@article{fdi:010090793,
  title = {{B}iogenic and lithogenic silicon along the {GEOTRACES} south {W}est {I}ndian {O}cean section ({SWINGS}-{GS}02) and the islands mass effect on regional {S}i biogeochemical cycle},
  author = {{D}eteix, {V}. and {C}otard, {E}. and {C}aquineau, {S}andrine and {L}anding, {W}. {M}. and {P}lanchon, {F}. and {R}yan-{K}eogh, {T}. and {C}ardinal, {D}.},
  editor = {},
  language = {{ENG}},
  abstract = {{T}he distribution and cycling of biogenic silica ({BS}i) and lithogenic silicon ({LS}i) in the ocean play crucial roles in the global silicon cycle and marine ecosystem dynamics. {T}his is especially the case in the {S}outhern {O}cean where diatoms constitute the predominant phytoplankton and participate in a major way to the biological carbon pump. {T}his study presents an assessment of {BS}i and {LS}i concentrations along the {GEOTRACES} {S}outh {W}est {I}ndian {O}cean {S}ection ({SWINGS}, late austral summer 2021), where several and contrasting regions were encountered: oligotrophic {M}ozambique basin, {HNLC} ({H}igh {N}utrient {L}ow {C}hlorophyll) areas and regions fertilized by the {S}ubantarctic islands. {S}uspended particles were sampled from {N}iskin bottles and in situ pumps, along with scanning electron microscope ({SEM}) observations and specific pigments measurements to support {BS}i and {LS}i analyses. {W}ith samples coming from a contrasting study area prone to diverse continental influences, our {BS}i and {LS}i results showed a reproducibility of 13 +/- 7%, in the same range as the established protocol. {BS}i concentrations show a north-south gradient with maxima encountered in the {A}ntarctic {Z}one, and contrasted results between {HNLC} open ocean areas and naturally fertilized regions in the vicinity of the {S}ubantarctic islands. {S}ome open ocean stations have unusually high {BS}i (e.g. > 5 mu mol {L}-1) likely resulting from fertilization by aerosols, upwelling or island mass effect when they are downstream of the islands. {C}oupling of {BS}i with {SEM} observations and pigments measurements respectively showed diatoms were the most representative of the carrying phase of {BS}i and suggested silicification changes, induced either by heavily silicified diatoms or by micronutrient limitation in {HNLC} regions. {BS}i is often dominated by the smallest size fraction (0.45-5 mu m) which represent 47 +/- 23% of the total {BS}i based on 29 measurements on size fractionated samples. {LS}i results highlighted atmospheric inputs at the surface and nepheloid layers in the water column, which makes {LS}i overall a good indicator of the origin of lithogenic materials. {SEM} observations supported these results, enabling characterization of the diversity of lithogenic materials in the vicinity of the {S}ubantarctic islands, more specifically volcanic ash around {H}eard {I}sland, and within the nepheloid layers.},
  keywords = {{B}iogenic and lithogenic silicon ; {GEOTRACES} ; {S}outhern {O}cean ; {S}canning electron microscopy ; {OCEAN} {INDIEN}},
  booktitle = {},
  journal = {{M}arine {C}hemistry},
  volume = {263-264},
  numero = {},
  pages = {104412 [16 p.]},
  ISSN = {0304-4203},
  year = {2024},
  DOI = {10.1016/j.marchem.2024.104412},
  URL = {https://www.documentation.ird.fr/hor/fdi:010090793},
}