Carbon-climate interactions in hard-water lakes

湖泊是碳处理的重要节点，在全球碳收支中起着重要作用，这一观点已被广泛接受。为了更好地预测湖泊对未来气候变化的贡献和反应，需要更好地了解湖泊中二氧化碳变化的模式和潜在原因。在软水和北方生态系统中进行的研究表明，随着这些湖泊二氧化碳排放量的增加，大多数气候变化预测将导致正反馈循环。例如，据预测，随着大气温度的升高，北方湖泊的呼吸源二氧化碳浓度会升高，来自流域的有机碳负荷会随着洪水事件的频率增加而升高。相比之下，人们对硬水系统的气候和碳动态知之甚少，而硬水系统占全球内陆水域的一半以上。迄今为止的工作表明，来自集水区的无机碳负荷对硬水湖泊的调节更为强烈，而随着气候变暖，二氧化碳吸收量增加的负反馈机制更为普遍。NSERC DG提出的工作旨在通过能量通量（如温度）和质量通量（如降水）等气候参数的变化，建立对气候变化如何影响许多不同类型湖泊的湖泊碳加工的机制理解。了解内陆水域碳与气候之间的相互作用对于预测加拿大乃至全球气候变化的未来至关重要。***我建议建立加拿大大草原硬水湖的碳与气候之间的关系：1)通过测量每日和季节时间尺度的二氧化碳浓度，为硬水湖和咸水湖制定准确的年度二氧化碳预算；2)沿生产力和盐度变化的空间梯度确定局地（湖内）CO2的主要调节因子；3)研究区域能量和质量通量变化（通过风暴、干旱和雨期）如何影响湖泊二氧化碳。这里提出的研究将导致一个预测和可量化的框架，可以修改和适应其他系统，以在全球湖泊类型连续体（低-高生产力，低-高碱度）中制定更准确的二氧化碳估算。总之，这些目标将有助于评价生态系统和景观水平的过程如何促进和响应大气温室气体浓度。

It is now widely accepted that lakes are important nodes of carbon processing and play a major role in the global carbon budget. A better understanding of the patterns and underlying causes of variability in CO2 among lakes is needed to improve predictions of how lakes will both contribute and respond to future climate change. Research conducted in soft-water, boreal ecosystems has shown that most projections of climate change will result in positive feedback loops with increasing CO2 emissions from these lakes. For example, boreal lakes are predicted to experience elevated respiratory-derived CO2 concentrations as the atmospheric temperature increases and organic carbon loadings from the watershed are elevated with increasing frequency of flooding events. In contrast, much less is known about the climate and carbon dynamics in hard-water systems, which comprise over half of the volume of inland waters worldwide. Work to date suggests that hard-water lakes are more strongly regulated by inorganic carbon loading from the catchment, and that negative feedback mechanisms, whereby CO2 uptake increases as the climate warms, are more prevalent. The work proposed in this NSERC DG seeks to establish a mechanistic understanding of how climate change affects lake carbon processing across many different types of lakes through variations in the climate parameters of Energy flux (e.g. temperature) and mass flux (e.g. precipitation). Understanding the interplay between carbon and climate in inland waters is critical in projecting the future of climate change in Canada and across the globe. *** I propose to establish the relationships between carbon and climate in hard-water lakes in the Canadian prairies by 1) developing accurate annual CO2 budgets for hard-water and saline lakes by measuring concentrations of CO2 at daily and seasonal time scales; 2) determining local (in-lake) chief regulators of CO2 along a spatial gradient of varying productivity and salinity; and 3) examining how regional Energy and mass flux variability (via storms, drought and pluvial periods) affect lake CO2. The research proposed here will lead to a predictive and quantifiable framework that can be modified and adapted to other systems to develop more accurate CO2 estimates across the continuum of lake types (low-high productivity, low-high alkalinity) worldwide. Together, these objectives will allow for the evaluation of how ecosystem and landscape level processes both contribute and respond to atmospheric greenhouse gas concentrations.