Concepción Pla

Subterranean atmospheres may act as daily methane sinks

In recent years, methane (CH4) has received increasing scientific attention because it is the most abundant non-CO2 atmospheric greenhouse gas (GHG) and controls numerous chemical reactions in the troposphere and stratosphere. However, there is much that is unknown about CH4 sources and sinks and their evolution over time. Here we show that near-surface cavities in the uppermost vadose zone are now actively removing atmospheric CH4. Through seasonal geochemical tracing of air in the atmosphere, soil and underground at diverse geographic and climatic locations in Spain, our results show that complete consumption of CH4 is favoured in the subsurface atmosphere under near vapour-saturation conditions and without significant intervention of methanotrophic bacteria. Overall, our results indicate that subterranean atmospheres may be acting as sinks for atmospheric CH4 on a daily scale. However, this terrestrial sink has not yet been considered in CH4 budget balances.

Definition of Microclimatic Conditions in a Karst Cavity: Rull Cave (Alicante, Spain)

Rull Cave (Alicante, SE Spain) is a shallow karstic cavity located in metre-thick beds of Miocene limestone conglomerate and overlain by soil with little profile development. A microenvironmental monitoring system was installed in order to record the exchange between the cave and the external atmosphere. Data were collected every 15 min over a period of 14 months (from 22/11/2012 to 13/01/2014). Both radon and CO2 concentration values changed over the course of the annual cycle and were strongly controlled by the difference in air temperature between the exterior and the cave atmosphere. Wavelet transform was applied to the data to determine the influence of visitors on the environmental parameters controlling the cave’s microclimate.

Predicting Daily Water Table Fluctuations in Karstic Aquifers from GIS-Based Modelling, Climatic Settings and Extraction Wells

In semiarid regions, karstic aquifers are in some cases essential since they often constitute the only source of water supply. The increasing demand for water in these regions is responsible for the decreasing water table levels. As a consequence, groundwater management becomes indispensable. A robust black-box model of the Solana aquifer, a large karstic aquifer in Alicante province, is developed considering GIS-based modelling of the studied area, climatic settings and anthropic disturbances (water extractions and irrigation returns). The proposed model accurately predicts water table levels evolution (with EF index of 0.97 and RMSE of 0.09) and assesses the recharge rates. The model aims to become a useful tool in order to better understand the characteristics of karstic aquifers. A distinctive feature of the model is that it estimates the heterogeneous effective porosities along the depth profiles of the aquifer, which provides an advantage related to detect changes in the hydraulic transmissivity within karstic formations.

Temporal evolution of urban growth and its impact on runoff rates generation

Financial support was provided partially by the University of Alicante, project GRE15-19. This study also has been conducted within the grant received from the Programa Nacional de Formacion de Profesorado Universitario (FPU) conceded by the Spanish Ministry of Science to the first author.

Validating the KAGIS black-box GIS-based model in a Mediterranean karst aquifer: Case of study of Mela aquifer (SE Spain)

This research was funded by the Spanish Ministry of Science and Innovation, Projects CGL2013‐48802‐C3‐3‐R and CGL2015‐69773‐C2‐1‐P; and by the University of Alicante, Projects GRE15‐19 and GRE17‐12.