Decreasing Vanadium Footprint of Bunker Fuel Emissions

Sources of personal PM2.5 exposure during pregnancy in the MADRES cohort

BACKGROUND

Personal exposure to fine particulate matter (PM2.5) is impacted by different sources each with different chemical composition. Determining these sources is important for reducing personal exposure and its health risks especially during pregnancy.

OBJECTIVE

Identify main sources and their contributions to the personal PM2.5 exposure in 213 women in the 3rd trimester of pregnancy in Los Angeles, CA.

METHODS

We measured 48-hr integrated personal PM2.5 exposure and analyzed filters for PM2.5 mass, elemental composition, and optical carbon fractions. We used the EPA Positive Matrix Factorization (PMF) model to resolve and quantify the major sources of personal PM2.5 exposure. We then investigated bivariate relationships between sources, time-activity patterns, and environmental exposures in activity spaces and residential neighborhoods to further understand sources.

RESULTS

Mean personal PM2.5 mass concentration was 22.3 (SD = 16.6) μg/m3. Twenty-five species and PM2.5 mass were used in PMF with a final R2 of 0.48. We identified six sources (with major species in profiles and % contribution to PM2.5 mass) as follows: secondhand smoking (SHS) (brown carbon, environmental tobacco smoke; 65.3%), fuel oil (nickel, vanadium; 11.7%), crustal (aluminum, calcium, silicon; 11.5%), fresh sea salt (sodium, chlorine; 4.7%), aged sea salt (sodium, magnesium, sulfur; 4.3%), and traffic (black carbon, zinc; 2.6%). SHS was significantly greater in apartments compared to houses. Crustal source was correlated with more occupants in the household. Aged sea salt increased with temperature and outdoor ozone, while fresh sea salt was highest on days with westerly winds from the Pacific Ocean. Traffic was positively correlated with ambient NO2 and traffic-related NOx at residence. Overall, 76.8% of personal PM2.5 mass came from indoor or personal compared to outdoor sources.

IMPACT

We conducted source apportionment of personal PM2.5 samples in pregnancy in Los Angeles, CA. Among identified sources, secondhand smoking contributed the most to the personal exposure. In addition, traffic, crustal, fuel oil, fresh and aged sea salt sources were also identified as main sources. Traffic sources contained markers of combustion and non-exhaust wear emissions. Crustal source was correlated with more occupants in the household. Aged sea salt source increased with temperature and outdoor ozone and fresh sea salt source was highest on days with westerly winds from the Pacific Ocean.

Vanadium in the Environment: Biogeochemistry and Bioremediation

Vanadium(V) is a highly toxic multivalent, redox-sensitive element. It is widely distributed in the environment and employed in various industrial applications. Interactions between V and (micro)organisms have recently garnered considerable attention. This Review discusses the biogeochemical cycling of V and its corresponding bioremediation strategies. Anthropogenic activities have resulted in elevated environmental V concentrations compared to natural emissions. The global distributions of V in the atmosphere, soils, water bodies, and sediments are outlined here, with notable prevalence in Europe. Soluble V(V) predominantly exists in the environment and exhibits high mobility and chemical reactivity. The transport of V within environmental media and across food chains is also discussed. Microbially mediated V transformation is evaluated to shed light on the primary mechanisms underlying microbial V(V) reduction, namely electron transfer and enzymatic catalysis. Additionally, this Review highlights bioremediation strategies by exploring their geochemical influences and technical implementation methods. The identified knowledge gaps include the particulate speciation of V and its associated environmental behaviors as well as the biogeochemical processes of V in marine environments. Finally, challenges for future research are reported, including the screening of V hyperaccumulators and V(V)-reducing microbes and field tests for bioremediation approaches.

Long-Term Observation of Mixing States and Sources of Vanadium-Containing Single Particles from 2020 to 2021 in Guangzhou, China

The distribution of vanadium (V) in aerosols is commonly used to track ship exhaust emissions, yet the atmospheric abundance of V has been greatly reduced due to the implementation of a clean fuel policy. Recent research mainly discussed the chemical compositions of ship-related particles during specific events, yet few studies focus on the long-term changes of V in the atmosphere. In this study, a single-particle aerosol mass spectrometer was used to measure V-containing particles from 2020 to 2021 in Huangpu Port in Guangzhou, China. The long-term trend of the particle counts of V-containing particles declined annually, but the relative abundance of V-containing particles in the total single particles increased in summer due to the influence of ship emissions. Positive matrix factorization revealed that in June and July 2020, 35.7% of the V-containing particles were from ship emissions, followed by dust and industrial emissions. Furthermore, more than 80% of the V-containing particles were found mixing with sulfate and 60% of the V-containing particles were found mixing with nitrate, suggesting that the majority of the V-containing particles were secondary particles processed during the transport of ship emissions to urban areas. Compared with the small changes in the relative abundance of sulfate in the V-containing particles, the relative abundance of nitrate exhibited clear seasonal variations, with a high abundance in winter. This may have been due to the increased production of nitrate from high concentrations of precursors and a suitable chemical environment. For the first time, the long-term trends of V-containing particles in two years are investigated to demonstrate changes in their mixing states and sources after the clean fuel policy, and to suggest the cautious application of V as an indicator of ship emissions.

