SO2 Measurements Research Articles

Ambient PM2.5 organic and elemental carbon in New York City: Changing source contributions during a decade of large emission reductions

ABSTRACT Fine particle (PM2.5) exposure is a public health issue affecting millions of people worldwide. In New York State, significant emission reductions occurred during the past decades due to fuel switching, increased renewable energy, and transformations in buildings and transportation. Between 2002 and 2018, anthropogenic emissions of CO, NOx, SO2, VOCs, and primary PM2.5 declined by 58%, 61%, 89%, 47%, and 29%, respectively, in New York and three adjoining states. Ambient PM2.5 mass concentrations decreased but contributions of source types to changes in PM2.5 elemental carbon (EC) and organic carbon (OC) are incompletely understood. Receptor modeling was used to estimate changing source contributions to EC and OC in New York City (NYC) between 2007 and 2019. Source identification was facilitated by incorporating measurements of CO, NO, NO2, O3, SO2, and speciated hydrocarbons (1,3-butadiene, n-butane, isobutane, n-pentane, isopentane, isoprene, benzene, toluene, xylenes, acetaldehyde, and formaldehyde). Hydrocarbon species identified mobile-source emissions, evaporative emissions, biogenics, and photochemical secondary organic aerosol. At three study locations, predicted reductions of TC (OC + EC) summed over all source types were 1.3 ± 0.2 μg m−3, compared with a measured TC reduction of 1.5 ± 0.2 μg m−3. Declining sulfate concentrations and cleaner mobile sources together reduced the predicted average TC by a combined 1 μg m−3. Smaller changes occurred in other source contributions, e.g., 0.15 ± 0.01 μg m−3 reduction likely in response to NYC regulations related to heating fuel oil. Biomass burning PM2.5 increased between 2007 and 2011, then declined between 2015 and 2019. Reductions contrast with a non-significant increase of 0.05 μg m−3 in photochemical TC. Further opportunities to decrease PM2.5 concentrations include wood burning and photochemical-related OC. Continued temporal analysis and source apportionment will be needed to track changes in air quality and source contributions as jurisdictions expand renewable energy and energy efficiency goals. Implications: Large emission reductions that occurred in the eastern U.S. between 2002 and 2019 lowered average fine particle concentrations in New York City by a factor of two. Secondary organic aerosol concentrations declined as sulfate decreased but increased non-significantly with rising ozone. Cleaner mobile-source emissions lowered elemental and organic carbon concentrations. Opportunities for further reductions of PM2.5 concentrations include biomass burning and photochemical secondary aerosol.

Evaluation of air pollutants (PM10 and SO2) in the first year of the COVID-19: A city sample from Turkey

The aim of this study is to evaluate the change of air pollutants in the province of Van compared to the previous year during the COVID-19 pandemic. The study is a cross-sectional study conducted in Van where is a city in eastern Turkey. PM10 and SO2 values obtained from the National Air Quality Monitoring Network website. The lockdowns imposed in the province of Van within the scope of combating COVID-19 have been recorded by examining the decisions of the Sanitary Board on the Van Governorship's official website. The mean of PM10 measurement values in the period before and after COVID-19 were 40.89±19.6 µg/m3 and 41.3±20.39 µg/m3, respectively. The mean of SO2 measurement values were 17.76±18.48 µg/m3 and 23.49±20.96 µg/m3 before and after COVID-19, respectively. When one year after and before COVID-19 was evaluated, there was no difference in PM10 values in terms of year averages, while SO2 value was found to be increased compared to the previous year. However, when analyzed by months, there were months when PM10 values were found to be increased (March, September and October) and decreased (July, August and November) compared to the previous year.

Evidence for SO2 latitudinal variations below the clouds of Venus

Context. Sulphur dioxide (SO2) is highly variable above the clouds of Venus, yet no spatial or temporal variability below the clouds had been known until now. Aims. In order to constrain Venus’s atmospheric circulation and chemistry (including possible volcanic outgassing), more accurate SO2 measurements below the clouds are therefore needed. Methods. We used the high-resolution iSHELL spectrometer located at the NASA IRTF to record thermal night-side spectra, which we fitted using an updated forward radiative transfer model that was previously employed to process SpeX/IRTF and VIRTIS-H/Venus Express spectra. Results. We report, for the first time, an increase in SO2 with increasing latitude (+30% between the minimum near 15°S and > 35°N). This is consistent with the interaction between the Hadley-cell circulation and a postulated vertical profile in SO2 estimated to increase between 30 and 40 km in altitude, as previously suggested by in situ ISAV measurements. Conclusions. This SO2 variability challenges our current understanding of Venus’s tropospheric thermochemistry and underlines the high scientific return from high-resolution spectroscopy from, for example, future orbiters.

