Glycerol dialkyl glycerol tetraethers (GDGTs) are microbial membrane-spanning lipids that are produced in a variety of environments. To better understand the potentially confounding effect of soil chemistry on the temperature relationship of branched GDGTs (brGDGTs), isoprenoid GDGTs (isoGDGTs) and GDGT-based proxies MBT’_5ME and TEX₈₆, soils from 6 elevation transects (mean annual air temperature 0 – 26 ℃, n = 74) were analyzed. Corroborating earlier work, the MBT’_5ME index correlates well with mean annual air temperature in the low pH (pH < 7), non-arid soils under study (r = 0.87, p < 0.001). However, a clear over-estimation of reconstructed temperature in the lowest pH (<3.5) soils is observed, explained by the correlation between brGDGT Ia and free acidity. TEX₈₆ also shows a significant correlation with mean annual air temperature (r = 0.45, p < 0.001), driven by temperature dependent concentration changes of isoGDGTs 3 and cren’. However, an overarching correlation with P/E values dominates concentration changes of all supposed Thaumarchaeotal isoGDGTs lipids (GDGT1-3, cren and cren’), implying a potential impact of soil moisture on TEX₈₆ values. In addition to identifying the impact of these confounding factors on the temperature proxy, GDGT ratios that can be used to constrain changes in soil chemistry, specifically exchangeable Ca²⁺, sum of basic cations, exchangeable Fe³⁺ and sum of soil metals are proposed (0.53 < r² < 0.68), while existing ratios for soil moisture availability are tested for the first time in a dataset of non-arid soils. While the impact of soil chemistry on GDGTs may complicate the interpretation of their temperature proxies, our proposed GDGT ratios can potentially be used to constrain a subset of soil chemistry changes through time.

甘油二烷基甘油四醚 (GDGT) 是在各种环境中产生的微生物跨膜脂质。_{为了更好地了解土壤化学对支链 GDGT (brGDGT)、类异戊二烯 GDGT (isoGDGT) 和基于 GDGT 的代理 MBT' 5ME}和 TEX ₈₆的温度关系的潜在混杂影响，来自 6 个海拔样带的土壤（年平均气温 0 – 26℃，n=74）进行了分析。证实了早期的工作，MBT' _5ME指数与所研究的低 pH 值 (pH < 7) 非干旱土壤中的年平均气温有很好的相关性 (r = 0.87，p < 0.001)。然而，观察到最低 pH (<3.5) 土壤中重建温度的明显高估，这可以通过 brGDGT Ia 和游离酸度之间的相关性来解释。TEX ₈₆还显示出与年平均气温显着相关（r = 0.45，p < 0.001），这是由 isoGDGTs 3 和 cren' 的温度依赖性浓度变化驱动的。然而，与 P/E 值的总体相关性主导了所有假定的奇古菌 isoGDGT 脂质（GDGT1-3、cren 和 cren'）的浓度变化，这意味着土壤湿度对 TEX ₈₆值的潜在影响。除了确定这些混杂因素对温度代理的影响外，还提出了可用于限制土壤化学变化的 GDGT 比率，特别是可交换 Ca ²⁺、碱性阳离子总和、可交换 Fe ³⁺和土壤金属总和(0.53 < r ²  < 0.68)，而现有的土壤水分有效性比率首次在非干旱土壤数据集中进行了测试。虽然土壤化学对 GDGT 的影响可能会使对其温度代理的解释复杂化，但我们提出的 GDGT 比率可潜在地用于限制土壤化学随时间变化的子集。