Mercury remobilization from flooded soils in a hydroelectric reservoir of northern Quebec, La Grande-2: results of a soil resuspension experiment

1995 ◽  
Vol 52 (11) ◽  
pp. 2507-2517 ◽  
Author(s):  
Alfonso Mucci ◽  
Shelagh Montgomery ◽  
Marc Lucotte ◽  
Yanick Plourde ◽  
Pierre Pichet ◽  
...  
Keyword(s):  
Water Column ◽  
Inorganic Mercury ◽  
Predatory Fish ◽  
Flooded Soils ◽  
Fine Grained ◽  
Erosion Processes ◽  
Submerged Soils ◽  
Organic Particles ◽  
Dissolved Mercury

An experiment was conducted during summer, 1992, in a protected bay of the La Grande-2 reservoir (northern Quebec) to evaluate the role of erosional processes in the transfer of mercury from a flooded soil to the water column. Up to 57% of the organic carbon, approximately 4% of the inorganic mercury, and nearly 71% of the methylmercury from the humic horizon of a flooded podzol were transferred to the water column and transported outside the experimental perimeter in the form of particulate matter after one resuspension event. In contrast, total dissolved mercury concentrations in the water column decreased during the resuspension event as a result of scavenging by suspended particles. We postulate that most of the methylmercury produced in the submerged soils is associated with fine-grained organic particles that remain in suspension for some time before flocculating and accumulating at the sediment–water interface. We suspect that these particles are a potential food source and can be readily ingested by pelagic and benthic detritus-feeders as well as trapped by periphyton. Resuspension and erosion processes along the exposed shores of a recently impounded reservoir may thus accelerate the transfer of mercury, primarily as methylmercury, from flooded soils to predatory fish.

Total dissolved mercury in the water column of several natural and artificial aquatic systems of Northern Quebec (Canada)

1995 ◽  
Vol 52 (11) ◽  
pp. 2483-2492 ◽  
Author(s):  
Shelagh Montgomery ◽  
Marc Lucotte ◽  
Pierre Pichet ◽  
Alfonso Mucci
Keyword(s):  
Water Column ◽  
Inorganic Mercury ◽  
Potential Vector ◽  
Hydroelectric Reservoirs ◽  
Average Value ◽  
Aquatic Food Chain ◽  
Reservoir Systems ◽  
Terrestrial Environments ◽  
Aquatic Food ◽  
Dissolved Mercury

Total dissolved mercury concentrations in the water column of the La Grande-2 and Laforge-1 hydroelectric reservoirs and four neighbouring lakes near James Bay, northern Quebec, were measured to establish the impacts of extensive flooding of terrestrial environments on this potential vector of contamination to the aquatic biota. During three field visits between June and October 1993, while the sites were free from ice cover and the water column was not strongly stratified, filtered water samples were collected from multiple depths at various locations within both reservoirs and the four lakes. To compare the diverse subenvironments within the reservoir systems, sampling sites were selected to represent differences in (i) type of flooded soil, (ii) impoundment history, and (iii) water depth. At all stations total dissolved mercury concentrations were nearly constant, with an average value of 2.30 ng∙L−1 and a standard error of 0.04 ng∙L−1. Furthermore, reservoir concentrations were not statistically different from those of the lakes. Hence, we propose that the dissolved component in the water column does not play a significant role in the transfer of inorganic mercury to the aquatic food chain in recently developed hydroelectric reservoirs.

Tongues of Fire

2018 ◽  
Author(s):  
Nancy Farriss
Keyword(s):  
Cultural Difference ◽  
Language Contact ◽  
Social Contexts ◽  
Culture Contact ◽  
Rhetorical Strategies ◽  
Southern Mexico ◽  
Fine Grained ◽  
Indigenous Church ◽  
Cultural Gaps

Language and translation governed the creation of Mexican Christianity during the first centuries of colonial rule. Spanish missionaries collaborated with indigenous intellectuals to communicate the gospel in dozens of local languages that had previously lacked grammars, dictionaries, or alphabetic script. The major challenge to translators, more serious than the absence of written aids or the great diversity of languages and their phonetic and syntactical complexity, was the vast cultural difference between the two worlds. The lexical gaps that frustrated the search for equivalence in conveying fundamental Christian doctrines derived from cultural gaps that separated European experiences and concepts from those of the Indians. This study focuses on the Otomangue languages of Oaxaca in southern Mexico, especially Zapotec, and relates their role in the Dominican evangelizing program to the larger frame of culture contact in postconquest Mesoamerica. Fine-grained analysis of translated texts is used to reveal the rhetorical strategies of missionary discourse and combines with an examination of language contact in different social contexts. A major aim is to spotlight the role of the native elites in shaping what emerged as a new form of Christianity. As translators, chief catechists, and parish administrators they made evangelization in many respects an indigenous enterprise and the Mexican church it created an indigenous church.

