Hydrogeochemical Characterization of Groundwater in the Outaouais Region (Quebec, Canada)-A Regional Scale Study

As part of the Québec regional groundwater characterization program (PACES), a detailed groundwater quality survey was undertaken in the Outaouais Region (Québec, Canada). During the summers of 2011 and 2012, 139 samples were taken from municipal and private wells which were analysed for major ions, nutrients, metals and sulphides. About 70% of the samples were obtained from bedrock wells, mainly in the Canadian Shield and the remainder from wells screened in Quaternary deposit aquifers. Analysis quality was evaluated by calculating the anion-cation balance. As a result, 127 samples with anion-cation charge balance errors within ±10 % were used for the determination of hydrogeochemical facies. The classification by facies is also supported by multivariate statistical analysis, namely Principal Component Analysis (PCA) and Hierarchical Clustering Analysis (HCA). The study has identified Champlain Sea invasion, cation exchange and freshwater recharge as the main geochemical processes affecting groundwater chemistry in this region

Baseline groundwater monitoring for shale gas extraction: definition of baseline conditions and recommendations from a real site (Wysin, Northern Poland)

Public concerns have been raised regarding the use of hydraulic fracturing for shale gas extraction and its potential impact on the environment. The absence of baseline monitoring data in the US experience has been identified as a major issue. Here, results from a 6-month groundwater baseline monitoring study near an active shale gas pad in northern Poland are presented. The data collected in dedicated boreholes include groundwater samples analysed for inorganic constituents, dissolved gases and stables isotopes (δ2H and δ18O) and downhole temperature and conductivity measurements at 15-min intervals. A robust statistical analysis combined with an estimation of data uncertainty helps to identify spatial and temporal variability within the datasets. As a result, baseline conditions are defined using confidence intervals around the mean on a per-well basis and these will serve for future reference for this site. The groundwater chemical composition is similar to regional background levels and typical of Quaternary aquifers in the region. It is also consistent with previous baseline monitoring carried out by the Polish Geological Institute. Only manganese and bromide occur in groundwater at concentrations above Polish drinking water standards. Based on this work, the paper provides some recommendations for future baseline monitoring and identifies areas for future research such as use of statistics for high-frequency datasets

Hydrogeochemical Characterization of Groundwater in the Outaouais Region (Quebec, Canada)-A Regional Scale Study

As part of the Québec regional groundwater characterization program (PACES), a detailed groundwater quality survey was undertaken in the Outaouais Region (Québec, Canada). During the summers of 2011 and 2012, 139 samples were taken from municipal and private wells which were analysed for major ions, nutrients, metals and sulphides. About 70% of the samples were obtained from bedrock wells, mainly in the Canadian Shield and the remainder from wells screened in Quaternary deposit aquifers. Analysis quality was evaluated by calculating the anion-cation balance. As a result, 127 samples with anion-cation charge balance errors within ±10 % were used for the determination of hydrogeochemical facies. The classification by facies is also supported by multivariate statistical analysis, namely Principal Component Analysis (PCA) and Hierarchical Clustering Analysis (HCA). The study has identified Champlain Sea invasion, cation exchange and freshwater recharge as the main geochemical processes affecting groundwater chemistry in this region

Hydrogeochemical evolution of groundwater in a Quaternary sediment and Cretaceous sandstone unconfined aquifer in Northwestern China

A better understanding of the hydrogeochemical evolution of groundwater in vulnerable aquifers is important for the protection of water resources. To assess groundwater chemistry, groundwater sampling was performed from different representative aquifers in 2012–2013. A Piper trilinear diagram showed that the groundwater types can be classified into Na–SO4 and Na–Cl types. Only one groundwater sample was Na–HCO3 type. The dominant cations for all samples were Na+. However, the dominant anions varied from HCO3− to SO42−, and as well Cl−. The mean total dissolved solid (TDS) content of groundwater in the region was 1889 mg/L. Thus, only 20% of groundwater samples meet Chinese drinking water standards (< 1000 mg/L). Principal component analysis (PCA) combined with hierarchical cluster analysis (HCA) and self-organizing maps (SOM) were applied for the classification of the groundwater geochemistry. The three first principal components explained 58, 20, and 16% of the variance, respectively. The first component reflects sulfate minerals (gypsum, anhydrite) and halite dissolution, and/or evaporation in the shallow aquifer. The second and third components are interpreted as carbonate rock dissolution. The reason for two factors is that the different aquifers give rise to different degree of hydrogeochemical evolution (different travel distances and travel times). Identified clusters for evolution characteristic and influencing factors were confirmed by the PCA–HCA methods. Using information from eight ion components and SOM, formation mechanisms and influencing factors for the present groundwater quality were determined

