@article{fdi:010049436,
  title = {{A}tmospheric nitrogen budget in {S}ahelian dry savannas},
  author = {{D}elon, {C}. and {G}aly-{L}acaux, {C}. and {B}oone, {A}. and {L}iousse, {C}. and {S}erca, {D}. and {A}don, {M}. and {D}iop, {B}. and {A}kpo, {A}. and {L}avenu, {F}ran{\c{c}}ois and {M}ougin, {E}. and {T}imouk, {F}ranck},
  editor = {},
  language = {{ENG}},
  abstract = {{T}he atmospheric nitrogen budget depends on emission and deposition fluxes both as reduced and oxidized nitrogen compounds. {I}n this study, a first attempt at estimating the {S}ahel nitrogen budget for the year 2006 is made, through measurements and simulations at three stations from the {IDAF} network situated in dry savanna ecosystems. {D}ry deposition fluxes are estimated from measurements of {NO}2, {HNO}3 and {NH}3 gaseous concentrations and from simulated dry deposition velocities, and wet deposition fluxes are calculated from {NH}4+ and {NO}3- concentrations in samples of rain. {E}mission fluxes are estimated including biogenic emission of {NO} from soils (an {A}rtificial {N}eural {N}etwork module has been inserted into the {ISBA}-{SURFEX} surface model), emission of {NO}x and {NH}3 from domestic fires and biomass burning, and volatilization of {NH}3 from animal excreta. {U}ncertainties are calculated for each contribution of the budget. {T}his study uses original and unique data from remote and hardly-ever-explored regions.{T}he monthly evolution of oxidized {N} compounds shows that emission and deposition increase at the beginning of the rainy season because of large emissions of biogenic {NO} (pulse events). {E}mission of oxidized compounds is dominated by biogenic emission from soils (domestic fires and biomass burning of oxidized compounds account for 0 to 13% at the most at the annual scale, depending on the station), whereas emission of {NH}3 is dominated by the process of volatilization from soils. {A}t the annual scale, the average gaseous dry deposition accounts for 47% of the total estimated deposition flux, for both oxidized and reduced compounds. {T}he average estimated wet plus dry deposition flux in dry savanna ecosystems is 7.5 +/- 1.8 kg{N} ha(-1) yr(-1), with approximately 30% attributed to oxidized compounds, and the rest attributed to {NH}x. {T}he average estimated emission flux ranges from 8.4(+/- 3.8) to 12.4(+/- 5.9) kg{N} ha(-1) yr(-1), dominated by {NH}3 volatilization (72-82%) and biogenic emission from soils (11-17%), depending on the applied volatilization rate of {NH}3. {W}hile larger, emission fluxes are on the same order of magnitude as deposition fluxes. {T}he main uncertainties are linked to the {NH}3 emission from volatilization. {W}hen scaled up from the 3 measurement sites to the {S}ahelian region (12 degrees {N}:18 degrees {N}, 15 degrees {W}:10 degrees {E}), the estimated total emission ranges from 2(+/- 0.9) to 3(+/- 1.4) {T}g{N} yr(-1), depending on the applied volatilization rate of {NH}3 and estimated total deposition is 1.8(+/- 0.4) {T}g{N} yr(-1). {T}he dry savanna ecosystems of the {S}ahel contribute around 2% to the global (biogenic + anthropogenic) nitrogen budget.},
  keywords = {},
  booktitle = {},
  journal = {{A}tmospheric {C}hemistry and {P}hysics},
  volume = {10},
  numero = {6},
  pages = {2691--2708},
  ISSN = {1680-7316},
  year = {2010},
  URL = {https://www.documentation.ird.fr/hor/fdi:010049436},
}