scholarly journals The Cr(VI) Stability in Contaminated Coastal Groundwater: Salinity as a Driving Force

Minerals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 160
Author(s):  
Ioannis-Porfyrios D. Eliopoulos ◽  
George D. Eliopoulos ◽  
Maria Economou-Eliopoulos
Keyword(s):  
Natural Attenuation ◽  
Coastal Aquifers ◽  
Driving Force ◽  
Management Strategies ◽  
Positive Trend ◽  
Groundwater Salinity ◽  
Geochemical Mapping ◽  
Coastal Groundwater ◽  
The Stability

Chromium concentrations in seawater are less than 0.5 μg/L, but the Cr(VI) in contaminated coastal groundwater affected by Cr-bearing rocks/ores and/or human activities, coupled with the intrusion of seawater may reach values of hundreds of μg/L. A potential explanation for the stability of the harmful Cr(VI) in contaminated coastal aquifers is still unexplored. The present study is an overview of new and literature data on the composition of coastal groundwater and seawater, aiming to provide potential relationships between Cr(VI) with major components in seawater and explain the elevated Cr(VI) concentrations. It is known that the oxidation of Cr(III) to Cr(VI) and the subsequent back-reduction of Cr(VI) processes, during the transport of the mobilized Cr(VI) in various aquifers, facilitate the natural attenuation process of Cr(VI). Moreover, the presented positive trend between B and Cr(VI) and negative trend between δ53Cr values and B concentration may suggest that seawater components significantly inhibit the Cr(VI) reduction into Cr(III), and provide insights on the role of the borate, [B(OH)4]− ions, a potential buffer, on the stability of Cr(VI) in coastal groundwater. Therefore, efforts are needed toward the prevention and/or minimization of the contamination by Cr(VI) of in coastal aquifers, which are influenced by the intrusion of seawater and are threatened by changes in sea level, due to climate change. The knowledge of the contamination sources, hotspots and monitoring of water salinization processes (geochemical mapping) for every coastal country may contribute to the optimization of agricultural management strategies.

scholarly journals Contamination of the Soil–Groundwater–Crop System: Environmental Risk and Opportunities

Minerals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 775
Author(s):  
Maria Economou-Eliopoulos ◽  
Ifigeneia Megremi
Keyword(s):  
Management Strategies ◽  
Toxic Metal ◽  
Industrial Wastes ◽  
Green Economy ◽  
Positive Trend ◽  
The European Union ◽  
Contamination Sources ◽  
Coastal Groundwater ◽  
The Stability ◽  
Crop System

The increasing development of industries, resulting in a large volume of mining, smelting, and combustion wastes, and intense agricultural activities, due to demand for food and energy, have caused environmental hazards for food quality and ecosystems. This is a review on the contamination of the soil–groundwater–crop system and a potential reduction of the contamination by a gradual shift towards green economy within the European Union and on a worldwide scale. Available mineralogical and geochemical features from contaminated Neogene basins have shown a diversity in the contamination sources for soil and groundwater, and highlighted the need to define the contamination sources, hot spots, degree/extent of contamination, and provide ways to restrict the transfer of heavy metals/metalloids into the food chain, without the reduction of the agricultural and industrial production. Among harmful elements for human health and ecosystems, the contamination of groundwater (thousands of μg/L Cr(VI)) by industrial activities in many European countries is of particular attention. Although Cr(VI) can be reduced to Cr(III) and be completely attenuated in nature under appropriate pH and Eh conditions, the contamination by Cr(VI) of coastal groundwater affected by the intrusion of seawater often remains at the hundreds μg/L level. A positive trend between B and Cr(VI) may provide insights on the role of the borate [B(OH)4]− ions, a potential buffer, on the stability of Cr(VI) in coastal groundwater. Efforts are needed towards reducing toxic metal(loids) from the industrial wastewaters prior to their discharge into receptors, as well as the transformation of hazardous mining/industrial wastes to new products and applications to the optimization of agricultural management strategies.

scholarly journals Paleo-modeling of coastal saltwater intrusion during the Holocene: an application to the Netherlands

2014 ◽  
Vol 18 (10) ◽  
pp. 3891-3905 ◽  
Author(s):  
J. R. Delsman ◽  
K. R. M. Hu-a-ng ◽  
P. C. Vos ◽  
P. G. B. de Louw ◽  
G. H. P. Oude Essink ◽  
...  
Keyword(s):  
The Netherlands ◽  
Boundary Conditions ◽  
Coastal Aquifers ◽  
Large Scale ◽  
Groundwater Salinity ◽  
Salinity Distribution ◽  
Marine Transgression ◽  
The Holocene ◽  
Coastal Groundwater ◽  
Groundwater Composition

