Atmospheric soot particle transformation from urban to rural

Abstract

The main objective of this work was to investigate if there is a contribution of aerosol from the urban region of Copenhagen at the rural station Vavihill. This was done by analyzing measurement data between 1st of January and the 28th
of February 2013 measured with a Dierential Mobility Particle Sizer (DMPS), Soot Particle Aerosol Mass Spectrometer (SP-AMS), a Cloud Condensation Nuclei Counter (CCNC) and a NOx-analyzer. To determine if the air masses passed over Copenhagen or not, the Hybrid Single-Particle Lagrangian Integrated Trajectory
4 (HYSPLIT4) was used to model air mass origin with six-hour intervals. The data consisted of measurements of particle number concentration, refractory black carbon (rBC) mass concentration, cloud condensation nuclei (CCN) concentration
and NOx concentration. The measurements showed a noticeable dierence with higher concentration (rBC: 33 %, CCN: 30-42 %, NOx: 58 %) and a larger number concentration of particles (36%) for the air masses passing over Copenhagen. The analyzed time series were too short to nd statically signicant contributions from Copenhagen to the aerosol composition in Vavihill. To determine if there really is a signicant contribution of aerosol from the urban region of Copenhagen at the rural
background station Vavihill, further investigations should be made.

Popular Abstract

In the air that surrounds us there are constantly millions of particles swirling around. These particles come from a large variety of sources, from flowers as pollen, from the sea as waterdrops, from fires as black carbon particles and many more. The source which the particle comes from has a large impact on how they are compounded and the way that they affect their surroundings. In cities, exhausts are a very common particle source since vehicles power by both gasoline and diesel release massive amounts of exhaust containing a mixture of gases and particles.
In todays´ society the human impact on the environment is a widely discussed topic and it is important for us to get an idea of how big of an impact we actually have. To find this out there are different tests and measurements that can be done. One way is to measure the amount of soot particles in the air. This is a good and widely used way to see how much the traffic effects the environment since a large portion of the soot particles come from exhaust.
Soot particles play a major part in climate change in the way they absorb energy from the sun when its rays hit the particles. Black carbon, which is the main component of soot, is the substance that can absorb the most energy from the sun out of all substances that can be found as particles in the atmosphere. Black carbon can absorb one million times more energy than, the much more discussed, carbon dioxide.
Soot particles affect not only the air around us but also the ground. When the particles have been suspended in the air for a while they form rain clouds and falls to the ground like rain or snow. The ground then becomes darkened which reduces its ability to reflect the ray of energy from the sun, this phenomenon especially affects the area that are covered by ice and snow, like glaciers. This process increases the warming of the snow and intensifies the melting. When the snow melts and then refreeze and melts and refreeze again, the meltwater sticks grains of snow together. When the snowflakes grow larger, more sunlight is absorbed and the melting increases which results in more darkened land being exposed.
By making measurements of air coming from cities with a lot of traffic and comparing to air from the countryside, it is possible to see how much particles we release into the air. The larger difference between cities and countryside there is in number of particle, the greater the impact humans have on the climate.
Due to the short life of soot particles, it has been suggested that focus on reducing emissions of soot particles, instead of carbon dioxide having a much longer life, can be a "quick fix" to reduce atmospheric heating.
The tricky aspect of developing strategies to reduce carbon emissions is that when things burns, they generate not only black carbon but also pollutants such as sulfur dioxide and nitrogen dioxide that have cooling effects. Knowing the relative amounts of these pollutants in each source is the key. Diesel engines produce, for example, most black carbon, as well as coal combustion, but other processes like fires and open biomass burn not only give black carbon but also provide organic carbon. The organic hydrocarbons create a fog that cools the atmosphere which makes sources that emit black carbon the best targets for action.
To target these pollutions, a large number of countries, including China, Germany, Britain and others, have started to work on a plan to ban vehicles powered by fossil fuels. This makes the research about soot particle a very relevant topic for the car industry, energy producers and investors

• author: Johansson, Fredrik
• supervisor: Pontus Roldin; Joakim Pagels
• organization: Nuclear physics; Department of Physics
• course: FYSK02 20181
• year: 2018
• type: M2 - Bachelor Degree
• subject: Physics and Astronomy; Earth and Environmental Sciences
• keywords: Aerosol, soot, atmosphere
• language: English
• id: 8954909
• date added to LUP: 2018-07-12 20:36:55
• date last changed: 2018-07-12 20:36:55