Groundwater as an archive of climatic and environmental change: Europe to Africa

Edmunds, W.M.; Dodo, A.; Djoret, Djaira; Gaye, Cheik H.; Goni, Ibrahim Baba; Travi, Yves; Zouari, Kamel; Zuppi, G.M.; Gasse, Françoise

doi:10.1007/978-1-4020-2121-3_14

Cited by 28 publications

(14 citation statements)

References 27 publications

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“…Palaeoclimatic studies based on nobles gas recharge temperatures (Edmunds et al, 2004) and speleothems (Valsero andJosé, 2002 andJiménez de Cisneros andCaballero, 2013) conclude that the Late Pleistocene recorded climatic periods with temperatures up to 5°C colder than the current annual average temperature. This coincides with the findings of Scheiber et al, 2015, where the groundwater travel time from the recharge zone to the deepest zone was N 30,000 years.…”

Section: Origin Of Major Solutesmentioning

confidence: 99%

Origin of high ammonium, arsenic and boron concentrations in the proximity of a mine: Natural vs. anthropogenic processes

Scheiber

Ayora

Vàzquez-Suñé

et al. 2016

Science of The Total Environment

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High ammonium (NH4), arsenic (As) and boron (B) concentrations are found in aquifers worldwide and are often related to human activities. However, natural processes can also lead to groundwater quality problems. High NH4, As and B concentrations have been identified in the confined, deep portion of the Niebla-Posadas aquifer, which is near the Cobre Las Cruces (CLC) mining complex. The mine has implemented a Drainage and Reinjection System comprising two rings of wells around the open pit mine, were the internal ring drains and the external ring is used for water reinjection into the aquifer. Differentiating geogenic and anthropogenic sources and processes is therefore crucial to ensuring good management of groundwater in this sensitive area where groundwater is extensively used for agriculture, industry, mining and human supply. No NH4, As and B are found in the recharge area, but their concentrations increase with depth, salinity and residence time of water in the aquifer. The increased salinity down-flow is interpreted as the result of natural mixing between infiltrated meteoric water and the remains of connate waters (up to 8%) trapped within the pores. Ammonium and boron are interpreted as the result of marine solid organic matter degradation by the sulfate dissolved in the recharge water. The light δ(15)NNH4 values confirm that its origin is linked to marine organic matter. High arsenic concentrations in groundwater are interpreted as being derived from reductive dissolution of As-bearing goethite by dissolved organic matter. The lack of correlation between dissolved Fe and As is explained by the massive precipitation of siderite, which is abundantly found in the mineralization. Therefore, the presence of high arsenic, ammonium and boron concentrations is attributed to natural processes. Ammonium, arsenic, boron and salinity define three zones of groundwater quality: the first zone is close to the recharge area and contains water of sufficient quality for human drinking; the second zone is downflow and contains groundwater suitable for continuous irrigation but not drinkable due to high ammonium concentrations; and the third zone contains groundwater of elevated salinity (up to 5940 μS cm(-1)) and is not useable due to high ammonium, arsenic and boron concentrations.

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Section: Origin Of Major Solutesmentioning

confidence: 99%

Origin of high ammonium, arsenic and boron concentrations in the proximity of a mine: Natural vs. anthropogenic processes

Scheiber

Ayora

Vàzquez-Suñé

et al. 2016

Science of The Total Environment

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“…This aquifer was last recharged during the early Holocene, probably in part by infiltration of precipitation in the Tibesti mountains to the northwest (Maley, 2000), and in the Kufra Basin to the northeast (Brinkmann et al , 1987). The vast Nubian Sandstone aquifer, which feeds the Ounianga lakes, extends to northern Sudan and to the Western Desert of Egypt (Hesse et al , 1987; Edmunds et al , 2004).…”

Section: Introductionmentioning

confidence: 99%

Modern and early Holocene mollusc fauna of the Ounianga lakes (northern Chad): implications for the palaeohydrology of the central Sahara