Improvements to a laser-induced fluorescence instrument for measuring SO<sub>2</sub> – impact on accuracy and precision

Abstract. This work describes key improvements made to the in situ laser-induced fluorescence instrument for measuring sulfur dioxide (SO2) that was originally described by Rollins et al. (2016). Here, we report measurements of the SO2 fluorescence emission spectrum. These measurements allow for the determination of the most appropriate bandpass filters to optimize the fluorescence signal, while reducing the instrumental background. Because many aromatic species fluoresce in the same spectral region as SO2, fluorescence spectra were also measured for naphthalene and anisole to determine if ambient SO2 measurements could be biased in the presence of such species. Improvement in the laser system resulted in better tunability, and a significant reduction in the 216.9 nm laser linewidth. This increases the online/offline signal ratio which, in turn, improves the precision and specificity of the measurement. The effects of these improvements on the instrumental sensitivity were determined by analyzing the signal and background of the instrument, using varying optical bandpass filter ranges and cell pressures and calculating the resulting limit of detection. As a result, we report an improvement to the instrumental sensitivity by as much as 50 %.

Synoptic analysis of a decade of daily measurements of SO<sub>2</sub> emission in the troposphere from volcanoes of the global ground-based Network for Observation of Volcanic and Atmospheric Change

Abstract. Volcanic plumes are common and far-reaching manifestations of volcanic activity during and between eruptions. Observations of the rate of emission and composition of volcanic plumes are essential to recognize and, in some cases, predict the state of volcanic activity. Measurements of the size and location of the plumes are important to assess the impact of the emission from sporadic or localized events to persistent or widespread processes of climatic and environmental importance. These observations provide information on volatile budgets on Earth, chemical evolution of magmas, and atmospheric circulation and dynamics. Space-based observations during the last decades have given us a global view of Earth's volcanic emission, particularly of sulfur dioxide (SO2). Although none of the satellite missions were intended to be used for measurement of volcanic gas emission, specially adapted algorithms have produced time-averaged global emission budgets. These have confirmed that tropospheric plumes, produced from persistent degassing of weak sources, dominate the total emission of volcanic SO2. Although space-based observations have provided this global insight into some aspects of Earth's volcanism, it still has important limitations. The magnitude and short-term variability of lower-atmosphere emissions, historically less accessible from space, remain largely uncertain. Operational monitoring of volcanic plumes, at scales relevant for adequate surveillance, has been facilitated through the use of ground-based scanning differential optical absorption spectrometer (ScanDOAS) instruments since the beginning of this century, largely due to the coordinated effort of the Network for Observation of Volcanic and Atmospheric Change (NOVAC). In this study, we present a compilation of results of homogenized post-analysis of measurements of SO2 flux and plume parameters obtained during the period March 2005 to January 2017 of 32 volcanoes in NOVAC. This inventory opens a window into the short-term emission patterns of a diverse set of volcanoes in terms of magma composition, geographical location, magnitude of emission, and style of eruptive activity. We find that passive volcanic degassing is by no means a stationary process in time and that large sub-daily variability is observed in the flux of volcanic gases, which has implications for emission budgets produced using short-term, sporadic observations. The use of a standard evaluation method allows for intercomparison between different volcanoes and between ground- and space-based measurements of the same volcanoes. The emission of several weakly degassing volcanoes, undetected by satellites, is presented for the first time. We also compare our results with those reported in the literature, providing ranges of variability in emission not accessible in the past. The open-access data repository introduced in this article will enable further exploitation of this unique dataset, with a focus on volcanological research, risk assessment, satellite-sensor validation, and improved quantification of the prevalent tropospheric component of global volcanic emission. Datasets for each volcano are made available at https://novac.chalmers.se (last access: 1 October 2020) under the CC-BY 4 license or through the DOI (digital object identifier) links provided in Table 1.

