2008年夏季加拿大海盆净二氧化碳吸收量评估

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.

Evaluation of the net CO2 uptake in the Canada Basin in the summer of 2008

The third Chinese National Arctic Research Expedition (CHINARE) was conducted in the summer of 2008. During the survey, the surface seawater partial pressure of CO₂ (ρCO₂) was measured, and sea water samples were collected for CO₂ measurement in the Canada Basin. The distribution of ρCO₂ in the Canada Basin was determined, the influencing factors were addressed, and the air-sea CO₂ 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, ρCO₂ was high (320 to 368 μatm, 1 μatm=0.101 325 Pa), primarily due to rapid equilibration with atmospheric CO₂ over a short time. In the partially ice-covered zone, the surface ρCO₂ was relatively low (250 to 270 μatm) due to ice-edge blooms and icemelt water dilution. In the heavily ice-covered zone, the seawater ρCO₂ varied between 270 and 300 μatm due to biological CO₂ removal, the transportation of low ρCO₂ water northward, and heavy ice cover. The surface seawater ρCO₂ during the survey was undersaturated with respect to the atmosphere in the Canada Basin, and it was a net sink for atmospheric CO₂. The summertime net CO₂ 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=10¹² g), respectively. Overall, the net CO₂ 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 CO₂ sink.