Impact of extreme drought and the Three Gorges Dam on transport of particulate terrestrial organic carbon in the Changjiang (Yangtze) River
Impact of extreme drought and the Three Gorges Dam on transport of particulate terrestrial organic carbon in the Changjiang (Yangtze) River
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DOI：
10.1029/2011jf002012
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发表时间：
2011-12
影响因子：
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通讯作者：
Hao Yu;Ying Wu;Jing Zhang;B. Deng;Zhuoyi Zhu
中科院分区：
文献类型：
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作者：
Hao Yu;Ying Wu;Jing Zhang;B. Deng;Zhuoyi Zhu
[1]为探讨极端干旱和三峡大坝对长江有机碳输出的影响，对2003年（平水年）和2006年（干旱年）长江中下游干流悬浮颗粒物样品的元素碳、稳定碳同位素和木质素-酚产率进行了分析。与2003年收集的悬浮粒子样本比较，2006年的样本显示有机碳含量[OC%：（1.91 ± 0.43）%，（0.95 ± 0.07）%]，较高的本地有机碳[Chl-a/OC：（20.68 ± 9.03）mg/g OC，（7.33 ± 2.97）mg/g OC]，木质素产量降低[Λ8：（Ad/Al）v：2006年为0.44 ± 0.21，2003年为0.27 ± 0.028。这些差异可能是由于2006年较低的水流量和泥沙负荷导致的颗粒物组成和悬浮颗粒物浓度的变化。极端干旱和三峡水库蓄水不仅影响了陆源有机碳的特征和通量，而且掩盖了河流有机碳的季节性特征。三峡大坝对长江中游的影响大于下游。长江下游的湖泊和支流为干流提供了大量的陆源有机碳。在干旱年份，下游湖泊和支流的补给作用更为显著。干旱和三峡大坝影响（2006年）期间长江陆源有机碳的绝对减少量将严重影响当地的碳循环，并将在一定程度上影响全球碳循环。
[1] To investigate the impact of extreme drought and the Three Gorges Dam on organic carbon (OC) exported by the Changjiang (Yangtze) River, suspended particulate matter samples collected in 2003 (normal year) and 2006 (drought year) from the middle and lower reaches of the mainstream of the river were analyzed for elemental carbon, stable carbon isotope, and lignin-phenol yields. In comparison with suspended particulate matter samples collected in 2003, the 2006 samples showed elevated organic carbon content [OC%: (1.91 ± 0.43)% and (0.95 ± 0.07)% respectively in 2006 and 2003], higher autochthonous OC [Chl-a/OC: (20.68 ± 9.03)mg/g OC and (7.33 ± 2.97)mg/g OC in 2006 and 2003], decreased lignin yields [Λ8: (0.90 ± 0.41)mg/100 mg OC and (1.91 ± 0.33)mg/100 mg OC in 2006 and 2003], and higher degradation state [(Ad/Al)v: 0.44 ± 0.21 and 0.27 ± 0.028 in 2006 and 2003]. These differences may be explained by changes in grain composition and concentration of the suspended particulate matter, which were caused by the lower water discharge and sediment load in 2006. Extreme drought and impoundment of water by the Three Gorges Dam not only affected the signatures and fluxes of terrestrial OC, but hid the seasonal signal of riverine OC. The impact of the Three Gorges Dam was more significant in the middle reach than in the lower reach. Lakes and tributaries in the lower Changjiang River supplied great amounts of terrestrial OC to the mainstream. In the drought year, the supplement of water provided by the lower lakes and tributaries was more significant. The absolute magnitude of reduction of terrestrial OC in the Changjiang River during drought and Three Gorges Dam influence (2006) would have severely affected the local carbon cycle and would have influenced the global carbon cycle to some extent.