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Spatially Resolved Measurements of CO2 and CH4 Concentration and Gas-Exchange Velocity Highly Influence Carbon-Emission Estimates of Reservoirs.
Environmental Science & Technology ( IF 10.8 ) Pub Date : 2018-01-03 , DOI: 10.1021/acs.est.7b05138
José R Paranaíba 1 , Nathan Barros 1 , Raquel Mendonça 1, 2 , Annika Linkhorst 2 , Anastasija Isidorova 2 , Fábio Roland 1 , Rafael M Almeida 1 , Sebastian Sobek 2
Affiliation  

The magnitude of diffusive carbon dioxide (CO2) and methane (CH4) emission from man-made reservoirs is uncertain because the spatial variability generally is not well-represented. Here, we examine the spatial variability and its drivers for partial pressure, gas-exchange velocity (k), and diffusive flux of CO2 and CH4 in three tropical reservoirs using spatially resolved measurements of both gas concentrations and k. We observed high spatial variability in CO2 and CH4 concentrations and flux within all three reservoirs, with river inflow areas generally displaying elevated CH4 concentrations. Conversely, areas close to the dam are generally characterized by low concentrations and are therefore not likely to be representative for the whole system. A large share (44-83%) of the within-reservoir variability of gas concentration was explained by dissolved oxygen, pH, chlorophyll, water depth, and within-reservoir location. High spatial variability in k was observed, and kCH4 was persistently higher (on average, 2.5 times more) than kCO2. Not accounting for the within-reservoir variability in concentrations and k may lead to up to 80% underestimation of whole-system diffusive emission of CO2 and CH4. Our findings provide valuable information on how to develop field-sampling strategies to reliably capture the spatial heterogeneity of diffusive carbon fluxes from reservoirs.

中文翻译:


CO2 和 CH4 浓度以及气体交换速度的空间分辨测量极大地影响了储层的碳排放估算。



人造水库扩散的二氧化碳 (CO2) 和甲烷 (CH4) 排放量不确定,因为空间变化通常没有得到很好的体现。在这里,我们使用气体浓度和 k 的空间分辨测量来研究三个热带水库中 CO2 和 CH4 的分压、气体交换速度 (k) 和扩散通量的空间变化及其驱动因素。我们观察到所有三个水库内 CO2 和 CH4 浓度和通量的高度空间变异性,河流流入区域通常显示出较高的 CH4 浓度。相反,靠近大坝的区域通常具有低浓度的特点,因此不太可能代表整个系统。储层内气体浓度变化的很大一部分(44-83%)是由溶解氧、pH、叶绿素、水深和储层内位置来解释的。观察到 k 的高空间变异性,并且 kCH4 持续高于 kCO2(平均高 2.5 倍)。如果不考虑储层内浓度和 k 的变化,可能会导致 CO2 和 CH4 的整个系统扩散排放被低估高达 80%。我们的研究结果为如何制定现场采样策略以可靠地捕获储层扩散碳通量的空间异质性提供了宝贵的信息。
更新日期:2018-01-03
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