The carbonate system at sub-zero temperatures and high ionic strength.

我们对海洋中碳的生物地球化学循环的理解发生了翻天覆地的变化，因为我们能够分析几个参数，这些参数通过气体交换和水相酸碱热力学平衡来描述碳酸盐体系。因此，单独或更常见的对溶解无机碳(DIC)、氢离子浓度(PH)、总碱度(TA)和二氧化碳分压(PCO2)的联合测量使我们能够确定初级生产力、呼吸作用以及碳酸钙沉淀和溶解对海洋化学的影响。尽管二氧化碳系统的地理和时间数据覆盖面自测量其所有直接可观测参数的技术问世以来有所增加，但海洋数据库中仍然存在很大差距。特别的黑点是极地海洋，特别是在海冰覆盖下。这是一个重要的考虑因素，特别是在极地海洋正经历海洋酸化的环境变化的情况下，海洋酸化在内陆的北冰洋尤为迅速。此外，海冰的存在增加了极地环境的复杂性，因为它由许多相互关联或孤立的微生境组成的动态环境，这些微生境在海冰形成和衰败的季节性周期期间扩张和收缩。对复杂的海冰环境的研究非常重要，因为它现在被认为是海洋和大气之间相互作用的活跃界面，碳物种通过这个界面进行转化和迁移。关于极地海洋的生物地球化学信息有限，部分原因是相对难以获取，特别是在有冰盖的情况下，环境复杂，难以在恶劣条件下工作，但也由于缺乏在这些温度下工作的适当方法，以及对在这些条件下确定二氧化碳系统参数所用的平衡常数值变化的了解。因此，与温度高于零的海洋水域相比，我们对近零极地水域的二氧化碳系统和富含卤水的海冰微生境中的零下温度的了解目前还处于初级阶段。由于在一些极地环境中并不能可靠地测量所有能够完整描述二氧化碳系统的参数(TA、DIC、pH、pCO2)，这意味着必须计算未测或不可测参数的值，这一过程需要外推物理化学方程，而物理化学方程实际上应该仅在高于零的温度和盐度低于50的情况下使用。这种类型的外推可能会导致计算出的二氧化碳和pH值有很大差异。因此，我们的研究目的是提供必要的分析工具和实验数据，以便能够以与目前在温带和热带温度和盐度条件下提供的相同程度的复杂程度来研究极地环境中的二氧化碳系统。为了能够实现这一点，我们选择了现有的测量海水中pH和PCO2的方法，我们可以可靠地修改这些方法，以在零度以下的浓盐水溶液中测量相同的参数。使用我们的高质量测量，我们将确定对确定二氧化碳系统至关重要的系数，并随后通过测量二氧化碳系统的任何两个(4个中的)直接可见的物理化学参数来预测其余两个，以测试该方法的有效性。在海洋界，这些常量、工具和分析方法的使用将有助于研究高纬度海洋中二氧化碳化学、碳基通量和碳酸钙矿物饱和度的持续和未来变化，对过去、现在和未来气候漂移的模型预测设置重要限制。

Our understanding of the biogeochemical cycling of carbon in the oceans has been revolutionised through our ability to analyse several of the parameters that describe the carbonate system via gas exchange and the aqueous acid-base thermodynamic equilibria. Thus, the individual, or more commonly, combined measurement of dissolved inorganic carbon (DIC), hydrogen ion concentration (pH), total alkalinity (TA) and the partial pressure of carbon dioxide (pCO2) has provided us with the ability to determine the influence that primary production, respiration, and calcium carbonate precipitation and dissolution have on the chemistry of the oceans. Although the geographical and temporal data coverage of the CO2 system has increased since the inception of techniques to measure all its directly observable parameters, large gaps still exist in the oceanic data base. Particular black spots are the polar oceans and especially under sea ice cover. This is an important consideration, especially as the polar oceans are experiencing environmental change as a result of ocean acidification, which is particularly rapid in the land-locked Arctic Ocean. In addition, the presence of sea ice adds complexity to the polar environment as it consists of a dynamic environment of numerous inter-connected or isolated micro-habitats that expand and contract during the seasonal cycle of formation and decay of sea ice. The study of the complex, sea ice environment is important as it in now recognized as an active interface in the interaction between the ocean and the atmosphere, through which carbon species, transform and migrate. The biogeochemical information about the polar oceans is limited in part due to its relative inaccessibility, especially when there is ice cover, the complexity of the environment and the difficulty in working in harsh conditions, but also due to a lack of appropriate methods to work at these temperatures and knowledge of the change in the value of equilibrium constants used in determining parameters of the CO2 system under these conditions. Thus, our knowledge of the CO2 system at near-zero polar waters and the sub-zero temperatures in the brine enriched micro-habitats of sea ice is currently rudimentary compared with that in oceanic waters where the temperature is above-zero.As not all of the parameters that can describe the CO2 system fully (TA, DIC, pH, pCO2) can be reliably measured in some of the polar environments, this has meant that the value of the unmeasured or unmeasurable parameters must be calculated, a process that requires extrapolation of physical-chemical equations that really should only be used with above-zero temperatures and salinity less than 50. This type of extrapolation of can lead to large differences in the calculated pCO2 and pH. Thus, the aim of our research is to provide the necessary analytical tools and experimental data so that the CO2 system in polar environments can be investigated with the same degree of sophistication as that currently afforded in temperate and tropical temperature and salinity conditions. To be able to achieve this, we have chosen existing methods of measuring pH and pCO2 in ocean waters, which we can reliable modify to measure the same parameters in brine enriched solutions at sub-zero temperatures. Using our high quality measurements, we will determine the coefficients that are essential for the determination of CO2 system and subsequently test the validity of this approach by measuring any 2 (out of 4) directly observable physical-chemical parameters of the CO2 system to predict the remaining two. In the marine community, the use of these constants, tools, and analytical methodology will aid investigation of ongoing and future changes in the CO2 chemistry, carbon-based fluxes, and saturation with respect to calcium carbonate minerals in high latitude oceans, setting important constraints on model predictions of past, present, and future climate excursions.