Revealing biogeochemical signatures of Arctic landscapes with river chemistry
Revealing biogeochemical signatures of Arctic landscapes with river chemistry
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DOI：
10.1038/s41598-019-49296-6
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发表时间：
2019-09
影响因子：
4.6
通讯作者：
Arial J. Shogren;J. Zarnetske;Benjamin W. Abbott;F. Iannucci;Rebecca J Frei;Natasha A. Griffin;W. Bowden
中科院分区：
文献类型：
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作者：
Arial J. Shogren;J. Zarnetske;Benjamin W. Abbott;F. Iannucci;Rebecca J Frei;Natasha A. Griffin;W. Bowden
在几乎所有受永久冻土影响的大型河流中，碳和无机营养物的河流通量都在增加，这表明北极景观发生了重大变化。然而，目前很难确定是什么导致了这些营养物加工和通量的变化，因为北极河流化学的大多数长期记录来自排水小于200平方公里的小水源集水区或排水小于10万平方公里的大河。这些尺度上的营养源和汇的相互作用最终控制了溶质流向北冰洋。在此背景下，我们对阿拉斯加三个跨越高山、苔原和冰湖景观的北极流域内的120个亚集水区进行了空间分布采样。研究发现，控制有机碳和主要营养物质浓度的主要空间尺度为3 ~ 30 km2，表明有机碳和主要营养物质的来源和加工动态具有分散和离散的连续性。这些模式在季节上是一致的，表明在北极的这个地区，相对小尺度的景观斑块驱动着溶质的生成。这些网络尺度的经验框架可以指导和基准未来的地球系统模型，以寻求在快速变化的北极景观中代表横向和纵向溶质运输。
Riverine fluxes of carbon and inorganic nutrients are increasing in virtually all large permafrost-affected rivers, indicating major shifts in Arctic landscapes. However, it is currently difficult to identify what is causing these changes in nutrient processing and flux because most long-term records of Arctic river chemistry are from small, headwater catchments draining <200 km2or from large rivers draining >100,000 km2. The interactions of nutrient sources and sinks across these scales are what ultimately control solute flux to the Arctic Ocean. In this context, we performed spatially-distributed sampling of 120 subcatchments nested within three Arctic watersheds spanning alpine, tundra, and glacial-lake landscapes in Alaska. We found that the dominant spatial scales controlling organic carbon and major nutrient concentrations was 3–30 km2, indicating a continuum of diffuse and discrete sourcing and processing dynamics. These patterns were consistent seasonally, suggesting that relatively fine-scale landscape patches drive solute generation in this region of the Arctic. These network-scale empirical frameworks could guide and benchmark future Earth system models seeking to represent lateral and longitudinal solute transport in rapidly changing Arctic landscapes.