Carbon-climate interactions in hard-water lakes

现在人们普遍认为，湖泊是碳加工的重要节点，在全球碳收支中发挥着重要作用。需要更好地了解湖泊之间二氧化碳变化的模式和根本原因，以改进对湖泊将如何对未来气候变化做出贡献和反应的预测。在软水、北方生态系统中进行的研究表明，大多数对气候变化的预测将随着这些湖泊二氧化碳排放量的增加而产生正反馈循环。例如，随着大气温度的升高和流域有机碳负荷的增加，北方湖泊预计将经历呼吸衍生的二氧化碳浓度上升，洪水事件的频率增加。相比之下，人们对硬水系统中的气候和碳动态知之甚少，硬水系统占全球内陆水域水量的一半以上。到目前为止的工作表明，硬水湖受到来自集水区的无机碳负荷的更强烈的调节，负反馈机制更普遍，即随着气候变暖，二氧化碳吸收增加。这项在NSERC DG中提出的工作试图建立一种机制上的理解，即气候变化如何通过能量通量(例如温度)和质量通量(例如降水)的气候参数的变化来影响许多不同类型湖泊的湖泊碳处理。了解内陆水域碳和气候之间的相互作用，对于预测加拿大和全球气候变化的未来至关重要。我建议通过以下方式建立加拿大草原硬水湖泊的碳与气候之间的关系：1)通过测量每日和季节性时间尺度上的二氧化碳浓度，为硬水和盐湖制定准确的年度二氧化碳预算；2)沿生产力和盐度不同的空间梯度确定当地(湖内)二氧化碳的主要调节器；以及3)研究区域能量和质量通量的变异性(通过风暴、干旱和雨季)如何影响湖泊二氧化碳。这里提出的研究将导致一个可预测和可量化的框架，该框架可以修改并适用于其他系统，以制定更准确的全球湖泊类型(低-高生产力，低-高碱度)连续体的二氧化碳估计。综合起来，这些目标将有助于评估生态系统和景观层面的进程如何对大气温室气体浓度作出贡献和作出反应。

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.