Water, carbon and mercury cycling in Arctic terrestrial and freshwater ecosystems

北极景观和生态系统对人为气候变暖和汞等全球大气污染物高度敏感。由气候驱动的水文和冰冻圈状况扰动将深刻改变控制汞在陆地和水生环境中迁移、归宿和影响的物理、地球化学和生态过程。气候变暖将提高生态系统的生产力，增加土壤和淡水中的有机物浓度，对汞的循环和生物利用度产生重要影响。积雪期的减少和生长季节的延长可能会增加陆地对汞的吸收，而年降水量和降雨量的增加将加强陆地与水生物的相互作用，增加碳和汞向下游淡水和海洋环境的通量。由于这些影响及其相互作用，需要同时测量水、碳和汞在生态系统范围内的通量，包括陆地和水生环境中的边界层交换，以及流域和湖泊的径流排放和输出。 NSERC的资金将用于扩大努纳武特的伊卡卢伊特附近流域水文学、微气象学、湖沼学和污染物研究领域的实地研究和培训机会。总体目标是提高对加拿大北极东部努纳武特南巴芬岛水、碳和汞循环的季节性和年际动态以及相互依存关系的机械理解。将对一个源头集水区和一个一级湖泊的水、碳和汞储存量和通量的累积年度变化进行测量。将同时监测陆地和水域的表面和次表面条件，包括雪、冰和植被物候以及地面/水的热状况，以确定整个生态系统动态的机械驱动因素。将使用实地观测、遥感图像和水文气候学输入进行建模，以扩大对伊卡卢伊特附近约52平方公里的Apex河流域的经验观测。

Arctic landscapes and ecosystems are highly sensitive to anthropogenic climate warming and global atmospheric pollutants such as mercury (Hg). Climate-driven perturbations to hydrologic and cryospheric regimes will profoundly alter the physical, biogeochemical and ecological processes that regulate Hg transport, fate and effects in terrestrial and aquatic environments. Warmer conditions will increase ecosystem productivity and organic matter concentrations in soils and freshwaters, with important implications for Hg cycling and bioavailability. Reduced snow cover periods and longer growing seasons may enhance terrestrial uptake of Hg, and increases in annual precipitation and rainfall amounts will strengthen terrestrial-aquatic interactions, increasing fluxes of carbon and Hg to downstream freshwater and marine environments. This multitude of effects and their interactions require simultaneous measurement of ecosystem-scale fluxes of water, carbon and mercury, including boundary-layer exchanges in terrestrial and aquatic environments, and streamflow discharge and export from catchments and lakes. NSERC funding will be used to expand field research and training opportunities near Iqaluit, Nunavut, in the areas of watershed hydrology, micrometeorology, limnology and contaminants research. The overarching objective is to improve mechanistic understanding of seasonal and inter-annual dynamics and interdependencies of water, carbon and Hg cycling in Canada's eastern Arctic on South Baffin Island, Nunavut. Cumulative annual changes in water, carbon and mercury storage and fluxes will be measured for a headwater catchment and a first-order lake. Surface and subsurface conditions on land and water will be monitored simultaneously, including snow, ice and vegetation phenologies, and ground/water thermal regimes, to identify mechanistic drivers of whole-ecosystem dynamics. Modelling using field observations, remote sensing imagery, and hydro-climatological inputs will be conducted to up-scale empirical observations to the ~52 km2 Apex River watershed near Iqaluit.