Thermal Degradation Mechanism of Low-Density Polyethylene Plastic Wastes in Cyclohexane

The thermal LDPE degradation mechanism harnessing a high-pressure autoclave surrounded by a furnace was investigated in this work. Rates of formation of gas, liquid, and solid during degradation of PE plastic wastes in cyclohexane as solvent at 400 and 425°C have been experimentally determined. Four reaction mechanisms have been proposed and tested to estimates of gas, liquid, and solid. Proposed mechanisms are based on the assumption that the reactions are pseudo-first-order with respect to the reacting species. Pseudo-first-order rate constants for each of the indicated mechanistic steps have been calculated by nonlinear regression analysis. The best fit was obtained by model 2 (pure parallel reaction mechanism), and its activation energy was determined.     

14C‐dimethoate residues in olive oil during oil processing

Abstract

An olive tree was treated twice in the field with ¹⁴C‐dimethoate (237.7 (μCi, 2.4 g) and ¹⁴C residues were determined in the olive fruits at harvest. The fruits were crushed and pressed to extract the crude oil, then refined by neutralization, bleaching and deodorization. The crude oil contained 14.1% of the total ¹⁴C in the olive fruits. Neutralization resulted in a reduction of ¹⁴C by about 50% of the total ¹⁴C residues in oil. Bleaching and deodorization processes further reduced the ¹⁴C residues and the refined oil contained 31.6% (which corresponds to 4.4% of ^I4C residues of the total ¹⁴C in olive fruits) of the total ¹⁴C in the crude oil. Industrially extracted crude oil was fortified with ¹⁴C‐dimethoate at 1.8 mg kg^‐1 (0.02 μCi) level and subjected to the same refining process. A sharp decrease in the amount of ¹⁴C was observed by neutralization and the amount of ¹⁴C remaining in the refined oil was about 7.3% of the total ^l4C in the crude fortified oil. The data suggest that the ¹⁴C residues in the aged and the fortified oil amples were not of the same nature. The terminal ¹⁴C residue in the refined oil obtained from the field experiment did not contain dimethoate and/or its oxon.     

Valorization of waste tire by pyrolysis and hydrothermal liquefaction: a mini-review

Journal of Material Cycles and Waste Management - An amount of 1.5 billion waste tires has been generated every year, resulting in serious environmental problems and damaging human health caused by...     

The relations of antioxidant vitamins A,E, and C with MDA levels in serum and liver of rats treated with nitrosamines

In this study, we investigated the levels of vitamins A, E, and C in serum and liver, and malondialdehyde (MDA) were followed by long-term administration of some nitrosamines. Sprague-Dawley rats were divided into four groups. N-Nitrosodiethylamine (NDEA), 1-Nitrosopiperidine (NPip), and N-Nitrosopyrrolidine (NPyr) were administered 200 ppb, orally with water for 30 consecutive days to experimental groups. Animals were decapitated at 3rd, 7th, 15th, and 30th days of the administrations. Significant increases were observed in MDA levels treated with nitrosamines at all times. Serum MDA levels were found to be significantly higher in NDEA-treated animals than in control and other groups at 30th day. Liver MDA levels were highly increased in NPyr-treated group. Significant decreases were observed in the levels of vitamins A, E, and C in rats treated with nitrosamines at all times. There were also significantly negative correlations at present changes among the serum or liver MDA levels and vitamin A, E, and C levels in all nitrosamines-treated groups. These findings demonstrate that exposure at low levels of nitrosamines decreased vitamin A, E, and C levels while it attributed lipid peroxidation. Therefore, maintaining an adequate level of antioxidant vitamins in serum and liver may be necessary for the prevention or protection of long-term nitrosamine exposures.     

Production and growth of microalgae in urine and wastewater: A review

Environmental Chemistry Letters - Issues of climate change, energy demand, and natural resources depletion are calling for circular methods to produce value-added products such as biomass, biofuel,...     

Analysing land cover changes for understanding of forest dynamics using temporal forest management plans

This study analyses forest dynamics and land use/land cover change over a 43-year period using spatial-stand-type maps of temporal forest management plans of Karaisal? Forest Enterprise in the Eastern Mediterranean Region of Turkey. Stand parameters (tree species, crown closures and developmental stages) of the dynamics and changes caused by natural or artificial intervention were introduced and mapped in a Geographic Information System (GIS) and subjected to fragmentation analysis using FRAGSTATS. The Karaisal? Forest Enterprise was first planned in 1969 and then the study area was planned under the Mediterranean Forest Use project in 1991 and five-term forest management plans were made. In this study, we analysed only four periods (excluding 1982 revision plans): 1969, 1991, 2002 and 2012. Between 1969 and 2012, overall changes included a net increase of 3,026 ha in forested areas. Cumulative forest improvement accounted for 2.12 % and the annual rate of total forest improvement averaged 0.08 %. In addition, productive forest areas increased from 36,174 to 70,205 ha between 1969 and 2012. This translates into an average annual productive forest improvement rate of 1.54 %. At the same time, fully covered forest areas with crown closure of “3” (>70 %) increased about 21,321 ha, and young forest areas in developmental stage of “a” (diameter at breast height (dbh)?<?8 cm) increased from 716 to 13,305 ha over the 43-year study period. Overall changes show that productive and fully covered forest areas have increased egregiously with a focus on regenerated and young developmental stages. A spatial analysis of metrics over the 43-year study period indicated a more fragmented landscape resulting in a susceptible forest to harsh disturbances.     

