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The third Chinese National Arctic Research Expedition(CHINARE) was conducted in the summer of 2008.During the survey,the surface seawater partial pressure of CO_2(pCO_2) was measured,and sea water samples were collected for CO_2 measurement in the Canada Basin.The distribution of pCO_2 in the Canada Basin was determined,the influencing factors were addressed,and the air-sea CO_2 flux in the Canada Basin was evaluated.The Canada Basin was divided into three regions:the ice-free zone(south of 77°N),the partially ice-covered zone(77°–80°N),and the heavily ice-covered zone(north of 80°N).In the ice-free zone,pCO_2 was high(320 to 368μatm,1 μatm=0.101 325 Pa),primarily due to rapid equilibration with atmospheric CO_2 over a short time.In the partially ice-covered zone,the surface pCO_2 was relatively low(250 to 270 μatm) due to ice-edge blooms and icemelt water dilution.In the heavily ice-covered zone,the seawater pCO_2 varied between 270 and 300 μatm due to biological CO_2 removal,the transportation of low pCO_2 water northward,and heavy ice cover.The surface seawater pCO_2 during the survey was undersaturated with respect to the atmosphere in the Canada Basin,and it was a net sink for atmospheric CO_2.The summertime net CO_2 uptake of the ice-free zone,the partially ice-covered zone and the heavily ice-covered zone was(4.14±1.08),(1.79±0.19),and(0.57±0.03) Tg/a(calculated by carbon,1Tg=10~(12) g),respectively.Overall,the net CO_2 sink of the Canada Basin in the summer of 2008 was(6.5±1.3) Tg/a,which accounted for 4%–10% of the Arctic Ocean CO_2 sink.
The third Chinese National Arctic Research Expedition (CHINARE) was conducted in the summer of 2008.During the survey, the surface seawater partial pressure of CO_2 (pCO_2) was measured, and sea water samples were collected for CO_2 measurement in the Canada Basin. The distribution of pCO_2 in the Canada Basin was determined, the influencing factors were addressed, and the air-sea CO_2 flux in the Canada Basin was evaluated. The Canada Basin was divided into three regions: the ice-free zone (south of 77 ° N the partially ice-covered zone (77 ° -80 ° N), and the heavily ice-covered zone (north of 80 ° N) .In the ice-free zone, pCO_2 was high (320 to 368 μatm, 1 μatm = 0.101 325 Pa), due due to rapid equilibration with atmospheric CO 2 over a short time. In the partially ice-covered zone, the surface pCO 2 was relatively low (250 to 270 μatm) due to ice-edge blooms and icemelt water dilution. the heavily ice-covered zone, the seawater pCO_2 varied between 270 and 300 μatm due to biological CO 2 remova l, the transportation of low pCO_2 water northward, and heavy ice cover. surface seawater pCO_2 during the survey was undersaturated with respect to the atmosphere in the Canada Basin, and it was a net sink for atmospheric CO_2. summertime net CO_2 uptake of the ice-free zone, the partially ice-covered zone and the heavily ice-covered zone was 4.14 ± 1.08, 1.79 ± 0.19, and 0.57 ± 0.03 Tg / a calculated by carbon, 1 Tg = 10 ~ (12) g), respectively. The net CO 2 sink of the Canada Basin in the summer of 2008 was (6.5 ± 1.3) Tg / a, which accounted for 4% -10% of the Arctic Ocean CO_2 sink.