The impacts of COVID-19 lockdown on PM10 and SO2 concentrations and association with human mobility across Turkey

The SARS-CoV-2 virus pandemic (COVID-19) has caused 2.25 million deaths worldwide by February 3, 2021 (JHU, 2021) and still causing severe health and economic disruptions with increasing rates. This study investigates the impact of lockdown measures on ambient air pollution and its association with human mobility in 81 cities of Turkey. We conducted a countrywide analysis using PM10 and SO2 measurement data by the Turkish Ministry of Environment and Urbanization and mobility data derived from cellular device movement by Google. We observed the most significant change in April 2020. PM10 and SO2 concentrations were lower in 67% and 59% of the cities, respectively in April 2020 compared to the previous five years (2015–2019). The correlation results show that Restaurant/Café, Transit, and Workplaces mobility is significantly correlated with PM10 and SO2 concentration levels in Turkey. This study is the first step of a long-term investigation to understand the air quality impacts on population susceptibility to COVID-19.

An assessment of ambient air quality using AQI and exceedance factor for Udaipur City, Rajasthan (India)

Air pollution is a severe issue of concern worldwide due to its most significant environmental risk to human health today. All substances that appear in excessive amounts in the environment, such as PM10, NO2, or SO2, may be associated with severe health problems. Anthropogenic sources of these pollutants are mainly responsible for the deterioration of urban air quality. These sources include stationary point sources, mobile sources, waste disposal landfills, open burning, and similar others. Due to these pollutants, people are at increased risk of various serious diseases like breathing problems and heart disease, and the death rate due to these diseases can also increase. Hence, air quality monitoring is essential in urban areas to control and regulate the emission of these pollutants to reduce the health impacts on human beings. Udaipur has been selected for the assessment of air quality with monitored air quality data. Air quality monitoring stations in Udaipur city are operated by the CPCB (Central Pollution Control Board) and RSPCB (Rajasthan State Pollution Control Board). The purpose of this study is to characterize the level of urban air pollution through the measurement of PM10, NO2, or SO2 in Udaipur city, Rajasthan (India). Four sampling locations were selected for Udaipur city to assess the effect of urban air pollution and ambient air quality, and it was monitored for a year from 1st January 2019 to 31st December 2019. The air quality index has been calculated with measured values of PM10, NO2, and SO2. The concentration of PM10 is at a critical level of pollution and primarily responsible for bad air quality and high air quality Index in Udaipur city.

Atmospheric Pollution Impact Assessment of Brick and Tile Industry: A Case Study of Xinmi City in Zhengzhou, China

The brick and tile industry was selected to investigate the impact of pollutants emitted from such industry on air quality. Based on the 2018 Zhengzhou City Census data and combined with field sampling and research visits, an emission inventory of the brick and tile industry in Xinmi City was established using the emission factor method. Based on the established emission inventory, the concentrations of SO2, NOX, and PM2.5 emitted by 31 brick and tile enterprises were then predicted using the CALPUFF model (California puff model, USEPA), which had been evaluated for accuracy, and the simulation results were compared with the observed results to obtain the impact of pollutant emissions from the brick and tile industry on air pollution in the simulated region. Results show that SO2, NOX, and PM2.5 emissions from the brick and tile industry in the study area in 2018 were 564.86 tons, 513.16 tons, and 41.01 tons, respectively. The CALPUFF model can simulate the characteristics of meteorological changes and pollutant concentration trends, and the correlation coefficient of the fit curve between the pollutant observed data and the simulated data was higher than 0.8, which can reproduce the impact of key industrial point sources on air quality well. The simulated concentration values and spatial and temporal distribution characteristics of SO2, NOX, PM2.5 in spring, summer, autumn, and winter were obtained from the model simulations. The contribution of pollutant emissions from the brick and tile industry to the monthly average concentrations of SO2, NOX, and PM2.5 in the simulated region were 6.58%, 5.38%, and 1.42%, respectively, with the Housing Administration monitoring station as the receptor point. The brick and tile industry should increase the emission control measures of SO2 and NOX, and at the same time, the emission control of PM2.5 cannot be slackened.

