Hydrochemical evidence of the depth of penetration of anthropogenic recharge in sandstone aquifers underlying two mature cities in the UK

Taylor, Richard G.; Cronin, Aidan A.; Lerner, David N.; Tellam, John H.; Bottrell, Simon H.; Rueedi, J.; Barrett, Mike

doi:10.1016/j.apgeochem.2006.06.015

Cited by 26 publications

(12 citation statements)

References 41 publications

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“…However, pore-water and piezometer profiles through plumes do confirm that transverse dispersion is often limited (<1-2 m) for the distance-time scales of even large pollution plumes (Lerner et al 2000;Thornton et al 2001b;Taylor et al submitted). On larger space and timescales, considerable lateral dispersion can develop: for example, the dispersion profile associated with a fresh-saline groundwater interface in an aquifer in NW England is many tens of metres thick, despite the fact that most of these profiles are in poorly fractured, deeper (100-300 m) parts of the aquifer Brassington et al 1992;Tellam 1995a;.…”

Section: Expected Modelling Work By Stafford Et Almentioning

confidence: 99%

Towards prediction of saturated-zone pollutant movement in groundwaters in fractured permeable-matrix aquifers: the case of the UK Permo-Triassic sandstones

Tellam

Barker

2006

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Abstract:The UK on-shore Permo-Triassic sandstones are fluvial and aeolian red beds showing a nested cyclic architecture on scales from millimetres to 100s of metres. They are typical of many continental sandstone sequences throughout the world. Groundwater flows through both matrix and fractures, with natural flow rates generally of less than 200 m year -1. At less than 30 m horizontal distances, below important minimum representative volumes for both matrix and fracture network permeability, breakthroughs are likely to be multimodal, especially close to wells, with proportionately large apparent dispersivities. 'Antifractures' -discontinuities with permeability much less than that of the host rockmay have a dominating effect. Where present, low-permeability matrix (e.g. mudstones) will significantly affect vertical flow, but will rarely prevent eventual breakthrough. Quantitative prediction of breakthrough is associated with large uncertainty. At scales of 30 to a few 100s of metres, multimodal breakthroughs from a single source become less common, although very rapid fracture flow has been recorded. At distances of hundreds of metres to a few kilometres, there is evidence that breakthroughs are unimodal, and may be more immediately amenable to quantitative prediction, even in some cases for reacting solutes. At this and greater scales, regional fault structures (both slip surfaces and granulation seams) can have major effects on sub-horizontal solute movement, and mudstones and cemented units will discourage vertical penetration. The aquifer has limited oxidizing capacity despite the almost ubiquitous presence of oxides, limited reductive capacity and limited organic sorption capacity. It has a moderate cation-exchange capacity, and frequently contains carbonate. Mn oxides are important for sorption and oxidation, but are present in limited quantity. Relationships between hydraulic and chemical properties are largely unknown. 'Hard' evidence for the solute transport conceptual model presented above is relatively limited. To be able to predict to a reasonably estimated degree of uncertainty requires knowledge of: the geological, and thence the hydraulic and geo-chemical, structure of the complex sandstone architecture (including the correlations between these properties); the development of suitable investigation techniques (especially geophysical) for mapping the structures; and the development of modelling tools incorporating matrix, fractures, 'antimatrix' and antifracture elements, each with associated hydraulic and possibly geochemical properties. In common with solute movement studies in most aquifer types, much more geological characterization needs to be undertaken. Although new investigation and modelling tools are being developed specifically for (shallow) hydrogeological applications with some considerable success, much greater advantage could be taken of importing techniques from other disciplines, and in particular from oil exploration and development.

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Section: Expected Modelling Work By Stafford Et Almentioning

confidence: 99%

Towards prediction of saturated-zone pollutant movement in groundwaters in fractured permeable-matrix aquifers: the case of the UK Permo-Triassic sandstones

Tellam

Barker

2006

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“…Lerner identified recharge rates of 30% in Lima (Peru), and also attributed 50% of total recharge in Hong Kong to leakage contributions with values ranging from 260 to 2950 mm/year . Contributions from leaking infrastructure to soil water, and thus groundwater recharge, have long been recognized but quantifying their impacts has proven problematic, often resulting in adoption of environmental tracer techniques and model applications . Whilst both approaches are valid, these estimates are often time consuming and uncertain.…”

