# name
Geochemical and isotopic study of abiotic nitrite reduction coupled to biologically produced Fe(II) oxidation in marine environments

# metadata.dc.description.abstract[].value
Estuarine sediments are often characterized by abundant iron oxides, organic matter, and anthropogenicnitrogen compounds (e.g., nitrate and nitrite). Anoxic dissimilatory iron reducing bacteria (e.g.,Shewa-nella loihica) are ubiquitous in these environments where they can catalyze the reduction of Fe(III) (oxyhydr)oxides, thereby releasing aqueous Fe(II). The biologically produced Fe(II) can later reduce ni-trite to form nitrous oxide. The effect on nitrite reduction by both biologically produced and artificiallyamended Fe(II) was examined experimentally. Ferrihydrite was reduced byShewanella loihicain a batchreaction with an anoxic synthetic sea water medium. Some of the Fe(II) released by S. loihica adsorbedonto ferrihydrite, which was involved in the transformation of ferrihydrite to magnetite. In a second setof experiments with identical medium, no microorganism was present, instead, Fe(II) was amended. Theamount of solid-bound Fe(II) in the experiments with bioproduced Fe(II) increased the rate of abiotic NO2- reduction with respect to that with synthetic Fe(II), yielding half-lives of 0.07 and 0.47 d, respec-tively. The d18O and d15N of NO2- was measured through time for both the abiotic and innoculated ex-periments. The ratio of ε18O/ε15N was 0.6 for the abiotic experiments and 3.1 when NO2- was reduced by S. loihica, thus indicating two different mechanisms for the NO2-reduction. Notably, there is a wide rangeof the ε18O/ε15N values in the literature for abiotic and biotic NO2- reduction, as such, the use of this ratioto distinguish between reduction mechanisms in natural systems should be taken with caution.Therefore, we suggest an additional constraint to identify the mechanisms (i.e. abiotic/biotic) controllingNO2 reduction in natural settings through the correlation of d15N-NO2- and the aqueous Fe(II)concentration.

# metadata.dc.source[].value
Articles publicats en revistes (Mineralogia, Petrologia i Geologia Aplicada)

# metadata.dc.title[].value
Geochemical and isotopic study of abiotic nitrite reduction coupled to biologically produced Fe(II) oxidation in marine environments