Air quality and preventable deaths in Tekirdağ, Turkey

Ambient air pollution is potentially harmful pollutants released by industries, households, vehicles, power plants, and biomass burning. Of all of these pollutants, fine particulate matter (PM2.5) has the greatest effect on human health and it is associated with an increased risk of several causes of death which cause cardiovascular and respiratory diseases and cancers. The purpose of this study was to examine the association of air pollution with mortality and to calculate mortality attributed to air pollution. It is an ecological study. The number of deaths attributed to air pollution was calculated with AirQ+ methodology. Twenty-four-hour SO2 measurements in the study region, with its intensive motor traffic, exceeded the national and WHO threshold values on 5 days and 143 days, while PM10 values exceeded those limits on 239 days and 331 days, respectively. According to AirQ+ calculation, 25.2% of deaths were caused by air pollution, with 415 in 100,000 deaths being attributable to air pollution. We recommend that PM2.5 be included among the air quality index evaluation criteria by means of amendment to the existing legislation, and that a national threshold limit for PM2.5 be determined in Turkey.

On the Fluctuations in Volcanic Plumes

AbstractSome basaltic open vent volcanoes show that spectroscopic SO2 measurements of a volcanic gas plume are characterized by a fluctuating signal. Understanding the origin of these fluctuations is of great interest for interpreting volcanic gas emission regimes. Although some fluctuations may be associated with intermittency in the source flux, some may be associated with the turbulence in the flow. A simple laboratory experiment, in which we release dye pulses into a turbulent wake in a small water‐filled channel, suggests that when the intermittency of the source has comparable or smaller timescale as the turbulence, the fluctuations are similar, whereas when the intermittency of the source has longer timescale than the turbulence, the fluctuations can be distinguished. We also present some small‐scale laboratory experiments of turbulent buoyant plumes produced from a steady source; these demonstrate a time‐fluctuating concentration of source fluid downstream and the fluctuation period tends to increase with distance.

Comparison of SCIPUFF predictions to SO2 measurements from instruments on the MetOp-A, MetOp-B, Aura and Suomi satellites from the 2016 fire at Al-Mishraq

On October 20th, 2016, Daesh (Islamic State) set fire to the sulfur production and storage site at Al-Mishraq, Iraq. The fire burned continuously for seven days resulting in the release of a buoyant dynamic sulfur dioxide (SO2) toxic plume extending geographically for over 300 km. This Al-Mishraq event provides an opportunity for scientists to address probabilistic atmospheric transport and dispersion (PATD) hazard model performance across multiple downwind scales over a large area. In using any PATD model, a fair evaluation of the model depends on the quality of the source term – especially for a very dynamic source term such as a burning sulfur stockpile. An innovative approach to derive such a source for Al-Mishraq was explored by the Swedish Defence Research Agency (in Swedish Totalförsvarets forskningsinstitut, or FOI). The experts from FOI characterized the SO2 source term based on satellite observations, which reflect vertically-integrated concentrations and are expressed in Dobson units (DU). The work throughout this paper is a novel approach and leverages the FOI analysis to evaluate a PATD, the Second Order Closure Integrated Puff (SCIPUFF) transport and dispersion code as adapted within the Hazard Prediction and Assessment Capability (HPAC). SCIPUFF predictions are compared to the satellite-based vertically-integrated SO2 measurements from the Moderate Resolution Imaging Spectro-radiometer (MODIS) instruments. Satellite measurements were available at 07Z and 11Z daily from 21 to 26 Oct 2016. A 1-DU background was assumed. SCIPUFF over predicts (factor of 2) column density (DU) peaks in the near field (40, 80, and 120 km) and under predicts in the far field (200, 280 and 320 km); best agreement is at the 160 km arc. Plume direction errors of 25–80° are found when comparing the azimuths of peak observed and predicted column densities. Performance metrics traditionally used for model evaluation included fractional bias (FB), normalized mean-square error (NMSE), and figure of merit in space (FMS). The FB at 07Z was −0.2 to +0.09 across the eight arcs, 40–320 km downwind. Upon analyses, SCIPUFF showed approximate equal over and under prediction for the 07Z; and the FB at 11Z under predicted seven of eight arcs, with values that ranged from −0.07 to +0.36. The NMSE was 3.11–5.06 with no identifiable trends on arc distance. The FMS, averaged over each arc, by day, was between 0.31 and 0.56. Higher values were found in the early and later stages of the fire 21–22 and 25–26 October. Lower averaged FMS values were calculated for 23–24 October which corresponds to a period where the fire burned hotter and SO2 mass was injected to higher altitudes of 1–4 km.

