Processes controlling carbon cycling in Antarctic glacier surface ecosystems
Processes controlling carbon cycling in Antarctic glacier surface ecosystems
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DOI：
10.7185/geochemlet.1605
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发表时间：
2016-01-01
影响因子：
4.9
通讯作者：
Fitzsimons, S.
中科院分区：
文献类型：
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作者：
Bagshaw, E. A.;Tranter, M.;Fitzsimons, S.
冰川表面生态系统，包括冰锥洞和冰冻湖，是区域碳循环的重要贡献者。用来测定冻石中有机质净生产量(NEP)的培养实验通常持续6-24小时，并产生了广泛的结果，其中许多结果表明该系统是净异养的。我们采用较长期的孵化方法来研究南极麦克默多干谷冰晶石中NEP的时间变化，以考察沉积物扰动对系统生产的影响，并了解在冰川表面生态系统生命周期中控制生产的过程。短期孵化历时一周，呈网状异养。大约一年的长期孵化显示出净自养，但只有在大约40天(类似于1000小时)之后才会出现自养。对有机碳净产量的控制是以下因素的综合作用：溶解的无机碳从冷锥体内的异养活动扩散到水中的速率，碳酸盐的溶解速率，以及水中碳酸盐的饱和度(这是封闭系统中光合作用的结果)。我们证明，冰川表面的沉积物有可能在几个月到几年的时间尺度上积累碳。
Glacier surface ecosystems, including cryoconite holes and cryolakes, are significant contributors to regional carbon cycles. Incubation experiments to determine the net production (NEP) of organic matter in cryoconite typically have durations of 6-24 hours, and produce a wide range of results, many of which indicate that the system is net heterotrophic. We employ longer term incubations to examine the temporal variation of NEP in cryoconite from the McMurdo Dry Valleys, Antarctica to examine the effect of sediment disturbance on system production, and to understand processes controlling production over the lifetimes of glacier surface ecosystems. The shorter-term incubations have durations of one week and show net heterotrophy. The longer term incubations of approximately one year show net autotrophy, but only after a period of about 40 days (similar to 1000 hours). The control on net organic carbon production is a combination of the rate of diffusion of dissolved inorganic carbon from heterotrophic activity within cryoconite into the water, the rate of carbonate dissolution, and the saturation of carbonate in the water (which is a result of photosynthesis in a closed system). We demonstrate that sediment on glacier surfaces has the potential to accumulate carbon over timescales of months to years.