Bocxlaer

Verschuren

Schettler

et al. 2011

J Quaternary Science

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The fresh and saline lakes of Ounianga Kebir and Serir in northeastern Chad are among the very few permanent aquatic ecosystems currently existing in the hyper-arid core of the Sahara desert. The confirmed modern fauna of aquatic molluscs at Ounianga comprises three widespread species (Melanoides tuberculata, Biomphalaria pfeifferi and Lymnaea natalensis), of which only the first appears to maintain a thriving population. We recovered seven more species of gastropods, among which one is new to science (Gabbiella ouniangaensis), and one bivalve species from early Holocene outcrops of diatomaceous limestone at Ounianga Serir. All species except one are known to be commonly spread between lake and river systems by birds, and in its entirety this species-rich fossil mollusc fauna of Ounianga Serir resembles that of other Saharan lake sites known to have been hydrologically isolated during the early Holocene. The impoverished modern mollusc fauna, which lacks even the widespread and opportunistic species Bulinus truncatus, may have become established relatively recently through new colonisation events, following eradication of the early Holocene mollusc fauna during a later episode of high salinity or desiccation.

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“…Isotopes (Fig. 3) indicate that the Casteldoria water should contain a relatively large component of very old water, with a lower heavy isotope content, that entered the bedrock during the past, when climatic conditions differed much from today (Clark and Fritz 1997;Edmunds et al 2004). Consequently, the observed oxygen shift can be explained by the long time that this fossil freshwater has had to react with the reservoir matrix.…”

Section: Water and Salinity Originmentioning

confidence: 84%

Fluid Geochemistry as Indicator of Tectonically-Related, Deep Water Circulations in the Sardinian Rift-Campidano Graben (Italy): New Insights from Environmental Isotopes

et al. 2008

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The EC funded Geochemical Seismic Zonation program (EEC GSZ Project 1996-1998 chose Sardinia as a low-seismicity site, in which the relationships between fluid geochemistry and seismo-tectonics had to be investigated and results compared with outcomes from other selected high-seismicity sites. A first article, examining the role of fault segmentation and seismic quiescence on the geochemical composition of groundwaters and gases, has already been presented (Angelone et al. 2005). This article deals with environmental isotopes which, together with selected hydrochemical data, give hints on tectonically-related fluid circulations. Four water-dominated hydrothermal systems were considered, all located along regional fault systems and discharging groundwaters belonging to the Na-HCO 3 and Na-Cl facies. In the considered systems, groundwater circulation takes place, principally, in the Palaeozoic Crystalline Basement (PCB), with the exception of the Logudoro system, where hydrological circuits develop in the Mesozoic Carbonate Platform (MCP). The high CO 2 contents, the non-attainment of fluid-rock equilibrium and the large lithological variability prevent the construction of a unique hydrogeological-geochemical conceptual model. In this case, stable isotopes provide a useful tool to describe the origin of fluids and their subterranean movements. Stable isotopes of water, integrated with hydrochemical data, indicate that fluids are derived from three main end members. The dominant component is a relatively recent local meteoric water; the second one is marine water; and the third one is a fossil freshwater, depleted in heavy isotopes with respect to modern rains. The latter end member entered the aquifer system in the past, when climatic conditions were greatly different from today. At least two circulation systems can be recognised, namely a shallow cold system and a deep hydrothermal system, as well as two distinct hydrological processes: (1) gravity-controlled descent of cold water towards greater depths and (2) convection linked to a thermal gradient, causing deep fluids to rise up from the hydrothermal reservoir towards the surface. The highly variable d 13 C TDIC values suggest the presence of two distinct CO 2 sources, namely, a biogenic one and a thermogenic one. The relation between the isotopic compositions of CO 2 and He indicates an increased mantle signature in uprising CO 2 -rich fluids.

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Groundwater as an archive of climatic and environmental change: Europe to Africa

Cited by 28 publications

References 27 publications

Origin of high ammonium, arsenic and boron concentrations in the proximity of a mine: Natural vs. anthropogenic processes

Origin of high ammonium, arsenic and boron concentrations in the proximity of a mine: Natural vs. anthropogenic processes

Modern and early Holocene mollusc fauna of the Ounianga lakes (northern Chad): implications for the palaeohydrology of the central Sahara

Fluid Geochemistry as Indicator of Tectonically-Related, Deep Water Circulations in the Sardinian Rift-Campidano Graben (Italy): New Insights from Environmental Isotopes

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