VolKilau: Volcano Rapid Response Balloon Campaign during the 2018 Kilauea Eruption

AbstractAfter nearly 35 years of stable activity, the Kilauea volcanic system in Hawaii went through sudden changes in May 2018 with the emergence of 20 volcanic fissures along the Lower Eastern Rift Zone (LERZ), destroying 700 homes in Leilani Estates and forcing more than 2,000 people to evacuate. Elevated volcanic emissions lasted for several months between May and September 2018, leading to low visibility and poor air quality in Hawaii and across the western Pacific. The NASA-funded VolKilau mission was rapidly mounted and conducted between 11 and 18 June 2018 to (i) profile volcanic emissions with SO2 and aerosol measurements, (ii) validate satellite observations, and (iii) increase readiness for the next large volcanic eruption. Through a series of balloon-borne measurements with tethered and free-released launches, we measured SO2 concentration, aerosol concentration, and optical properties 60–80 km downwind from the volcanic fissures using gas sensors, optical particle counters, backscatter sondes, and an aerosol impactor. While most of the measurements made during the Kilauea eruption were ground based, the VolKilau mission represented a unique opportunity to characterize plume properties, constrain emission profiles, study early chemistry involving the conversion of SO2 into sulfuric acid, and understand the influence of water clouds in the removal of SO2. This unprecedented combination of measurements has significantly improved our team’s ability to assess the atmospheric and human impacts of a major event such as this.

Updated tropospheric chemistry reanalysis and emission estimates, TCR-2, for 2005–2018

Abstract. This study presents the results from the Tropospheric Chemistry Reanalysis version 2 (TCR-2) for the period 2005–2018 at 1.1∘ horizontal resolution obtained from the assimilation of multiple updated satellite measurements of ozone, CO, NO2, HNO3, and SO2 from the OMI, SCIAMACHY, GOME-2, TES, MLS, and MOPITT satellite instruments. The reanalysis calculation was conducted using a global chemical transport model MIROC-CHASER and an ensemble Kalman filter technique that optimizes both chemical concentrations of various species and emissions of several precursors, which was efficient for the correction of the entire tropospheric profile of various species and its year-to-year variations. Comparisons against independent aircraft, satellite, and ozonesonde observations demonstrate the quality of the reanalysis fields for numerous key species on regional and global scales, as well as for seasonal, yearly, and decadal scales, from the surface to the lower stratosphere. The multi-constituent data assimilation brought the model vertical profiles and interhemispheric gradient of OH closer to observational estimates, which was important in improving the description of the oxidation capacity of the atmosphere and thus vertical profiles of various species. The evaluation results demonstrate the capability of the chemical reanalysis to improve understanding of the processes controlling variations in atmospheric composition, including long-term changes in near-surface air quality and emissions. The estimated emissions can be employed for the elucidation of detailed distributions of the anthropogenic and biomass burning emissions of co-emitted species (NOx, CO, SO2) in all major regions, as well as their seasonal and decadal variabilities. The data sets are available at https://doi.org/10.25966/9qgv-fe81 (Miyazaki et al., 2019a).

Quantifying gas emissions associated with the 2018 rift eruption of Kīlauea Volcano using ground-based DOAS measurements

Starting on 3 May 2018, a series of eruptive fissures opened in Kīlauea Volcano’s lower East Rift Zone (LERZ). Over the course of the next 3 months, intense degassing accompanied lava effusion from these fissures. Here, we report on ground-based observations of the gas emissions associated with Kīlauea’s 2018 eruption. Visual observations combined with radiative transfer modeling show that ultraviolet light could not efficiently penetrate the gas and aerosol plume in the LERZ, complicating SO2 measurements by differential optical absorption spectroscopy (DOAS). By applying a statistical method that integrates a radiative transfer model with the DOAS retrievals, we were able to calculate sulfur dioxide (SO2) emission rates along with estimates of their uncertainty. We find that sustained SO2 emissions were highest in June and early July, when approximately 200 kt SO2 were emitted daily. At the 68% confidence interval, we estimate that 7.1–13.6 Mt SO2 were released from the LERZ during the entire May to September eruptive episode. Scaling our results with in situ measurements of plume composition, we calculate that 11–21 Mt H2O and 1.5–2.8 Mt CO2 were also emitted. The gas and aerosol emissions caused hazardous conditions in areas proximal to the active vents, but plume dispersion modeling shows that the eruption also significantly impacted air quality hundreds of kilometers downwind. Combined with petrologic studies of the erupted lavas, our measurements indicate that 1.1–2.3 km3 dense-rock equivalent of lava were erupted from the LERZ, which is approximately twice the concomitant collapse volume of the volcano’s summit.

