@article{PAR00006171,
  title = {{L}ong term measurements of sulfur dioxide, nitrogen dioxide, ammonia, nitric acid and ozone in {A}frica using passive samplers},
  author = {{A}don, {M}. and {G}aly-{L}acaux, {C}. and {Y}obou{\'e}, {V}. and {D}elon, {C}. and {L}acaux, {J}. {P}. and {C}astera, {P}. and {G}ardrat, {E}. and {P}ienaar, {J}. and {A}l {O}urabi, {H}. and {L}aouali, {D}. and {D}iop, {B}. and {S}igha-{N}kamdjou, {L}. and {A}kpo, {A}. and {T}athy, {J}. {P}. and {L}avenu, {F}ran{\c{c}}ois and {M}ougin, {E}.},
  editor = {},
  language = {{ENG}},
  abstract = {{I}n this paper we present the long term monitoring of ambient gaseous concentrations within the framework of the {IDAF} ({IGAC}-{DEBITS}-{AFRICA}) program. {T}his study proposes for the first time an analysis of long-term inorganic gas concentrations (1998 to 2007) of {SO}2, {NO}2, {HNO}3, {NH}3 and {O}-3, determined using passive samplers at seven remote sites in {W}est and {C}entral {A}frica. {S}ites are representative of several {A}frican ecosystems and are located along a transect from dry savannas-wet savannas-forests with sites at {B}anizoumbou ({N}iger), {K}atibougou and {A}goufou ({M}ali), {D}jougou ({B}enin), {L}amto ({C}ote d'{I}voire), {Z}oetele ({C}ameroon) and {B}omassa ({C}ongo). {T}he strict control of measurement techniques as well as the validation and inter-comparison studies conducted with the {IDAF} passive samplers assure the quality and accuracy of the measurements. {F}or each type of {A}frican ecosystem, the long term data series have been studied to document the levels of surface gaseous concentrations. {T}he seasonal and interannual variability have also been analyzed as a function of emission source variations. {W}e compared the measured {W}est and {C}entral {A}frican gas concentrations to results obtained in other parts of the world. {R}esults show that the annual mean concentrations of {NO}2, {NH}3, {HNO}3 measured in dry savannas are higher than those measured in wet savannas and forests that have quite similar concentrations. {A}nnual mean {NO}2 concentrations vary from 0.9+/-0.2 in forests to 2.4+/-0.4 ppb in the dry savannas, {NH}3 from 3.9+/-1.4 to 7.4+/-0.8 ppb and {HNO}3 from 0.2+/-0.1 to 0.5+/-0.2 ppb. {A}nnual mean {O}-3 and {SO}2 concentrations are lower for all ecosystems and range from 4.0+/-0.4 to 14.0+/-2.8 and from 0.3+/-0.1 to 1.0+/-0.2 ppb, respectively. {A} focus on the processes involved in gas emissions from dry savannas is presented in this work, providing explanations for the high concentrations of all gases measured at the three dry savannas sites. {A}t these sites, seasonal concentrations of all gases are higher in the wet season. {C}onversely, concentrations are higher in the dry season in the wet savannas. {I}n forested regions, we measure no significant difference between wet and dry seasons. {T}his unique database of long term gases concentrations monitoring is available at: http://medias.obs-mip.fr/idaf/.},
  keywords = {},
  booktitle = {},
  journal = {{A}tmospheric {C}hemistry and {P}hysics},
  volume = {10},
  numero = {15},
  pages = {7467--7487},
  ISSN = {1680-7316},
  year = {2010},
  DOI = {10.5194/acp-10-7467-2010},
  URL = {https://www.documentation.ird.fr/hor/{PAR}00006171},
}