The effects of using reprocessable material on the durability and mechanical properties of landfill leachate collection HDPE pipes

This paper investigated the durability and mechanical properties of landfill leachate collection HDPE pipes which had been made of different weight percent amounts of virgin and reprocessable HDPE compounds (VC and RC). Durability is reported base on the chemical properties, obtained through oxidative induction time (OIT) and melt flow index (MFI) measurements, at the temperature of 50 °C and over a period of 12 months immersion in a synthetic leachate. Mechanical properties are also described according to tensile and pressure tests which had been conducted on the pipes samples. All of the factors were examined had been affected by the addition of RC, but for the special combination the antioxidant depletion was significantly affected by the experimental aging condition and no important changes had been observed in the other pipe properties. The results from OIT tests indicate that the rate of antioxidant depletion is reduced by an increase in the weight percent amounts of RC, during the experimental aging condition. This reduction is probably attributed to the extraction of antioxidants from RC in their recovery process. Finally, although these results are related to the particular HDPE compound, antioxidant formulation and condition examined, but it can be said that the use of clean own reprocessable material for the production of landfill leachate pipes shall be permitted without limitations.     

Determination of mercury and arsenic levels in fish caught in the Beheshtabad River,Chaharmahal and Bakhtiari Province,Iran

Mercury and arsenic pollution has been recognized as a potential environmental and public health problem for over 40 years. The major source of exposure to mercury for humans is the ingestion of fish. This study was conducted with the aim of determining the levels of mercury and arsenic in the muscles of four fish species caught in the Beheshtabad River and comparing the results with the maximum tolerance levels for mercury and arsenic. The samples of 90 fish were used for the determination of both the metals by graphite furnace atomic absorption spectrometry. The results showed that the concentrations ranged from 1.5 to 3.8 µg kg^?1 for mercury and from 35 to 70 µg kg^?1 for arsenic, with means of 2.7 ± 0.5 and 57 ± 12 µg kg^?1, respectively. Both mean levels were lower than the threshold limits acceptable by WHO standards.     

Worst-case identification of gas dispersion for gas detector mapping using dispersion modeling

To quickly and accurately quantify the material release in process units, gas detectors may be placed according to the results of gas dispersion modeling. DNV's PHAST software is one of the most useful and reliable tools for material dispersion modeling. In this software, fluid dispersion is modeled based on the process conditions, the weather conditions and the specifications of the material release point. However, varying weather conditions throughout the year and the exact determination of the release point on the plot plan and the release elevation are problematic; these issues cause the results to be non-exact and non-integrated. Choosing the most appropriate conditions is challenging. In this paper, a scheme was provided to select the most appropriate conditions for gas dispersion modeling. This scheme approaches modeling based on the worst-case scenario (the situation in which the dispersed gas reaches the detector later in comparison to the other cases). Therefore, different weather conditions, release elevations and release points on the plot plan were modeled for an absorber tower of the Gonbadli Dehydration Unit of the Khangiran Refinery. The worst case of each release condition was then chosen. Finally, gas detectors were placed using the gas dispersion modeling results based on the worst-case scenario.     

Biopolymer-based membranes from polysaccharides for CO2 separation: a review

Environmental Chemistry Letters - The application of natural biopolymers such as polysaccharides for the fabrication of bio-based membranes has recently attracted attention for CO2...     

Metal pollution status of Tajan River – Northern Iran

The monitoring of surface water quality of rivers is crucial to protect aquatic life and receiving water bodies of economic importance. The aim of the current study was to examine selected physicochemical parameters of River Tajan due to its ecological importance in Iran. Water samples from nine points covering the entire Tajan River and Caspian Sea estuary were collected and analyzed for pH, electrical conductivity (EC), total dissolved solids (TDS), carbonates, chlorides and selected heavy metals including zinc, cadmium, lead and chromium. The pH and levels of EC, TDS, chlorides, carbonates and all metals were within the USEPA reference guidelines for surface water quality standards. Although these water quality parameters are considered safe, continuous monitoring and assessment is recommended in order to protect the coastal receiving waters of Caspian Sea which serves as a tourist attraction in northern Iran.     

