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Lowering N2O emissions from soils using eucalypt biochar: the importance of redox reactions.

Quin P, Joseph S, Husson O, Donne S, Mitchell D, Munroe P, Phelan D, Cowie A, Van Zwieten L - Sci Rep (2015)

Bottom Line: X-ray photoelectron spectroscopy identified changes in surface functional groups suggesting interactions between N2O and the biochar surfaces.With increasing rates of biochar application, higher pH adjusted redox potentials were observed at the lower water contents.Evidence suggests that biochar has taken part in redox reactions reducing N2O to dinitrogen (N2), in addition to adsorption of N2O.

View Article: PubMed Central - PubMed

Affiliation: University of New England, Armidale, NSW 2351, Australia.

ABSTRACT
Agricultural soils are the primary anthropogenic source of atmospheric nitrous oxide (N2O), contributing to global warming and depletion of stratospheric ozone. Biochar addition has shown potential to lower soil N2O emission, with the mechanisms remaining unclear. We incubated eucalypt biochar (550 °C)--0, 1 and 5% (w/w) in Ferralsol at 3 water regimes (12, 39 and 54% WFPS)--in a soil column, following gamma irradiation. After N2O was injected at the base of the soil column, in the 0% biochar control 100% of expected injected N2O was released into headspace, declining to 67% in the 5% amendment. In a 100% biochar column at 6% WFPS, only 16% of the expected N2O was observed. X-ray photoelectron spectroscopy identified changes in surface functional groups suggesting interactions between N2O and the biochar surfaces. We have shown increases in -O-C = N /pyridine pyrrole/NH3, suggesting reactions between N2O and the carbon (C) matrix upon exposure to N2O. With increasing rates of biochar application, higher pH adjusted redox potentials were observed at the lower water contents. Evidence suggests that biochar has taken part in redox reactions reducing N2O to dinitrogen (N2), in addition to adsorption of N2O.

No MeSH data available.


Related in: MedlinePlus

(a) SEM image of xylem in the biochar after interaction with soil; (b) Internal surfaces of the xylem of the biochar coated in an organomineral film containing significant amounts of Ca and Mg; (c) external surface of the biochar and a pore coated with a range of minerals, and (d) the EDS spectrum of (c).
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f3: (a) SEM image of xylem in the biochar after interaction with soil; (b) Internal surfaces of the xylem of the biochar coated in an organomineral film containing significant amounts of Ca and Mg; (c) external surface of the biochar and a pore coated with a range of minerals, and (d) the EDS spectrum of (c).

Mentions: Figure 3 characterises some of the changes that have occurred on the surfaces of the LMH5%. Some of the internal pores have a layer of organic molecules that are rich in Ca and Mg (Fig. 3b: energy dispersive x-ray (EDS)) and some of the pores have filled with organic matter and mineral matter that is high in Al/Si/O, Fe/O /, Ca/C/O and Ti/O compounds (Fig. 3c). Figure 3d illustrates the range of different mineral phases observed on the surface of the biochar. The EDS data mirrors the survey analysis carried out using x-ray photoelectron spectroscopy (XPS).


Lowering N2O emissions from soils using eucalypt biochar: the importance of redox reactions.

Quin P, Joseph S, Husson O, Donne S, Mitchell D, Munroe P, Phelan D, Cowie A, Van Zwieten L - Sci Rep (2015)

(a) SEM image of xylem in the biochar after interaction with soil; (b) Internal surfaces of the xylem of the biochar coated in an organomineral film containing significant amounts of Ca and Mg; (c) external surface of the biochar and a pore coated with a range of minerals, and (d) the EDS spectrum of (c).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4663753&req=5

f3: (a) SEM image of xylem in the biochar after interaction with soil; (b) Internal surfaces of the xylem of the biochar coated in an organomineral film containing significant amounts of Ca and Mg; (c) external surface of the biochar and a pore coated with a range of minerals, and (d) the EDS spectrum of (c).
Mentions: Figure 3 characterises some of the changes that have occurred on the surfaces of the LMH5%. Some of the internal pores have a layer of organic molecules that are rich in Ca and Mg (Fig. 3b: energy dispersive x-ray (EDS)) and some of the pores have filled with organic matter and mineral matter that is high in Al/Si/O, Fe/O /, Ca/C/O and Ti/O compounds (Fig. 3c). Figure 3d illustrates the range of different mineral phases observed on the surface of the biochar. The EDS data mirrors the survey analysis carried out using x-ray photoelectron spectroscopy (XPS).

Bottom Line: X-ray photoelectron spectroscopy identified changes in surface functional groups suggesting interactions between N2O and the biochar surfaces.With increasing rates of biochar application, higher pH adjusted redox potentials were observed at the lower water contents.Evidence suggests that biochar has taken part in redox reactions reducing N2O to dinitrogen (N2), in addition to adsorption of N2O.

View Article: PubMed Central - PubMed

Affiliation: University of New England, Armidale, NSW 2351, Australia.

ABSTRACT
Agricultural soils are the primary anthropogenic source of atmospheric nitrous oxide (N2O), contributing to global warming and depletion of stratospheric ozone. Biochar addition has shown potential to lower soil N2O emission, with the mechanisms remaining unclear. We incubated eucalypt biochar (550 °C)--0, 1 and 5% (w/w) in Ferralsol at 3 water regimes (12, 39 and 54% WFPS)--in a soil column, following gamma irradiation. After N2O was injected at the base of the soil column, in the 0% biochar control 100% of expected injected N2O was released into headspace, declining to 67% in the 5% amendment. In a 100% biochar column at 6% WFPS, only 16% of the expected N2O was observed. X-ray photoelectron spectroscopy identified changes in surface functional groups suggesting interactions between N2O and the biochar surfaces. We have shown increases in -O-C = N /pyridine pyrrole/NH3, suggesting reactions between N2O and the carbon (C) matrix upon exposure to N2O. With increasing rates of biochar application, higher pH adjusted redox potentials were observed at the lower water contents. Evidence suggests that biochar has taken part in redox reactions reducing N2O to dinitrogen (N2), in addition to adsorption of N2O.

No MeSH data available.


Related in: MedlinePlus