Cave ventilation and rainfall signals in dripwater in a monsoonal setting - a monitoring study from NE India
Cave ventilation and rainfall signals in dripwater in a monsoonal setting - a monitoring study from NE India
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DOI：
10.1016/j.chemgeo.2015.03.011
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发表时间：
2015-05-08
期刊：
影响因子：
3.9
通讯作者：
Marwan, Norbert
中科院分区：
文献类型：
--
作者：
Breitenbach, Sebastian F. M.;Lechleitner, Franziska A.;Marwan, Norbert
对地下小气候和水文条件的详细监测可以描述影响基于洞穴沉积物的气候代用数据的因素，并有助于对其进行解释。水稳定同位素，空气温度，相对湿度，滴率和P-CO2在地表，土壤和洞穴空气的多年监测提供了详细的了解滴水同位素，温度和通风动力学Mawmluh洞，印度东北部。水同位素季节性变化，以响应季风降雨。大多数负值出现在印度夏季风（ISM）后期，ISM降雨和滴水响应之间的滞后时间不到一个月。两个旱季和两个不太好区分雨季动态通风制度确定在Mawmluh洞。洞穴的空气温度高于地面空气，导致干燥季节的夜晚烟囱通风。干燥季节的日子显示减少通风，由于凉爽的洞穴空气相对于地面空气和冷空气湖的发展。高水流和低于地表的洞穴空气温度都导致了潮湿季节夜晚的空气流入。丰水期白天通风受河流流量控制，但容易停滞和发展冷空气湖。CO2监测表明，P-CO2水平在日至年尺度上变化。Mawmluh洞穴似乎在旱季的部分时间充当二氧化碳汇。虽然很有可能，但需要更多的数据来确定雨季洞穴空气中的二氧化碳水平是否高于大气值。滴水行为是高度非线性的，与有效的补给动力学，并进一步复杂的人类影响表层岩溶含水层。(C)2015爱思唯尔B. V.保留所有权利。
Detailed monitoring of subterranean microclimatic and hydrological conditions can delineate factors influencing speleothem-based climate proxy data and helps in their interpretation. Multi-annual monitoring of water stable isotopes, air temperature, relative humidity, drip rates and P-CO2 in surface, soil and cave air gives detailed insight into dripwater isotopes, temperature and ventilation dynamics in Mawmluh Cave, NE India.Water isotopes vary seasonally in response to monsoonal rainfall. Most negative values are observed during late Indian Summer Monsoon (ISM), with a less than one-month lag between ISM rainfall and drip response. Two dry season and two less-well distinguishable wet season dynamic ventilation regimes are identified in Mawmluh Cave. Cave air temperatures higher than surface air result in chimney ventilation during dry season nights. Dry season days show reduced ventilation due to cool cave air relative to surface air and cold-air lake development. Both, high water flow and cooler-than-surface cave air temperatures result in air inflow during wet season nights. Wet season daytime ventilation is governed by river flow, but is prone to stagnation and development of cold air lakes. CO2 monitoring indicates that P-CO2 levels vary at diurnal to annual scale. Mawmluh Cave seems to act as CO2 sink during part of the dry season. While very likely, additional data is needed to establish whether wet season cave air CO2 levels rise above atmospheric values. Drip behavior is highly nonlinear, related to effective recharge dynamics, and further complicated by human influence on the epikarst aquifer. (C) 2015 Elsevier B.V. All rights reserved.