Performance of small group of geosynthetic-reinforced granular piles

Granular piles are frequently used as a method of improving soft grounds as they provide increased bearing capacity and reduce foundation settlements. However, in very soft clayey soils, they may not derive their load-carrying capacity by low confining pressure provided by the surrounding soil. In such circumstances, granular piles may be reinforced with suitable geosynthetic to increase its load-carrying capacity and to reduce excessive bulging. In this study, the performance of small group of geosynthetic-reinforced granular piles (GRGPs) is examined in terms of load-carrying capacity, settlement, and modulus by laboratory model tests. The parameters investigated include modulus of reinforcement material, area replacement ratio (ARR) based on the column diameter and reinforcement length. The results indicated that increasing the modulus of the reinforcement and the ARR based on the column diameter enhances the overall performance of the GRGP group. It was also observed that reinforcement on top portion of the granular pile is sufficient to substantially increase the load-carrying capacity of granular pile group.     

Elimination of natural organic matter by electrocoagulation using bipolar and monopolar arrangements of iron and aluminum electrodes

The aim of this research was to evaluate the efficiency of electrocoagulation (EC) for the removal of natural organic matter (NOM) by using iron (Fe) and aluminum (Al) electrodes. The effects of several operational parameters such as initial pH (3–10), time of electrolysis (5–30 min), initial concentration of organic matter (10–50 mg NOM/L), current density (0.25–1.25 mA/cm²), type of electrode material (n = 4, 2 sides × 11 cm × 10 cm, wall thickness = 2 mm, distance between each electrode = 5 mm), and type of connection of electrodes (bipolar and monopolar configurations) were explored for the removal of NOM from synthetic humic acid solution in a 2 L laboratory-scale EC cells (A _s/V = 0.110 cm^?1). The optimum conditions for the process were identified as pH = 3 and 7, electrolysis time = 20 and 10 min for Fe and Al electrodes, respectively. Using both electrodes at current density = 0.25 mA/cm² and initial concentration of organic matter = 50 mg/L, a NOM removal efficiency of almost 100% could be achieved in the bipolar mode. Based on the optimum conditions, specific reactor electrical energy consumptions were 14.90 kWh/kg Al (or 0.092 kWh/m³) and 2.88 kWh/kg Fe (or 0.11 kWh/m³). Specific electrode consumptions were obtained to be 0.0062 and 0.0382 kg/m³, and operating costs of the EC system were preliminary estimated at 0.057 and 0.119 $/m³ for Al and Fe electrodes, respectively.     

Metal fractionation and pollution risk assessment of different sediment sizes in three major southwestern rivers of Caspian Sea

To assess the risk of release and percentage of heavy metals in river sediment, nine stations were set up to sample surface sediments from three important rivers situated southwest of the Caspian Sea (the Shafaroud, Karaganroud, and Choubar Rivers). Chemical analyses were conducted on sediment with particle sizes of >38, 63–38, 63–125, 125–250, 250–500 and 500–1000 µm using metal fractionation to determine the degree of risk release and the heavy metal pollution. Common risk indices were used including the cumulative indices of pollution intensity assessment and risk release standards (the modified pollution degree and ecological risk). Generally, when sediment sizes are decreased, the concentration of heavy metals is both larger and greater than the mean concentration of global sediments and earth crust. However, in this research, the concentration of all the metals did not necessarily increase with a decrease in the size of particles. In fact, concentration of cobalt, vanadium, cadmium, and chromium was greater in sediment particle sizes over 63 μm. The results of chemical fractionation analyses indicated that the release risk of metals has two initial phases for: (1) exchangeable bond (F1) and (2) carbonated bond (F2). When compared with other metals, nickel had the greatest tendency to bond within the loose exchangeable phase (F1) across all the stations. Furthermore, with changes in the size of particles, the percentage of heavy metal changes across different bond phases, but will be the greatest in the loose exchangeable phase (F1). This was observed with cobalt, nickel, and chromium at particle sizes larger than 63 μm. The results of ecological risk and modified pollution degree indices indicated that the highest level of pollution was related to sediments with sizes between 63 and 250 μm. Eventually, in order to assess the risk extent of metals present in sediment, a cumulative index referred to as the modified risk assessment code was utilized. It suggested that the greatest risk of toxicity in some stations has been related to particles larger than 63 μm.     

