The stability of railway embankment is essential for safe transport. In order to ensure safe transport, water should be allowed to freely drain. Furthermore, as the engine driver has to be able to see signs, and people working on the embankment are supposed to easily see flaws on the rails to ensure safety for the passing trains, plants should not be allowed to grow on the embankment. In Sweden there are 12 000 kilometers of railway tracks and 25–30 % of them are treated for weed control every year. The Swedish Transport Administration is currently using the pesticide “Roundup Bio” to remove weeds on the embankment. To prevent the dispersal of chemicals to sensitive ecosystems, chemical transport has to be investigated carefully. In this master thesis a transport model for the transport of pesticides has been simulated using the software “GoldSim”. The model have been developed, optimized and controlled by a sensitivity analysis. In addition to this an analysis of worst case scenarios has been tested. The pesticides “Arsenal 250” with the active substance imazapyr and “Roundup Bio” with the active substance glyphosate have been used in the calibrating of the model. The transport model for imazapyr shows a good estimation of the mass of herbicides in the embankment compared to measurements. There is also a good estimation in the groundwater even if the concentration at the beginning of the simulation period is underestimated. The simulation with glyphosate, on the on the other hand, showed very small quantities of both glyphosate and its degradation product AMPA (aminometylphosphateacid) in both the embankment and in the groundwater. The sensitivity test showed that the parameter half-life and Kd-value (adsorption capacity) were the most sensitive parameters in the model. When it comes to the concentration in the groundwater the distance to the groundwater level was the most sensitive parameter, as well as the Kd-value in the embankment, the half-life and the precipitation. As expected, the worst-case analysis showed that a small distance to the groundwater level, a low Kd-value and a short half-life produced even larger concentrations of herbicides in the groundwater. In conclusion it should be mentioned that the stimulation model generally works well in regards to with imazapyr. For stimulation of glyphosate and its metabolite AMPA more work with the model is required for the Swedish Transport Administration to apply it in the future.
| Identifer | oai:union.ndltd.org:UPSALLA1/oai:DiVA.org:uu-179988 |
| Date | January 2012 |
| Creators | Peters, Erica |
| Publisher | Uppsala universitet, Luft-, vatten och landskapslära |
| Source Sets | DiVA Archive at Upsalla University |
| Language | Swedish |
| Detected Language | English |
| Type | Student thesis, info:eu-repo/semantics/bachelorThesis, text |
| Format | application/pdf |
| Rights | info:eu-repo/semantics/openAccess |
| Relation | UPTEC W, 1401-5765 ; 12014 |
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