Composition and Fluxes of Organic Carbon Species from the Yukon River Basin

育空河流域有机碳物种的组成和通量来自国际北极研究中心/阿拉斯加州费尔班克斯大学的科学家试图了解支配育空河流域有机碳物种的组成、反应、转化和通量的生物地球化学过程，包括育空河流域的溶解有机碳、胶体有机碳和颗粒有机碳。育空河流域是一个原始的流域，受冰、雪和永久冻土动态的严重影响，对环境和气候变化非常敏感。由于世界上高达50%的土壤有机碳储存在北部地区，北极/亚北极河流在有机碳再动员以及海洋和全球碳循环中的作用比以前认识到的要重要得多。由于育空河的偏远和极端的天气条件，通过育空河进入海洋的有机碳物种的组成和反应活性在很大程度上仍然未知，河流碳出口通量的量化也很差。观察将包括有机碳在溶解相、胶体相和颗粒相之间的相分配，以及粒度分级有机碳的浓度、光学性质、分子和同位素(d13C、d15N和？14C)组成和反应性。还将进行实地和实验室实验，以检查在冰形成过程中有机碳的分馏程度，以及这种分馏如何驱动碳的分配和转化。该项目将是首次将分子水平和流域规模的观测结合起来，以了解一个大型但原始的、受人类活动影响较小的河流流域有机碳物种组成和通量的时空变化。拟议的研究将为流域之间的比较研究提供有价值的数据，并为综合碳循环方案和模型的开发以及了解气候变化对环境的影响提供投入和有效贡献。

Composition and flux of organic carbon species from the Yukon River BasinA scientist from the International Arctic Research Center/University of Alaska Fairbanks seeks to understand the biogeochemical processes governing the composition, reactivity, transformation and flux of organic carbon species, including dissolved, colloidal and particulate organic carbon from the Yukon River Basin. Being heavily influenced by ice, snow and permafrost dynamics, the Yukon River Basin, a pristine river basin, is sensitive to environmental and climate change. With up to 50% of the world's soil organic carbon stored in the northern region, the role of arctic/subarctic rivers in the remobilization of organic carbon and thus marine and global carbon cycles is far more important than previously recognized. Due to the Yukon River's remoteness and the extreme weather conditions, the composition and reactivity of organic carbon species entering the ocean via the Yukon remain largely unknown and the riverine carbon export flux is poorly quantified. Observations will include phase partitioning of organic carbon between dissolved, colloidal and particulate phases, and concentrations, optical properties, molecular and isotopic (d13C, d15N and ?14C) composition and reactivity of size fractionated organic carbon. Field and laboratory experiments will also be carried out to examine the extent to which organic carbon fractionates during ice formation and how the fractionation drives carbon partitioning and transformation. This project will be among the first to combine both molecular-level and basin-scale observations to understand temporal and spatial variations in composition and flux of organic carbon species in a large but pristine and less anthropogenically influenced river basin. The proposed research will provide valuable data for comparative studies between drainage basins, and provide inputs for and contribute effectively to the integrated carbon cycle program and model development, and the understanding of the environmental impacts from a changing climate.