Determination of optimum cutoff grade with considering dilution

In open pit mining, cutoff grade is one of the most important factors in production planning, which is simply defined as a grade that discriminates between ore and waste. It is also a sensitive parameter can have a major impact on the net present value and cash flow of the projects. On the other hand, dilution is one of the most important and sensitive parameters in the mining projects, which is closely related to the cutoff grade. Choosing the optimum cutoff grade is of considerable importance, since it has a significant impact on the mining operations. One of the most popular algorithms for determination of the optimum cutoff grade is the Lane’s algorithm. But in the Lane’s algorithm, mining dilution and its cost is not considered during the cutoff grade optimization. In this paper, effects of dilution on the cutoff grade are studied using Lane’s theory. Dilution and its cost is inserted directly into cutoff grade optimization process. The cutoff grades obtained using suggested method will be more realistic rather than ones by using the original form of the Lane’s formulation. Results of the study showed that with an increase of dilution, average grade decreases and consequently the cutoff grade increases. As a result of dilution, the quantity Q _m increases and the quantities Q _c and Q _r decrease. Therefore, the annual profit and NPV of project is very significantly reduced.     

Analysis of contamination hazard of surface water by the methodology of TECHNEAU: a case study from the dam 9 April 1947 in northern Morocco

Preventive protection of surface waters against pollution and the guarantee of the best quality water are the major challenges to provide a sustainable supply of drinking water for the future generations. In this article, we present a hazard mapping application for water contamination of the dam “9 April 1947” located in the northwest of Morocco. This study was motivated by the proliferation of many pollution sources in the study area knowing that the dam feeds the region of Tanger-Asilah that has over 3 million inhabitants. The methodology used was applied for the first time in the city of Freiburg-Ebnet in Germany under the TECHNEAU project funded by the European commission and based on weighting of the different sources of contamination according to three indices: the toxicity index, quantity index, and probability index. The multiplication of the three indices has given us a hazard index named HI varying between 0 and 120 depending on the harmfulness of hazard; the later index has been used to create the final contamination hazard map. The hazard map shows 65% of the watershed area is witnessing a very low danger, 22% of the watershed area is witnessing a low danger, 10% of the watershed area is witnessing a the high danger, and 3% of the watershed area is witnessing a moderate.     

Community collaboration and climate change research in the Canadian Arctic

Research on climate change impacts, vulnerability and adaptation, particularly projects aiming to contribute to practical adaptation initiatives, requires active involvement and collaboration with community members and local, regional and national organizations that use this research for policy-making. Arctic communities are already experiencing and adapting to environmental and socio-cultural changes, and researchers have a practical and ethical responsibility to engage with communities that are the focus of the research. This paper draws on the experiences of researchers working with communities across the Canadian Arctic, together with the expertise of Inuit organizations, Northern research institutes and community partners, to outline key considerations for effectively engaging Arctic communities in collaborative research. These considerations include: initiating early and ongoing communication with communities, and regional and national contacts; involving communities in research design and development; facilitating opportunities for local employment; and disseminating research findings. Examples of each consideration are drawn from climate change research conducted with communities in the Canadian Arctic.     

Improvement of groundwater resources potential by artificial recharge technique: A case study of Charf El Akab aquifer in the Tangier region,Morocco