Dynamic Ni/V Ratio in the Ship-Emitted Particles Driven by Multiphase Fuel Oil Regulations in Coastal China

This study aims to investigate the effect of the stepwise marine fuel oil regulations on the concentrations of vanadium (V) and nickel (Ni) in ambient air based on a 4-y (2017-2020) online measurement in Shanghai, a coastal city in China. The annual concentration of V was reduced by 58% due to the switch from Domestic Emission Control Area (DECA) 1.0 to DECA 2.0 and further by 74% after the implementation of the International Maritime Organization (IMO) 2020 regulation, while the reduction rate for Ni was only 27% and then 18% respectively. Consistently, a reduction of 84% in V content and a negligible change in Ni content were measured in 180cst ship oil samples from 2010 to 2020. The similar increasing trend of Ni/V ratios (from <0.4 to >2.0) in both ambient measurement and heavy fuel oil samples suggests that the DECA and IMO 2020 regulations effectively reduced the ambient V. However, nickel content is still enriched in the in-use desulfurized residual oils and ship-emitted particles in coastal China. Meanwhile, the previous ratio between V and Ni cannot be used as a tracer for identifying ship-emitted particles due to its large variation in oils. Further updating of the source profile of ship traffic emissions in coastal cities is necessary in the future.

Atmospheric Vanadium Emission Inventory from Both Anthropogenic and Natural Sources in China

Vanadium is a strategically important metal in the world, although sustained exposure under high vanadium levels may lead to notable adverse impact on health. Here, we leverage a bottom-up approach to quantitatively evaluate vanadium emissions from both anthropogenic and natural sources during 1949-2017 in China for the first time. The results show that vanadium emissions increased by 86% from 1949 to 2005 to a historical peak value and then gradually decreased to 12.9 kt in 2017. With the effective implementation of air pollution control measures, vanadium emissions from anthropogenic sources decreased sharply after 2011. During 2011-2017, about half of vanadium emissions came from coal and oil combustion. In addition, industrial processes and natural sources also cannot be ignored, with the total contributions of more than 24%. The high levels of vanadium emissions were mainly distributed throughout the North China Plain and the eastern and coastal regions, especially in several urban agglomerations. Furthermore, the comprehensive evaluation by incorporating contrastive analysis, Monte Carlo approach, and GEOS-Chem simulation shows that vanadium emissions estimated in this study were reasonable and acceptable. The findings of our study provide not only a scientific foundation for investigating the health effects of vanadium but also useful information for formulating mitigation strategies.

Source apportionment of PM2.5 at two Seattle chemical speciation sites

Positive Matrix Factorization analysis of PM_2.5 chemical speciation data collected from 2015-2017 at Washington State Department of Ecology's urban NCore (Beacon Hill) and near-road (10th and Weller) sites found similar PM_2.5 sources at both sites. Identified factors were associated with gasoline exhaust, diesel exhaust, aged and fresh sea salt, crustal, nitrate-rich, sulfur-rich, unidentified urban, zinc-rich, residual fuel oil, and wood smoke. Factors associated with vehicle emissions were the highest contributing sources at both sites. Gasoline exhaust emissions comprised 26% and 21% of identified sources at Beacon Hill and 10th and Weller, respectively. Diesel exhaust emissions comprised 29% of identified sources at 10th and Weller but only 3% of identified sources at Beacon Hill. Correlation of the diesel exhaust factor with measured concentrations of black carbon and nitrogen oxides at 10th and Weller suggests a method to predict PM_2.5 from diesel exhaust without a full chemical speciation analysis. While most PM_2.5 sources exhibit minimal change over time, primary PM_2.5 from gasoline emissions is increasing on average 0.18 µg m^-3 per year in Seattle.

IMPLICATIONS

This study utilizes Positive Matrix Factorization to determine PM_2.5 sources from chemical speciation measurements at two urban Seattle sites from 2015-2017. The paper reports PM_2.5 source trends, and extends previous source apportionment analyses in Seattle to the present day. The study also quantifies diesel PM_2.5 at a near-road site, and describes a predictive model that allows estimation of the contribution of diesel PM_2.5 to the total measured PM_2.5 at near-road sites across the country without a full chemical speciation analysis.