Historical changes of heavy metals content and sequential extraction in a sediment core from the Gorgan Bay, Southeastern Caspian Sea

267-272In the present investigation sedimentation rate, contents of heavy metals (Zn, Co and Ni), enrichment factors and speciation of Zn, Co and Ni of a sediment core from Gorgan Bay have been studied. Sedimentation rate in the study area has given an ample opportunity to track contents of Zn, Co and Ni with different sedimentary phases for the past 500 years (1500 t0 2002). Sedimentation rate of 1.4 mm/yr was obtained based on ²¹⁰Pb activity study of sediment core. A very low content of Al and Fe in the core compared to those of the mean crust was observed. Heavy metal contents increase towards the top of the sediment core. Chemical partitioning studies revealed that percentiles and amounts of Zn, Ni and Co in non-lithogenous phases increase slightly towards the top of the core sediment sample. There seems to be a slight increasing trend in pollution level of the sediments of the study area over the last 70 years. Further, despite many research reports, application of Enrichment Factors (EFs) for determination of origin of heavy metals in sediments and pollution detection may lead to incorrect results due to naturally lower concentration of Al than the mean crust and/or higher contents of heavy metals in sediments than those in the crust, as the EFs in the present investigation were high even in 17th century when there were no significant sources of pollution. The results of Igeo values, on the other hand, show that minor elements fall within non-polluted classification which can obviously show the error of the enrichment factor calculations with the use of Al as earth reference element

Seasonal variation of phytoplankton populations in relation to hydro-biological factors in coastal waters of Persian Gulf and Oman Sea (Hormozgan province)

The aim of the present study was to investigate the relationship between environmental factors and phytoplankton community structure and abundance. The samples were collected from 11 stations selected at Hormozgan coastal waters of the Persian Gulf and Oman Sea in winter 2015 and summer 2016. Various environmental factors including water temperature, salinity, dissolved oxygen, phosphate, nitrite, nitrate, and silicate as well as biological parameters such as chlorophyll a and phytoplankton community were measured. The results showed that the maximum phytoplankton density (1.25×106 cell/L) was in summer and the minimum density (2.01×105cell/L) was in the winter season. Based on the results, 46 genera belonging to five phyla of phytoplanktons were recorded. Bacilariophyta and Dinophyta were the most dominant phylum of the total phytoplankton communities. The results of this study revealed that water temperature, salinity, nitrate, nitrite, phosphate, and chlorophyll-a were the most important factors affecting the dynamics of total phytoplankton distribution in coastal waters of the Persian Gulf and Oman Sea

Investigating the sustainable performance of a nanoscale zerovalent iron permeable reactive barrier for removal of nitrate, sulfide, and arsenic

The quality of groundwater resources is at catastrophic risk. The proper performance of iron nanoparticles has made a permeable reactive barrier (PRB) an alternative to conventional filtration methods. The performance of nanozerovalent iron (nZVI) PRBs is limited by particle aggregation, instability, and phase separation, even at low iron concentrations. Therefore, the precipitation of reactive materials and a decrease in the longevity of PRB are fundamental challenges. A laboratory setup is used to compare the performance of bare nZVI and xanthan gum (XG)-nZVI + Mulch PRB to simultaneously remove nitrate, sulfide, and arsenic in groundwater. nZVI (average diameter of 35–55 nm) particles are used as reactive media. The objectives are (1) to develop a method for treating nitrate, sulfide, and arsenic simultaneously in groundwater using organic mulch and XG-nZVI; and (2) to evaluate the longevity performance of the XG-nZVI + Mulch and bare nanoparticles treatment system over 10 days. The results showed that the XG-nZVI + Mulch barrier's performance for eliminating NO3-, As, and S2− was generally improved compared to the bare nZVI barriers by 5.7, 19.2, and 10.9%, respectively. Finally, despite the need for long-term sustainability assessment, XG-nZVI PRB performance is impressive, and this stability promises to improve the longevity of nanoparticles while used in PRBs. HIGHLIGHTS Permeable reactive barriers (PRBs) based on XG-nZVI + Mulch can lead to adequate remediation of NO3, As(V), S2− compared to the bare nZVI barriers by 5.7, 19.2, and 10.9%, respectively.; The stability and longevity of the XG-nZVI + Mulch barrier are outstandingly better than the bare nanoparticles barrier.; XG-nZVI + Mulch PRB's footprint is green and sustainable because of using recycled materials.