Monitoring forest structure at landscape level: a case study of Scots pine forest in NE Turkey

This study aims to investigate the change in spatial-temporal configuration of secondary forest succession and generate measurements for monitoring the changes in structural plant diversity in Yaln?zçam Scots pine forest in NE Turkey from 1972 to 2005. The successional stages were mapped using the combination of Geographic Information System (GIS), Global Positioning System (GPS), aerial photos and high resolution satellite images (IKONOS). Forest structure and its relationship with structural plant diversity along with its changes over time were characterized using FRAGSTATS. In terms of spatial configuration of seral stages, the total number of fragments increased from 572 to 735, and mean size of patch (MPS) decreased from 154.97 ha to 120.60 ha over 33 years. The situation resulted in forestation serving appropriate conditions for plant diversity in the area. As an overall change in study area, there was a net increase of 1823.3 ha forest during the period with an average annual forestation rate of 55.25 ha year^?1(0.4% per year). In conclusion, the study revealed that stand type maps of forest management plans in Turkey provide a great chance to monitor the changes in structural plant diversity over time. The study further contributes to the development of a framework for effective integration of biodiversity conservation into Multiple Use Forest Management (MUFM) plans using the successional stages as a critical mechanism.     

Afforestation areas defined by GIS in Gölbaşı specially protected area Ankara/Turkey

This paper concentrates on determining the areas for afforestation and the development of conservation strategies and actions in the case where there is high demand for the conservation of a particular land area. The analysis of hydrological landscape structure and of erodibility was prerequisite in the methodological design considering the site-specific natural landscape characteristics of the study area. The Gölba?? Specially Protected Area (SPA) being the case area has many local environmental disturbances, especially with respect to its hydrological system, and the area is beset by increasing demands for its use by the burgeoning human population. It is obviously clear that the present intensive demand for recreational use will be forecasted further increase in the future. The count of rural residences is estimated to increase by 50% over the next decade. This intensive demand shall further strain the carrying capacity of the ecological milieu, which has already suffered to a significant degree because of the present urban and rural activities. The Gölba?? district is located only 20 km from the city center of Ankara, and its surroundings were legally designated to be a Specially Protected Area primarily for the existence of lacustral and fluvial systems where two interconnected lakes exist: Mogan and E?mir Lakes. Essentially, the continuity of the lacustral and fluvial system of Lakes Mogan and E?mir depends on the preservation and improvement of the water sources. However, interconnected surface water bodies of these lakes are actually quite contaminated, and a decline in the water flow from Mogan to E?mir has been observed. For the elaboration of the present method, required conventional maps (at 1/25,000 scale) of topography (for slope analysis) and geology (for erodibility and permeability analysis) were transferred to computer media using AutoCAD® R.14 software. The rectification of the transferred data was done using ERDAS® Imagine 8.3. All data were then transferred into a GIS engine (Arcview® 3.2). This software provided the ability to create, manipulate, analyze and display topologically correct geographic data in digital form. The method proceeded according to the following phases: 1. Analysis of the hydrologic landscape structure; 2. Permeability of the soil structure; 3. Permeability of the geological structure; 4. Conservation zones.     

Monitoring of bisphenol A diglycidyl ether (BADGE) and some derivatives in fish products in the Turkey market

The exposure to bisphenols and their derivatives was assessed in 33 fish products sold in Turkey using high-performance liquid chromatography-tandem mass spectrometry (LC–MS/MS). BADGE was determined in only four samples at concentrations ranging between 0.06 and 0.22 mg/kg. As the most abundant bisphenol groups, BADGE-hydrolyzed products such as BADGE·H₂O and BADGE·2H₂O were present in nine and fourteen samples in the range between 0.06–0.16 and 0.06–0.72 mg/kg, respectively. The total concentration of BADGE and hydrolyzed products was below the specific migration limit (SML) value of 9 mg/kg food, which in the European Union stated as tolerable. Chlorinated derivatives of BADGE were detected in fewer samples compared with hydrolyzed ones. BADGE·H₂O·HCl was the predominant migrant among chlorinated derivatives and was present in seven samples in a range between 0.02 and 0.06 mg/kg. All other samples contained less than or equal to 0.03 mg/kg of BADGE·HCl and BADGE·2HCl. The sum of these derivatives was lower than the SML value (1 mg/kg) of BADGE chlorohydrins legislated by the European Union. Besides these migrants, the analyzed samples did not contain any BFDGE and 3R-NOGE, which are prohibited in manufacturing food contact materials.