Cumulative effects on sediment and associated chemical fluxes at the landscape scale: the role of geomorpological connectivity

环境科学目前的研究主题之一是，自然和人为的压力或应激源--如气候变化、林业和采矿等土地利用活动以及野火等自然事件--如何影响水资源和水生生态系统。引起这种兴趣的原因是认识到，大多数(如果不是全部)水体都受到影响水量(例如水流)和水质(例如化学物质、沉积物浓度)的多种压力因素(通常称为累积效应)的影响。这项研究项目的目的是通过集中在不列颠哥伦比亚省中部的奎斯奈尔河流域(QRB，约12,000平方公里)来确定多种应激源对环境的累积影响。整个研究项目将特别侧重于地貌连通性(例如，陆地和河流之间的联系，以及渠道内的联系)如何影响沉积物和相关化学物质--如痕量金属(如砷、铜、锌)、营养物质(如磷)和颗粒碳--由于压力作用而在QRB中的转移。一个项目将评估储存要素(特别是冰川前场、河岸缓冲区、泛滥平原和河床)在控制沉积物和相关化学物质如何在受气候变化和土地利用活动影响的景观中移动方面的作用。特别是，该项目将确定这种储存元素是否会削弱和/或改变物质流动和命运。第二个项目将采用与沉积物示踪剂相结合的嵌套监测计划，以跟踪特定土地利用活动(如农业、林业和采矿)下游的沉积物和化学物质的移动。第三个项目将利用现有的空间分布模型，利用前两个项目获得的经验信息和青藏高原现有的地理信息系统平台，研究地貌连通性对沉积物的作用以及流域尺度上相关的对压力源的化学反应。这项工作将有助于更好地了解流域如何应对快速变化的世界中的累积影响，这将有助于保护加拿大的水资源和水生栖息地。

One of the current research themes in environmental science is how natural and anthropogenic pressures or stressors - such as climate change, land-use activities like forestry and mining, and natural events like wildfires - affect water resources and aquatic ecosystems. This interest is driven by the recognition that most, if not all, water bodies are affected by multiple stressors (often termed cumulative effects) that impact water quantity (e.g. water flows) and water quality (e.g. chemistry, sediment concentrations). The objective of this research project is to determine the cumulative effects of multiple stressors on the environment by focusing on the Quesnel River Basin (QRB, ca. 12,000 km2) in central British Columbia. The overall research project will specifically focus on how geomorphological connectivity (e. g. linkages between land and rivers, and linkages within channels) influences the transfer of sediment and associated chemicals - like trace metals (i.e. arsenic, copper, zinc), nutrients (e.g. phosphorus) and particulate carbon - due to stressors acting in the QRB. One project will evaluate the role of storage elements (specifically glacial forefields, riparian buffers, floodplains, and channel beds) in controlling how sediment and associated chemicals move through landscapes that have been influenced by climate change and land-use activities. In particular, this project will determine if such storage elements attenuate and/or modify material flows and fates. A second project will employ a nested monitoring program in conjunction with sediment tracers, to follow the movement of sediment and chemicals downstream of specific land-use activities such as agriculture, forestry and mining. A third project will use existing spatially distributed models to examine the role of geomorphological connectivity on sediment and associated chemical responses to stressors at the watershed-scale, utilizing the empirical information obtained from the first two projects and an existing GIS platform available for the QRB. The work will provide an improved understanding of how watersheds respond to cumulative effects in a rapidly changing world, which will help to protect water resources and aquatic habitats in Canada.