Abstract. The magnitude of termite methane (CH₄) emissions is still an uncertain part of the global CH₄ budget and current emission estimates are based on limited field studies. We present in-situ CH₄ emission measurements of termite mounds and termite mound sub samples, performed in the Amazon rain forest. Emissions of five termite mounds of the species Neocapritermes brasiliensis were measured by use of a large flux chamber connected to a portable gas analyser, measuring CH₄ and CO₂. In addition, the emission of mound sub samples was measured, after which termites were counted, so that a termite CH₄ and CO₂ emission factor could be determined. Mound emissions were found to range between 17.0–34.8 nmol mound⁻¹ s⁻¹ for CH₄ and between 1.6–13.5 μmol mound⁻¹ s⁻¹ for CO₂. A termite emission factor of 0.32 μmol CH₄ g_termite⁻¹ h⁻¹ was found, which is twice as high as the only other reported average value for the Amazon. By combining mound emission measurements with the termite emission factor, colony sizes could be estimated, which were found to range between 50–120 thousand individuals. Estimates were similar to literature values, and we therefore propose that this method can be used as a quick non-intrusive method to estimate termite colony size in the field. The role of termites in the ecosystems CH₄ budget was evaluated by use of two approaches. Termite mound emission values were combined with local termite mound density numbers, leading to an estimate of 0.15–0.71 nmol CH₄ m⁻² s⁻¹ on average emitted by termite mounds. In addition, the termite CH₄ emission factor from this study was combined with termite density numbers, resulting in an estimate of termite emitted CH₄ of ~1.0 nmol m⁻² s⁻¹. Considering the relatively low net CH₄ emissions previously measured at this ecosystem, we expect that termites play an important role in the CH₄ budget of this Terra Firme ecosystem.

中文翻译：

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白蚁CH ₄排放在生态系统规模中的作用：以亚马逊雨林为例

摘要。白蚁甲烷（CH ₄）排放量仍是全球CH ₄预算中不确定的部分，目前的排放量估算是基于有限的现场研究得出的。我们介绍了在亚马逊雨林中进行的白蚁丘和白蚁丘子样品的原位CH ₄排放测量。通过使用连接到便携式气体分析仪的大型通量室测量CH ₄和CO ₂，测量了巴西新龟种的五个白蚁丘的排放。另外，测量丘子样品的排放，然后对白蚁计数，从而使白蚁CH ₄和CO ₂可以确定排放因子。发现对于CH _4而言，堆放物的排放范围在17.0–34.8 nmol堆^-1  s ^-1之间，对于CO ₂在1.6–13.5μmol堆^-1  s ^-1之间。白蚁排放因子为0.32μmolCH ₄  g_白蚁^-1  h ^-1被发现，这是亚马逊唯一报告的平均值的两倍。通过结合土丘排放测量值与白蚁排放因子，可以估计菌落大小，发现其范围为50-12万个个体。估计值与文献值相似，因此，我们建议将该方法用作估计田间白蚁菌落大小的快速非侵入性方法。通过使用两种方法评估了白蚁在生态系统CH ₄预算中的作用。将白蚁丘的排放值与当地白蚁丘的密度值相结合，得出白蚁丘的平均排放量估计为0.15–0.71 nmol CH ₄  m ^-2  s ^-1。另外，白蚁CH这项研究中的₄排放因子与白蚁密度数相结合，得出白蚁排放的CH ₄估计为〜1.0 nmol m ^-2  s ^-1。考虑到以前在此生态系统中测得的相对较低的CH ₄净排放量，我们预计白蚁在Terra Firme生态系统的CH ₄预算中将发挥重要作用。