Abstract. A long-term, robust observational record of atmospheric
black carbon (BC) concentrations at Fukue Island for 2009–2019 was produced by unifying the data from a continuous soot monitoring system (COSMOS) and a Multi-Angle Absorption Photometer (MAAP). This record was then used to analyze emission trends from China. We identified a rapid reduction in BC concentrations of (-5.8±1.5) % yr−1 or −48 % from 2010 to 2018. We concluded that an emission change of (-5.3±0.7) % yr−1, related to changes in China of as much as −4.6 % yr−1, was the main underlying driver. This evaluation was made after correcting for the interannual meteorological variability (IAV) by using the regional atmospheric chemistry model simulations from the Weather Research and Forecasting (WRF) and Community Multiscale Air Quality (CMAQ) models (collectively WRF/CMAQ) with the constant emissions. This resolves the current fundamental disagreements about the sign of the BC emissions trend from China over the past decade as assessed from bottom-up emission inventories. Our analysis supports inventories reflecting the governmental clean air actions after 2010 (e.g., MEIC1.3, ECLIPSE versions 5a and 6b, and the Regional Emission inventory in ASia (REAS) version 3.1) and recommends revisions to those that do not (e.g., Community Emissions Data System – CEDS). Our estimated emission trends were
fairly uniform across seasons but diverse among air mass origins. Stronger BC reductions, accompanied by a reduction in carbon monoxide (CO) emissions, occurred in regions of south-central East China, while weaker BC reductions occurred in north-central East China and northeastern China. Prior to 2017, the BC and CO emissions trends
were both unexpectedly positive in northeastern China during winter months,
which possibly influenced the climate at higher latitudes. The pace of the estimated
emissions reduction over China surpasses the Shared Socioeconomic Pathways (SSPs with reference to SSP1, specifically) scenarios for 2015–2030, which suggests highly successful
emission control policies. At Fukue Island, the BC fraction of fine particulate matter (PM2.5) also steadily decreased over the last decade. This suggests that reductions in BC emissions started without significant delay when compared to other pollutants such as NOx and SO2, which are among the key precursors of scattering PM2.5.
The prevalence of allergic diseases in children has increased for several decades. We evaluated the correlation between pollen count of weeds and their sensitization rate in Seoul, 1997-2009. Airborne particles carrying allergens were collected daily from 3 stations around Seoul. Skin prick tests to pollen were performed on children with allergic diseases. Ragweed pollen gradually increased between 1999 and 2005, decreased after 2005 and plateaued until 2009 (peak counts, 67 in 2003, 145 in 2005 and 83 grains/m3/day in 2007). Japanese hop pollen increased between 2002 and 2009 (peak counts, 212 in 2006 and 492 grains/m3/day in 2009). Sensitization rates to weed pollen, especially ragweed and Japanese hop in children with allergic diseases, increased annually (ragweed, 2.2% in 2000 and 2.8% in 2002; Japanese hop, 1.4% in 2000 and 1.9% in 2002). The age for sensitization to pollen gradually became younger since 2000 (4 to 6 yr of age, 3.5% in 1997 and 6.2% in 2009; 7 to 9 yr of age, 4.2% in 1997 and 6.4% in 2009). In conclusion, sensitization rates for weed pollens increase in Korean children given increasing pollen counts of ragweed and Japanese hop.
Abstract. The black carbon (BC) and carbon monoxide (CO) emission ratios were
estimated and compiled from long-term, harmonized observations of the
ΔBC∕ΔCO ratios under conditions unaffected by wet deposition
at four sites in East Asia, including two sites in South Korea (Baengnyeong and
Gosan) and two sites in Japan (Noto and Fukuoka). Extended spatio-temporal
coverage enabled estimation of the full seasonality and elucidation of the
emission ratio in North Korea for the first time. The estimated ratios were
used to validate the Regional Emission inventory in ASia (REAS) version 2.1
based on six study domains (“East China”, “North China”, “Northeast China”, South
Korea, North Korea, and Japan). We found that the ΔBC∕ΔCO
ratios from four sites converged into a narrow range (6.2–7.9 ng m−3 ppb−1), suggesting consistency in the results from independent
observations and similarity in source profiles over the regions. The BC∕CO ratios from the REAS emission inventory (7.7 ng m−3 ppb−1 for East
China – 23.2 ng m−3 ppb−1 for South Korea) were overestimated by
factors of 1.1 for East China to 3.0 for South Korea, whereas the ratio for
North Korea (3.7 ng m−3 ppb−1 from REAS) was underestimated by a
factor of 2.0, most likely due to inaccurate emissions from the road
transportation sector. Seasonal variation in the BC∕CO ratio from REAS was
found to be the highest in winter (China and North Korea) or summer (South
Korea and Japan), whereas the measured ΔBC∕ΔCO ratio was the
highest in spring in all source regions, indicating the need for further
characterization of the seasonality when creating a bottom-up emission
inventory. At levels of administrative districts, overestimation in Seoul,
the southwestern regions of South Korea, and Northeast China was noticeable,
and underestimation was mainly observed in the western regions in North
Korea, including Pyongyang. These diagnoses are useful for identifying
regions where revisions in the inventory are necessary, providing guidance
for the refinement of BC and CO emission rate estimates over East Asia.
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