Asian Journal of Atmospheric Environment最新文献

The livestock industry is a major source of atmospheric volatile organic compounds(VOCs), but details on these emissions are not well documented in Japan. In particular, it remains unclear how the rearing method affects the emissions of VOCs from livestock, which originate primarily from feces and urine. Here we aimed to estimate the amounts of VOCs emitted from the feces and urine of tethered Holstein dairy cattle in a cattle shed in Japan. Dimethyl sulfide and acetone accounted for about 60% of the total VOCs emitted from feces, followed by formaldehyde and acetaldehyde. Also, dimethyl sulfide and acetone were the dominant VOCs emitted from urine, accounting for 90% of the total VOCs. The VOCs from manure were considered to be emitted between the excretion and removal of the manure during the cleaning of the shed. As a result of analyzing images from three cameras installed in the shed, the average time between excretion and cleaning during the daytime (8:00 am–5:00 pm) was 80 min for feces and urine, whereas at night (5:00 pm–7:00 am), the average time between excretion and cleaning was 480 min. Based on the above findings, the emissions of VOCs in the interval between excretion and cleaning of the shed were estimated. As a result, the emissions of VOCs from feces and urine per head of cattle in the shed were estimated to be 1.75 and 1.52 g day⁻¹, respectively. Furthermore, contribution of VOCs emitted from manure to odor activity value (OAV) and hydroxyl radical reactivity (OHR) were also estimated. Volatile fatty acids and sulfur compounds emitted from feces estimated to have high contribution to OAV, whereas aldehydes contributed mainly for OHR from manure.

A comprehensive analysis of pollutant’s trend and their measurement techniques are crucial for evaluating the air quality, and thereby helpful in formulating better control policies. In this report, we summarise ground based PM_2.5 and PM₁₀ data report in India (2015–2019). The important points discussed here are: (i) review of the ground-based data of PM_2.5 and PM₁₀ and the techniques used, (ii) mapping of the data over India with spatial and temporal distribution so that better understanding on PM pollution level can be made, (iii) identifying the technological gaps in measurement of PM concentration in India, and (iv) evaluation of MERRA-2’s (Modern-Era Retrospective Analysis for Research and Applications, Version 2) simulation of PM_2.5 against surface measurements in India to better understand biases for spatial and seasonal distribution, and then (v) suggestions for better PM measurement protocols, policies and metrological aspects for both measurement and control policies. It is observed that the amount of ground data on ambient monitoring of fine PM is insufficient and has several inconsistencies which require adequate attention. In India, not much work has been done on developing certified reference materials, traceable standards and calibration facility for particulate matter measurement which is a crucial step to ensure quality checks. Further, the comparison of MERRA-2 and ground PM_2.5 concentrations revealed huge discrepancies with underestimating PM_2.5 measurements in highly polluted regions like the Indo-Gangetic plain, especially during winter when pollution load was high. Better PM_2.5 agreement was found in summer and monsoon season, based on performance statistics explained in this paper. Inconsistencies between MERRA-2 and ground PM_2.5 are partly due to few limitations in MERRA-2 reanalysis method which are discussed in this paper, apart from several issues in ground-based observation. The aim of this review and comparison is to highlight such issues and give more attention to the importance of data quality assurance for effective air quality management. The present study may be helpful for the researchers in evaluating and choosing appropriate reanalysis products for their future studies.

