Basin scale controls on CO2 and CH4 emissions from the Upper Mississippi River
Basin scale controls on CO2 and CH4 emissions from the Upper Mississippi River
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DOI：
10.1002/2015gl067599
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发表时间：
2016-03-16
影响因子：
5.2
通讯作者：
Striegl, Robert G.
中科院分区：
文献类型：
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作者：
Crawford, John T.;Loken, Luke C.;Striegl, Robert G.
密西西比河上游在20世纪30年代为了河流航运而进行了工程改造，包括一系列低水头水坝和航运水域，这些水域接收了来自以农业为主的流域的大量泥沙和营养物质。通过对1385公里河段进行高分辨率、空间分辨的水质传感器测量，我们发现初级生产力和有机物积累会影响河流向大气排放二氧化碳和甲烷。在生长季节，浮游植物使二氧化碳接近或低于大气平衡水平，而厌氧碳氧化在很大程度上支持了二氧化碳和甲烷的产生。在营养物质没有大幅减少的情况下，悬浮泥沙负荷的减少可能会进一步降低河流的二氧化碳净排放。像佩平湖这样的大型河流水域，它拦截了大部分上游泥沙，以及下游输送大量泥沙和营养物质的大型农业支流，可能会继续作为温室气体排放的主要地理驱动因素。
The Upper Mississippi River, engineered for river navigation in the 1930s, includes a series of low-head dams and navigation pools receiving elevated sediment and nutrient loads from the mostly agricultural basin. Using high-resolution, spatially resolved water quality sensor measurements along 1385 river kilometers, we show that primary productivity and organic matter accumulation affect river carbon dioxide and methane emissions to the atmosphere. Phytoplankton drive CO2 to near or below atmospheric equilibrium during the growing season, while anaerobic carbon oxidation supports a large proportion of the CO2 and CH4 production. Reductions of suspended sediment load, absent of dramatic reductions in nutrients, will likely further reduce net CO2 emissions from the river. Large river pools, like Lake Pepin, which removes the majority of upstream sediments, and large agricultural tributaries downstream that deliver significant quantities of sediments and nutrients, are likely to persist as major geographical drivers of greenhouse gas emissions.