Groundwater geochemistry of the Outaouais Region (Québec, Canada): a regional-scale study

As part of a province-wide groundwater characterization program, a detailed groundwater geochemistry survey was undertaken in the Outaouais Region (Québec, Canada) in order to identify the primary processes responsible for groundwater quality and to develop a conceptual model for groundwater flow and geochemical evolution. During the summers of 2011 and 2012, 139 samples were collected from municipal and private wells which were analysed for major ions, nutrients, trace elements and sulphides. About 70 % of the samples were obtained from bedrock wells, mainly in the silicate rocks of the Canadian Shield and the remainder from wells screened in Quaternary deposit aquifers. Hydrogeochemical facies distributions were determined from 127 of these samples which had anion-cation charge balance errors within ±10 %. The classification by facies was also supported by a multivariate statistical analysis, namely factor analysis combined with hierarchical cluster analysis. The study identified Champlain Sea invasion, cation exchange and freshwater recharge as the main geochemical processes affecting groundwater chemistry in this region. Secondary processes, related to the bedrock geology, are responsible for exceedances of Canadian drinking-water standards, namely for fluoride, uranium, iron and manganese

A conceptual model for groundwater flow and geochemical evolution in the southern Outaouais Region, Québec, Canada

A conceptual model was developed for a hydrogeological flow system in the southern Outaouais Region, Quebec, Canada, where the local population relies heavily on groundwater pumped from shallow overburden aquifers and from deeper fractured crystalline bedrock. The model is based on the interpretation of aqueous inorganic geochemical data from 14 wells along a cross-section following the general flow direction, of which 9 were also analysed for isotopes (δ18O, δ2H, 3H, δ13C, 14C) and 4 for noble gases (He, Ne, Ar, Xe, Kr). Three major water types were identified: (1) Ca–HCO3 in the unconfined aquifer as a result of silicate (Ca-feldspar) weathering, (2) Na–Cl as a remnant of the post-glacial Champlain Sea in stagnant confined zones of the aquifer, and (3) Na–HCO3, resulting from freshening of the confined aquifer due to Ca–Na cation exchange. Chemical data also allowed the identification of significant mixing zones. Isotope and noble gas data confirm the hypothesis of remnant water from the Champlain Sea and also support the hypothesis of mixing processes between a young tritium-rich component with an older component containing high 4He concentrations. It is still unclear if the mixing occurs under natural flow conditions or if it is induced by pumping during the sampling, most wells being open boreholes in the bedrock. It is clear, however, that the hydrogeochemical system is dynamic and still evolving from induced changes since the last glaciation. As a next step, the conceptual model will serve as a basis for groundwater flow, mass transport and geochemical modelling to validate the hypotheses developed in this paper

Vibration isolation and damping using a piezoelectric flextensional suspension with a negative capacitance shunt

International audienceA suspension combining a piezoelectric component and a mechanical amplifier is studied in view to reducing vibration transmission over a wide frequency band. The principle and design of the piezoelectric suspension are approached using electromechanical and finite element models. The aim is to combine high damping at resonant frequency and high isolation at high frequency. The electromechanical coupling of the transducer allows implementing mechanical damping and electric damping with different shunts based on resistive and negative capacitance. The first design of the device is tested experimentally

