Detecting hydrologic distinctions among Andean lakes using clumped and triple oxygen isotopes
Detecting hydrologic distinctions among Andean lakes using clumped and triple oxygen isotopes
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使用簇同位素和三氧同位素检测安第斯山脉湖泊之间的水文差异
DOI：
10.1016/j.epsl.2022.117927
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发表时间：
2023
影响因子：
5.3
通讯作者：
Abbott, Mark B.
中科院分区：
文献类型：
--
作者：
Katz, Sarah A.;Levin, Naomi E.;Rodbell, Donald T.;Gillikin, David P.;Aron, Phoebe G.;Passey, Benjamin H.;Tapia, Pedro M.;Serrepe, Analucía R.;Abbott, Mark B.
湖泊碳酸盐氧同位素分布特征为研究气候和水文变化提供了重要信息，但很难将流域降水、水温和蒸发量对湖泊碳酸盐δ 18 O值的影响分离开来。最近的工作表明，使用聚集（Δ 47）和三重氧同位素（Δ ′ 17 O）测量的组合，以确定温度和蒸发对湖泊碳酸盐δ 18 O值的作用，允许降水δ 18 O值推断和促进古气候重建的潜力。然而，这种方法的现代校准主要局限于蒸发损失与输入（X E）的高比率和低相对湿度（h <0.7）的干旱地区。开发这种用于古气候和古海拔重建的工具需要将现代校准扩展到更大范围的气候和水文条件。我们采样四湖在不同的水文状态下的一个单一的，高湿度的气候制度（h = 0.7 - 0.9）在胡宁湖地区的秘鲁中部。湖泊碳酸盐的成块同位素温度反映了碳酸盐形成过程中的水温。湖泊水文是碳酸盐和沃茨Δ ′ 17 O值的主要控制因素：与蒸发量最小且Δ ′ 17 O与降水量难以区分的较小的源头湖泊相比，具有较高XE的较大湖泊的Δ ′ 17 O值最低。重建来自沃茨湖水的未蒸发集水降水δ '18 O（δ' 18 O rucp）值依赖于λ湖（三重氧同位素蒸发斜率）的准确表征。我们使用新的观测数据和模拟数据来探讨湿度对λ湖的影响。考虑到当地的湿度改善了λ湖的估计，这使得δ ′ 18 O rucp的重建更加准确。我们从胡宁湖地区的现代碳酸盐和沃茨（n = 15）中得出的δ ′ 18 O rucp值为− 15.2 ± 2.1 ‰，这与加权平均年降水量− 14.1（± 2.2 ‰）相似。研究表明：（1）Δ ′ 17O可用于区分湿润气候条件下具有不同XE的湖泊;（2）湖泊碳酸盐Δ ′ 17O和δ 18O值可用于评价一定气候条件下蒸发对湖水δ 18O值的影响;（3）在适当湿度条件下模拟λ湖，可提高湖泊碳酸盐δ ′ 17 O估算δ ′ 18 O rucp的精度。
Oxygen isotope distributions from lacustrine carbonates provide insights into climate and hydrological change, but it is difficult to isolate the influences of catchment precipitation δ 18 O, water temperature, and evaporation on lacustrine carbonate δ 18 O values. Recent work shows the potential for using a combination of clumped (Δ 47) and triple oxygen isotope (Δ′ 17 O) measurements to identify the roles of temperature and evaporation on carbonate δ 18 O values in lakes, allowing precipitation δ 18 O values to be inferred and facilitating paleoclimate reconstructions. However, modern calibration of this approach has been mostly limited to arid regions with a high ratio of evaporative losses over inputs (X E) and low relative humidity (h< 0.7). Developing this tool for paleoclimate and paleoelevation reconstructions requires expanding the modern calibrations to a greater range of climatic and hydrologic conditions. We sampled four lakes in different hydrologic states under a single, high humidity climate regime (h= 0.7–0.9) in the Lake Junín region of central Peru. Clumped isotope temperatures from lake carbonates reflect water temperatures during carbonate formation. Lake hydrology is the main control on the Δ′ 17 O values of carbonates and waters: Δ′ 17 O values are lowest in the larger lakes with higher X E when compared to smaller, headwater lakes where evaporation is minimal and Δ′ 17 O is indistinguishable from that of precipitation. Reconstructed unevaporated catchment precipitation δ′ 18 O (δ′ 18 O rucp) values from lake waters rely on accurate characterization of λ lake, the triple oxygen isotope evaporation slope. We explore the influence of humidity on λ lake using both new observations and modeled data. Accounting for local humidity improves λ lake estimates, which allows for more accurate reconstructions of δ′ 18 O rucp. We generate a δ′ 18 O rucp value of− 15.2±2.1‰ from modern carbonates and waters (n= 15) in the Lake Junín region, which is similar to amount weighted mean annual precipitation− 14.1 (±2.2‰). This study illustrates that (1) Δ′ 17 O can be used to differentiate between lakes with differing X E in humid climates,(2) lake carbonate Δ′ 17 O and δ 18 O values can be used to evaluate the influence of evaporation on lake water δ 18 O values in a range of climates, and (3) modeling λ lake under appropriate humidity conditions improves δ′ 18 O rucp estimates from lake carbonate Δ′ 17 O.
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