Integrated Coastal Tourism Zone Management (ICTZM) as a basis for sustainable development of the south coastline of the Caspian Sea

635-646<span style="mso-bidi-font-family: " times="" new="" roman";mso-ansi-language:en"="" lang="EN">Present study consists an Integrated Coastal Tourism Zone Management (ICTZM) plan regarded simultaneously social, cultural and economical criteria along with spatial planning in terms of environmental capabilities to overcome the various problems., Areas with tourism potentiality owing less<span style="mso-bidi-font-family: " times="" new="" roman";mso-ansi-language:en"="" lang="EN"> environmental vulnerability<span style="mso-bidi-font-family: " times="" new="" roman";mso-ansi-language:en"="" lang="EN"> were identified using Fuzzy and Boolean logics in the environment of IDRISI KILIMANJARO Software. Thereafter a strategic planning for tourism management was presented for the selected zones using SWOT Method. Based on the country’s macro policies for tourism industry, an Integrated Coastal Tourism Zone Management (ICTZM) framework was provided in the form of a conceptual model. Results revealed that the main strategy to implement the sustainable coastal tourism in the study area should be based on a conservative approach and<span style="mso-ansi-language: EN" lang="EN"> after the<span style="mso-ansi-language: EN" lang="EN"> improvement in the conditions; the development and construction strategy can be executed in the coastal zone. </span

A Cost-Benefit Analysis of Bakhtiari Hydropower Dam Considering the Nexus between Energy and Water

Hydropower stations have supplied most of the green electricity in various parts of the world. Nonetheless, the economic profit of hydro-electricity lies beyond its social costs in many cases. Despite the short-term economic benefits of large dams, their sustainable pros and cons are doubted. This study aims to investigate the long-term profitability of large hydropower stations by considering the nexus between the environmental, economic, and social aspects. Much progress has been made in simplifying feasibility studies of hydropower stations by developing comprehensive software and models according to the United Nations Sustainable development goals. Developed by International Atomic Energy Agency (IAEA), the SimPacts has become one of the most frequently-used simple models to estimate the external costs of electricity generation since 2003. Hydropower’s Environmental Costs Analysis Model (HECAM) is a popular user-friendly version of the model that includes more details for benefits estimation. In the present investigation, sedimentation and evaporation effects of constructing hydropower dams are added to previous cost estimation factors to upgrade the HECAM model to HECAM II. Bakhtiari hydropower dam (located in Lorestan province in Iran) is employed as a case study to verify the new model. The results showed that the total cost and revenue, as well as the benefit to cost ratio, were 79.13 US$/MWh, 203 US$/MWh, and 2.57, respectively. The new HECAM II model showed that the operation of Bakhtiari Dam would alleviate the socio-environmental doubts through a long-term plan in the region

Incorporating climate change risk management into mitigation and adaptation strategies in urban areas

1183-1192A 10-year prediction of changes in climatic parameters in Tehran metropolis which is faced with increasing environmental issues shows that, by 2021, temperature and precipitation will increase with a steeper slope in comparison to the past. In this study, 14 urban environmental risks raised by changes in temperature and precipitation were identified. Then, the risks were quantified and prioritized using climate change risk assessment method and AHP (Analytic Hierarchy Process) rendered by Expert Choice software. Finally, several strategies were provided for mitigating impacts and making adaptation to changes of climatic parameters. Results showed that defensive strategies were the optimal strategies