Colombia River Stories Datasets Archive, 1994-2020

The goal of the project is the environmental monitoring of water resources using an innovative and multi-disciplinary methodology that brings social scientists and natural scientists together - integrating their research methods and techniques to capture human stories through community-level, participatory research and the river's story through field-based scientific monitoring and environmental reconstruction and mapping. The social science data of the project includes in-depth life history style interviews with individuals from the Afro-Colombian and Indigenous communities of the Atrato. The project used purposive sampling, recruiting participants through local contacts and then ‘snowballing’ for additional participants. As part of our citizen science programme, monitoring of the Rio Quito was carried out on a weekly basis by a local community. The monitoring consisted of measurement of in-situ parameters (turbidity, pH, conductivity, dissolved oxygen and temperature) and water sampling of Rio Quito. They also monitored the bacterial contamination of their drinking water. The hydrogeochemical data sets were based on a range of analytical results carried out on water (river and rain) and soil (riverbank and river bottom) samples, predominantly from the Rio Quito and the town of Quibdo. The parameters being acquired were the water temperature, pH, specific electrical conductivity (SEC), total dissolved solids (TDS), oxidation reduction potential (ORP), dissolved oxygen (DO), alkalinity, major anion and cations, water stable isotopes and suite of dissolved and total metals in water. The satellite images archive consists of temporal satellite images between 1994- 2020 that were pre-processed and processed in order to highlight changes that were observed along the river bank due to anthropogenic action. A temporal change detection analysis has been evaluated by highlighting the observed changes through time. Atrato Subcatchment Sediment Load Estimation & analysis of mining impacts on the planform of the Rio Quito quantifies the ways and extent to which alluvial gold mining in the Chocó has impacted the geomorphological form and function of the rivers in which it occurs. It specifically focusses on the assessment of mining impacts on: 1. total river sediment loads; 2. river suspended sediment concentration and turbidity; 3. river channel planform. The results presented contribute to the wider project objective of understanding the ways in which mining-driven changes to river form and function intersect with, and influence, the socio-economic, social-political, and socio-cultural systems that drive alluvial gold mining and conflict in the Chocó.Colombia is in the process of transitioning from one of the most protracted civil conflicts in the world to peace. However, one of the major societal issues for post-conflict transitions in Colombia is how to ensure the inclusion and participation of vulnerable and marginalised groups in transition processes so that their knowledges, abilities and capacities are represented, and so that they can influence post-conflict development. This raises questions of how innovative community- engaged and participatory processes can achieve greater inclusivity in peace building processes. It also raises the question of how different conflict actors can be encouraged and facilitated to articulate their knowledge and experience of conflict in ways that enable their actions to be explained to one another, and that support a shift from narrow understandings of the causes of conflict based on personal experience to more expansive understandings that are based on collective experiences. In this research, we focus on riverine communities along the Atrato River - the main artery of Choco. These communities have been deeply impacted by armed actors who are engaged in widespread, illegal alluvial gold mining which is a key factor in their forced displacement and the loss of traditional, sustainable livelihoods. Despite a 2017 Colombian Constitutional Court ruling to empower riverine communities with 'bio-cultural rights' that protect their land title and livelihoods, they remain marginalised. They struggle to make their voices heard and to influence and inform peace building processes. This marginalisation has also been experienced by the river itself, whose voice has been silenced through the abandonment of state-sponsored environmental monitoring programmes at the height of the conflict. As a result, the effects of conflict and alluvial mining on the form and function of the river, and the impacts of these on interactions between armed actors, the river, and the communities it sustains are poorly understood. This will only be addressed if marginalised voices of communities and the river are articulated and amplified so that their knowledges, abilities and capacities can be integrated into sustainable peace building processes. Achieving this is the primary aim of this project. Conceptually, our project builds on a key emphasis of peace processes worldwide: the capture and re-telling of testimony so that conflict actors can better appreciate the complexities of the conflict in which they are engaged, and the inter-relationships and feedbacks between their actions, and those of others, which fuel the conflict. Such knowledge is a fundamental precursor to the development of sustainable and feasible strategies for peace. The project is structured and designed to elicit, analyse and co-produce testimonies as an integrated 'river story', sourced from multiple participants and perspectives - including marginalised human actors and the river itself. The project therefore uses an innovative and multi- disciplinary methodology that brings social scientists and natural scientists together - integrating their research methods and techniques to capture human stories through community-level, participatory research and the river's story through field- based scientific monitoring and environmental reconstruction and mapping. The story books that are produced, and the policy briefs that they underpin, will be the vehicles through which policy-makers are bought into dialogue with the marginalised voices of both riverine communities and the river itself, and thorough which they improved understandings of the key actors and drivers of conflict in Choco' and the priorities and strategies for sustainable peace building, will be gained.</p