In arid and semi-arid zones,water is the most vulnerable resource to climate change.In fact,various techniques such as artificial recharge are adopted to restore aquifers and to ensure aquifer sustainability in relation to the accelerated pace of exploitation.Morocco is a Mediterranean country highly vulnerable to climate change,many of its main aquifers are subjected to excessive drawdowns.This technique is practiced to increase potentiality of these aquifers.In the Northwestern area of Morocco,the significant development experienced by Tangier City in the industrial,tourism,and commercial sectors will lead to increased water requirements-up to 5 067 L/s(159.8 mm^3)by 2030.However,the Charf El Akab aquifer system,subject to artificial recharge,is the only groundwater resource of Tangier region;hence,a rational management context is needed to ensure aquifer sustainability,and optimized exploitation under the background of differing constraints,such as increased water requirements,and climate change impacts.This work aims to respond,for the first time,to the Charf El Akab aquifer overexploitation problem,and to evaluate the future scenarios of its exploitation in the event of failure of one of the superficial resources.This work also presents a synthesized hydrodynamic modeling based on the results of the numerical simulations carried out using Feflow software for 2004(date of cessation of injections)and 2011(date of resumption of these facilities),making it possible to evaluate the impact of the artificial recharge on the piezometric level of the aquifer on a spatiotemporal scale.Finally,the exploitation scenarios have shown that the aquifer of Charf El Akab will not adequatly provide for the region's water requirements on the future horizon,entailing an optimal management of water resources in the region and an intentionally increased recharge rate.     

Characterizing and monitoring global landscapes using GlobeLand30 datasets: the first decade of the twenty-first century

Global land cover maps are important sources of information for a wide range of studies including land change analysis and climate change research. While the global land cover maps attempt to present a consistent and homogenous data in terms of the production process, the existing datasets offer coarse resolution data, e.g. 1000 m for IGBP DISCover and 300 m for GlobeCover 2009 that is oftentimes challenging. Recently, GlobeLand30 data based on Landsat archive for two timestamps of 2000 and 2010 has been released. It presents a finer spatial resolution of 30 m, which provides numerous opportunities for a wide range of studies. The main objective of this study is to use this dataset for characterizing global land cover patterns, monitoring, and identifying extreme land change cases with their types and magnitude. The findings reveal massive land change patterns including deforestation, desertification, shrinkage of water bodies, and urbanization across the globe. The results and discussions of this research can help policy-makers, environmental planners, ecosystem services providers and climate change researchers to gain finer insights about the forms of global land change. Future research calls for further investigation of the underlying causes of the massive changes and their consequences on our ecosystems and human populations.     

Metal pollution assessment and multivariate analysis in sediment of Anzali international wetland

Anzali international wetland located in southwestern Caspian Sea coast is one of the most important wetlands of Iran from environmental and ecological points of view. Metal concentrations (Cu, Zn, Cr, Fe, Mn, Pb, Ni, Cd, and Li) in 41 surface sediment samples from Anzali wetland were determined. Assessment of ecological risk of sediment samples as well as their degree of contamination revealed considerable ecological risk and moderate degree of contamination in eastern part of the study area. Multivariate statistical analyses were used to identify metal content relationship and their origin. Higher enrichment factors of Cd, Pb, and Zn exhibited probable effects on human activities. Based on sediment quality guidelines (SQGs), moderate potential toxicity levels of sediment samples were identified. A new sediment quality index named sediment toxicity degree was developed based on the results of the multivariate statistical analysis to assess metal toxicity in surface sediments of aquatic systems. Results showed higher sensitivity of the new index (ST_d) to assess toxic effect of heavy metals on sediments and better capability to differentiate zones with different levels of risk within the study area than that of some other indices such as SQG-Q.     

Role of riverine sediment and particulate matter in adsorption of heavy metals

Riverine sediments and suspended matters have been subjected to several bench scale tests for the evaluation of adsorption potential of heavy metals. For this purpose water, sediment and suspended particulate matters of Tadjan River (southern part of the Caspian Sea) were collected. In the vicinity of the river many polluting sources were recognized; for instance, pulp and paper mill, dairy factory and municipal sewage that can introduce various amounts of heavy metals into the river water. Bottom sediments and suspended particulate matters have been individually subjected to adsorption tests. The results of analysis showed that riverine bottom sediments have greater potential for adsorbing heavy metals than suspended matters. However the trend of adsorption in both sediments and suspended matters are similar. Maximum adsorption capacity of heavy metals (in terms of mg of metal per kg of sediments and suspended matters) by sediments and suspended matters are as: Sediments: Cu (2200)> Mn (2000)> Ni (1400)> Zn (320) Suspended matters: Cu (2100)> Ni (1500)> Mn (1200)> Zn (310) Further, results revealed that increasing concentration of metals would cause desorbing Cadmium from both sediments and suspended matters.