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Carbon inputs of the Rhône River to the Mediterranean Sea: Biogeochemical implications
Author(s) -
Sempéré Richard,
Charrière Bruno,
Van Wambeke France,
Cauwet Gustave
Publication year - 2000
Publication title -
global biogeochemical cycles
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.512
H-Index - 187
eISSN - 1944-9224
pISSN - 0886-6236
DOI - 10.1029/1999gb900069
Subject(s) - biogeochemical cycle , mediterranean sea , mediterranean climate , dissolved organic carbon , total organic carbon , phytoplankton , oceanography , environmental chemistry , organic matter , carbon cycle , environmental science , sedimentation , particulates , sediment , autotroph , chemistry , ecology , nutrient , geology , ecosystem , biology , bacteria , paleontology , organic chemistry
Since the damming of the Nile, the Rhône River is the main freshwater and sediment supplier to the Mediterranean Sea. We estimated for the period 1987–1996, the dissolved and particulate organic carbon (DOC and POC), dissolved inorganic carbon (DIC), and total suspended matter (TSM) fluxes of the Rhône River to the Mediterranean Sea to be 1.1 ± 0.2, 1.6 ± 0.5, 16.2 ± 0.3 × 10 10 moles C yr −1 , and 9.9 ± 6.4 × 10 6 t yr −1 , respectively. PIC flux was estimated to be 8.2 ± 5.4 × 10 9 moles C yr −1 . On the basis of literature data, we estimated that nearshore bacterial respiration of Rhône derived labile‐POC and ‐DOC (LPOC and LDOC) might produce in a few days ∼0.21 and 0.12 × 10 10 moles CO 2 yr −1 , respectively. Extended to the whole Mediterranean, this study suggests that bacterial respiration of labile organic carbon derived from Mediterranean rivers might rapidly (days) produce 2.6‐11 × 10 10 moles CO 2 yr −1 . On the continental shelf, up to 4.7 × 10 10 moles of organic carbon introduced by primary production and Rhône export would escape each year to sedimentation and bacterial mineralization and would be exported off the shelf. Moreover, as total carbon fixed by phytoplankton exceeds (+ 5.2 × 10 10 moles C yr −1 ) the CO 2 produced by bacterial respiration (on average), the biological system on the shelf, could be considered as an autotrophic system and then a sink for atmospheric CO 2 . However, these numbers need further examination because of the large uncertainties associated currently to the bacterial growth efficiency values (±100%).