Estimates of ratios of anthropogenic halocarbon emissions from Japan based on aircraft monitoring over Sagami Bay, Japan

Abstract

Regional‐ and national‐scale emission rates of halocarbons have been a great concern in the field of global environmental studies and policy making. Emissions have been inventoried mainly by bottom‐up approaches, which involve adding up emissions from various industrial sources. To verify and supplement those bottom‐up inventories, top‐down approaches based on measurements of air concentrations are required. In this study, aircraft monitoring over Sagami Bay, Japan, was used to estimate the emission ratios of halocarbons (perfluorocarbons (PFCs), hydrofluorocarbons (HFCs), CFCs, hydrochlorofluorocarbons (HCFCs), and others) from Japan. The enhanced concentrations in the boundary layer of air masses having traveled over Japanese mainland were used for the calculation under the assumption that the air masses over Sagami Bay represented average emission ratios for anthropogenic halocarbons on a countrywide basis. Given their emission ratios, a single compound with a credible emission rate can yield the emission estimates for all the other compounds. When we employed an inventory‐based emission estimate of HCFC‐22 from the Pollutant Release and Transfer Register (PRTR) system 2002 of Japan (9.1 Gg/yr) as the reference, the estimated emission rates of HCFC‐141b, HCFC‐142b, CFC‐12, chloroform, and trichloroethylene for 2002 were consistent with their PRTR values within 10%. Emissions of carbon tetrachloride (CCl4) and 1,1,1‐trichloroethane (CH3CCl3) were much higher than their PRTR values, suggesting that their sources are not adequately accounted for in the current inventories. The present study also presents probable annual emission rates for individual HFCs and PFCs that previously had no reported estimates; for example, 4.4 Gg/yr for HFC‐134a as of 2002.

Global and regional emissions estimates of 1,1-difluoroethane (HFC-152a, CH<sub>3</sub>CHF<sub>2</sub>) from in situ and air archive observations

“…We also present regional emissions estimates using interspecies correlation (ISC) methods (Yokouchi et al, 2005). Emissions of a number of trace gases from the Melbourne/Port Phillip region (CFCs, HCFCs, HFCs, carbon tetrachloride: Dunse et al, 2001Dunse et al, , 2002Dunse et al, , 2005Fraser et al, 2014a, b), including HFC-152a (Greally et al, 2007), have been estimated utilizing in situ high frequency measurements from Cape Grim and ISC with coincident carbon monoxide (CO) measurements.…”

Hydrochlorofluorocarbon and hydrofluorocarbon emissions in East Asia determined by inverse modeling

“…Thus, there is presently large uncertainty in the emissions of HCFCs and HFCs from China. While for Japan, top-down estimates are also available (Yokouchi et al, 2005;Stohl et al, 2009), for the Taiwan region, South Korea and North Korea, there exists even less information than for China. This motivated the present study which uses measurement data from several stations in East Asia, an atmospheric transport model and an inversion algorithm to compute HCFC and HFC emissions for several countries in East Asia (mainland China including Hong Kong and Macao abbreviated as "China" in the following, North Korea, South Korea, Japan) as well as the Taiwan region.…”

Assessment of Risk Due to Chemicals Transferred in a Watershed: A Case of an Aquifer Storage Transfer and Recovery Site

“…Being a voluntary report system, PRTR may have a problem in the accuracy of data. Reports can be found that there are discrepancies between PRTR data and real release data [30][31][32]. The gap between PRTR and real data generally occurs in all chemicals rather than a specific chemical.…”