Spatial patterns in CO2 evasion from the global river network
Spatial patterns in CO2 evasion from the global river network
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DOI：
10.1002/2014gb004941
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发表时间：
2015-05-01
影响因子：
5.2
通讯作者：
Regnier, Pierre A. G.
中科院分区：
文献类型：
--
作者：
Lauerwald, Ronny;Laruelle, Goulven G.;Regnier, Pierre A. G.
河流CO2逃逸（FCO 2）是全球碳收支的重要组成部分。在这里，我们提出了第一个全球地图的CO2分压（pCO（2））在河流的流级3和更高的FCO 2在0.5度分辨率与统计模型构建。基于地理信息系统的方法被用来获得pCO（2）预测函数，该预测函数是在来自1182个采样位置的数据上训练的。虽然来自亚洲和非洲的数据很少，训练数据集主要由美洲、欧洲和澳大利亚的采样地点组成，但采样地点涵盖了从高纬度到低纬度的全部范围。pCO（2）的预测因子是净初级生产力，人口密度，河流流域内的坡度以及采样点的平均气温（r（2）=0.47）。然后将预测的pCO（2）图与从已发表的经验方程和数据集计算的流表面积A（河流）和气体交换速度k的空间显式估计值相结合，以得出FCO 2图。使用蒙特卡罗模拟，我们评估了我们估计的不确定性。在全球范围内，我们估计平均河流pCO（2）为2400（2019-2826）mu atm，FCO 2为650（483-846）Tg C yr（-1）（置信区间的第5和第95位）。我们的全球CO2逃逸远低于最近估计的1800 Tg C yr（-1），尽管两项研究中pCO（2）的训练集非常相似，主要是由于本研究中热带pCO（2）估计值较低。我们的地图显示强烈的纬度梯度pCO（2），A（河流），和FCO 2。北纬10度和南纬10度之间的地带贡献了全球二氧化碳排放量的一半。收集该区域的pCO（2）数据，特别是非洲和东南亚河流的pCO（2）数据，是减少FCO 2不确定性的一个高度优先事项。
CO2 evasion from rivers (FCO2) is an important component of the global carbon budget. Here we present the first global maps of CO2 partial pressures (pCO(2)) in rivers of stream orders 3 and higher and the resulting FCO2 at 0.5 degrees resolution constructed with a statistical model. A geographic information system based approach is used to derive a pCO(2) prediction function trained on data from 1182 sampling locations. While data from Asia and Africa are scarce and the training data set is dominated by sampling locations from the Americas, Europe, and Australia, the sampling locations cover the full spectrum from high to low latitudes. The predictors of pCO(2) are net primary production, population density, and slope gradient within the river catchment as well as mean air temperature at the sampling location (r(2)=0.47). The predicted pCO(2) map was then combined with spatially explicit estimates of stream surface area A(river) and gas exchange velocity k calculated from published empirical equations and data sets to derive the FCO2 map. Using Monte Carlo simulations, we assessed the uncertainties of our estimates. At the global scale, we estimate an average river pCO(2) of 2400 (2019-2826) mu atm and a FCO2 of 650 (483-846) Tg C yr(-1) (5th and 95th percentiles of confidence interval). Our global CO2 evasion is substantially lower than the recent estimate of 1800 Tg C yr(-1) although the training set of pCO(2) is very similar in both studies, mainly due to lower tropical pCO(2) estimates in the present study. Our maps reveal strong latitudinal gradients in pCO(2), A(river), and FCO2. The zone between 10 degrees N and 10 degrees S contributes about half of the global CO2 evasion. Collection of pCO(2) data in this zone, in particular, for African and Southeast Asian rivers is a high priority to reduce uncertainty on FCO2.