Influence of Moisture in Flue Gas after Wet Desulfurization on the Measurement of SO2 Concentration

Wet desulfurization is dominant in China’s coal power industry as flue gas discharged from wet desulfurization is over-saturated, includes lots of moisture, and can bring huge interference to the measurement of SO2. When using existing SO2 measuring methods, especially wet desulfurization technology aiming at ultra-low emissions, it is necessary to take into account the impact of water in flue gas. The pH value of condensate water of flue gas after desulfurization with limestone gypsum wet desulfurization is 2, lower than that of desulfurizing slurry, indicating that some SO2 has been dissolved in the water carried by flue gas after desulfurization. In order to avoid the interference of water, infrared online continuous emission monitoring system (CEMS) is equipped with a water removal device. When a conventional condensate water removal method is applied, condensate water will dissolve SO2 and then lead to the relatively low concentration of SO2 in the flue gas measured. When a proper water removal method is adopted, it can effectively avoid the measuring error as a result of SO2 dissolved in condensate water.

Impact of Covid-19 lockdown on PM10, SO2 and NO2 concentrations in Salé City (Morocco)

Covid-19 was first reported in Morocco on March 2, 2020. Since then, to prevent its propagation, the Moroccan government declared a state of health emergency. A set of rapid and strict countermeasures have taken, including locking down cities, limiting population's mobility and prohibiting almost all avoidable activities. In the present study, we attempted to evaluate the changes in levels of some air pollutants (mainly PM10, NO2 and SO2) in Salé city (North-Western Morocco) during the lockdown measures. In this context, a continuous measurement of PM10, SO2 and NO2 was carried before and during the Covid-19 lockdown period. As a consequence of the security measures and control actions undertaken, the emissions from vehicle exhaust and industrial production were significantly reduced, which contribute to the decrease in the concentrations of the studied pollutants. The obtained results showed that the difference between the concentrations recorded before and during the lockdown period were respectively 75%, 49% and 96% for PM10, SO2 and NO2. PM10 levels were much less reduced than NO2. The three-dimensional air mass backward trajectories, using the HYSPLIT model, demonstrated the benefits of PM10 local emission reductions related to the lockdown were overwhelmed by the contribution of long-range transported aerosols outside areas. In addition, noteworthy differences in the air mass back trajectories and the meteorology between these two periods were evidenced.

A 24-h real-time emissions assessment of 41 uncontrolled household raw coal combustion stoves in four provinces of Northern China

Abstract Air pollutants from household heating stoves are attracting growing public concern. Although several previous studies have investigated pollutant emissions from the household heating stoves, the emission factors reported might be less representative because most of the studies conducted the measurement only during the relatively short period for one combustion process, which is far from the real case. In this study, therefore, 24-h continuous measurements of CO, PM2.5, SO2, NOx, and CO2 emissions from the chimneys of household stoves fueled with raw coal in four provinces of Northern China were conducted during winter heating periods to reveal their actual emissions. The measured emission factors of CO, CO2, SO2, NOx, and PM2.5 were 6.163 ± 2.113, 82.875 ± 4.709, 0.190 ± 0.113, 0.076 ± 0.046, and 0.127 ± 0.061 g/MJ for the radiant heating stove; 5.801 ± 2.323, 86.602 ± 8.376, 0.083 ± 0.048, 0.062 ± 0.033, and 0.119 ± 0.081 g/MJ for the water heating stove, respectively. Compared with previously published results with relatively short-time measurements, a lower PM2.5 emission factor (p

Effects of cleaner ship fuels on air quality and implications for future policy: A case study of Chongming Ecological Island in China