Abstract. Coastal groundwater reserves often reflect a complex evolution of marine transgressions and regressions, and are only rarely in equilibrium with current boundary conditions. Understanding and managing the present-day distribution and future development of these reserves and their hydrochemical characteristics therefore requires insight into their complex evolution history. In this paper, we construct a paleo-hydrogeological model, together with groundwater age and origin calculations, to simulate, study and evaluate the evolution of groundwater salinity in the coastal area of the Netherlands throughout the last 8.5 kyr of the Holocene. While intended as a conceptual tool, confidence in our model results is warranted by a good correspondence with a hydrochemical characterization of groundwater origin. Throughout the modeled period, coastal groundwater distribution never reached equilibrium with contemporaneous boundary conditions. This result highlights the importance of historically changing boundary conditions in shaping the present-day distribution of groundwater and its chemical composition. As such, it acts as a warning against the common use of a steady-state situation given present-day boundary conditions to initialize groundwater transport modeling in complex coastal aquifers or, more general, against explaining existing groundwater composition patterns from the currently existing flow situation. The importance of historical boundary conditions not only holds true for the effects of the large-scale marine transgression around 5 kyr BC that thoroughly reworked groundwater composition, but also for the more local effects of a temporary gaining river system still recognizable today. Model results further attest to the impact of groundwater density differences on coastal groundwater flow on millennial timescales and highlight their importance in shaping today's groundwater salinity distribution. We found free convection to drive large-scale fingered infiltration of seawater to depths of 200 m within decades after a marine transgression, displacing the originally present groundwater upwards. Subsequent infiltration of fresh meteoric water was, in contrast, hampered by the existing density gradient. We observed discontinuous aquitards to exert a significant control on infiltration patterns and the resulting evolution of groundwater salinity. Finally, adding to a long-term scientific debate on the origins of groundwater salinity in Dutch coastal aquifers, our modeling results suggest a more significant role of pre-Holocene groundwater in the present-day groundwater salinity distribution in the Netherlands than previously recognized. Though conceptual, comprehensively modeling the Holocene evolution of groundwater salinity, age and origin offered a unique view on the complex processes shaping groundwater in coastal aquifers over millennial timescales.

scholarly journals Palaeo-modeling of coastal salt water intrusion during the Holocene: an application to the Netherlands

2013 ◽  
Vol 10 (11) ◽  
pp. 13707-13742 ◽  
Author(s):  
J. R. Delsman ◽  
K. R. M. Hu-a-ng ◽  
P. C. Vos ◽  
P. G. B. de Louw ◽  
G. H. P. Oude Essink ◽  
...  
Keyword(s):  
The Netherlands ◽  
Groundwater Flow ◽  
Coastal Aquifers ◽  
Salt Water ◽  
Groundwater Salinity ◽  
Salinity Distribution ◽  
The Holocene ◽  
Coastal Groundwater ◽  
History Of ◽  
The Impact

Abstract. Management of coastal fresh groundwater reserves requires a thorough understanding of the present-day groundwater salinity distribution and its possible future development. However, coastal groundwater often still reflects a complex history of marine transgressions and regressions, and is only rarely in equilibrium with current boundary conditions. In addition, the distribution of groundwater salinity is virtually impossible to characterize satisfactorily, complicating efforts to model and predict coastal groundwater flow. A way forward may be to account for the historical development of groundwater salinity when modeling present-day coastal groundwater flow. In this paper, we construct a palaeo-hydrogeological model to simulate the evolution of groundwater salinity in the coastal area of the Netherlands throughout the Holocene. While intended as a perceptual tool, confidence in our model results is warranted by a good correspondence with a hydrochemical characterization of groundwater origin. Model results attest to the impact of groundwater density differences on coastal groundwater flow on millennial timescales and highlight their importance in shaping today's groundwater salinity distribution. Not once reaching steady-state throughout the Holocene, our results demonstrate the long-term dynamics of salinity in coastal aquifers. This stresses the importance of accounting for the historical evolution of coastal groundwater salinity when modeling present-day coastal groundwater flow, or when predicting impacts of e.g. sea level rise on coastal aquifers. Of more local importance, our findings suggest a more significant role of pre-Holocene groundwater in the present-day groundwater salinity distribution in the Netherlands than previously recognized. The implications of our results extend beyond understanding the present-day distribution of salinity, as the proven complex history of coastal groundwater also holds important clues for understanding and predicting the distribution of other societally relevant groundwater constituents.

