Carbon cycling of Lake Kivu (East Africa): net autotrophy in the epilimnion and emission of CO2 to the atmosphere sustained by geogenic inputs.
Carbon cycling of Lake Kivu (East Africa): net autotrophy in the epilimnion and emission of CO2 to the atmosphere sustained by geogenic inputs.
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DOI：
10.1371/journal.pone.0109500
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发表时间：
2014
期刊：
影响因子：
3.7
通讯作者：
Darchambeau F
中科院分区：
文献类型：
--
作者：
Borges AV;Morana C;Bouillon S;Servais P;Descy JP;Darchambeau F
我们报告了在四次实地调查中获得的一个大型(>；2000 km2)贫营养热带湖泊(东非基伍湖)的有机和无机碳分布和通量，这些调查捕捉到了季节变化(2007年3月-雨季中期，2007年9月-旱季后期，2008年6月-旱季早期，以及2009年4月-雨季晚期)。基伍湖主要流域表层水的二氧化碳分压表现出适度的空间变化(变异系数在3%至6%之间)和季节变化，幅度为163ppm(2007年3月平均为579±23ppm，2007年9月平均为742±28ppm)。二氧化碳分布的最突出的空间特征是卡布诺湾(一个与主湖泊几乎没有联系的小次盆地)的二氧化碳分水值非常高，介于11213 ppm至14213 ppm之间(比主盆地高18至26倍)。基伍湖主要盆地的地表水是向大气排放二氧化碳的净来源，平均速率为10.8mmolm−2d−1，低于淡水、盐湖和火山湖的全球平均值。在卡布诺湾，向大气排放的二氧化碳平均为500.7 mmolm−2d−1(∼是主盆地的46倍)。根据全湖溶解无机碳(DIC)的质量平衡和稳定的碳同位素组成，我们认为基伍湖的表层是净自养的。这是由于集水面积与湖泊表面积的比率较小(2.15)，因此河流的有机碳输入不多。碳收支意味着，向大气排放的二氧化碳必须由深地温泉的地源DIC输入来维持。
We report organic and inorganic carbon distributions and fluxes in a large (>2000 km2) oligotrophic, tropical lake (Lake Kivu, East Africa), acquired during four field surveys, that captured the seasonal variations (March 2007–mid rainy season, September 2007–late dry season, June 2008–early dry season, and April 2009–late rainy season). The partial pressure of CO2 (pCO2) in surface waters of the main basin of Lake Kivu showed modest spatial (coefficient of variation between 3% and 6%), and seasonal variations with an amplitude of 163 ppm (between 579±23 ppm on average in March 2007 and 742±28 ppm on average in September 2007). The most prominent spatial feature of the pCO2 distribution was the very high pCO2 values in Kabuno Bay (a small sub-basin with little connection to the main lake) ranging between 11213 ppm and 14213 ppm (between 18 and 26 times higher than in the main basin). Surface waters of the main basin of Lake Kivu were a net source of CO2 to the atmosphere at an average rate of 10.8 mmol m−2 d−1, which is lower than the global average reported for freshwater, saline, and volcanic lakes. In Kabuno Bay, the CO2 emission to the atmosphere was on average 500.7 mmol m−2 d−1 (∼46 times higher than in the main basin). Based on whole-lake mass balance of dissolved inorganic carbon (DIC) bulk concentrations and of its stable carbon isotope composition, we show that the epilimnion of Lake Kivu was net autotrophic. This is due to the modest river inputs of organic carbon owing to the small ratio of catchment area to lake surface area (2.15). The carbon budget implies that the CO2 emission to the atmosphere must be sustained by DIC inputs of geogenic origin from deep geothermal springs.
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影响因子：
5.3
作者：
EMRICH, K;VOGEL, JC
通讯作者：
VOGEL, JC
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作者：
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作者：
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6.5
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Zimov, SA
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作者：
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