Browsing by Author "Scheiber, L"

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    Hydrochemical apportioning of irrigation groundwater sources in an alluvial aquifer
    (Elsevier B. V., 2020-11-20) Scheiber, L; Cendón, DI; Iverach, CP; Hankin, SI; Vázquez-Suñé, E; Kelly, BFJ
    River floodplains sustain irrigated agriculture worldwide. Despite generalised groundwater level falls, limited hard data are available to apportion groundwater sources in many irrigated regions. In this paper, we propose a workflow based on: hydrochemical analysis, water stable isotopes, radiocarbon contents and multivariate statistical analysis to facilitate the quantification of groundwater source attribution at regional scales. Irrigation water supply wells and groundwater monitoring wells sampled in the alluvial aquifer of the Condamine River (Queensland, Australia) are used to test this approach that can easily be implemented in catchments worldwide. The methodology identified four groundwater sources: 1) river/flood water; 2) modified river/flood water; 3) groundwater recharged through regional volcanic materials and 4) groundwater recharged predominantly through sands and/or sandstone materials. The first two sources are characterised by fresh water, dominant sodium bicarbonate chemistry, short residence time and depleted water stable isotope signatures. Groundwater sources 3 and 4 are characterised by saline groundwater, sodium chloride chemistries, enriched water stable isotopes and very low radiocarbon contents, inferred to correspond to long residence times. The majority of wells assessed are dominated by flood water recharge, linked to decadal >300 mm rainfall events and associated flooding in the region. The approach presented here provides a groundwater source fingerprint, reinforcing the importance of floodwater recharge in the regional water budgets. This apportioning of groundwater sources will allow irrigators, modelers and managers to assess the long-term sustainability of groundwater use in alluvial catchments. Crown Copyright © 2020 Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND licence
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    A nine-year record of groundwater environmental tracer variations in a weathered sandstone plateau aquifer
    (American Geophysical Union, 2016-12-15) Cendón, DI; Hankin, SI; Hughes, CE; Meredith, KT; Peterson, MA; Scheiber, L; Shimizu, Y
    Most groundwater isotopic studies are limited to one snapshot in time due to high costs associated with sampling and analytical procedures. The timing of sampling within long-term seasonal climatic cycles may affect interpretations, particularly in unconfined or semi-confined aquifer systems. To test the potential influence of decadal climatic trends, particularly on groundwater residence time, we have combined results from a multi-year sampling programme. Hydrogeochemistry and isotopic tracer analysis including H2O stable isotopes, δ13CDIC, 3H, 14CDIC for all samples and 87Sr/86Sr and NO3-δ15N, have been applied to groundwater recovered from the Kulnura – Mangrove Mountain aquifer hosted by a weathered sandstone plateau within the Sydney Basin (Australia). In general, the study area is characterised by alternating dry and wet periods that can be prolonged as they are linked to wider climatic events such as El Niño, La Niña and modulated by the Indian Ocean Dipole. The region experienced above average rainfall from 1985-1990 followed by generally drier conditions (1991-2007) and slightly wetter conditions to 2015. Groundwater results from the first years (2006-2010), under generally dry conditions resulted in lower groundwater levels, revealed important inter-annual variations. These are interpreted to be locally driven by groundwater extraction, resulting in a progressive influx of modern groundwater. The progressive input of modern water has exposed deeper parts of the aquifer to increased NO3- concentrations of anthropogenic origin. The change in chemistry of the groundwater, particularly the lowering of groundwater pH, has accelerated the dissolution of carbonate mineral phases that in turn affects 14C residence time assessments. Subsequent sampling results (2012-2015), under higher rainfall conditions, suggest modern recharge in areas previously without measurable tritium activities. The complex interplay between recharge, anthropogenic influences and climate may be further complicated by the local irregularities in the sandstone weathering profile and the transition to preferential groundwater fracture-flow with depth. © AGU 2016
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    Origen de las altas concentraciones de amonio, arsénico y boro en el acuífero Niebla-Posadas en la proximidad de la actividad minera de Cobre Las Cruces (Gerena-Sevilla)
    (Geological and Mining Institute of Spain, 2015) Scheiber, L; Ayora, C; Vázquez-Suñé, E; Cendón, DI; Soler, A; Baquero, JC
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    Origin of high ammonium, arsenic and boron concentrations in the proximity of a mine: natural vs. anthropogenic processes
    (Elsevier, 2016-01-15) Scheiber, L; Ayora, C; Vázquez-Suñé, E; Cendón, DI; Soler, A; Baquero, JC
    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 δ15NNH4 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. © 2015, Elsevier B.V.
