Global occurrence, chemical properties, and ecological impacts of e-wastes (IUPAC technical report)

The waste stream of obsolete electronic equipment grows exponentially, creating a worldwide pollution and resource problem. Electrical and electronic waste (e-waste) comprises a heterogeneous mix of glass, plastics (including flame retardants and other additives), metals (including rare earth elements) and metalloids. The e-waste issue is complex and multi-faceted. In examining the different aspects of e-waste, informal recycling in developing countries has been identified as a primary concern due to widespread illegal shipments, weak environmental as well as health and safety regulations, lack of technology and inadequate waste treatment structure. For example, Nigeria, Ghana, India, Pakistan and China have all been identified as hotspots for the disposal of e-waste. This article presents a critical examination on the chemical nature of e-waste and the resulting environmental impacts on, for example, microbial biodiversity, flora and fauna in e-waste recycling sites around the world. It highlights the different types of risk assessment approaches required when evaluating the ecological impact of e-waste. Additionally, it presents examples of chemistry playing a role in potential solutions. The information presented here will be informative to relevant stakeholders to devise integrated management strategies to tackle this global environmental concern

Using Laser Perforation to Enhance Decorative Properties of Siberian Fir (Abies sibirica) Wood

This paper presents research into the possibilities of using laser perforation to enhance the decorative properties of Siberian fir (Abies sibirica) wood. Fir wood is characterized by fairly modest physical and mechanical properties and featureless appearance, which is why it is in low demand. With enhanced decorative properties, fir wood could find its use in the production of finish materials. The literature review reveals that the existing wood dyeing technologies are not really effective for the hard-to-impregnate fir wood. Therefore, laser perforation was used to achieve higher wood impregnation and its controlled coloring to form the texture. The study also explored the features of dyeing laser-perforated fir wood, depending on the set parameters of impregnation and wood structure. To do so, the fir samples (with the size of 165×65×32 mm) were laser perforated to form slots up to 0.2 mm in diameter and 15 mm deep. Then the samples were impregnated in an autoclave. The set parameters were determined in accordance with the two-factor experiment schedule: the pressure standing at 0.2, 0.5 and 0.8 MPa, with the impregnation time of 30, 225 and 480 min. The study showed that when perforated wood is impregnated, the dyeing solution penetrates the laser-cut slots first and mainly spreads along the wood fibers. Depending on the impregnation time and pressure applied, the dye moves from the perforated slots along the wood fibers covering a distance of 10.9 mm to 24.6 mm. The dye does not spread as well across the fibers, only coloring a total width of 1.3 to 1.7 mm both ways from the slot depending on applied pressure and time of impregnation. It was found that, first and foremost, the set parameters affect the size of colored areas along the wood fibers and make little difference to lateral coloring in absolute values. Pressure applied to perforated wood during impregnation was determined to have the biggest impact on the size of colored areas. The study proves it possible to use the developed technology in forming artificial wood textures, including those that imitate valuable wood species. For citation: Eliseev S.G., Ermolin V.N., Duk D.V. Using Laser Perforation to Enhance Decorative Properties of Siberian Fir (Abies sibirica) Wood. Lesnoy Zhurnal = Russian Forestry Journal, 2023, no. 5, pp. 151–163. (In Russ.). https://doi.org/10.37482/0536-1036- 2023-5-151-16

AMT SOUNDINGS IN THE DEAD BAND WITHIN THE CHUKOTKA REGION (RUSSIAN FAR EAST)

The article analyzes the amplitude spectra of audio magnetotelluric sounding (AMTs) data. Particular attention is focused on the frequency range from 1 to 5 kHz, which is called dead band. We analyzed the data of base stations used in the fieldwork during the summer and autumn seasons in 2013, 2014, and 2017. The area of work is located in the Chukotka Autonomous Area beyond the Arctic Circle. Previous researchers noted that a reliable signal in the dead band can only be obtained at nighttime. The authors of the article found that in Chukotka region in the daytime against the minimum signal within the dead band there is a local maximum at a frequency of 2.4 kHz. When registering a field for more than 3 hours during daytime, in most cases, it is possible to restore the frequencies of 2.2 and 2.6 kHz. These frequencies are reliable benchmarks, allowing in some cases to restore the AMT curve using the correlation between amplitude and phase. We have proposed ways to improve data quality in the dead band when measured during the daytime