Using Water Temperature, Electrical Conductivity, and pH to Characterize Surface–Groundwater Relations in a Shallow Ponds System (Doñana National Park, SW Spain)

Abstract

The physical limnology of a shallow pond system was characterized using field measurements of water temperature, pH, and electrical conductivity (EC). We determined the spatial variability in surface and groundwater temperature, pH, and EC along the pond’s shore and along the several pond-shore transects, analyzed the water column temperature gradient and estimated the groundwater discharge rate using a heat transfer model. The fieldwork was conducted in Santa Olalla and Dulce ponds located in Doñana National Park in southwestern Spain during different stages from 2016 to 2018. The results of this study have improved the understanding of the thermal structure and the surface–subsurface heat exchange in the ponds and highlighted the importance of groundwater discharge in the pond water balance. It also showed the heterogeneous nature of groundwater discharge through the bottom sediments of the Santa Olalla pond. These results are consistent with previous studies and strengthen the existing hydrological and limnological knowledge of these ponds located in the protected area which is receiving a great deal of public attention.

Drivers and variability of CO2:O2 saturation along a gradient from boreal to Arctic lakes

“…Groundwater input has been shown to correlate well with conductivity, as water in contact with bedrock is likely to become enriched in ions and minerals. The positive relationship between CO 2 saturation and conductivity may thus indicate lateral input of CO 2 55 , in particular in the studied subarctic and arctic systems. Further, lake pH may regulate the CO 2 concentration with a higher proportion of the DIC staying as free CO 2 at low pH values while at higher pH values, more CO 2 enters the carbonate cycle, forming carbonate and bicarbonate.…”

“…This is supported by the positive correlation between CO 2 :O 2 ratio and conductivity, while the influence of DOC concentration was weak or non-significant. This may suggest that the major share of CO 2 in these lakes is of allochthonous origin, likely from organic carbon mineralization and carbonate weathering in the catchment soils, entering via groundwater flow 41 , 55 . This points to fundamentally different drivers of CO 2 and O 2 concentrations in boreal and Arctic lakes due to differences in vegetation, landscape structure, hydrology and lake bathymetry.…”

Integration of sensors for dam water quality analysis – a prototype

“…The circuit consists of an amplifier and a conversion unit to read the potential difference between the electrodes. The sensitivity of the electrodes depends on the electrode material and the efficiency of the amplifier (Rodríguez-Rodríguez et al 2018). pH is termed as the measurement of acidity or alkalinity of drinking water.…”

Análisis del hidroperíodo de tres lagunas de la Reserva Biológica de Doñana (2018-2020)

“…Las lagunas peridunares de Doñana han sido objeto de numerosos estudios de tipo hidrogeológico en los últimos años (Rodríguez-Rodríguez et al, 2017;Rodríguez-Rodríguez et al, 2018;Fernández-Ayuso et al, 2018;Rodríguez-Rodríguez et al, 2020). Dichos estudios han puesto de manifiesto la importancia de la descarga subterránea hacia estas lagunas desde el acuífero costero del manto eólico litoral de Doñana (MASb 0055104) y la alteración del régimen hidrológico en dos de estos sistemas: la laguna de Zahíllo y la laguna de Taraje (Rodríguez-Rodríguez et al, 2020).…”