Economic Growth: New Problems and New Risks

2006 ◽  
pp. 20-37 ◽  
Author(s):  
M. Ershov
Keyword(s):  
Economic Growth ◽  
Foreign Exchange ◽  
Driving Force ◽  
Structural Changes ◽  
Rate Of Growth

The economic growth, which is underway in Russia, raises new questions to be addressed. How to improve the quality of growth, increasing the role of new competitive sectors and transforming them into the driving force of growth? How can progressive structural changes be implemented without hampering the rate of growth in general? What are the main external and internal risks, which may undermine positive trends of development? The author looks upon financial, monetary and foreign exchange aspects of the problem and comes up with some suggestions on how to make growth more competitive and sustainable.

A Statistical Study of Process Variables to Optimize a High Speed Curtain Coater: Part I

TAPPI Journal ◽  
2009 ◽  
Vol 8 (1) ◽  
pp. 20-26 ◽  
Author(s):  
PEEYUSH TRIPATHI ◽  
MARGARET JOYCE ◽  
PAUL D. FLEMING ◽  
MASAHIRO SUGIHARA
Keyword(s):  
Boundary Layer ◽  
Experimental Design ◽  
High Speed ◽  
Statistical Study ◽  
Process Variables ◽  
High Speeds ◽  
The Stability ◽  
Air Removal ◽  
Removal System

Using an experimental design approach, researchers altered process parameters and material prop-erties to stabilize the curtain of a pilot curtain coater at high speeds. Part I of this paper identifies the four significant variables that influence curtain stability. The boundary layer air removal system was critical to the stability of the curtain and base sheet roughness was found to be very important. A shear thinning coating rheology and higher curtain heights improved the curtain stability at high speeds. The sizing of the base sheet affected coverage and cur-tain stability because of its effect on base sheet wettability. The role of surfactant was inconclusive. Part II of this paper will report on further optimization of curtain stability with these four variables using a D-optimal partial-facto-rial design.

Moderating Role of Learning Strategies Between Meta-Cognitive Awareness and Study Habits Among University Students

2019 ◽  
Vol 34 (Spring 2019) ◽  
pp. 215-231
Author(s):  
Mussarat J. Khan ◽  
Seemab Rasheed
Keyword(s):  
Regression Analysis ◽  
Resource Management ◽  
University Students ◽  
Learning Strategies ◽  
Management Strategies ◽  
Cognitive Strategies ◽  
Study Habits ◽  
Good Reliability ◽  
Cognitive Awareness

The purpose of present study is to examine the role of learning strategies as moderator between meta-cognitive awareness and study habits among university students. Sample comprises of 200 students (100 male students and 100 female students) of various universities of Islamabad and Rawalpindi with age ranging from 18-25 years. In order to assess study variables questionnaires were used included Meta-Cognitive Awareness Inventory (Schraw & Dennison, 1994) measuring two-components of meta-cognition that are knowledge and regulation of cognition. Study habits demonstrated by the students were measured by the Study Habits Inventory (Wrenn, 1941). Motivated Strategies for Learning Questionnaire (Pintrich, Smith, Garcia, & McKeachie, 1991) which includes motivation and learning strategies scales. In the present study, only the learning strategies section was utilized, which measures the cognitive strategies and resource management strategies. Results revealed positive correlation between research instruments and are also having good reliability. Regression analysis reflected that meta-cognitive awareness predicts study habits among university students. Regression analysis also suggested that learning strategies including resource management strategies and cognitive strategies significantly moderates the relationship between meta-cognitive awareness and study habits. It is also explored gender differences on learning strategies, meta-cognitive awareness and study habits. Future implications of the study were also discussed.

BİLGİ YÖNETİMİ UYGULAMALARI KAPSAMINDA İNSAN KAYNAKLARI YÖNETİMİNDE MEYDANA GELEN DEĞİŞİMLER

2013 ◽  
Vol 1 (1) ◽  
pp. 83
Author(s):  
Ozan Büyükyılmaz
Keyword(s):  
Knowledge Management ◽  
Human Resources ◽  
Performance Management ◽  
Management Practices ◽  
Human Resources Management ◽  
Management Strategies ◽  
Resources Management ◽  
Management Philosophy ◽  
Management Processes

The development and expansion of knowledge management as an important management philosophy has a significant impact on human resources management as well as on organization as a whole. In this context, knowledge management processes have been used as a strategic tool within human resources management.Therefore, functions of human resources management must adapt itself to this change. The purpose of this study is to determine the role of human resources management in the management of knowledge and to reveal the effects of knowledge management practices on the functions of human resources byexamining the relationship between human resources and knowledge management. In this context, a theoretical investigation was conducted. It has been determined that significant changes occurred on the functions of human resources management such as selection and recruitment, performance management, remuneration and reward, training and development within the framework of the knowledge management strategies.

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