How Artefacts Do Leadership: A Ventriloquial Analysis

2021 ◽  
pp. 089331892199807
Author(s):  
Jonathan Clifton ◽  
Fernando Fachin ◽  
François Cooren
Keyword(s):  
Organizational Communication ◽  
Recent Work ◽  
Distributed Leadership ◽  
Network Theory ◽  
Actor Network Theory ◽  
Fine Grained ◽  
Naturally Occurring ◽  
Human Actors

To date there has been little work that uses fine-grained interactional analyses of the in situ doing of leadership to make visible the role of non-human as well as human actants in this process. Using transcripts of naturally-occurring interaction as data, this study seeks to show how leadership is co-achieved by artefacts as an in-situ accomplishment. To do this we situate this study within recent work on distributed leadership and argue that it is not only distributed across human actors, but also across networks that include both human and non-human actors. Taking a discursive approach to leadership, we draw on Actor Network Theory and adopt a ventriloquial approach to sociomateriality as inspired by the Montreal School of organizational communication. Findings indicate that artefacts “do” leadership when a hybrid presence is made relevant to the interaction and when this presence provides authoritative grounds for influencing others to achieve the group’s goals.

scholarly journals Delta band activity contributes to the identification of command following in disorder of consciousness

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Gonzalo Rivera-Lillo ◽  
Emmanuel A. Stamatakis ◽  
Tristan A. Bekinschtein ◽  
David K. Menon ◽  
Srivas Chennu
Keyword(s):  
Functional Neuroimaging ◽  
Brain Activity ◽  
Disorder Of Consciousness ◽  
Fine Grained ◽  
Electrical Brain Activity ◽  
Delta Band ◽  
Delta Modulation ◽  
Command Following ◽  
Band Activity

AbstractThe overt or covert ability to follow commands in patients with disorders of consciousness is considered a sign of awareness and has recently been defined as cortically mediated behaviour. Despite its clinical relevance, the brain signatures of the perceptual processing supporting command following have been elusive. This multimodal study investigates the temporal spectral pattern of electrical brain activity to identify features that differentiated healthy controls from patients both able and unable to follow commands. We combined evidence from behavioural assessment, functional neuroimaging during mental imagery and high-density electroencephalography collected during auditory prediction, from 21 patients and 10 controls. We used a penalised regression model to identify command following using features from electroencephalography. We identified seven well-defined spatiotemporal signatures in the delta, theta and alpha bands that together contribute to identify DoC subjects with and without the ability to follow command, and further distinguished these groups of patients from controls. A fine-grained analysis of these seven signatures enabled us to determine that increased delta modulation at the frontal sensors was the main feature in command following patients. In contrast, higher frequency theta and alpha modulations differentiated controls from both groups of patients. Our findings highlight a key role of spatiotemporally specific delta modulation in supporting cortically mediated behaviour including the ability to follow command. However, patients able to follow commands nevertheless have marked differences in brain activity in comparison with healthy volunteers.

scholarly journals Large subglacial source of mercury from the southwestern margin of the Greenland Ice Sheet

2021 ◽  
Author(s):  
Jon R. Hawkings ◽  
Benjamin S. Linhoff ◽  
Jemma L. Wadham ◽  
Marek Stibal ◽  
Carl H. Lamborg ◽  
...  
Keyword(s):  
Natural Waters ◽  
Inorganic Mercury ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Annual Runoff ◽  
Arctic Ecosystems ◽  
High Mercury ◽  
Southwestern Margin ◽  
High Concentrations ◽  
Dissolved Mercury

