Cave Ventilation and Dripwater Geochemistry: Modern Time Series Speleothem Paleoproxy Calibration

研究小组的目标是研究洞穴空气动力学和滴水化学，以更好地了解洞穴如何生长，以及它们如何将古气候信号融入方解石带。这项研究是对佛罗里达州马里亚纳州霍洛岭洞穴(HRC)正在进行的监测活动的补充。作为持续努力的一部分，研究人员已经能够建立一个简单的模型，用于研究洞穴空气与外部空气的交换，从而确定洞穴呼吸时进出洞穴的二氧化碳通风率。这是通过连续测量222Rn(氡)、二氧化碳、温度、大气压、相对湿度(就地空气密度)、降雨量(洞穴滴速)、风速和风向(洞穴空气流动)和太阳辐照度来实现的。通过扩展这种洞穴现场监测仪器阵列来确定洞穴中高分辨率的3D和时间空气和水(水滴)流动和化学(水力学)，研究人员的目标是更好地了解利用洞穴作为古气候指标的过程和环境控制。实际上，研究小组将校准保存在？现代？的同位素和化学信号。研究人员计划进行几项具体实验，包括：(1)部署密集的微型温度和气流传感器阵列以绘制通风图；(2)测量现有活动石笋的生长速度和同位素及微量元素组成；(3)分析雨水和滴水的化学和同位素组成(时间序列)；(4)进行海底通量实验，以确定222Rn从石灰岩墙壁和滴水进入洞穴的速率；(5)建立内部可交换的洞穴风量；(6)估计表层岩溶量和流动模式的探测仪；(7)洞穴周围的地下水水力梯度。主要的更广泛的影响涉及到更好地理解广泛使用的气候指标的局限性和实用性的可能性，以及本科生和研究生的支持。

The research team aims to study cave aerodynamics and dripwater chemistry to better understand how speleothems grow and how they incorporate paleoclimate signals into their calcite bands. This research complements an ongoing monitoring campaign established in Hollow Ridge Cave (HRC), Marianna, Florida. As part of ongoing efforts, the researchers have been able to establish a simple model for cave air exchange with outside air and, thus, the rate of carbon dioxide ventilation in and out of this cave as it breathes. This has been achieved by continuously measuring 222Rn (radon), carbon dioxide, temperature, barometric pressure, relative humidity (in situ air density), rainfall (cave drip rates), wind speed and direction (cave air flow), and solar irradiance.By expanding this array of in situ cave monitoring instruments to determine high resolution 3D and temporal air and water (drip) flow and chemistry through the cave (hydraulics), the researchers aim to provide a better understanding of the processes and environmental controls on using speleothems as paleoclimate proxies. In effect, the research team will calibrate the isotopic and chemical signals preserved in ?modern? calcite precipitated in a well-understood cave with the isotopic and chemical signatures in the cave air and drip.The researchers plan several specific experiments that include: (1) deploying a dense array of micro-scale temperature and air flow sensors to map ventilation; (2) measuring existing active stalagmites for growth rates and isotopic and trace element compositions; (3) analyzing rainwater and drip water for chemistry and isotopic composition (time series); (4) running benthic flux experiments to establish rates of 222Rn emanation into the cave from limestone walls and drips; (5) establishing internal exchangeable cave air volume; (6) dye-chasers to estimate the epikarst volume and flow patterns; and (7) hydraulic groundwater gradients around the cave.The primary broader impacts involve the potential for improved understanding of the limitations and utility of a widely used climate proxy and the support of undergraduate and graduate students.