Wave propagation in nonlinear left-handed transmission line media

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Geospatial investigation on self-purification capacity of river Estuaries in the Caspian region: reducing heavy metals pollution

Abstract In today’s context, the adoption of sustainable wastewater treatment methods is crucial. River estuaries have the potential to offer an economically viable and environmentally friendly solution for wastewater treatment through the flocculation of pollutants. This study investigates the role of river estuaries flowing into the southern part of the Caspian Sea in the treatment of heavy metals. Two sets of experiments were designed for this purpose. The first set involved adjusting a series of discrete aquaria in various salinity regimes, while the second set utilized only one aquarium. The results from the first set indicate the capacity of the studied estuaries to remove heavy metals through the flocculation process in the following order: Zn (70%) > Mn (60%) > Cu (49%) > Pb (24%) > Ni (19%). However, the removal rates in the second set were reduced as follows: Zn (57%) > Mn (56%) > Cu (40%) > Pb (20%) > Ni (17%). It was observed that the flocculation process exhibits an unstable nature. Furthermore, the findings reveal that heavy metals flocculation primarily occurs upstream of the estuary. However, instability in the flocculation process occurs downstream, where water parameters undergo drastic changes. Statistical analyses indicate that an increase in pH plays a significant role in the destabilization of flocs. Conversely, the initial concentration of heavy metals, dissolved oxygen, and redox potential have a positive impact on the flocculation process

Investigation of Phasic Process of Biogas Yield by Measuring pH, ORP and Electrical Power Changes

Background & Aims of the Study: Studying the phasic process of the biogas yieldis required to optimize the design and operations; it also helps to lower energy production costs by decreasing the capital investment and operational costs. Here we determine the biogas process by measuring pH, ORP, electrical power and make compatibility to the biogas production trend. Materials and Methods: In this research, one 1150 ml single chamber reactor is used. Biogas production trend was precisely followed by a probable compatibleness with pH, Oxidation Reduction Potential (ORP), electrical Power at a temperature of 37+ 0.5˚C with the substrate of cattle manure. The experiment was followed for 120 days approximately. Results: As a result, the phases of biogas yield could be determined by the measuring of pH, ORP and its compatibility to gas production. In the reactor, hydrolytic, acetogenic and methanogenic phases were occurred in the days 1-7, 8-16 and 17-104, respectively. Also the electrical power at first showed to be produced at high range but by increasing, the production of biogas decreased and then by decreasing the biogas production gradually, it increased slightly. Conclusion: Our results indicated that the phases of biogas production can be separated &nbsp;completely and by diffracting the phases, the efficiency of biogas production could be increased

Effect of Physical and Chemical Operating Parameters on Anaerobic Digestion of Manure and Biogas Production: A Review

Introduction: The need for food produced from animal husbandry has made it a growing industry which result in increment of livestock waste. On the basis of environmental and economic considerations, these materials require treatment and management. Anaerobic digestion and creation of biogas are the most effective methods of waste management. Several parameters affect the anaerobic digestion of animal wastes which should be studied in order to optimize the biogas production of reactors. Materials and Methods: The parameters affecting the performance of anaerobic processes in different scientific databases within 1984 -2016 were searched and related information were obtained. Results: A wide range of reactors with retention times of 0.5 to 140 days and organic loading rates from 0.11 to 7.5 grams per liter of organic matter in a day were studied based on the Volatile Solid (VS) in different temperature range. Also, studies conducted on mixing, co-digestion, changes in pH and ammonia content of the substrate, C/N ratio, as well as the effect of chemical interference were investigated. Conclusion: High COD removal decrease of VS were achieved in the range of 80-95 % and 65- 92 % respectively in bioreactors. The produced methane was also 48 mmol L-1 to 4681.3 m3 per month for reactors with a volume of 120 ml to 1330 m3 achieved respectively at 37 and 55˚C from the Mesophilic and thermophilic temperatures. Results summarized on the physical and chemical conditions in this paper, can be used to study the effective parameters and optimize conditions used in biogas production