Abstract
Nitrate can be reduced to other N inorganic species via denitrification and incorporated into organic matter by immobilization; however, the effect of biotic/abiotic and redox condition on immobilization and denitrification processes from a single system are not well documented. We hypothesize nitrate (NO3 -) transformation pathways leading to the formation of dissolved- and solid-phase organic N are predominantly controlled by abiotic reactions, but the formation of soluble inorganic N species is controlled by redox condition. In this study, organic matter in the form of leaf compost (LC) was spiked with 15NO3 - and incubated under oxic/anoxic and biotic/abiotic conditions at pH 6.5. We seek to understand how variations in environmental conditions impact NO3 - transformation pathways through laboratory incubations. We find production of NH4 + is predominantly controlled by redox whereas NO3 - conversion to dissolved organic nitrogen (DON) and immobilization in solid-phase N are predominantly controlled by abiotic processes. Twenty % of added 15N-NO3 - was incorporated into DON under oxic conditions, with abiotic processes accounting for 85% of the overall incorporation. Nitrogen immobilization processes resulted in N concentrations of 4.1–6.6 μg N (g leaf compost)-1, with abiotic processes accounting for 100% and 66% of the overall (biotic+abiotic) N immobilization under anoxic and oxic conditions, respectively. 15N-NMR spectroscopy suggests 15NO3 - was immobilized into amide/aminoquinones and nitro/ oxime under anoxic conditions. A fraction of the NH4 + was produced abiotically under anoxic conditions (~10% of the total NH4 + production) although biotic organic N mineralization contributed to most of NH4 + production. Our results also indicate Fe(II) did not act as an electron source in biotic-oxic incubations; however, Fe(II) provided electrons for NO3 - reduction in biotic-anoxic incubations although it was not the sole electron source. It is clear that, under the experimental conditions of this investigation, abiotic and redox processes play important roles in NO3 - transformations. As climatic conditions change (e.g., frequency/intensity of rainfall), abiotic reactions that shift transformation pathways and N species concentrations from those controlled by biota might become more prevalent.
| Original language | English (US) |
|---|---|
| Article number | e0218752 |
| Journal | PloS one |
| Volume | 14 |
| Issue number | 7 |
| DOIs | |
| State | Published - Jan 1 2019 |
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All Science Journal Classification (ASJC) codes
- Biochemistry, Genetics and Molecular Biology(all)
- Agricultural and Biological Sciences(all)
- General
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Nitrate transformation and immobilization in particulate organic matter incubations : Influence of redox, iron and (a)biotic conditions. / Kizewski, Fiona R.; Kaye, Jason Philip; Martínez, Carmen Enid.
In: PloS one, Vol. 14, No. 7, e0218752, 01.01.2019.Research output: Contribution to journal › Article
TY - JOUR
T1 - Nitrate transformation and immobilization in particulate organic matter incubations
T2 - Influence of redox, iron and (a)biotic conditions
AU - Kizewski, Fiona R.
AU - Kaye, Jason Philip
AU - Martínez, Carmen Enid
PY - 2019/1/1
Y1 - 2019/1/1
N2 - Nitrate can be reduced to other N inorganic species via denitrification and incorporated into organic matter by immobilization; however, the effect of biotic/abiotic and redox condition on immobilization and denitrification processes from a single system are not well documented. We hypothesize nitrate (NO3 -) transformation pathways leading to the formation of dissolved- and solid-phase organic N are predominantly controlled by abiotic reactions, but the formation of soluble inorganic N species is controlled by redox condition. In this study, organic matter in the form of leaf compost (LC) was spiked with 15NO3 - and incubated under oxic/anoxic and biotic/abiotic conditions at pH 6.5. We seek to understand how variations in environmental conditions impact NO3 - transformation pathways through laboratory incubations. We find production of NH4 + is predominantly controlled by redox whereas NO3 - conversion to dissolved organic nitrogen (DON) and immobilization in solid-phase N are predominantly controlled by abiotic processes. Twenty % of added 15N-NO3 - was incorporated into DON under oxic conditions, with abiotic processes accounting for 85% of the overall incorporation. Nitrogen immobilization processes resulted in N concentrations of 4.1–6.6 μg N (g leaf compost)-1, with abiotic processes accounting for 100% and 66% of the overall (biotic+abiotic) N immobilization under anoxic and oxic conditions, respectively. 15N-NMR spectroscopy suggests 15NO3 - was immobilized into amide/aminoquinones and nitro/ oxime under anoxic conditions. A fraction of the NH4 + was produced abiotically under anoxic conditions (~10% of the total NH4 + production) although biotic organic N mineralization contributed to most of NH4 + production. Our results also indicate Fe(II) did not act as an electron source in biotic-oxic incubations; however, Fe(II) provided electrons for NO3 - reduction in biotic-anoxic incubations although it was not the sole electron source. It is clear that, under the experimental conditions of this investigation, abiotic and redox processes play important roles in NO3 - transformations. As climatic conditions change (e.g., frequency/intensity of rainfall), abiotic reactions that shift transformation pathways and N species concentrations from those controlled by biota might become more prevalent.
AB - Nitrate can be reduced to other N inorganic species via denitrification and incorporated into organic matter by immobilization; however, the effect of biotic/abiotic and redox condition on immobilization and denitrification processes from a single system are not well documented. We hypothesize nitrate (NO3 -) transformation pathways leading to the formation of dissolved- and solid-phase organic N are predominantly controlled by abiotic reactions, but the formation of soluble inorganic N species is controlled by redox condition. In this study, organic matter in the form of leaf compost (LC) was spiked with 15NO3 - and incubated under oxic/anoxic and biotic/abiotic conditions at pH 6.5. We seek to understand how variations in environmental conditions impact NO3 - transformation pathways through laboratory incubations. We find production of NH4 + is predominantly controlled by redox whereas NO3 - conversion to dissolved organic nitrogen (DON) and immobilization in solid-phase N are predominantly controlled by abiotic processes. Twenty % of added 15N-NO3 - was incorporated into DON under oxic conditions, with abiotic processes accounting for 85% of the overall incorporation. Nitrogen immobilization processes resulted in N concentrations of 4.1–6.6 μg N (g leaf compost)-1, with abiotic processes accounting for 100% and 66% of the overall (biotic+abiotic) N immobilization under anoxic and oxic conditions, respectively. 15N-NMR spectroscopy suggests 15NO3 - was immobilized into amide/aminoquinones and nitro/ oxime under anoxic conditions. A fraction of the NH4 + was produced abiotically under anoxic conditions (~10% of the total NH4 + production) although biotic organic N mineralization contributed to most of NH4 + production. Our results also indicate Fe(II) did not act as an electron source in biotic-oxic incubations; however, Fe(II) provided electrons for NO3 - reduction in biotic-anoxic incubations although it was not the sole electron source. It is clear that, under the experimental conditions of this investigation, abiotic and redox processes play important roles in NO3 - transformations. As climatic conditions change (e.g., frequency/intensity of rainfall), abiotic reactions that shift transformation pathways and N species concentrations from those controlled by biota might become more prevalent.
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U2 - 10.1371/journal.pone.0218752
DO - 10.1371/journal.pone.0218752
M3 - Article
VL - 14
JO - PLoS One
JF - PLoS One
SN - 1932-6203
IS - 7
M1 - e0218752
ER -