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Characterization of chlorinated solvent contamination in limestone using innovative FLUTe® technologies in combination with other methods in a line of evidence approach.

https://arctichealth.org/en/permalink/ahliterature283305
Source
J Contam Hydrol. 2016 Jun;189:68-85
Publication Type
Article
Date
Jun-2016
Author
Mette M Broholm
Gry S Janniche
Klaus Mosthaf
Annika S Fjordbøge
Philip J Binning
Anders G Christensen
Bernt Grosen
Torben H Jørgensen
Carl Keller
Gary Wealthall
Henriette Kerrn-Jespersen
Source
J Contam Hydrol. 2016 Jun;189:68-85
Date
Jun-2016
Language
English
Publication Type
Article
Keywords
Calcium Carbonate
Denmark
Environmental Monitoring - methods
Groundwater - analysis
Halogenation
Hydrology - methods
Models, Theoretical
Solvents - analysis - chemistry
Water Pollutants, Chemical - analysis - chemistry
Abstract
Characterization of dense non-aqueous phase liquid (DNAPL) source zones in limestone aquifers/bedrock is essential to develop accurate site-specific conceptual models and perform risk assessment. Here innovative field methods were combined to improve determination of source zone architecture, hydrogeology and contaminant distribution. The FACT™ is a new technology and it was applied and tested at a contaminated site with a limestone aquifer, together with a number of existing methods including wire-line coring with core subsampling, FLUTe® transmissivity profiling and multilevel water sampling. Laboratory sorption studies were combined with a model of contaminant uptake on the FACT™ for data interpretation. Limestone aquifers were found particularly difficult to sample with existing methods because of core loss, particularly from soft zones in contact with chert beds. Water FLUTe™ multilevel groundwater sampling (under two flow conditions) and FACT™ sampling and analysis combined with FLUTe® transmissivity profiling and modeling were used to provide a line of evidence for the presence of DNAPL, dissolved and sorbed phase contamination in the limestone fractures and matrix. The combined methods were able to provide detailed vertical profiles of DNAPL and contaminant distributions, water flows and fracture zones in the aquifer and are therefore a powerful tool for site investigation. For the limestone aquifer the results indicate horizontal spreading in the upper crushed zone, vertical migration through fractures in the bryozoan limestone down to about 16-18m depth with some horizontal migrations along horizontal fractures within the limestone. Documentation of the DNAPL source in the limestone aquifer was significantly improved by the use of FACT™ and Water FLUTe™ data.
PubMed ID
27116640 View in PubMed
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Continuum-based DFN-consistent numerical framework for the simulation of oxygen infiltration into fractured crystalline rocks.

https://arctichealth.org/en/permalink/ahliterature285056
Source
J Contam Hydrol. 2017 May;200:60-69
Publication Type
Article
Date
May-2017
Author
Paolo Trinchero
Ignasi Puigdomenech
Jorge Molinero
Hedieh Ebrahimi
Björn Gylling
Urban Svensson
Dirk Bosbach
Guido Deissmann
Source
J Contam Hydrol. 2017 May;200:60-69
Date
May-2017
Language
English
Publication Type
Article
Keywords
Groundwater - chemistry
Hydrology - methods
Iron - chemistry
Minerals - chemistry
Models, Theoretical
Oxidation-Reduction
Oxygen - analysis - chemistry
Sweden
Water Movements
Abstract
We present an enhanced continuum-based approach for the modelling of groundwater flow coupled with reactive transport in crystalline fractured rocks. In the proposed formulation, flow, transport and geochemical parameters are represented onto a numerical grid using Discrete Fracture Network (DFN) derived parameters. The geochemical reactions are further constrained by field observations of mineral distribution. To illustrate how the approach can be used to include physical and geochemical complexities into reactive transport calculations, we have analysed the potential ingress of oxygenated glacial-meltwater in a heterogeneous fractured rock using the Forsmark site (Sweden) as an example. The results of high-performance reactive transport calculations show that, after a quick oxygen penetration, steady state conditions are attained where abiotic reactions (i.e. the dissolution of chlorite and the homogeneous oxidation of aqueous iron(II) ions) counterbalance advective oxygen fluxes. The results show that most of the chlorite becomes depleted in the highly conductive deformation zones where higher mineral surface areas are available for reactions.
PubMed ID
28412014 View in PubMed
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Hydrologic monitoring tools for freshwater municipal planning in the Arctic: the case of Iqaluit, Nunavut, Canada.

