Coupled Aquatic Biogeochemical Cycles in the Anthropocene

湖泊和河流为加拿大人提供基本的水生生态系统服务，包括饮用水、娱乐机会、内陆渔业和精神满足。然而，淡水及其生物多样性正受到农业集约化、城市化加剧和气候变化的严重威胁。这些压力给水生生态系统带来了过量的营养物质，并导致了富营养化，这是植物生命的过度繁殖。这可能会导致有毒蓝藻的存在，栖息地退化，以及水中的低氧水平。然而，一些水体比其他水体更能抵御富营养化，因为周围的景观具有不同的物理特征，影响它们处理或代谢进入它们的物质的能力，从而保持健康状态。然而，人们对这种关系仍然知之甚少。发展新的知识以更好地量化分水岭中与人类相关的、物理的和生物的特征之间的关系，对于做出基于证据的决策以可持续地管理我们的淡水是必不可少的。因此，本程序的目的是描述流域尺度上控制点的相互作用，以了解河网的新陈代谢潜力。控制点是景观中的区域或时间上的时刻，对元素的生物地球化学存量或通量有不成比例的影响，在这种情况下是碳、氮和磷。在分水岭中，陆地上的活动代表接受水将“吃掉”的东西--来自不同人类活动的过量营养可能充当控制点。该计划的第一步将是量化人类如何以与管理相关的规模改变流向魁北克各地河流的营养通量。在第二步中，我们将解开不同形状和配置的河流如何能够处理或代谢进入它们的物质。为什么有些河流保持“健康”，而另一些则不是？一条河流可以安全地‘吃掉’多少营养物质，能持续多久？我们将使用长期数据集、遥感、现场采样(包括使用高分辨率传感器)和高级建模来回答这些问题，以了解不同形状和土地利用的河流在不同季节和不同气候下碳、营养物质和不同生物气体的浓度是如何变化的。通过我的项目，一个由11名学生组成的不同小组将接受多学科培训，成为生态系统科学家，并进行科学交流。培训产生的知识将填补在广泛使用的河流模型中生物地球化学处理的动态性质的空白，并确定特定流域的干预点，从而向管理层通报情况。此外，旨在更好地确定通过该计划产生的分水岭发展阈值的新方法将有助于水生生态系统服务的长期可持续性。

Lakes and rivers provide essential aquatic ecosystem services to Canadians including water to drink, recreational opportunities, inland fisheries, and spiritual fulfilment. However, freshwaters and their biodiversity are under serious threat from agricultural intensification, increased urbanization and climate changes. These pressures contribute an excess of nutrients to aquatic ecosystems and result in eutrophication, which is an over-proliferation of plant life. This can result in the presence of toxic cyanobacteria, habitat degradation, and low oxygen levels in the water. Yet some water bodies can withstand eutrophication better than others because the surrounding landscape has different physical features that influence their ability to process or metabolize what enters them and thereby to maintain a healthy state. However, this relationship remains poorly understood. Developing new knowledge to better quantify the relationships among human-related, physical, and biological features in a watershed is imperative to make evidence-based decisions to manage our freshwaters sustainably. Therefore, the purpose of this program is to characterize the interaction of control points at the watershed scale to understand the metabolic potential of river networks. Control points are areas in the landscape or moments in time that have a disproportionate influence on the biogeochemical stock or flux of elements, in this case carbon, nitrogen, and phosphorus. In a watershed, activities on land represent what the receiving water will `eat'- where excess nutrients from different human activities may act as control points. The first step of the program will be to quantify how humans are altering nutrient fluxes to rivers across Quebec at scales that are relevant to management. In a second step, we will disentangle how rivers with different shapes and configurations are able to process or metabolize what enters them. Why do some rivers remain "healthy" while others do not? What amount of nutrients can a river safely `eat' and for how long? We will answer these questions using long-term data sets, remote sensing, field sampling including the use of high-resolution sensors, and advanced modelling to understand how concentrations of carbon, nutrients, and different biological gases change across rivers with varying shapes and land uses through seasons and under different climates. A diverse group of 11 students will receive multidisciplinary training as ecosystem scientists and in scientific communication through my program. Knowledge generated by their training will inform management by filling in gaps about the dynamic nature of biogeochemical processing in widely used river models, and identifying points of intervention in specific watersheds. Furthermore, new approaches aimed at better characterising watershed development thresholds generated through this program will contribute to the long-term sustainability of aquatic ecosystem services.