Spatiotemporal variations in urban CO2 flux with land-use types in Seoul

Abstract

Background Cities are a major source of atmospheric CO2; however, understanding the surface CO2 exchange processes that determine the net CO2 flux emitted from each city is challenging owing to the high heterogeneity of urban land use. Therefore, this study investigates the spatiotemporal variations of urban CO2 flux over the Seoul Capital Area, South Korea from 2017 to 2018, using CO2 flux measurements at nine sites with different urban land-use types (baseline, residential, old town residential, commercial, and vegetation areas). Results Annual CO2 flux significantly varied from 1.09 kg C m− 2 year− 1 at the baseline site to 16.28 kg C m− 2 year− 1 at the old town residential site in the Seoul Capital Area. Monthly CO2 flux variations were closely correlated with the vegetation activity (r = − 0.61) at all sites; however, its correlation with building energy usage differed for each land-use type (r = 0.72 at residential sites and r = 0.34 at commercial sites). Diurnal CO2 flux variations were mostly correlated with traffic volume at all sites (r = 0.8); however, its correlation with the floating population was the opposite at residential (r = − 0.44) and commercial (r = 0.80) sites. Additionally, the hourly CO2 flux was highly related to temperature. At the vegetation site, as the temperature exceeded 24 ℃, the sensitivity of CO2 absorption to temperature increased 7.44-fold than that at the previous temperature. Conversely, the CO2 flux of non-vegetation sites increased when the temperature was less than or exceeded the 18 ℃ baseline, being three-times more sensitive to cold temperatures than hot ones. On average, non-vegetation urban sites emitted 0.45 g C m− 2 h− 1 of CO2 throughout the year, regardless of the temperature. Conclusions Our results demonstrated that most urban areas acted as CO2 emission sources in all time zones; however, the CO2 flux characteristics varied extensively based on urban land-use types, even within cities. Therefore, multiple observations from various land-use types are essential for identifying the comprehensive CO2 cycle of each city to develop effective urban CO2 reduction policies.

A Concise Review on Carbon Fiber-Reinforced Polymer (CFRP) and Their Mechanical Significance Including Industrial Applications

“…Low thickness, high strength, and high hardness are the characteristics of carbon fiber. These strands typically have a carbon content of between 80 and 95 percent, can have a staple or fiber structure, have excellent mechanical properties, are lightweight, and have a thickness of 2268 g/cm 3 [2,[25][26][27][28][29][30]. Numerous advantages of this composite type include its extremely high rigidity/weight ratios, elastic modulus/weight ratios, low coefficient of warm development, high weakness properties, and warm A Concise Review on Carbon Fiber-Reinforced Polymer (CFRP) and their Mechanical… DOI: http://dx.doi.org/10.5772/intechopen.109339 conductivity.…”

“…Recently, carbon fiber has emerged as one of the most important supporting materials due to its incredible strength, modulus, and high temperature resistance (Figure 1). Many logical efforts have been made to enhance and analyze their exhibition, particularly composite frameworks [1][2][3][4][5]. Despite these advantages and efforts, it should be noted that a composite framework's interfacial bond between the carbon strands and the framework is too weak to ensure excellent mechanical performance [6,7].…”

Assessing impacts of environmental perturbations on urban biogenic carbon exchange in the Chicago region

“…Multisite studies are usually required to account for urban heterogeneity (Bergeron and Strachan, 2011;Park et al, 2022). Additional efforts for flux decomposition are also required to distinguish biogenic signals from their anthropogenic counterparts (Menzer and McFadden, 2017;Salgueiro et al, 2020;Stagakis et al, 2019).…”

Intra-urban Variations of the CO2 Fluxes at the Surface-Atmosphere Interface in the Seoul Metropolitan Area

“…The EC method allows continuous monitoring of surface CO 2 fluxes at fine temporal resolutions, typically from 30 min to 1 h. Because fluxes observed at the same site vary following wind directions and speeds if the sources and sinks of the trace-gas around the site are spatially and/or temporally heterogeneous, the high-rate sampling capability of the EC method is advantageous for monitoring CO 2 fluxes and understanding the carbon cycle related to urban ecosystems (Feigenwinter et al 2012). A number of studies successfully quantified CO 2 fluxes and their variabilities, as well as the key elements that affect CO 2 fluxes at various urban areas, using the EC method (e.g., Coutts et al 2007;Lietzke et al 2015;Velasco and Roth 2010;Ward et al 2015;Hong et al 2019Hong et al , 2020Park et al 2022). Previous urban CO 2 flux studies typically analyzed the differences between cities, or, for the same city, between different periods using data from a single site (e.g., Coutts et al 2007;Velasco and Roth 2010).…”

“…Previous urban CO 2 flux studies typically analyzed the differences between cities, or, for the same city, between different periods using data from a single site (e.g., Coutts et al 2007;Velasco and Roth 2010). Because CO 2 fluxes vary widely according to the land-use and main business types, the CO 2 flux characteristics in large urban areas that include diverse landscapes and human activities cannot be represented by single-site measurements (Grimmond et al 2002;Kleingeld et al 2018;Park et al 2022).…”