Journal
SCIENCE OF THE TOTAL ENVIRONMENT
Volume 807, Issue -, Pages -Publisher
ELSEVIER
DOI: 10.1016/j.scitotenv.2021.150835
Keywords
Iron oxidation; DNRA; Denitrification; Fe(II)-dependent nitrate reduction; Betaproteobacteria
Categories
Funding
- National Key Research and Development Project of China [2019YFC0409202]
- Foundation for Innovative Research Groups of the National Natural Science Foundation of China [51721006]
- Government of Alberta
- China Scholarship Council [201906010124]
Ask authors/readers for more resources
In long-term microcosm incubations, the addition of nitrate and Fe(II) can stimulate denitrification and dissimilatory nitrate reduction to ammonia (DNRA), leading to a higher nitrate reduction rate. Iron (II) contributes to the production of lepidocrocite, promoting the process of nitrate reduction.
Nitrate is an abundant pollutant in aquatic environments. Competition between the nitrate reduction processes, denitrification, which converts nitrate into nitrogen gas, and dissimilatory nitrate reduction to ammonia (DNRA), which converts nitrate into ammonia, decides whether an ecosystem removes or retains nitrogen. The presence of iron was previously reported to stimulate DNRA while sometimes inhibiting denitrification in in situ studies, but long-term effect of iron(II) inputs on the competition is unknown. Here we inoculated longterm microcosms with sediments from two freshwater lakes. During 540 days of incubations, the microcosms with nitrate and Fe(II) additions of both lakes were able to sustain high nitrate reduction rates. Lepidocrocite was produced as a product of iron oxidation. We found both denitrification and DNRA were stimulated by nitrate and iron in the absence of external organic carbon addition. Phylogenetic analysis of denitrification genes, nirK and nirS, and DNRA genes, nirB and nrfA, was performed with metagenomic sequencing results. Enrichment was shown for reported Fe(II)-dependent nitrate reducers associated with nirS and nirB. Most of these bacteria are affiliated with Betaproteobacteria. From 16S rRNA gene analysis, Betaproteobacteria was enriched as well. In parallel, heterotrophic denitrifiers and methanotrophic DNRA archaea increased in abundance. Our results suggested heterotrophic and Fe(II)-dependent nitrate reducers both contributed to denitrification and DNRA in long-term microcosm incubations provided with iron. (c) 2021 Elsevier B.V. All rights reserved.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available