Kent Salo

Aging of biogenic secondary organic aerosol via gas-phase OH radical reactions

The Multiple Chamber Aerosol Chemical Aging Study (MUCHACHAS) tested the hypothesis that hydroxyl radical (OH) aging significantly increases the concentration of first-generation biogenic secondary organic aerosol (SOA). OH is the dominant atmospheric oxidant, and MUCHACHAS employed environmental chambers of very different designs, using multiple OH sources to explore a range of chemical conditions and potential sources of systematic error. We isolated the effect of OH aging, confirming our hypothesis while observing corresponding changes in SOA properties. The mass increases are consistent with an existing gap between global SOA sources and those predicted in models, and can be described by a mechanism suitable for implementation in those models.

Saturation Vapor Pressures and Transition Enthalpies of Low-Volatility Organic Molecules of Atmospheric Relevance: From Dicarboxylic Acids to Complex Mixtures

There are a number of techniques that can be used that differ in terms of whether they fundamentally probe the equilibrium and the temperature range over which they can be applied. The series of homologous, straight-chain dicarboxylic acids have received much attention over the past decade given their atmospheric relevance, commercial availability, and low saturation vapor pressures, thus making them ideal test compounds. Uncertainties in the solid-state saturation vapor pressures obtained from individual methodologies are typically on the order of 50-100%, but the differences between saturation vapor pressures obtained with different methods are approximately 1-4 orders of magnitude, with the spread tending to increase as the saturation vapor pressure decreases. Some of the dicarboxylic acids can exist with multiple solid-state structures that have distinct saturation vapor pressures. Furthermore, the samples on which measurements are performed may actually exist as amorphous subcooled liquids rather than solid crystalline compounds, again with consequences for the measured saturation vapor pressures, since the subcooled liquid phase will have a higher saturation vapor pressure than the crystalline solid phase. Compounds with equilibrium vapor pressures in this range will exhibit the greatest sensitivities in terms of their gas to particle partitioning to uncertainties in their saturation vapor pressures, with consequent impacts on the ability of explicit and semiexplicit chemical models to simulate secondary organic aerosol formation.

Thermal characterization of aminium nitrate nanoparticles.

Amines are widely used and originate from both anthropogenic and natural sources. Recently, there is, in addition, a raised concern about emissions of small amines formed as degradation products of the more complex amines used in CO(2) capture and storage systems. Amines are bases and can readily contribute to aerosol mass and number concentration via acid-base reactions but are also subject to gas phase oxidation forming secondary organic aerosols. To provide more insight into the atmospheric fate of the amines, this paper addresses the volatility properties of aminium nitrates suggested to be produced in the atmosphere from acid-base reactions of amines with nitric acid. The enthalpy of vaporization has been determined for the aminium nitrates of mono-, di-, trimethylamine, ethylamine, and monoethanolamine. The enthalpy of vaporization was determined from volatility measurements of laboratory generated aerosol nanoparticles using a volatility tandem differential mobility analyzer set up. The determined enthalpy of vaporization for aminium nitrates range from 54 up to 74 kJ mol(-1), and the calculated vapor pressures at 298 K are around 10(-4) Pa. These values indicate that aminium nitrates can take part in gas-to-particle partitioning at ambient conditions and have the potential to nucleate under high NO(x) conditions, e.g., in combustion plumes.

Particle- and Gaseous Emissions from an LNG Powered Ship

Measurements of particle number and mass concentrations and number size distribution of particles from a ship running on liquefied natural gas (LNG) were made on-board a ship with dual-fuel engines installed. Today there is a large interest in LNG as a marine fuel, as a means to comply with sulfur and NOX regulations. Particles were studied in a wide size range together with measurements of other exhaust gases under different engine loads and different mixtures of LNG and marine gas oil. Results from these measurements show that emissions of particles, NOX, and CO2 are considerably lower for LNG compared to present marine fuel oils. Emitted particles were mainly of volatile character and mainly had diameters below 50 nm. Number size distribution for LNG showed a distinct peak at 9-10 nm and a part of a peak at diameter 6 nm and below. Emissions of total hydrocarbons and carbon monoxide are higher for LNG compared to present marine fuel oils, which points to the importance of considering the methane slip from combustion of LNG.

Influence of Ozone and Radical Chemistry on Limonene Organic Aerosol Production and Thermal Characteristics

Limonene has a strong tendency to form secondary organic aerosol (SOA) in the atmosphere and in indoor environments. Initial oxidation occurs mainly via ozone or OH radical chemistry. We studied the effect of O(3) concentrations with or without a OH radical scavenger (2-butanol) on the SOA mass and thermal characteristics using the Gothenburg Flow Reactor for Oxidation Studies at Low Temperatures and a volatility tandem differential mobility analyzer. The SOA mass using 15 ppb limonene was strongly dependent on O(3) concentrations and the presence of a scavenger. The SOA volatility in the presence of a scavenger decreased with increasing levels of O(3), whereas without a scavenger, there was no significant change. A chemical kinetic model was developed to simulate the observations using vapor pressure estimates for compounds that potentially contributed to SOA. The model showed that the product distribution was affected by changes in both OH and ozone concentrations, which partly explained the observed changes in volatility, but was strongly dependent on accurate vapor pressure estimation methods. The model-experiment comparison indicated a need to consider organic peroxides as important SOA constituents. The experimental findings could be explained by secondary condensed-phase ozone chemistry, which competes with OH radicals for the oxidation of primary unsaturated products.