AbstractThe Greenland Ice Sheet is currently not accounted for in Arctic mercury budgets, despite large and increasing annual runoff to the ocean and the socio-economic concerns of high mercury levels in Arctic organisms. Here we present concentrations of mercury in meltwaters from three glacial catchments on the southwestern margin of the Greenland Ice Sheet and evaluate the export of mercury to downstream fjords based on samples collected during summer ablation seasons. We show that concentrations of dissolved mercury are among the highest recorded in natural waters and mercury yields from these glacial catchments (521–3,300 mmol km−2 year−1) are two orders of magnitude higher than from Arctic rivers (4–20 mmol km−2 year−1). Fluxes of dissolved mercury from the southwestern region of Greenland are estimated to be globally significant (15.4–212 kmol year−1), accounting for about 10% of the estimated global riverine flux, and include export of bioaccumulating methylmercury (0.31–1.97 kmol year−1). High dissolved mercury concentrations (~20 pM inorganic mercury and ~2 pM methylmercury) were found to persist across salinity gradients of fjords. Mean particulate mercury concentrations were among the highest recorded in the literature (~51,000 pM), and dissolved mercury concentrations in runoff exceed reported surface snow and ice values. These results suggest a geological source of mercury at the ice sheet bed. The high concentrations of mercury and its large export to the downstream fjords have important implications for Arctic ecosystems, highlighting an urgent need to better understand mercury dynamics in ice sheet runoff under global warming.

Job Resources and Strengths Use in Relation to Employee Performance: A Contextualized View

2021 ◽  
pp. 003329412199778
Author(s):  
Luca Tisu ◽  
Andrei Rusu ◽  
Coralia Sulea ◽  
Delia Vîrgă
Keyword(s):  
Employee Performance ◽  
Job Demands ◽  
Job Resources ◽  
Conservation Of Resources ◽  
Role Clarity ◽  
Fine Grained ◽  
Strengths Use ◽  
Individual Strategies ◽  
Moderator Role

Job resources play a prominent role in employee performance literature, yet a fine-grained understanding of how resources are relevant for several performance types is still needed. Relying on the Job Demands-Resources and Conservation of Resources theories, the present study addresses this call in two ways. First, it examines the predictive effect of four job resources (i.e., role clarity, feedback, autonomy, and opportunities for development) on nine types of performance (i.e., proficiency, adaptivity, and proactivity as an individual, team, and organization member). Second, it tests the moderator role of strengths use in these relationships. Data was gathered from a sample of Romanian employees (N = 332) and analyzed via hierarchical multiple linear regression. The results indicate that the selected job resources are, indeed, predictors of different types of employee performance and not in a unitary manner. Role clarity and feedback appear to be the most relevant predictors for various performance types, while autonomy seems to be the least important. Also, strengths use moderates these relationships, but in a reinforcing manner only regarding opportunities for development. The interaction of strengths use with role clarity and feedback renders the latter two obsolete, indicating that individual strategies may act as substitutes for job resources. These findings add to the Job Demands-Resources theory's versatile nature and provide more clarity to practitioners who plan interventions to enhance specific performance types, taking individual strategies into account.

scholarly journals Adopting the Situation in School Questionnaire to Examine Physical Education Teachers’ Motivating and Demotivating Styles Using a Circumplex Approach

2021 ◽  
Vol 18 (14) ◽  
pp. 7342
Author(s):  
Géraldine Escriva-Boulley ◽  
Emma Guillet-Descas ◽  
Nathalie Aelterman ◽  
Maarten Vansteenkiste ◽  
Nele Van Doren ◽  
...  
Keyword(s):  
Physical Education ◽  
Autonomy Support ◽  
Future Research ◽  
Physical Education Teachers ◽  
Structure Control ◽  
Fine Grained ◽  
Circular Structure ◽  
Need Support ◽  
Academic Courses

Grounded in SDT, several studies have highlighted the role of teachers’ motivating and demotivating styles for students’ motivation, learning, and physical activity in physical education (PE). However, most of these studies focused on a restricted number of motivating strategies (e.g., offering choice) or dimensions (e.g., autonomy support). Recently, researchers have developed the Situations-in-School (i.e., SIS-Education) questionnaire, which allows one to gain a more integrative and fine-grained insight into teachers’ engagement in autonomy-support, structure, control, and chaos through a circular structure (i.e., a circumplex). Although teaching in PE resembles teaching in academic courses in many ways, some of the items of the original situation-based questionnaire (e.g., regarding homework) are irrelevant to the PE context. In the present study, we therefore sought to develop a modified, PE-friendly version of this earlier validated SIS-questionnaire—the SIS-PE. Findings in a sample of Belgian (N = 136) and French (N = 259) PE teachers, examined together and as independent samples, showed that the variation in PE teachers’ motivating styles in this adapted version is also best captured by a circumplex structure, with four overarching styles and eight subareas differing in their level of need support and directiveness. The SIS-PE possesses excellent convergent and concurrent validity. With the adaptations being successful, great opportunities for future research on PE teachers (de-)motivating styles are created.

