voltammetric microsensor measurements and demonstrated light-induced Fe2+ release in freshwater sediments from Lake Constance. Fe2+ concentrations increased up to 40 μM in the top 3 mm of the sediment during illumination in the visible range of light (400-700 nm), even in the presence of oxygen (100-280 μM). The Fe2+ release was strongly dependent on the organic matter content of the sediment. A lack of photoreduced Fe2+ was measured in sediments with concentrations of organic carbon <6 mg L-1. The simultaneous presence of sedimentary Fe(III) photoreduction besides microbial and abiotic Fe2+ oxidation by oxygen suggests an active Fe redox cycling in the oxic and photic zone of aquatic sediments. Here, we provide evidence for a relevant contribution of Fe(III) photoreduction to the bio-geochemical Fe redox cycle in aquatic freshwater sediments.
AB - Iron(III) (Fe(III)) photoreduction plays an important role in Fe cycling and Fe(II) bioavailability in the upper ocean. Although well described for water columns, it is currently unknown to what extent light impacts the production of dissolved Fe(II) (Fe2+) in aquatic sediments. We performed high-resolution voltammetric microsensor measurements and demonstrated light-induced Fe2+ release in freshwater sediments from Lake Constance. Fe2+ concentrations increased up to 40 μM in the top 3 mm of the sediment during illumination in the visible range of light (400-700 nm), even in the presence of oxygen (100-280 μM). The Fe2+ release was strongly dependent on the organic matter content of the sediment. A lack of photoreduced Fe2+ was measured in sediments with concentrations of organic carbon <6 mg L-1. The simultaneous presence of sedimentary Fe(III) photoreduction besides microbial and abiotic Fe2+ oxidation by oxygen suggests an active Fe redox cycling in the oxic and photic zone of aquatic sediments. Here, we provide evidence for a relevant contribution of Fe(III) photoreduction to the bio-geochemical Fe redox cycle in aquatic freshwater sediments.
UR - http://www.scopus.com/inward/record.url?scp=85078395385&partnerID=8YFLogxK
U2 - 10.1021/acs.est.9b05682
DO - 10.1021/acs.est.9b05682
M3 - Journal article
C2 - 31886652
AN - SCOPUS:85078395385
SN - 0013-936X
VL - 54
SP - 862
EP - 869
JO - Environmental Science & Technology
JF - Environmental Science & Technology
IS - 2
ER -