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    Recent and old groundwater in the Niebla-Posadas regional aquifer (southern Spain): implications for its management
    (Elsevier Science B.V., 2015-04-01) Scheiber, L; Ayora, C; Vazquez-Sune, E; Cendón, DI; Soler, A; Custodio, E; Baquero, JC
    The Niebla-Posadas (NP) aquifer in southern Spain is one of the main groundwater sources for the lower Guadalquivir Valley, a semiarid region supporting an important population, agriculture and industry. To contribute to the understanding of this aquifer the assessment of sustainable use of groundwater, the residence time of groundwater in the NP aquifer has been estimated using H-3, C-14 and Cl-36. Along the flow paths, recharged groundwater mixes with NaCl-type waters and undergoes calcite dissolution and is further modified by cation exchange (Ca-Na). Consequently, the water loses most of its calcium and the residual delta C-13(DIC) in the groundwater is isotopically enriched. Further modifications take place along the flow path in deeper zones, where depleted delta C-13(DIC) values are overprinted due to SC42- and iron oxide reduction, triggered by the presence of organic matter. Dating with H-3, C-14 and Cl-36 has allowed the differentiation of several zones: recharge zone (<0.06 ky), intermediate zone (0.06-20 ky), deep zone 1(20-30 ky), and deep zone 2 (>30 ky). An apparent link between the tectonic structure and the groundwater residence time zonation can be established. Regional faults clearly separates deep zone 1 from the distinctly older age (>30 ky) deep zone 2. From the estimated residence times, two groundwater areas of different behavior can be differentiated within the aquifer. © 2015, Elsevier B.V.
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    The use of the hydrogeochemistry and multivariate statistical methods as a tool for groundwater management. Condamine River Alluvial Aquifer (CRAA), Australia
    (Copernicus Publications, 2018-04-08) Scheiber, L; Iverach, CP; Kelly, BFJ; Cendón, DI; Vázquez-Suñé, E
    The alluvial aquifers of the Condamine River near Dalby have been increasingly used since the 1960s as a water resources to support Irrigated agriculture of mainly cotton and grain crops. Groundwater abstraction from the underlying Condamine River Alluvial Aquifer (CRAA) supplies 30% of the irrigation water (Dafny and Silburn, 2014). Over the past decade, Coal Seam Gas (CSG) exploration and production has expanded rapidly in the Queensland portion of the Surat Basin (SB), targeting the underlying Walloon Coal Measures (WCM), with tenements to multiple companies along the western flank of the Condamine Plain. To produce the gas, groundwater will be extracted in large quantities, depressurising the WCM. There is concern that the zone of depressurisation will impact the groundwater levels within the CRAA. In the last decade, great efforts have been made to improve hydrogeological conceptualization and modeling. The rapid expansion of CSG exploration and production in Australia has generated controversy within the public who are concerned about the impact on adjacent aquifers used to support irrigated agriculture, stock and domestic water supplies. The proximity of gas extraction to aquifers used for irrigation or domestic water supply is common to many CSG production sites globally. To address these concerns there has been increased research within the region to improve our understanding of aquifer connectivity and the regional water balance. To solve the uncertainties about the impact of CSG exploitation on the groundwater of the adjacent aquifers is necessary to have a robust conceptual model to understand the hydrological dynamics and hydrochemical processes. Most cases, spatial and temporal variability of groundwater chemistry is the result of mixing processes between different water sources. Understanding the mixing processes which take place between several groundwater inputs or groundwater with other water bodies is crucial for groundwater management. Mixing calculations have been successfully applied in many hydrogeological setting to improve the conceptual model and understanding the origins of groundwater compositions. The main aims of this work are to improve the knowledge of the hydrogeologic system in the Condamine alluvium and to investigate the possible impacts of CSG exploration and production to the Condamine Alluvium. To attain these objectives, this study applies a methodology based on multivariate statistical methods for computing the mixing ratios of different water sources (end-members) in several observation points to evaluate the potential impacts. This included the identification and chemical characterization of the recharge sources (end-members), the evaluation of the mixing proportions for each sample, the quantification of the geochemical processes undergone, and the evaluation of CSG exploitation effects. Mixing ratios are computed using MIX code developed by (Carrera et al., 2004). MIX code is based on the maximum likelihood algorithm to estimate the mixing ratios taking into account the uncertainty of the end-members and mixed samples. Building a robust conceptual model together with the application of multivariate statistical methods will serve as a useful tool for groundwater management. © Author(s) 2018. CC Attribution 4.0 license.