Cyclone sampling devices have been helpful in assessing the toxic effects of fine particulate matter (PM_2.5). The particle collection efficiency of sampling devices is critical. This study investigated the effect of cyclone size on particle size, chemical composition, and particle toxicity. Three cyclones with different inner diameters (12–68 mm) were tested for penetration using an aerodynamic particle sizer, fluorescent polystyrene latex, and a differential mobility analyzer. The elemental and water-soluble ion compositions of the particles collected by different cyclones were compared. An evaluation of the particles’ toxicity was conducted by comparing the results of dithiothreitol (DTT), limulus amebocyte lysate (LAL), and cell exposure assays. The experimental evaluation showed a 50% cut-size of the cyclones between 0.17–0.28, 0.34–0.36, and 0.70 μm for the small, medium, and large cyclones, respectively. To collect PM_2.5 and evaluate separation performance in the real environment, the small and large cyclones were selected according to the particle penetration and flow rate. A comparison of chemical composition and enrichment factor values found that the particles in the small cyclone samples contained smaller and more anthropogenic sources than those in the large cyclone samples. The oxidative potential (OP) measured by the DTT assay of the samples collected using the small and large cyclones differed across sampling periods and associated with the transition metals. The viability of human epithelial A549 cells after exposure to the collected particles using the cyclones was different across sampling periods and associated with OP. The endotoxin concentrations measured in the LAL assay were found only in the large cyclone samples; they affected the estimated level of cytokine based on IL(interleukin)-6 release from human leukemia monocytic (THP-1) cells derived macro-phage-like cells. Regardless of the size, the cyclone techniques used in this study to collect aerosol particles would be a powerful tool for a detailed evaluation of particle toxicity.

In Japan, the achievement rate of environmental standards for air pollution has been improving in recent years, but for photochemical oxidants, including ozone, improvement are required. In this study, we investigated trends in ozone counter-measures in the United States and Europe from the State Implementation Plan (SIP) and National Air Pollution Control Program (NAPCP) and examined whether there are any points recommended in Japan. The United States and Europe have different policies on environmental standards for air pollution and ozone control. In the United States, states that do not meet the environmental standards for ozone concentration are required to develop an SIP to attain the standards. There was an urgent need to find a cost-effective approach to addressing the ozone problem, and forest control measures were one of the possibilities. In Europe, the European Union has set “target values” for ozone and NAPCP does not mention forest control measures or ozone sensitivity regimes. The main focus in Europe is on the win-win solution of reducing emissions of air pollutants at the same time as greenhouse gases. Japan should consider a framework including setting feasible step-by-step goals to attain the desired standards. As ozone is greatly affected by advection, wide-regional measures against ozone precursors and prediction of the future precursor reduction and concentration are required. The preparation of an emissions inventory and estimated reduction amount is prerequisites as basic data for simulation. To achieve this, cooperation between national, local and private research institutes is crucial. Since the international community has agreed to prioritize greenhouse gas counter-measures, Japan could consider a win-win solution for both ozone and greenhouse gas reduction.

The present study was conducted in Lucknow city to assess the impact of firecracker burning during Diwali, from 2 November 2021–6 November 2021 including the pre and post-Diwali days. The concentrations of PM₁₀, PM_2.5, SO₂, NO₂, CO, O₃, benzene and toluene, were monitored from the Central Pollution Control Board site on an hourly basis. The Air Quality Index was also recorded for PM₁₀, PM_2.5, SO₂ and NO₂. A questionnaire survey was done with 51 doctors to know the reported complaints post-Diwali. On Diwali night the PM_2.5 value reached 262 µg m⁻³ around 22:00 hours and the maximum value (900 µg m⁻³) was obtained on 5 November, reported from the Central School monitoring station. From Gomti Nagar highest PM_2.5 value obtained on Diwali day was 538 µg m⁻³ at 23:00 hours reaching 519 µg m⁻³ post-Diwali. Areas belonging to the old part of the city witnessed higher variations as PM_2.5 crossed 900 µg m⁻³, in Lalbagh and Talkatora areas. The multivariate analysis showed that on Diwali night there was an increase of 204, 386, 344 and 341 in the PM_2.5 concentration reported from Gomtinagar, Central School, Talkatora and Lalbagh stations, showing that firecracker burning resulted in a significant increase in air pollution. The Toluene/Benzene ratio was mostly more than 1 indicating that toluene and benzene may be emitted from other sources as well including the mobile sources. Around 50–75% rise was seen in the number of patients post-Diwali. 57.1% of the reported cases had respiratory issues, followed by allergic reactions. The data obtained from Lalbagh, Talkatora and Central School showed that although the values remained high, a decreasing trend was seen in the AQI compared to previous years which is a good sign and may be attributed to public awareness and the ongoing pandemic making people conscious.

