@article{fdi:010088435,
  title = {{N}utrient fluxes associated with submarine groudnwater discharge from karstic coastal aquifers ({C}{\^o}te {B}leue, {F}rench {M}editerranean coastline)},
  author = {{B}ejannin, {S}. and {T}amborski, {J}.{J}. and {V}an {B}eek, {P}. and {S}ouhaut, {M}. and {S}tieglitz, {T}homas and {R}adakovitch, {O}. and {C}laude, {C}. and {C}onan, {P}. and {P}ujo-{P}ay, {M}. and {C}rispi, {O}. and {L}e {R}oy, {E}. and {E}stournel, {C}.},
  editor = {},
  language = {{ENG}},
  abstract = {{D}etermination of submarine groundwater discharge ({SGD}) from karstic coastal aquifers is important to constrain hydrological and biogeochemical cycles. {H}owever, {SGD} quantification using commonly employed geochemical methods can be difficult to constrain under the presence of large riverine inputs, and is further complicated by the determination of the karstic groundwater endmember. {H}ere, we investigated a coastal region where groundwater discharges from a karstic aquifer system using airborne thermal infrared mapping and geochemical sampling conducted along offshore transects. {W}e report radium data ({R}a-223, {R}a-224, {R}a-228) that we used to derive fluxes (water, nutrients) associated with terrestrial groundwater discharge and/or seawater circulation through the nearshore permeable sediments and coastal aquifer. {F}ield work was conducted at different periods of the year to study the temporal variability of the chemical fluxes. {O}ffshore transects of {R}a-223 and {R}a-224 were used to derive horizontal eddy diffusivity coefficients that were subsequently combined with surface water nutrient gradients ({NO}2- + {NO}3-, {DS}i) to determine the net nutrient fluxes from {SGD}. {T}he estimated {DS}i and ({NO}2- + {NO}3-) fluxes are 6.2 +/- 5.0 *10(3) and 4.0 +/- 2.0 *10(3) mol d(-1) per km of coastline, respectively. {W}e attempted to further constrain these {SGD} fluxes by combining horizontal eddy diffusivity and {R}a-228 gradients. {H}owever, {SGD} endmember selection in this area (terrestrial groundwater discharge vs. porewater) adds further uncertainty to the flux calculation and thus prevented us from calculating a reliable flux using this latter method. {A}dditionally, the relatively long half-life of {R}a-228 (5.75 y) makes it sensitive to specific circulation patterns in this coastal region, including sporadic intrusions of {R}hone river waters that impact both the {R}a-228 and nutrient surface water distributions. {W}e show that {SGD} nutrient fluxes locally reach up to 20 times the nutrient fluxes from a small river ({H}uveaune {R}iver). {O}n a regional scale, {DS}i fluxes driven by {SGD} vary between 0.1 and 1.4% of the {DS}i inputs of the {R}hone {R}iver, while the ({NO}2- + {NO}3-) fluxes driven by {SGD} on this 22 km long coastline are between 0.1 and 0.3% of the {R}hone {R}iver inputs, the largest river that discharges into the {M}editerranean {S}ea. {I}nterestingly, the nutrient fluxes reported here are similar in magnitude compared with the fluxes quantified along the sandy beach of {L}a {F}ranqui, in the western {G}ulf of {L}ions ({T}amborski et al., 2018), despite the different lithology of the two areas (karst systems vs. unconsolidated sediment).},
  keywords = {{FRANCE} ; {MEDITERRANEE} ; {MARSEILLE} ; {BLEUE} {COTE}},
  booktitle = {},
  journal = {{F}rontiers in {E}nvironmental {S}cience},
  volume = {7},
  numero = {},
  pages = {205 [20 ]},
  ISSN = {2296-665{X}},
  year = {2020},
  DOI = {10.3389/fenvs.2019.00205},
  URL = {https://www.documentation.ird.fr/hor/fdi:010088435},
}