Section: Review Of Advances In Monitoring To Support Integrated Modelmentioning

confidence: 99%

Integrated modeling in urban hydrology: reviewing the role of monitoring technology in overcoming the issue of ‘big data’ requirements

et al. 2016

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Increasingly, the application of models in urban hydrology has undergone a shift toward integrated structures that recognize the interconnected nature of the urban landscape and both the natural and engineered water cycles. Improvements in computational processing during the past few decades have enabled the application of multiple, connected model structures that link previously disparate systems together, incorporating feedbacks and connections. Many applications of integrated models look to assess the impacts of environmental change on physical dynamics and quality of landscapes. Whilst these integrated structures provide a more robust representation of natural dynamics, they often place considerable data requirements on the user, whereby data are required at contrasting spatial and temporal scales which can often transcend multiple disciplines. Concomitantly, our ability to observe complex, natural phenomena at contrasting scales has improved considerably with the advent of increasingly novel monitoring technologies. This has provided a pathway for reducing model uncertainty and improving our confidence in modeled outputs by implementing suitable monitoring regimes. This commentary assesses how component models of an exemplar integrated model have advanced over the past few decades, with a critical focus on the role of monitoring technologies that have enabled better identification of the key physical process. This reduces the uncertainty of processes at contrasting spatial and temporal scales, through a better characterization of feedbacks which then enhances the utility of integrated model applications

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“…Once infiltrating waters enter the subsurface, oxygen (O 2 ) may rapidly decrease and NO 3 -can be used by denitrifying bacteria as electron acceptor (Appelo and Postma 2005) in organic matter and sulfide oxidation processes (Aravena and Robertson 1998). If these substrates are not abundant, denitrification occurs at low rate and, therefore, NO 3 -can travel long distances within aquifers (Andersen and Kristiansen 1984;Shomar et al 2008;Taylor et al 2006), depending on aquifer materials and structure heterogeneities. Thus, to determine the direction and rate of groundwater flow and to predict NO 3 -solute transport, hydraulic conductivity distribution has to be ascertained (Gelhar 1993;Webb and Davis 1998).…”

Section: Introductionmentioning

confidence: 99%

Large tank experiment on nitrate fate and transport: the role of permeability distribution

et al. 2010

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A long-term elution experiment to study the saturated transport of pre-accumulated fertilizers by-products, was conducted within a large tank (4 x 8 x 1.4 m) equipped with 26 standard piezometers. Sandy sediments (35 m(3)), used to fill the tank, were excavated from an unconfined alluvial aquifer near Ferrara (Northern Italy); the field site was connected to a pit lake located in a former agricultural field. To evaluate spatial heterogeneity, the tank's filling material was characterized via slug tests and grain-size distribution analysis. The investigated sediments were characterized by a large spectrum of textures and a heterogeneous hydraulic conductivity (k) field. Initial tank pore water composition exhibited high concentration of nitrate (NO(3) (-)) sulfate (SO(4) (2-)) calcium (Ca(2+)), and magnesium (Mg(2+)), due to fertilizer leaching from the top soil in the field site. The initial spatial distribution of NO(3) (-) and SO(4) (2-) was heterogeneous and not related to the finer grain-size content (< 63 mu m). The tank's material was flushed with purified tap water for 800 days in steady-state conditions; out flowing water was regularly sampled to monitor the migration rate of fertilizer by-products. Complete removal of NO(3) (-) and SO(4) (2-) took 500 and 600 days, respectively. Results emphasized organic substrate availability and spatial heterogeneities as the most important constraints to denitrification and nitrogen removal, which increase the time required to achieve remediation targets. Finally, the obtained clean-up time was compared with a previous column experiment filled with the same sediments

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Hydrochemical evidence of the depth of penetration of anthropogenic recharge in sandstone aquifers underlying two mature cities in the UK

Cited by 26 publications

References 41 publications

Towards prediction of saturated-zone pollutant movement in groundwaters in fractured permeable-matrix aquifers: the case of the UK Permo-Triassic sandstones

Towards prediction of saturated-zone pollutant movement in groundwaters in fractured permeable-matrix aquifers: the case of the UK Permo-Triassic sandstones

Integrated modeling in urban hydrology: reviewing the role of monitoring technology in overcoming the issue of ‘big data’ requirements

Large tank experiment on nitrate fate and transport: the role of permeability distribution

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