The global limit on the sulfur content of ship fuel was reduced from 3.50% to 0.50% in January 2020 to reduce ship emissions of SO₂ and particulate matter. We conducted observational campaigns before and after the new global limit was introduced to detect changes in coastal air quality. We measured ambient concentrations of SO₂ and CO₂ ship plumes on shore with the sniffing method under the Kanmon Bridge over the Kanmon Straits between Honshu and Kyusyu Islands, Japan, for several weeks in August to September in 2019 and 2020. The fuel sulfur content (FSC) estimated from our measurements mainly varied from 0.50% to 3.00% in 2019, whereas the range narrowed to 0.10% to 0.40% in 2020, showing that all the ships complied. The mean FSC in 2020 was reduced to 16% of that in 2019, which was consistent with the reduction in the ambient SO₂ concentration. Sakurai et al.(2021) estimated that after the 2020 global limit was brought in, SO₂ emissions from ships were reduced to 24% of their previous values by assuming that all ships have a FSC of 0.50%. Our results indicate the 2020 global limit led to much greater reductions in SO₂ emissions from ships than expected.

The objective of this study was to analyze the temporal and spatial characteristics of fine particulate matters by using huge hourly datasets of PM_2.5, including chemical information monitored at the 6 national intensive monitoring sites (NIMSs) from 2013 to 2018 in Korea. Hourly PM_2.5 raw datasets were obtained from the National Institute of Environmental Research (NIER) in Korea. Monitoring sites included urban, rural/agricultural, industrial, and marine environments. Since the PM_2.5 concentration steadily decreased nationwide, each species concentration also decreased in general. One of key reasons for decreasing PM_2.5 might be explained by the implementation of domestic fine dust reduction policies and external influences such as PM_2.5 concentration reduction in China. It was observed that 45.0% of all datasets for 6 years were classified as good condition. The average sum of 14 elements over all sites in 2018 was calculated to be 501.5 ng/m³, and its mass ratio for PM_2.5 (21.9 μg/m³) was 2.30%. The inorganic elements were generally higher in industrial/urban areas than in agricultural areas. In addition, the average TC (total carbon) over all 6 sites was 28.3% of PM_2.5 with the range of 23.6% to 31.4%. The TC in small urban areas was much higher than that in marine areas or even that in large, populated urban area/industrial areas. It seemed that the latter areas were better controlled than the former area in terms of combustion activities of fossil fuels. It is suggested that these results could be play an important role as important basic data to manage ambient air quality and establish effective emission reduction strategies in each region.

Two Japanese rice cultivars with different heat-tolerance, Hinohikari (sensitive) and Nikomaru (tolerant), were grown in pots inside open-top chambers and exposed to ambient CO₂ (400 µmol mol⁻¹) or elevated CO₂ (550 µmol mol⁻¹) from the beginning of the tillering stage to maturity. The study was conducted in Nagasaki, in the Kyushu region of Japan, where heat stress on rice has become increasingly evident. Although elevated CO₂ significantly improved the net photosynthesis and whole-plant growth of the cultivars, there were no significant effects on grain yield, which in turn reduced harvest index. In both cultivars, adverse effects occurred with elevated CO₂, such as reductions in spikelet fertility and grain appearance quality, which are typical manifestations of heat stress in rice. During the flowering period, the air temperature was high that spikelet fertility was reduced even under ambient CO₂ conditions for both cultivars. These results suggest that, under high-temperature conditions, elevated CO₂ could induce or exacerbate the manifestations of heat stress in rice. Because transpiration rate in the flag leaf was significantly reduced by the exposure to elevated CO₂, it is possible that elevated CO₂ increased plant temperature via a reduction in transpiration during flowering period, although we did not detect significance of the increase in leaf and panicle temperature. To ensure a more confident conclusion, further studies focusing on the effects of elevated CO₂ on the determinants of spikelet fertility and grain appearance quality with other cultivars in different year are required.

