Using 13C/12C Measurements to Trace the Ocean Carbon Cycle and Anthropogenic CO2 Uptake in the Subtropical Ocean

海洋是人类活动产生的二氧化碳的主要汇，但很少有站点在足够长的时间内以固定的间隔测量海洋二氧化碳的增加。由于物理强迫和生物生产力的变化导致溶解无机碳(DIC)预算的自然变化，量化人为CO2吸收导致的这些时间序列地点的DIC浓度增加是复杂的。夏威夷海洋时间序列(HOTS)站点的13C/12C测量提供了影响表层海洋中DIC浓度的主要过程的独特指纹，并且是跟踪由于吸收人为二氧化碳而增加DIC的良好指标。自1995年以来，DICs(DIC归一化为恒定盐度)和D13C-DIC下降的速度相对于1990-1995年间的数值翻了一番。PI建议继续在HOTS现场制作13C/12C和DIC的月度概况，以确定加速的DIC增加和d13C-DIC下降是否继续。此外，倡导者还将测量HOT附近地表水的DIC和D13C-DIC的水平梯度，以确定HOT表面DIC的年际增加中有多少可以用水团平流和生物碳输出速率相对于人为二氧化碳吸收的变化来解释。

ABSTRACTOCE-9911913The ocean is a major sink for CO2 produced by human activities, yet there are few sites where the oceanic CO2 increase is being measured at regular intervals over a long enough time to be detectable. Quantifying the increase in dissolved inorganic carbon (DIC) concentrations at these time series sites caused by uptake of anthropogenic CO2 is complicated by the natural variability in the DIC budget caused by changes in physical forcing and biological productivity. Measurements of 13C/12C at the Hawaii Ocean Time Series (HOTS) site have been shown to provide a unique fingerprint of the primary processes affecting DIC concentrations in the surface ocean and an excellent proxy for tracking the increase in DIC due to uptake of anthropogenic CO2. Since 1995, the rate of increase in DICs (DIC normalized to constant salinity) and decrease in d13C-DIC has doubled relative to values obtained between 1990-1995. The PI proposes to continue making monthly profiles of 13C/12C and DIC at the HOTS site to determine whether the accelerated DICs increase and d13C-DIC decrease continues. In addition, the proponent also will measure the horizontal gradients of DIC and d13C-DIC of surface waters in the vicinity of HOTS to determine how much of the interannual increase in surface DICs at HOTS can be explained by changes in the advection of water masses and rates of biological carbon export versus uptake of anthropogenic CO2.