Suchergebnisse

Since black carbon (BC) has become one of the most harmful pollutants and partly accelerated the melting of the Arctic sea ice, internationally mandatory policy to limit black carbon emissions in the whole Polar Code Area is on the agenda. To cope with this policy, some potential measures from both the coastal government and the shipowners, as well as the economic impacts of these measures, are considered in this paper. We analyze the daily navigation profits and the corresponding BC emissions after these measures are adopted. Since equipment-related cost is usually regarded as fixed and cannot be calculated on a daily basis, this paper also proposes an equipment investment payback period to access the time needed to achieve a balance between the investments and the profits of applying the equipment. A case of a dry bulk carrier navigating through the Northwest Passage is presented for concrete quantitative analysis. The results indicate that wind propulsion system can help shipowners mitigate the largest amount of BC emission. Wind-driven generators, which are used for auxiliary generating system, are the most economic-beneficial to shipowners under the current technology environment. Besides, we found that BC emission tax rate set by coastal governments plays an important role in the selection of different measures by shipowners. ; October 2021

This thesis presents research focusing on the improvement of high-resolution global black carbon (BC) emission inventory and application in assessing the population exposure to ambient BC. A particular focus of the thesis is on the construction of a high-resolution (both spatial and sectorial) fuel consumption database, which is used to develop the emission inventory of black carbon. Above all, the author updates the global emission inventory of black carbon, a resource subsequently used to study the atmospheric transport of black carbon over Asia with the help of a high-resolution nested model. The thesis demonstrates that spatial bias in fuel consumption and BC emissions can be reduced by means of the sub-national disaggregation approach. Using the inventory and nested model, ambient BC concentrations can be better validated against observations. Lastly, it provides a complete uncertainty analysis of global black carbon emissions, and this uncertainty is taken into account in the atmospheric modeling, helping to better understand the role of black carbon in regional and global air pollution

Abstract
The overall aim of our research is to study chimney sweeps exposure to soot to be able to give recommendations on how to effectively reduce the exposure. To do this a suitable method to study soot exposure is required. In this study we use a new method to study the personal airborne exposure to soot measured as black carbon (BC). BC is measured with a AethLabs MA200 micro aethalometer with a flow rate of 100 mL/min and sampling time of 1 min. By using a direct-reading instrument we aim to identify variability in exposure levels during the workday, and potential work tasks contributing to elevated exposure to soot. The study includes 20 chimney sweeps performing black sweeping in Sweden and BC is measured for eight workdays for each individual. During these days individuals also fill out a diary of work tasks performed. To assess the value of the BC levels, airborne polycyclic aromatic hydrocarbon (PAH) is also measured with personal sampler for particulate- and gas phase PAH. PAH is measured in parallel with BC during one workday. Preliminary results show variability of BC levels between different individuals as well as different workdays for the same individual. We are also able to link BC levels with work tasks from the diaries. Significantly elevated PAH levels and especially the particle-bound PAHs, including the carcinogenic benzo(a)pyrene, were observed in most samples.

This is the author accepted manuscript. The final version is available from Wiley via the DOI in this record ; Methane and black carbon aerosols have been identified as exerting the two strongest positive radiative forcings after carbon dioxide and therefore drastic reductions in these atmospheric constituents could potentially offer strong leverage in reducing global warming. Using the HadGEM2-ES model we reduce concentrations of methane and black carbon while holding all other emissions at representative concentration pathway RCP2.6 levels to examine whether we can achieve the target of keeping global-mean temperature rise below 1.5 oC relative to the pre-industrial level during the remainder of the 21st century. We find that even total cessation of black carbon aerosol emissions is ineffective in attaining this goal. Reducing methane concentrations at four times the rate assumed in RCP2.6 is able to return warming levels to below 1.5 oC by the 2070s but overshoots the target level prior to that. As RCP2.6 represents an optimistic scenario relative to the Intended Nationally Determined Contributions our results highlight the importance of deep and rapid reductions in both CO2 and methane emissions if humanity is serious about attaining the 1.5 oC target. ; This work was supported by the Joint UK BEIS/Defra Met Office Hadley Centre Climate Programme (GA01101). CDJ was also supported by the European Union's Horizon 2020 research and innovation programme under grant agreement No 641816

