<p>An extensive investigation with parallel field andlaboratory exposures has been conducted to elucidateatmospheric corrosion and metal runoff processes on copper andzinc used for roofing applications. Detailed studies have beenperformed to disclose the effect of various parameters on therunoff rate including: surface inclination and orientation,natural patination (age), patina composition, rain duration andvolume, rain pH, and length of dry periods inbetween rainevents. Annual and average corrosion rates and runoff rateshave been determined consecutively during urban field exposuresin Stockholm on naturally patinated copper and zinc of varyingage and patina composition. The corrosion rate was found todecrease with time, amounting to 6.7 g Cu/(m2.y) and 5.0 gZn/(m2.y) after 48 weeks of exposure, whereas the runoff ratewas relatively constant with time on a yearly basis, being 1.3g/(m2.y) and 3.1 g/(m2.y) for copper and zinc, respectively.The annual runoff rate was found to be significantly lower thanthe corresponding corrosion rate for both copper and zinc.Somewhat higher runoff rates of copper were determined fromnaturally green-patinated copper (>40 years old, 2.0g/(m2.y)) compared to brown-patinated copper (1 year old). Themain reasons are specific environmental conditions combinedwith characteristics of the patina layer, which increase themagnitude of dissolved species flushed from the surface duringthe first flush volume of a rain event. No intrinsic effect ofpanel age on the runoff rate was seen for naturally patinatedzinc. However, differences in prevailing environmentalconditions during the initial exposure period and, hence,differences in formation rate and surface coverage of thecorrosion patina, resulted in variations in runoff rate. Thisinitial difference remained also during prolonged exposureperiods and was referred to as a memory effect.</p><p>Model roof investigations and laboratory studies showedsurface orientation and inclination to have a detrimentaleffect on the runoff rate with high runoff rates from surfacesof low inclination from horizon and surfaces exposed towardsthe wind direction.</p><p>Based on fieldexposures and literature data, a correlationwas established between the runoff rate and the prevailingSO2-concentration. The runoff rate increases with increasingSO2 level for exposure sites of similar annual precipitationquantities (500-1000 mm/y). A rain device, using artificialrain, was shown to successfully simulate outdoor rain events ofvarying intensity and pH and result in realistic runoff ratesof both copper and zinc. The device was used to monitor changesin metal concentration and quantity of runoff water duringindividual rain events. High metal concentrations are found inthe initial rain volume flushing the surface (first flush),which decreased to rather constant metal concentrations duringthe subsequent rain volume (steady-state). The magnitude offirst flush depends primarily on environmental conditions priorto a rain event and the characteristics of the corrosionpatina. The metal concentration in runoff water increases withrain acidity, decreases with rain intensity and increases withlength of the dry period preceding a rain event.</p><p>A comparison between instantaneous corrosion rates,monitored by electrochemical impedance spectroscopy using a2-electrode set-up, and runoff rates during a continuous rainevent was performed for naturally patinated copper panels.Corrosion rates were found to be approximately 10 (brownishpatina) and 25 times (greenish patina) lower than correspondinginstantaneous runoff rates.</p><p>A schematic description of the first flush and steady-stateregion of the runoff process was established. The magnitude ofthe concentration during first flush is primarily affected byprevailing environmental conditions prior to a rain event,while rain pH and intensity primarily affect the concentrationduring steady-state.</p><p><b>Key words:</b>atmospheric corrosion, corrosion rate, runoffrate, copper, zinc, field study, laboratory study, roof, firstflush, rain quantity, rain intensity, rain pH, dry and wetdeposition, corrosion and runoff process.</p>

Measurement of chemical composition of precipitation is important both to understand acidification of terrestrial and aquatic ecosystems and neutralization process in the atmosphere. Such data are scarce in the Mediterranean region. In this study, chemical composition of daily, wet-only, 387 number of rain water samples collected between 1991 and 1999 were investigated to determine levels, temporal variation and long-term trends in concentrations of major ions and trace elements between 1991 and 1999. Samples had already been collected and some of the analysis had been completed. The anions SO42-, NO3- and Cl- were analyzed by HPLC coupled with UV-VIS detector, NH4+ was analyzed by colorimetry and H+ ion was analyzed by pH meter. The major ions and trace metals were analyzed by using Atomic Absorption Spectrometry (AAS) and Graphite Furnace Atomic Absorption Spectrometry (GFAAS). In this study complete data set were generated by analyzing samples that had not been previously analyzed for major ions and trace elements with Inductively Coupled Plasma with Optical Emission Spectrometry (ICP-OES). Statistical tools were used to determine the distribution of the pollutants. The rain water data tends to be log-normally distributed since data show large variations due to meteorological conditions, physical and chemical transformations and air mass transport patterns. The median pH of the rain water was found to be 5.29, which indicates that the rain water is not strongly acidic. This case is not a result of lacking of acidic compounds but rather indicates extended neutralization process in rain water. Eastern Mediterranean atmosphere is under the influence of three general source types: (1) anthropogenic sources, which are located to the north and northwest of the basin brings low pH values to the region (SO42-, NO3- ions) / (2) a strong crustal source, which is dried and suspended local soil and air masses transported from North Africa transport which have high pH values (Ca2+, Al, Fe ions) and (3) a marine source, which is the Mediterranean Sea itself (Na+, Cl- ions). In the region, the main acid forming compounds are H2SO4 and HNO3 whereas / CaCO3 and NH3 are responsible for the neutralization process. To describe the level of pollutant concentrations and the factors that affect their variations in rain water / ion compositions, neutralization of acidity, short and long-term variability of ions and elements, their time trend analysis and wet deposition fluxes were investigated briefly. Positive matrix factorization (PMF) was used to determine components of ionic mass in the precipitation. In Antalya Station the rain water has five factors: free acidity factor, crustal factor, marine factor, NO3- factor and SO42- factor. Potential Source Contribution Function (PSCF) and trajectory statistics were used to determine source regions generating these components. NO3- has potential source regions of Western Mediterranean countries and North Africa, whereas SO42- has additional southeasterly trajectory components of Israel and south east of Turkey.

In the event of a radioactive release in an urban environment the consequent response mustbe swift and precise. As soon as first responders have correct information, they can make anaccurate risk assessment. However, if the position, release rate and time of the radioactiverelease is unknown it is hard to know how the pollutant will spread. This thesis aims to testa model which approximates these three unknowns using weather data (wind and rain) as wellas measurement data collected at sensors placed around an urban environment. An atmospheric dispersion model based on an existing Reynolds Averaged Navier-Stokes modelis set up in two geometries of different complexity to create forward mode synthetic depositiondata and adjoint mode concentration fields resulting from a fixed dry deposition velocity andscavenging effect for wet deposition. Variations of time- and space-dependent rainfall is simu-lated. The resulting data is used in an existing optimization model, where a parameter studyis conducted regarding regularization coefficients. This thesis shows that the optimization model accurately estimates position and its approximaterelease rate of a 2D geometry of radioactive releases using a logarithmic optimization approach,and fail to do so using a linear optimization approach. The logarithmic optimization model alsoapproximately estimates position and release rate in a 3D geometry. Regularization parametersshould be within the range of 0.1 and 1.2 depending on rain. More rain requires smallerparameters and will estimate a lower release rate. Time-dependent rainfall is shown to have amajor negative effect on simulation time.iii