Measurements of abatement of particles and exhaust gases in a marine gas scrubber

Measurements of exhaust gases from a marine engine equipped with an open-loop wet scrubber using seawater for sulphur dioxide (SO2) abatement are reported. The scrubber reduces the SO2 emissions effectively to levels corresponding to <0.1% S in the fuel (the level that applies to sulphur emission control areas from 2015). The scrubber also reduces the emissions of particulate matter by mass by 75%. The impact on the number of particles is studied for the total particle number and the solid fraction. The total number of particles is reduced by about 92% and the solid fraction by 48% in the scrubber indicating most effective abatement of volatile particles. Also, the content of polycyclic aromatic compounds in the exhaust is significantly reduced by the scrubber. The captured SO2 gives a low pH and high sulphate content in the scrubber water. The reduction in particulate matter is of the same order as what is obtained with a fuel switch from heavy fuel oil to marine gas oil.

catena-Poly[[(3-acetyl­pyridine)copper(I)]-μ3-chloro]

In the search for ketone complexes suitable for absolute asymmetric synthesis, that is, complexes crystallizing in Sohncke space groups, we have studied complexes between copper( I) halides and acetylpyridines. The structure of polymeric [CuCl(3-acpy)](n) (3-acpy is 3-acetylpyridine, C7H7NO), a compound which was found to form achiral chains crystallizing in a centrosymmetric space group, is reported here. The complex forms ladder-type chains, in which the Cu-I atom is coordinated by one N atom and three Cl atoms in a tetrahedral geometry. In the crystal structure, the chains are interconnected through C - H....Cl and C - H.....O intermolecular contacts.

The Natural Environment and Human Impacts

To comprehend the implications of the various environmental issues that man is inducing on the Earth (with a focus on the shipping industry), an understanding of the Earths major systems is necessary. The natural environment, which consists of air, water, land and living organisms, is a dynamic system in which material and energy are exchanged within and between the individual components. The system is divided into four spheres (atmosphere, hydrosphere, geosphere, and biosphere), and fluxes of energy and material are exchanged amongst these spheres. The spheres also largely govern the fate of various environmental problems originating from the shipping industry. Therefore, background information related to these spheres is provided, and their major properties and implications are explained. Regarding the atmosphere, radiation and energy budgets are explained in conjunction with the weather and climate. Concerning the hydrosphere, oceanography is introduced together with marine ecology. Addressing the geosphere, the elements in the Earths crust and mineral commodities are discussed. Regarding the biosphere, energy is transferred through food chains; the differences between life in water and life on land are examined. Energy flows through and is stored in these spheres; this stored energy is essential to the natural environment and human society. The different primary energy sources are described and divided into non-renewable and renewable sources. Finally, an introduction to human impacts on the natural environment and to major environmental issues is provided.

Emissions to the Air

Seeing the black smoke coming out of the funnel of a manoeuvring ship makes it easy to understand that the ship’s propulsion contributes to the emission of air pollutants. However, there is more than meets the eye going up in smoke. A vast majority of ships use fossil fuels, increasing a positive net contribution of carbon dioxide to the atmosphere when they are combusted. Because the fuels that are used are often of low quality and possess a high sulphur content, a number of other air pollutants are also emitted. Emissions to the air from ships include greenhouse gases (such as carbon dioxide, methane and nitrous oxide), sulphur and nitrogen oxides, with both acidifying and eutrophication effects, and different forms of particles, with impacts on health and climate. However, not all emissions to the atmosphere from ships originate from the combustion of fuels for propulsion and energy production. The handling of crude oil as cargo and compounds used in refrigeration systems cause emissions of volatile organic compounds and ozone-depleting substances. The sources of the most important emissions and relevant regulations are described in this chapter.

Measures to Reduce Discharges and Emissions

Discharges and emissions from shipping can be reduced through different technical measures, many of which apply similar principles, e.g., filtration or absorption. Ballast water treatment systems can be used to limit the spread of invasive species. Selective catalytic reduction units and exhaust gas recirculation can be used to reduce nitrogen oxide emissions, and scrubbers and diesel particulate filters can be used to reduce sulphur dioxide and particle emissions . The restoration or remediation of natural environments may also be required after large oil spills. Possible remediation methods include booms, mechanical techniques and dispersant chemicals. These and several additional technical measures to reduce discharges and emissions are described in this chapter, including measures to reduce the impact of the infrastructure related to the shipping industry.