Previous calculations of total diffuse carbon dioxide (CO₂) emissions from Yellowstone National Park have been based on flux measurements from thermally active, altered basins. However, our recent measurements show that thermally inactive, cold degassing sites can emit more diffuse CO₂ per km² than thermally active basins. The contribution of these cold degassing sites must be included in calculations of total diffuse CO₂ flux for adequate quantification of Yellowstone's role as a major contributor within the global CO₂ budget.

We acquired 1342 diffuse CO₂ flux point measurements across 19 different sites in Yellowstone National Park during summer 2018 and 2019. Eleven of the measured sites are thermally active with heat flux elevated above background, four sites are vegetation sites, and four sites are thermally inactive, cold degassing sites outside the caldera. Our measurements of diffuse CO₂ flux agree with previous findings that the highest average flux occurs in acid sulfate soils (706 ± 79 gm⁻² day⁻¹, average for both thermally active and cold degassing sites) with lower diffuse CO₂ flux in travertine (189 ± 98 gm⁻² day⁻¹) and neutral-chloride (19 ± 8 gm⁻² day⁻¹) soils. All cold degassing sites measured were in acid sulfate dominated soil chemistries. The average diffuse CO₂ flux for these cold degassing sites was higher (840 ± 163 gm⁻² day⁻¹) than the average flux through acid sulfate soils in thermally active basins (625 ± 79 gm⁻² day⁻¹). We also measured the carbon isotope composition of diffuse CO₂ soil gas samples from most sites to characterize the potential source(s) of these emissions. The majority of carbon isotope values from cold degassing sites are within the typical range of values for Yellowstone fumaroles. This suggests that cold degassing sites have a similar magmatic source for diffuse CO₂.

Previous calculations of the total daily diffuse CO₂ emitted through Yellowstone National Park use the arithmetic average flux per soil chemistry and extrapolate that value across the entire park using only thermally active altered soils. Instead, we calculate the total CO₂ flux per site in tons CO₂ per km² per day using Gaussian Geostatistical Simulations through the Geostatistical Analyst toolbox in ArcGIS. To account for the large component of cold degassing CO₂, we extrapolate the average emission rate per soil chemistry to all hydrothermally altered soils rather than only thermally active soils across the entire area of Yellowstone National Park. We calculate a total deeply sourced (biogenic flux removed) CO₂ flux of 24 ± 12 kt CO₂ per day, with nearly two-thirds of that flux estimated to be from cold degassing acid sulfate soils. Cold diffuse degassing sites can be significant sources of magmatic carbon emissions and this has implications for the relationship between the flux of CO₂ and heat as well as for global contributions from mantle CO₂ emissions.

以前对黄石国家公园总扩散二氧化碳 (CO ₂ ) 排放量的计算是基于热活动、改变盆地的通量测量。然而，我们最近的测量表明，与热活动盆地相比，热不活跃、冷脱气站点每 km ²可以排放更多的扩散 CO ₂。这些冷脱气站点的贡献必须包含在总扩散 CO ₂通量的计算中，以充分量化黄石公园作为全球 CO ₂预算中的主要贡献者的作用。

2018 年和 2019 年夏季，我们在黄石国家公园的 19 个不同地点获得了 1342 个扩散 CO ₂通量点测量值。其中 11 个测量地点是热活跃的，热通量高于背景，四个地点是植被地点，四个地点是热不活跃的, 火山口外的冷脱气场所。我们对扩散 CO ₂通量的测量与先前的发现一致，即最高平均通量出现在酸性硫酸盐土壤中（706 ± 79 gm ^-2 天^-1，热活性和冷脱气地点的平均值），石灰华中的扩散 CO ₂通量较低(189 ± 98 gm ^-2 天^-1 ) 和中性氯化物 (19 ± 8 gm ^-2 第^-1天）土壤。测量的所有冷脱气点都在酸性硫酸盐占主导地位的土壤化学中。这些冷脱气地点的平均扩散 CO ₂通量（840 ± 163 gm ^-2  day ^-1）高于热活动盆地中酸性硫酸盐土壤的平均通量（625 ± 79 gm ^-2  day ^-1）。我们还测量了来自大多数地点的扩散 CO ₂土壤气体样本的碳同位素组成，以表征这些排放的潜在来源。来自冷脱气场地的大部分碳同位素值都在黄石喷气孔的典型值范围内。这表明冷脱气地点具有类似的扩散 CO 的岩浆来源₂ .

以前对通过黄石国家公园排放的每日总扩散 CO ₂的计算使用每种土壤化学成分的算术平均通量，并仅使用热活性改变土壤来推断整个公园的该值。相反，我们通过 ArcGIS 中的 Geostatistical Analyst 工具箱使用 Gaussian Geostatistical Simulations计算每个站点的总 CO ₂通量，以吨 CO ₂每公里²每天为单位。考虑到冷脱气 CO ₂的大部分成分，我们将每种土壤化学的平均排放率外推到所有热液改变的土壤，而不仅仅是黄石国家公园整个区域的热活性土壤。我们计算了每天24 ± 12 kt CO ₂的总深度来源（去除生物源通量）CO ₂通量，估计该通量的近三分之二来自冷脱气酸性硫酸盐土壤。冷扩散脱气地点可能是岩浆碳排放的重要来源，这对 CO ₂通量与热量之间的关系以及地幔 CO ₂排放的全球贡献有影响。