An accurate simulation of the absorption properties is key for assessing the radiative effects of aerosol on meteorology and climate. The representation of how chemical species are mixed inside the particles (the mixing state) is one of the major uncertainty factors in the assessment of these effects. Here we compare aerosol optical properties simulations over Europe and North America, coordinated in the framework of the third phase of the Air Quality Model Evaluation International Initiative (AQMEII), to 1 year of AERONET sunphotometer retrievals, in an attempt to identify a mixing state representation that better reproduces the observed single scattering albedo and its spectral variation. We use a single post-processing tool (FlexAOD) to derive aerosol optical properties from simulated aerosol speciation profiles, and focus on the absorption enhancement of black carbon when it is internally mixed with more scattering material, discarding from the analysis scenes dominated by dust. We found that the single scattering albedo at 440nm (omega(0,440)) is on average overestimated (underestimated) by 3-5% when external (core-shell internal) mixing of particles is assumed, a bias comparable in magnitude with the typical variability of the quantity. The (unphysical) homogeneous internal mixing assumption underestimates omega(0,440) by 14%. The combination of external and core-shell configurations (partial internal mixing), parameterized using a simplified function of air mass aging, reduces the omega(0,440) bias to-1/-3%. The black carbon absorption enhancement (E-abs) in core-shell with respect to the externally mixed state is in the range 1.8-2.5, which is above the currently most accepted upper limit of 1.5. The partial internal mixing reduces E-abs to values more consistent with this limit. However, the spectral dependence of the absorption is not well reproduced, and the absorption Angstrom exponent AAE(675)(440) is overestimated by 70-120%. Further testing against more comprehensive campaign data, including a ...

Abstract

Objectives
Daily driving of diesel-powered tractors has been linked to increased lung cancer risk in farmers, yet few studies have quantified exposure levels to diesel exhaust during tractor driving or during other farm activities. We expanded an earlier task-based descriptive investigation of factors associated with real-time exposure levels to black carbon (BC, a surrogate of diesel exhaust) in Iowa farmers by increasing the sample size, collecting repeated measurements, and applying statistical models adapted to continuous measurements.


Methods
The expanded study added 43 days of sampling, for a total of 63 sample days conducted in 2015 and 2016 on 31 Iowa farmers. Real-time, continuous monitoring (30-s intervals) of personal BC concentrations was performed using a MicroAeth AE51 microaethelometer affixed with a micro-cyclone. A field researcher recorded information on tasks, fuel type, farmer location, and proximity to burning biomass. We evaluated the influence of these variables on log-transformed BC concentrations using a linear mixed-effect model with random effects for farmer and day and a first-order autoregressive structure for within-day correlation.


Results
Proximity to diesel-powered equipment was observed for 42.5% of the overall sampling time and on 61 of the 63 sample days. Predicted geometric mean BC concentrations were highest during grain bin work, loading, and harvesting, and lower for soil preparation and planting. A 68% increase in BC concentrations was predicted for close proximity to a diesel-powered vehicle, relative to far proximity, while BC concentrations were 44% higher in diesel vehicles with open cabins compared with closed cabins. Task, farmer location, fuel type, and proximity to burning biomass explained 8% of within-day variance in BC concentrations, 2% of between-day variance, and no between-farmer variance.


Conclusion
Our findings showed that farmers worked frequently near diesel equipment and that BC concentrations varied between tasks and by fuel type, farmer location, and proximity to burning biomass. These results could support the development of exposure models applicable to investigations of health effects in farmers associated with exposure to diesel engine exhaust.