Seasonal variations in the Amazon plume-related atmospheric carbon sink
Abstract
The Amazon River plume is a highly seasonal feature that can reach more than 3000 km across the tropical Atlantic Ocean, and cover ∼2 million km2. Ship observations show that its seasonal presence significantly reduces sea surface salinity and inorganic carbon. In the western tropical North Atlantic during April-May 2003, plume-influenced stations exhibited surface DIC concentrations lowered by as much as 563 μmol C kg-1 (∼28%) and pCO2 as low as 201 μatm. We combine our data with other data sets to understand the annual uptake and seasonal variability of the plume-related CO2 sink. Using flux estimates from all seasons with monthly plume areas determined by satellite, we calculate the annual carbon uptake by the outer plume alone (28 < S < 35) to be 15 ± 6 TgC yr-1. Diazotroph-supported net community production enhanced the air-sea CO2 disequilibrium by 100x and reversed the typical CO2 outgassing from the tropical North Atlantic. The carbon sink in the Amazon plume depends on climate-sensitive conditions that control river hydrology, CO2 solubility, and gas exchange.
- Publication:
-
Global Biogeochemical Cycles
- Pub Date:
- September 2007
- DOI:
- 10.1029/2006GB002831
- Bibcode:
- 2007GBioC..21.3014C
- Keywords:
-
- Oceanography: Biological and Chemical: Biogeochemical cycles;
- processes;
- and modeling (0412;
- 0414;
- 0793;
- 1615;
- 4912);
- Global Change: Climate variability (1635;
- 3305;
- 3309;
- 4215;
- 4513);
- Oceanography: General: Physical and biogeochemical interactions;
- Geographic Location: Atlantic Ocean;
- Amazon River;
- inorganic carbon;
- tropical North Atlantic Ocean