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Peter Brimblecombe

Publications and source records attributed to Peter Brimblecombe.

7 recordsLinked to original sources
PubMed2005

Aesthetic thresholds and blackening of stone buildings.

This work investigates public perception of the blackening of light coloured stone historic buildings in some European countries. It used on-site questionnaires to explore the perceived lightness of the façades in terms of opinions that the building is dirty or needs cleaning. There was a clear relation between opinions about the dirtiness of a building and views that it should be cleaned. Visitors to buildings found the assignment of colour or a grey scale value to buildings relatively easy despite the fact that they are typically made up of many shades. There was a strong relationship between the perceived lightness of a building and the opinion that it was dirty. This relationship was used to establish potential levels of blackening that may be publicly acceptable and propose some aesthetic thresholds. Such thresholds suggest approaches to setting limit values for elemental carbon in the air, such that significant buildings do not become unacceptably discoloured. Developments of this kind contribute to the regulation of non health aspects of air pollution and aid decision making in the management of significant buildings.

Air Pollution↗
PubMed2004

Surfactants in atmospheric aerosols.

The concentration and characteristics of anionic and cationic aerosol surfactants at a range of locations were determined as methylene blue active substances (MBAS) and ethyl violet active substances (EVAS) for anionic surfactants and as disulfine blue active substances (DBAS) for the cationic surfactants. Results showed that the anionic surfactants (in the pmol m(-3) range) dominated the concentration of surfactant in atmospheric aerosols. The concentration of both MBAS and EVAS is typically higher on the finer aerosol fractions. Further study on the aerosols found both MBAS and EVAS had the ability to reduce the surface tension of aqueous extracts of the aerosol. MBAS were more readily destroyed on exposure to a high intensity of UV light than were EVAS. The source of these seemingly ubiquitous compounds is not clear, but we note that anionic surfactants are easily derived from degraded or oxidized soots, especially that from diesel engines.

Aerosols↗
PubMed2004

Aesthetics of simulated soiling patterns on architecture.

Two desk-top exercises investigated public acceptability of idealized soiling patterns on buildings, using methodologies typical of the psychology of art. The exercises used a range of simulated soiling patterns around a simple architectural element, a pedimented window. In the first experiment respondents were asked to arrange the images from the "most acceptable" pattern to the "least acceptable". Results hinted at the importance of certain soiling features in driving the ranking. The second exercise explored the characteristics of soiling patterns that most affected their acceptability. In this experiment the images were organized in pairs. People were requested to choose the pattern they found more acceptable in each pair. Uniform patterns and those which created shadowing effects proved more acceptable. Patterns with non-integer fractal dimension that obscured architectural forms were less acceptable. There was usually a preference for images showing less soiling, whereas vertical features and lumpiness were not as acceptable. Results gave an insight into spatial factors that might influence the acceptability of soiling on real buildings. Thus suggesting it is necessary to consider both the level and the distribution of soiling when trying to gauge public reaction.

Architecture↗
PubMed2004

Photodegradation of haloacetic acids in water.

The global distribution and high stability of some haloacetic acids (HAAs) has prompted concern that they will tend to accumulate in surface waters and pose threats to humans and the ecosystem. It is important to study the degradation pathways of HAAs in aqueous systems to understand their ecotoxicological effects. Previous studies involving thermal degradation reactions show relatively long lifetimes for HAAs in the natural environment. Photolysis and photocatalytic dissociation are potentially efficient routes for the degradation of HAAs such as trichloroacetic acid to hydrochloric acid, carbon dioxide and chloroform, although such processes are poorly understood in surface waters. In our present study, we have used light to degrade the HAAs in the presence of titanium dioxide suspensions. All chloro and bromo HAAs degrade in photocatalysis experiments and the rate of degradation is directly proportional to the number of halogen atoms in the acid molecule. The half-lives of the HAAs from the photodegradation at 15 degrees C in the presence of suspended titanium dioxide photocatalyst are 8, 14, 83 days for the tri-, di- and mono-bromoacetic acids. Tri-, di- and mono-chloroacectic acids have half-lives of 6, 10 and 42 days respectively. The mixed bromochloro and chlorodifluoroacetic acids degrade with half-lives of 18 and 42 days respectively. Our results therefore suggest that the photocatalytic process can provide an additional degradation pathway for the HAAs in natural waters.

Acetates↗
PubMed2002

Ionic surface active compounds in atmospheric aerosols.

Surfactants in the atmosphere have several potential roles in atmospheric chemistry. They can form films on aqueous surfaces, which lowers the surface tension and possibly delays water evaporation and gaseous transportation across the aqueous interface. They can also increase the solubility of organic compounds in the aqueous phase. Recently, the decrease of surface tension in cloud growing droplets has been suggested as relevant to increases in the number of droplets of smaller size, potentially enhancing cloud albedo. Natural surfactants in the lung aid gas transfer and influence the dissolution rate of aerosol particles, so surfactants in atmospheric aerosols, once inhaled, may interact with pulmonary surfactants. Ambient aerosols were collected from the edge of Norwich, a small city in a largely agricultural region of England, and analysed for surfactants. Methylene blue, a conventional dye for detecting anionic surfactants, has been used as a colorimetric agent. The concentration of surfactants expressed as methylene blue active substances (MBAS) is in the range of 6-170 pmol m(-3)(air). A negative correlation with chloride aerosol indicates that these surfactants are probably not the well-known surfactants derived from marine spray. A more positive correlation with aerosol nitrate and gaseous NOx supports an association with more polluted inland air masses. The surfactants found in aerosols seem to be relatively strong acids, compared with weaker acids such as the long-chain carboxylic acids previously proposed as atmospheric surfactants. Surfactants from the oxidation of organic materials (perhaps vegetation- or soil-derived) seem a likely source of these substances in the atmosphere.

Acids↗
PubMed2002

Potential trace metal-organic complexation in the atmosphere.

It is possible that metal-organic complexation enhances the uptake of gaseous organic compounds and the solubility of metals in aerosols and atmospheric water. We investigated potential atmospheric organic ligands and the enhanced uptake of hydroxy-, oxo-, and dicarboxylic acids as well as dicarbonyls into atmospheric aqueous aerosol. We examined complexation with transition metals (iron, manganese, nickel, copper, zinc) and lead on the basis of available references and our experimental data. Humic-like substances are most likely ligands in the atmosphere, although this is a poorly characterized material. A number of polycarboxylic acids and hydroxy forms (e.g., citric and tartronic acids) effectively complex metals such as copper in atmospheric aerosols. The simple equilibrium model calculations show that the effect of the complexation on the gas-aqueous phase partition of gaseous atmospheric ligands is quite small for the ligands with the high physical Henry's law constants, e.g., dicarboxylic acids represented by oxalic acid, even if they have high affinity with metal ions. The lower Henry's law constants of the alpha-dicarbonyls, such as glyoxal and methylglyoxal, mean that the complexation could lead to profound increases in their partition into the aqueous phase. Despite quantum mechanical arguments for copper-glyoxal complexes, experiments showed no evidence of complexation between either hydrated or unhydrated alpha-dicarbonyls and the cupric ion. By contrast the beta-dicarbonyl, malondialdehyde, has properties that would allow it to partition into atmospheric water via the complexation with metal ions under some conditions.

Aerosols↗