scholarly journals The Role of Frost Processes in the Retreat of River Banks

Water ◽  
2021 ◽  
Vol 13 (13) ◽  
pp. 1812
Author(s):  
Karol Augustowski ◽  
Józef Kukulak
Keyword(s):  
Relative Role ◽  
Freezing And Thawing ◽  
Fine Grained ◽  
Fluvial Processes ◽  
Precise Calculation ◽  
Erosion Pins ◽  
Summer Half ◽  
Lateral Erosion ◽  
Summer Flood

The rate of bank retreat was measured using erosion pins on the alluvial banks of the rivers in the Podhale region (the boundary zone between Central and Outer Carpathians) during the hydrological year 2013/2014. During the winter half-year (November–April), the bank retreat was mainly caused by processes related to the freezing and thawing of the ground (swelling, creep, downfall). During the summer half-year (May–October), fluvial processes and mass movements such as lateral erosion, washing out, and sliding predominated. The share of fluvial processes in the total annual amount of bank retreat (71 cm on average) was 4 times greater than that of the frost phenomena. Erosion on bank surfaces by frost phenomena during the cold half-year was greatest (up to 38 cm) on the upper parts of banks composed of fine-grained alluvium, while fluvial erosion during the summer half-year (exceeding 80 cm) mostly affected the lower parts of the banks, composed of gravel. The precise calculation of the relative role of frost phenomena in the annual balance of bank erosion was precluded at some stations by the loss of erosion pins in the summer flood.

Seasonal variations of water column nutrients in the inner area of Ariake Bay, Japan: the role of muddy sediments

2013 ◽  
Vol 185 (8) ◽  
pp. 6831-6846 ◽  
Author(s):  
Masumi Koriyama ◽  
Yuichi Hayami ◽  
Akane Koga ◽  
Koichi Yamamoto ◽  
Alim Isnasetyo ◽  
...  
Keyword(s):  
Water Column ◽  
Seasonal Variations ◽  
Ariake Bay ◽  
Muddy Sediments

Effects of Fe addition on sediment P dynamics in a eutrophic lake

2021 ◽  
Author(s):  
Melanie Münch ◽  
Rianne van Kaam ◽  
Karel As ◽  
Stefan Peiffer ◽  
Gerard ter Heerdt ◽  
...  
Keyword(s):  
Water Quality ◽  
Organic Matter ◽  
Surface Water ◽  
Water Column ◽  
Sediment Cores ◽  
Surface Water Quality ◽  
Water Interface ◽  
Eutrophic Lakes ◽  
Fe Addition

<p>The decline of surface water quality due to excess phosphorus (P) input is a global problem of increasing urgency. Finding sustainable measures to restore the surface water quality of eutrophic lakes with respect to P, other than by decreasing P inputs, remains a challenge. The addition of iron (Fe) salts has been shown to be effective in removing dissolved phosphate from the water column of eutrophic lakes. However, the resulting changes in biogeochemical processes in sediments as well as the long-term effects of Fe additions on P dynamics in both sediments and the water column are not well understood.</p><p>In this study, we assess the impact of past Fe additions on the sediment P biogeochemistry of Lake Terra Nova, a well-mixed shallow peat lake in the Netherlands. The Fe-treatment in 2010 efficiently reduced P release from the sediments to the surface waters for 6 years. Since then, the internal sediment P source in the lake has been increasing again with a growing trend over the years.</p><p>In 2020, we sampled sediments at three locations in Terra Nova, of which one received two times more Fe during treatment than the other two. Sediment cores from all sites were sectioned under oxygen-free conditions. Both the porewaters and sediments were analysed for their chemical composition, with sequential extractions providing insight into the sediment forms of P and Fe. Additional sediment cores were incubated under oxic and anoxic conditions and the respective fluxes of P and Fe across the sediment water interface were measured.</p><p>The results suggest that Fe and P dynamics in the lake sediments are strongly coupled. We also find that the P dynamics are sensitive to the amount of Fe supplied, even though enhanced burial of P in the sediment was not detected. The results of the sequential extraction procedure for P, which distinguishes P associated with humic acids and Fe oxides, as well as reduced flux of Fe(II) across the sediment water interface in the anoxic incubations, suggest a major role of organic matter in the interaction of Fe and P in these sediments.</p><p>Further research will include investigations of the role of organic matter and sulphur in determining the success of Fe-treatment in sequestering P in lake sediments. Based on these data in combination with reactive transport modelling we aim to constrain conditions for successful lake restoration through Fe addition.</p>

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