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

摘要：海洋是人类活动产生的二氧化碳的主要汇，但很少有地点在足够长的时间内定期测量海洋二氧化碳的增加。由于物理强迫和生物生产力变化引起的溶解无机碳（DIC）收支的自然变率，对这些时间序列站点上由人为CO2吸收引起的溶解无机碳（DIC）浓度增加的量化变得复杂。夏威夷海洋时间序列（HOTS）站点的13C/12C测量已被证明为影响海洋表面DIC浓度的主要过程提供了独特的指纹，并且是跟踪由于人为二氧化碳吸收而导致DIC增加的极好代理。自1995年以来，与1990-1995年期间获得的数值相比，DICs （DIC归一化为恒定盐度）的增长率和d13C-DIC的下降率增加了一倍。PI建议继续在HOTS站点进行13C/12C和DIC的月度分析，以确定加速的DICs增加和d13C-DIC降低是否会继续。此外，倡议者还将测量热区附近地表水DIC和d13C-DIC的水平梯度，以确定热区地表DIC年际增加的多少可以用水团平流和生物碳输出速率与人为二氧化碳吸收速率的变化来解释。

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.