https://arctichealth.org/en/permalink/ahliterature297764
Source
Environ Sci Pollut Res Int. 2018 Nov; 25(33):32913-32925
Publication Type
Journal Article
Date
Nov-2018
Author
Michael Bakaic
Andrew Scott Medeiros
Jessica F Peters
Brent B Wolfe
Author Affiliation
Department of Environmental Studies, York University, Toronto, ON, Canada.
Source
Environ Sci Pollut Res Int. 2018 Nov; 25(33):32913-32925
Date
Nov-2018
Language
English
Publication Type
Journal Article
Keywords
Climate
Climate change
Environmental monitoring
Fresh Water - analysis
Humans
Hydrology - methods
Nunavut
Planning Techniques
Rain
Rivers - chemistry
Seasons
Water supply
Abstract
Freshwater and the services it provides are vital to both natural ecosystems and human needs; however, extreme climates and their influence on freshwater availability can be challenging for municipal planners and engineers to manage these resources effectively. In Arctic Canada, financial and human capital limitations have left a legacy of freshwater systems that underserve current communities and may be inadequate in the near future under a warming climate, growing population, and increasing demand. We address this challenge to community water resource planning by applying several novel water supply forecasting methods to evaluate the Apex River as an alternative freshwater source for Iqaluit, Nunavut (Canada). Surveys of water isotope composition of the Apex River and tributaries indicated that rainfall is the main source of water replenishment. This information was utilized to calibrate a water resource assessment that considered climate forecasting scenarios and their influence on supply, and alternative scenarios for freshwater management to better adapt to a changing climate. We found that under current climate and demand conditions, the freshwater supply of Iqaluit would be in a perpetual state of drawdown by 2024. Analysis of current infrastructure proposals revealed significant deficiencies in the supply extensions proposed whereby the Apex replenishment pipeline would only provide a 2-year extension to current municipal supply. Our heuristic supply forecast methods allowed for several alternative supply strategies to be rapidly evaluated, which will aid the community planning process by specifically quantifying the service life of the city's current and future primary water supply.
PubMed ID
28589278 View in PubMed
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Reconstruction of in-situ porosity and porewater compositions of low-permeability crystalline rocks: Magnitude of artefacts induced by drilling and sample recovery.

https://arctichealth.org/en/permalink/ahliterature274064
Source
J Contam Hydrol. 2015 Dec;183:55-71
Publication Type
Article
Date
Dec-2015
Author
D B Meier
H N Waber
T. Gimmi
F. Eichinger
L W Diamond
Source
J Contam Hydrol. 2015 Dec;183:55-71
Date
Dec-2015
Language
English
Publication Type
Article
Keywords
Artifacts
Computer simulation
Diffusion
Finland
Geology - methods
Hydrology - methods
Iodides - analysis
Microscopy - methods
Permeability
Porosity
Ultraviolet Rays
Water
Water Pollution - analysis
Abstract
Geological site characterisation programmes typically rely on drill cores for direct information on subsurface rocks. However, porosity, transport properties and porewater composition measured on drill cores can deviate from in-situ values due to two main artefacts caused by drilling and sample recovery: (1) mechanical disruption that increases porosity and (2) contamination of the porewater by drilling fluid. We investigated the effect and magnitude of these perturbations on large drill core samples (12-20 cm long, 5 cm diameter) of high-grade, granitic gneisses obtained from 350 to 600 m depth in a borehole on Olkiluoto Island (SW Finland). The drilling fluid was traced with sodium-iodide. By combining out-diffusion experiments, gravimetry, UV-microscopy and iodide mass balance calculations, we successfully quantified the magnitudes of the artefacts: 2-6% increase in porosity relative to the bulk connected porosity and 0.9 to 8.9 vol.% contamination by drilling fluid. The spatial distribution of the drilling-induced perturbations was revealed by numerical simulations of 2D diffusion matched to the experimental data. This showed that the rims of the samples have a mechanically disrupted zone 0.04 to 0.22 cm wide, characterised by faster transport properties compared to the undisturbed centre (1.8 to 7.7 times higher pore diffusion coefficient). Chemical contamination was shown to affect an even wider zone in all samples, ranging from 0.15 to 0.60 cm, in which iodide enrichment was up to 180 mg/kg water, compared to 0.5 mg/kg water in the uncontaminated centre. For all samples in the present case study, it turned out that the magnitude of the artefacts caused by drilling and sample recovery is so small that no correction is required for their effects. Therefore, the standard laboratory measurements of porosity, transport properties and porewater composition can be taken as valid in-situ estimates. However, it is clear that the magnitudes strongly depend on site- and drilling-specific factors and therefore our results cannot be transferred simply to other locations. We recommend the approach presented in this study as a route to obtain reliable values in future drilling campaigns aimed at characterising in-situ bedrock properties.
PubMed ID
26529302 View in PubMed
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Testate amoeba transfer function performance along localised hydrological gradients.

https://arctichealth.org/en/permalink/ahliterature278132
Source
Eur J Protistol. 2016 Sep;55(Pt B):141-151
Publication Type
Article
Date
Sep-2016
Author
Andrey N Tsyganov
Olga A Mityaeva
Yuri A Mazei
Richard J Payne
Source
Eur J Protistol. 2016 Sep;55(Pt B):141-151
Date
Sep-2016
Language
English
Publication Type
Article
Keywords
Amoeba - physiology
Classification
Groundwater - analysis - parasitology
Hydrology - methods
Reproducibility of Results
Russia
Soil - parasitology
Wetlands
Abstract
Testate amoeba transfer functions are widely used for reconstruction of palaeo-hydrological regime in peatlands. However, the limitations of this approach have become apparent with increasing attention to validation and assessing sources of uncertainty. This paper investigates effects of peatland type and sampling depth on the performance of a transfer function using an independent test-set from four Sphagnum-dominated sites in European Russia (Penza Region). We focus on transfer function performance along localised hydrological gradients, which is a useful analogue for predictive ability through time. The performance of the transfer function with the independent test-set was generally weaker than for the leave-one-out or bootstrap cross-validations. However, the transfer function was robust for the reconstruction of relative changes in water-table depth, provided the presence of good modern analogues and overlap in water-table depth ranges. When applied to subsurface samples, the performance of the transfer function was reduced due to selective decomposition, the presence of deep-dwelling taxa or vertical transfer of shells. Our results stress the importance of thorough testing of transfer functions, and highlight the role of taphonomic processes in determining results. Further studies of stratification, taxonomy and taphonomy of testate amoebae will be needed to improve the robustness of transfer function output.
PubMed ID
26776269 View in PubMed
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