The Pantanal region of Brazil is the largest seasonally flooded tropical grassland and, according to local chamber measurements, a substantial CH₄ source. CH₄ emissions from wetlands have recently become of heightened interest because global atmospheric ¹³CH₄ data indicate they may contribute to the resumption of atmospheric CH₄ growth since 2007. We have regularly measured vertical atmospheric profiles for 2 years in the center of the Pantanal with the objectives to obtain an estimate of CH₄ emissions using an atmospheric approach, and provide information about flux seasonality and its relation to controlling factors. Boundary layer-free troposphere differences observed in the Pantanal are large compared to other wetlands. Total emissions based on a planetary boundary layer budgeting technique are 2.0–2.8 TgCH₄ yr⁻¹ (maximum flux ∼0.4 gCH₄ m⁻² d⁻¹) while those based on a Bayesian inversion using an atmospheric transport model are ∼3.3 TgCH₄ yr⁻¹. Compared to recent estimates for Amazonia (∼41 ± 3 TgCH₄ yr⁻¹_, maximum flux ∼0.3 gCH₄ m⁻² d⁻¹) these emissions are not that large. Our Pantanal data suggest a clear flux seasonality with CH₄ being released in large amounts just after water levels begin to rise again after minimum levels have been reached. CH₄ emissions decline substantially once the maximum water level has been reached. While predictions with prognostic wetland CH₄ emission models agree well with the magnitude of the fluxes, they disagree with the phasing. Our approach shows promise for detecting and understanding longer-term trends in CH₄ emissions and the potential for future wetlands CH₄ emissions climate feedbacks.

中文翻译：

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定期测量的对流层低层 CH4 剖面显示水位上升期间潘塔纳尔湿地的大量甲烷排放

巴西的潘塔纳尔地区是最大的季节性洪水热带草原，根据当地的室内测量，这是一个重要的 CH ₄源。最近，来自湿地的CH ₄排放引起了人们的高度关注，因为全球大气¹³ CH ₄数据表明它们可能有助于自 2007 年以来大气 CH ₄的恢复增长。我们在潘塔纳尔湿地中心定期测量了 2 年的垂直大气剖面，其中获得 CH ₄估计值的目标使用大气方法排放，并提供有关通量季节性及其与控制因素关系的信息。与其他湿地相比，在潘塔纳尔湿地观察到的无边界层对流层差异很大。基于行星边界层预算技术的总排放量为 2.0–2.8 TgCH ₄  yr ^-1（最大通量 ~0.4 gCH ₄  m ^-2  d ^-1），而基于使用大气传输模型的贝叶斯反演的排放量为 ~3.3 TgCH ₄ 年^-1。与亚马逊最近的估计值相比（~41 ± 3 TgCH ₄  yr ^-1 _，最大通量~0.3 gCH ₄ m ^-2 d ^-1 ) 这些排放量并不大。我们的 Pantanal 数据表明通量季节性明显，在达到最低水位后水位再次开始上升后，CH _{4 就会}大量释放。一旦达到最高水位，CH ₄排放量就会大幅下降。虽然预测湿地 CH ₄排放模型的预测与通量的大小非常吻合，但他们不同意分阶段。我们的方法有望检测和了解 CH ₄排放的长期趋势以及未来湿地 CH ₄排放气候反馈的潜力。