Climate extremes dominating seasonal and interannual variations in carbon export from the Mississippi River Basin
Climate extremes dominating seasonal and interannual variations in carbon export from the Mississippi River Basin
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DOI：
10.1002/2014gb005068
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发表时间：
2015-09
影响因子：
5.2
通讯作者：
H. Tian;W. Ren;Jia Yang;B. Tao;W. Cai;S. Lohrenz;C. Hopkinson;Mingliang Liu;Qichun Yang
中科院分区：
文献类型：
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作者：
H. Tian;W. Ren;Jia Yang;B. Tao;W. Cai;S. Lohrenz;C. Hopkinson;Mingliang Liu;Qichun Yang
了解世界主要河流向沿海海洋输出有机碳和无机碳（C）的年度和季节性模式，对于我们理解和潜在管理全球碳收支，从而限制人类对全球气候的改变至关重要。不幸的是，我们对控制碳输出的时间、规模和质量的预测性理解仍然很基础。在这里，我们使用一个基于过程的水文/生态系统生物地球化学耦合模型（动态陆地生态系统模型）来研究气候变异性和极端事件、土地利用变化以及大气化学如何影响密西西比河流域向墨西哥湾输出碳的年度和季节性模式。我们基于过程的模拟估计，21世纪00年代溶解有机碳（DOC）、颗粒有机碳（POC）和溶解无机碳（DIC）的年平均输出量分别为2.6±0.4太克碳/年、3.4±0.3太克碳/年和18.8±3.4太克碳/年。尽管在过去的一个世纪里，土地利用变化是碳输出变化的最重要因素，但气候变异性和极端事件（如洪水和干旱）是该流域碳输出季节性和年际变化的主要原因。DIC的最大季节性输出出现在夏季，而DOC和POC的最大输出出现在冬季。相对于10年平均值（2001 - 2010年），我们的建模分析表明，碳输出最大和最小的年份与湿润和干旱年份同时出现（2008年：比平均值高32%；2006年：比平均值低32%）。鉴于政府间气候变化专门委员会预测的21世纪剩余时间里气候变异性以及湿润和干旱年份降雨事件和干旱的严重程度的变化，我们的建模结果表明陆地和海洋领域之间的河流联系将发生重大变化，这可能对向沿海海洋的碳输送产生重大影响。
Knowledge about the annual and seasonal patterns of organic and inorganic carbon (C) exports from the major rivers of the world to the coastal ocean is essential for our understanding and potential management of the global C budget so as to limit anthropogenic modification of global climate. Unfortunately our predictive understanding of what controls the timing, magnitude, and quality of C export is still rudimentary. Here we use a process‐based coupled hydrologic/ecosystem biogeochemistry model (the Dynamic Land Ecosystem Model) to examine how climate variability and extreme events, changing land use, and atmospheric chemistry have affected the annual and seasonal patterns of C exports from the Mississippi River basin to the Gulf of Mexico. Our process‐based simulations estimate that the average annual exports of dissolved organic C (DOC), particulate organic C (POC), and dissolved inorganic C (DIC) in the 2000s were 2.6 ± 0.4 Tg C yr−1, 3.4 ± 0.3 Tg C yr−1, and 18.8 ± 3.4 Tg C yr−1, respectively. Although land use change was the most important agent of change in C export over the past century, climate variability and extreme events (such as flooding and drought) were primarily responsible for seasonal and interannual variations in C export from the basin. The maximum seasonal export of DIC occurred in summer while for DOC and POC the maximum occurred in winter. Relative to the 10 year average (2001–2010), our modeling analysis indicates that the years of maximal and minimal C export cooccurred with wet and dry years (2008: 32% above average and 2006: 32% below average). Given Intergovernmental Panel on Climate Change‐predicted changes in climate variability and the severity of rain events and droughts of wet and dry years for the remainder of the 21st century, our modeling results suggest major changes in the riverine link between the terrestrial and oceanic realms, which are likely to have a major impact on C delivery to the coastal ocean.