Scott Wesley P, Contreras Sergio, Bowen Gabriel J, Arnold T Elliott, Bustamante-Ortega Ramón, Werne Josef P
Department of Geology and Environmental Science, University of Pittsburgh, Pittsburgh, PA, USA.
Departamento de Química Ambiental, Facultad de Ciencias & Centro de Investigación en Biodiversidad y Ambientes Sustentables (CIBAS), Universidad Católica de la Santísima Concepción, Casilla 297, Concepción, Chile.
Sci Rep. 2021 Apr 22;11(1):8725. doi: 10.1038/s41598-021-87566-4.
Warming across the globe is expected to alter the strength and amount of regional precipitation, but there is uncertainty associated with the magnitude of these expected changes, and also how these changes in temperature and the hydrologic cycle will affect humans. For example, the climate in central-south Chile is projected to become significantly warmer and drier over the next several decades in response to anthropogenically driven warming, but these anthropogenic changes are superimposed on natural climate variability. The stable isotope composition of meteoric water provides significant information regarding the moisture source, pathways, and rain-out history of an air mass, but precipitation samples suitable for stable isotope measurements require long-term placement of field equipment making them difficult to obtain. The International Atomic Energy Agency (IAEA) Global Network of Isotopes in Precipitation (GNIP) stations generate isotopic and ancillary data of precipitation from many locations around the world, but remote areas of developing countries like Chile typically have sparse networks of meteorological stations, which inhibit our ability to accurately model regional precipitation. Central-south Chile, in particular, has a sparse network of GNIP stations and, as a result, the isotopic composition of meteoric water is underrepresented in the global database complicating efforts to constrain modern day hydroclimate variability as well as paleohydrologic reconstruction for southern South America. In this study, we measured the stable isotope compositions of hydrogen (δH) and oxygen (δO) in surface lacustrine waters of central-south Chile to determine what physical and/or climatic features are the dominant controls on lacustrine δO and δH composition, assess whether or not the isotopic composition of the lakes record time-averaged isotope composition of meteoric water, and determine whether an isoscape map based on lake surface waters could predict the H and O isotope compositions of precipitation at the few GNIP stations in the region.
预计全球变暖将改变区域降水的强度和总量，但这些预期变化的幅度以及温度和水文循环的这些变化将如何影响人类仍存在不确定性。例如，由于人为驱动的变暖，预计智利中南部的气候在未来几十年将变得明显更温暖和干燥，但这些人为变化叠加在自然气候变率之上。大气降水的稳定同位素组成提供了有关气团的水分来源、路径和降雨历史的重要信息，但适合进行稳定同位素测量的降水样本需要长期放置野外设备，因此难以获取。国际原子能机构（IAEA）的全球降水同位素网络（GNIP）站点生成了来自世界许多地方的降水同位素和辅助数据，但像智利这样的发展中国家的偏远地区通常气象站网络稀疏，这限制了我们准确模拟区域降水的能力。特别是智利中南部，GNIP站点网络稀疏，结果，大气降水的同位素组成在全球数据库中的代表性不足，这使得限制现代水文气候变率以及南美洲南部古水文重建的工作变得复杂。在这项研究中，我们测量了智利中南部地表湖泊水中氢（δH）和氧（δO）的稳定同位素组成，以确定哪些物理和/或气候特征是湖泊δO和δH组成的主要控制因素，评估湖泊的同位素组成是否记录了大气降水的时间平均同位素组成，并确定基于湖泊地表水的等同位素线图是否可以预测该地区少数GNIP站点降水的H和O同位素组成。