In recent years, natural gas is increasingly being used in the heating and power generation sectors as a clean fuel with an aim to reduce air pollution. In this study, a standard test method was used to measure air pollutants and identify emission characteristics for gas turbines and small domestic boilers, which use LNG as fuel. For gas turbines, the air pollutants were measured at 14 sites, whereas for small domestic boilers, six of them were installed in a laboratory to run tests due to limitations in on-site measuring and testing. However, the small domestic boilers were all new machines and were operated for long consecutive hours for testing, meaning that the results could vary from that of on-site boilers. The results show that gas turbines and small domestic boilers not only emit PM_2.5, but also particulate matters larger than PM_2.5. According to the measurements, the average concentration level of PM_total, PM₁₀, and PM_2.5 generated from gas turbines are 51.8, 38.5, and 28.1 µg/m³ (@O₂ 15%), respectively. Those generated from small domestic boilers were 31.3, 26.2, and 20.0 µg/m³ (@O₂ 4%), respectively. The NOx concentration levels complied with the emission limits. Especially where a NOx control device was in place, both the NOx and CO concentration levels were relatively low. However, the NOx and CO concentration levels were generated from small domestic boilers were relatively high, since the emission limits were not applied. VOCs were measured at 10 facilities where 28 samples were collected. The compounds that were identified were Aromatics, Oxygenated VOCs, Alkanes, in that order, which were consistent across the samples. Aromatics consisted mostly of toluene, o,m,p-xylenes, benzene, and ethylbenzene. Among oxygenated VOCs, ethyl acetate, vinyl acetate, and isopropyl alcohol, etc. were identified. In other words, gas turbines generated a wider range and higher concentration levels of VOCs compared to small domestic boilers. The emission factors of gas turbines and small domestic boilers were derived from the measurements, and then compared with the standard emission factors of other countries (NAER, U.S. EPA AP-42, EMEP/EEA). PM emission factors calculated in this study were lower than that of existing emission factors and the calculated NOx emission factors (uncontrolled) for the small boilers were also lower. The CO emission factor for gas turbines was lower than that of existing emission factors, but higher for the small domestic boilers. Emission factors of benzene, toluene, and xylenes, which are hazardous air pollutants, were lower than those of U.S. EPA AP-42.

Ammonia (NH₃) is an important, albeit sticky, precursor for producing secondary inorganic aerosols (SIA), especially in the form of ammonium nitrate (NH₄NO₃) and ammonium sulfate ((NH₄)₂SO₄). To reduce SIAs, many researchers have attempted to measure the concentration of ambient NH₃ using real-time or passive methods. However, NH₃ is a highly sticky gas and is therefore difficult to measure using real-time methods without incurring losses during measurement. In this study, four different tubing materials, semi seamless tubes, perfluoroalkoxy (PFA), polytetrafluoroethylene (PTFE), and polyvinylidene fluoride (PVDF), were used to ascertain the adsorption of NH₃ in inlets using real-time instruments. Without heating sample tubes and at 0% relative humidity (RH), this study shows that PTFE had the least adsorption(i.e., 0% at 1 and 2m of sample tube), and semi-seamless tubes had the highest adsorption (i.e., 27.5% at 1 m of sample tube). To calculate the adsorption of NH₃ under ambient conditions, at various inlet lengths, the RH of NH₃ was varied from 20% to 80%, which showed that shorter inlets and higher RH lower NH₃ adsorption at inlets (i.e., 1.74 ppb m⁻¹ at 80% RH and 7.48 ppb m⁻¹ at 20% RH). Additionally, inlet heating was effective in reducing the adsorption of NH₃ as the RH decreased. Applying the inlet system (i.e., 2 m of PTFE tube with heating) showed excellent correlation (slope: 0.995 and coefficient: 0.992) between two different real-time measurements while measuring ambient air.