China has implemented the domestic emission control area (DECA) policy for shipping in different phases, such as DECA1.0 (2016–2018) and DECA2.0 (2019). This study aimed to examine the effects of cleaner ship fuels on air pollutants. The long-term online field measurements of SO2, NOX, CO, and PM2.5 have been carried out at Chongming Island, located at the cross section of the Yangtze River and the East China Sea, to observe the variation driven by the evolution of different-phased DECA policy during 2013–2019. Our results revealed that SO2 showed an evident declining trend in different seasons. Meanwhile, on-line hourly elemental vanadium and nickel concentrations in PM2.5 at Chongming Island and two other inland sites in Shanghai were measured. There were covariations and a decreasing gradient in the vanadium concentration from the Chongming Island site to the coastal site to the inland site in Shanghai. In retrospect to 2015, i.e., before DECA, the vanadium concentration had a reduction of 5.8% for DECA1.0 (2016–2018) and one of 60–70% for DECA2.0 (2019). The observed reduction was confirmed by the estimated decrease in ship emission amount of SO2 and vanadium around the Shanghai port after DECA policy. The annual average concentrations of vanadium and nickel in Chongming Island were still 5.69 ng/m3 and 3.1 ng/m3 even after DECA2.0, respectively. The ambient concentration of metals at the ecological Island could reduce the most in future cleaner fuel oils scenario. Our study provided the evidence for the environmental benefit of clean fuel oil and indicated the need of a full-scale switching to a stricter ship ECA policy in future.

Evaluation of Fluence Correction Algorithms in Multispectral Photoacoustic Imaging

Multispectral photoacoustic imaging (MPAI) is a promising emerging diagnostic technology, but fluence artifacts can degrade device performance. Our goal was to develop well-validated phantom-based test methods for evaluating and comparing MPAI fluence correction algorithms, including a heuristic diffusion approximation, Monte Carlo simulations, and an algorithm we developed based on novel application of the diffusion dipole model (DDM). Phantoms simulated a range of breast-mimicking optical properties and contained channels filled with chromophore solutions (ink, hemoglobin, or copper sulfate) or connected to a previously developed blood flow circuit providing tunable oxygen saturation (SO2). The DDM algorithm achieved similar spectral recovery and SO2 measurement accuracy to Monte Carlo-based corrections with lower computational cost, potentially providing an accurate, real-time correction approach. Algorithms were sensitive to optical property uncertainty, but error was minimized by matching phantom albedo. The developed test methods may provide a foundation for standardized assessment of MPAI fluence correction algorithm performance.

Myocardial Oxygen Saturation Measured by Photoacoustic EKV Imaging

Cardiac remodeling following myocardial infarction (MI) leads to structural and vascular changes in the myocardium. To better understand the mechanisms involved, we used photoacoustic ECG‐gated Kilohertz Visualization imaging (PA EKV) to measure oxygen saturation in the myocardium. Photoacoustic imaging is a noninvasive imaging technique that uses near‐infrared laser light to optically excite molecules in vivo. Oxygenated hemoglobin absorbs laser light at a different wavelength (850nm) from non‐oxygenated hemoglobin (750nm) which allows for the detection of the relative oxygen saturation (sO2) of a tissue and the amount of hemoglobin present (HbT). In this study, photoacoustic imaging was combined with EKV imaging for continuous measurement of sO2 and HbT throughout the contraction cycle.Imaging was done on C57Bl/6J mice (F, 4–5 months of age) to measure baseline sO2 levels in the anterior and posterior myocardium. An MI was induced by ligation of the left anterior descending coronary artery. Mice were imaged at days 1, 7, and 14 after MI to measure changes in myocardial sO2. All data presented here are from diastole of the long axis orientation and similar results were obtained from short axis measurements. Oxygen saturation on the anterior myocardial wall decreased from 74.7% pre‐MI to 19.9% 1 day after MI (p<0.0001). Oxygen saturation showed recovery at 7 (54.9%, p=0.023) and 14 (49.9%, p=0.007) days post infarct, yet remained significantly reduced from pre‐MI levels. Oxygen saturation was lower on the posterior myocardium (57.2%) compared to the anterior myocardium but did not change following MI.Our results demonstrate oxygen saturation begins to recover 7 days after MI as the heart adapts to ligation and neoangiogenesis is stimulated. This study validates the use of PA EKV for the measurement of oxygen saturation in the infarcted myocardium.Support or Funding InformationWe acknowledge funding from National Institutes of Health under Award Numbers HL075360, HL129823, and HL137319, and from the Biomedical Laboratory Research and Development Service of the Veterans Affairs Office of Research and Development under Award Numbers 5I01BX000505. The UNMC Ultrasound Core is supported by an Institutional Development Award (IDeA) from the National Institute of General Medical Sciences of the National Institution of Health under grant P30 GM127200.