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Organochlorine pesticides in the urban, suburban, agricultural, and industrial soil in South Korea after three decades of ban: Spatial distribution, sources, time trend, and implicated risks
No full textOrganochlorine pesticides in soil samples across urban, suburban, agricultural, and industrial sites were analyzed every year between 2013 and 2016 in South Korea. The study aims to understand the residual status, diminution of occurrence from the South Korean environment, and its risk to humans after three decades of the ban. A general decreasing trend of OCPs has been observed over the years. The OCP concentrations were below the guideline values prescribed for soil pollution. Metabolites like p,p'-DDD and endosulfan sulfate contributed a major portion to the total OCP concentration over the years. The agricultural sites showed higher OCP levels than other site types. Compositional profile and diagnostic ratios suggested that the occurrence of DDT and endosulfan residues were due to historical inputs, but those of HCH and chlordane reflect recent usage in some pockets. The calculated incremental lifetime cancer risk was within the safety limit for all age groups across the genders in the majority of the sites. It is evident that the OCP load on soil is decreasing since the ban on usage. However, regular monitoring with a special focus on metabolites can be an effective control measure to regulate and eliminate the contamination of OCPs
Thermodynamic, economic, and emissions assessment of integrated power to methanol concept with membrane-based biogas up-gradation and plasma electrolysis
No full textThe utilization of carbon dioxide to create valuable products such as methanol shows promise for addressing the issue of carbon emissions and global warming. Concurrently, it provides a solution to the intermittency and security of renewable energy supply via the water-splitting hydrogen production process. This power-to-methanol concept has gained increased attention because methanol is a liquid that can be conveniently stored and transported under ambient conditions. While direct air capture is an expensive solution, the carbon dioxide readily available from biogas can serve as a win-win situation. Similarly, water electrolysis technologies have modular, operational, and production challenges. In the present study, carbon dioxide was sourced from biogas via membrane separation, whereas H-2 was produced using plasma electrolysis. The entire power-to-methanol scenario was simulated using Aspen Plus v11. High purity and recovery of carbon dioxide and methane (99.51 mol.% and 98.29% and 98.88 mol.% and 99.68%, respectively) were achieved via membrane separation. The plasma reactor supplied H-2 with a mass yield of similar to 50%. Pure methanol (99.97%) was produced with a perpass conversion of 19.91% (15.7% higher than the base case). A detailed exergy analysis was performed on the process, highlighting the losses in heaters, separators, and reactors. Subsequent heat integration resulted in energy savings of 6.6%, while wind power as an energy source yielded carbon-neutral emissions. This conceptual study showcases the tremendous potential of the concept of zero-carbon-emission methanol production
Amplitude Non-Uniformity of Millimeter-Wave Vortex Beams Generated by Transmissive Structures
No full textWe investigate the origin of non-uniformity in an orbital angular momentum (OAM) beam generated by a transmissive structure in the millimeter-wave frequency range. This work includes the study of amplitude non-uniformity including modal composition analysis using the angular spectrum method (ASM) for OAM beams generated by spiral phase plates (SPPs) and flat-surface metamaterial structures (MSs). The dependency of the axial dimension, over which the OAM beam transforms from a Gaussian beam, on the amplitude non-uniformity of both the structures has been rigorously analyzed. For experimental verification, we designed a perforated planar dielectric slab to convert the Gaussian beam into an OAM beam of order 2 with improved amplitude uniformity. Within the manufacturing limitations, the design of the transmissive MS was fabricated and tested to obtain optimum amplitude uniformity in the generation of OAM beams and to compare with simulation results
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No full textCentral Bank Swap Lines and Currency Internationalization in Trade
No full textInternationalization of emerging market currencies, especially the RMB, is of great interest to both academic and policy worlds. This paper investigates the role of central-bank local currency swap lines in promoting the use of local currencies in trade invoicing. While the existing literature has emphasized the direct role of swap lines in trade invoicing, we suggest an indirect role of risk reduction. Using exporter-trading partner-year level data on currency invoicing from South Korea during 2006-2019, we show that signing swap lines between Korea and China has likely played a role in a rise of the Chinese Yuan (CNY) in the invoicing share among Korean exporters. Conversely, the expiration of a swap line between Korea and Japan has likely played a role in a decline in the Japanese Yen's invoicing share. Cross-???rm heterogeneity helps with our identi???cation. In particular, those Korean exporting ???rms whose main banks had more preswap line exposure to the CNY exhibit a more pronounced increment in CNY invoicing share. In addition, Korean banks raised the interest rates on CNY deposits but lowered those on JPY deposits. In our theory, the ???nancial safety net afforded by the swap line incentivizes banks to provide higher interest rates for deposits in the partner's currency, and hence promotes the use of the same currency in trade invoicing