The prevalence of heavy metals in Cladophora glomerata L. from Farahabad Region of Caspian Sea – Iran

The presence of toxic heavy metals in the environment is considered as a risk factor for adverse human and environmental health effects. Farahabad Region is a tourist center in the southern coast of Caspian Sea in Mazandaran Province of Iran. Environmental monitoring of this site is important for public health for individuals visiting and residing in this region. Although numerous biomonitoring data are available globally, very few if any apparent investigations have been conducted in this region. In this study, concentration of three heavy metals chromium (Cr), lead (Pb), and cadmium (Cd) was determined for one year in Cladophora glomerata, the predominant macroalga species present in this region. Detection of heavy metals was performed with atomic absorption spectrophotometer using standard methods. Results showed that the range of Cr metal in various algal samples was 29–55 ppm/g dry weight. The levels of Pb in algal samples (Cladophora) ranged from 2 to 8 ppm/g dry weight. The Cd concentrations in C. glomerata biomass ranged from 1.5 to 8.2 ppm/g dry biomass. In view of potential threats of such high metal concentrations in coastal waters and in algal tissues, it is necessary to adopt conservation measures to ensure public health safety.     

RETRACTED ARTICLE: Consequences of health risk assessment of wastewater irrigation in Pakistan

Statement of Retraction

We, the Editors and Publisher of Toxicological & Environmental Chemistry, have retracted the following article:

Maria Sabeen, Qaisar Mahmood, Abdol Ghaffar Ebadi, Zulfiqar Ahmad Bhatti, Faridullah, Muhammad Irshad, Allauddin Kakar, Muhammad Bilal, Hafiz Muhammad Arshad and Naeem Shahid, ‘Consequences of health risk assessment of wastewater irrigation in Pakistan Israel Affairs’, Toxicological & Environmental Chemistry, 2019, DOI: 10.1080/02772248.2019.1619335

The article is retracted due to the oversights that were made during peer review process that resulted in the article being published online in error. Further review from independent reviewers was sought. This confirmed that the central findings and methodology of the study in question are unreliable and therefore unsuitable for publication.

We have been informed in our decision-making by our policy on publishing ethics and integrity and the COPE guidelines on retractions.

The retracted article will remain online to maintain the scholarly record, but it will be digitally watermarked on each page as “Retracted”.     

Physicochemical characterization of sediments from Tajan river basin in the northern Iran

Abstract

Continuous monitoring of water quality of freshwater bodies may prevent outbreak of diseases and occurrence of hazards through employment of effective protection measures. The aim of the current investigation was to determine occurrence of water and sediment pollution in Tajan River North Iran which ultimately may be a threat to recreational beaches of Caspian Sea. Water samples were analyzed for various physicochemical parameters including pH, electrical conductivity (EC), total dissolved solids (TDS), bicarbonates, sulfates, cations, chlorides and heavy metals. The concentrations of zinc (Zn), cadmium (Cd), chromium (Cr) and lead (Pb) were determined using atomic absorption spectroscopy. Similarly, sediment samples were assessed for physicochemical characteristics including pH, EC, saturation percentage, organic matter, organic carbon, texture and cations. Overall, pH, EC, organic matter, and cation values were within acceptable limits according to USEPA water quality guidelines. However, phosphorus (P) concentration up to 5.6?mg/L was considered as “unsafe” which might result in undesirable eutrophication and increased accumulation of sediment organic content leading to excessive growth of algal species in riverine ecosystem. Heavy metal concentrations of Cd (0.08?ppm) and Pb (3?ppm) were above USEPA threshold limits which may consequently affect sustainability of Tajan River. The unacceptable levels of Cd, Pb and P may produce eutrophication of Caspian Sea coasts and damage the ecosystem.