Urban Coastal Site Research Articles

Surface ozone measurements at urban coastal site Chennai, in India

The present study was carried out to gain knowledge of current surface ozone concentrations and the effects of meteorological parameters in the highly populated urban area of Chennai, in South India. We have reported measurement results of surface ozone (O 3) and meteorological parameters from 17th March to 10th October 2005. A photometric ozone analyzer continuously recorded the ozone concentrations at this site. The present study deals with the statistical characteristics of daily and monthly mean ozone levels under different meteorological conditions. The highest ozone concentrations were recorded in ESE-SE sectors. The monthly mean concentrations were higher in May (23 ± 14 ppb) and lower in April at this site (10 ± 8 ppb). The maximum hourly ozone concentration reached 69 ppb on 21st April.

Spatial and temporal variability of PM levels and composition in a complex summer atmospheric scenario in Barcelona (NE Spain)

Summer atmospheric coastal dynamics exert a significant influence on the levels and composition ofatmospheric particulate matter (PM) in the North-Eastern Iberian Peninsula. Summer atmospheric scenarios in this region present a high degree ofcomplexity as they are characterised by the absence ofsynoptic-scale air mass advections, the development ofbreeze circulations, enhanced photochemistry, local mineral dust re-suspension and the occurrence of African dust outbreaks. Three sampling sites were selected in Barcelona (NE Spain), an urban coastal site surrounded by complex topography. Regional dust modelling (DREAM) and high resolution meteorological modelling (MM5) were used to interpret PM levels and composition at the three sites. The results outline the effect of breeze dynamics and thermal internal boundary layer f ormation as the main meteorological drivers ofthe hourly evolution ofPM levels. Levels ofcrustal components, secondary inorganic and carbon species are higher during the night, and only the marine aerosol content is higher during the day. Nitrate levels are higher during the night due to the thermal stability on NH4NO3. Sulphate levels are higher during the night as a consequence ofthe drainage flows. Lidar measurements and model results signalled the occurrence of two African dust episodes during the study period which mainly affected the free troposphere over Barcelona. r 2005 Elsevier Ltd. All rights reserved.

Aerosol size distributions and air mass back trajectories over a Mediterranean coastal site

In this paper we present the results obtained from ground-based measurements using a CIMEL sunphotometer during selected clear days corresponding to the winter and summer periods of 2002 in Valencia, an urban coastal Mediterranean site. From the direct solar extinction data the spectral aerosol optical depth (AOD) has been retrieved. This spectral AOD has been used to obtain the size distribution function from the King inversion algorithm. The results show the great dependence of the optical aerosol characteristics on the dominant winds in this area. This location is subject to winds which have either a land or Mediterranean origin which frequently mask the aerosols coming from the Atlantic or north Africa, respectively.

Contrasting weathering rates in coastal, urban and rural areas in southern Britain: preliminary investigations using gravestones

Weathering rates were calculated using the height differences between lead lettering on marble gravestones from inland urban, inland rural, coastal urban and coastal rural sites within southern Britain. All sites exhibit similar amounts and variations in rainfall over the study period for which gravestone measurements are available. Comparison of mean weathering rates suggested that the coastal urban site of Clacton had a similar weathering rate to the nearby coastal rural site. The other urban sites of Oxford, Lodge Hill and Portsmouth had similar weathering rates, despite their diverse locations and histories. The inland rural site had a significantly lower mean weathering rate than any other site. Analysis of covariance confirms that there are similarities between some sites. Linear and curvilinear regression of depth of loss against age suggests that a linear regression adequately describes the relationship over the period for which data are available, although there are problems with this simple interpretation. Copyright © 2000 John Wiley & Sons, Ltd.

Comparison between fungal airspore concentration at two different sites in the South of Sardinia

Abstract The occurrence of airborne fungi at an urban coastal site was compared with that at a rural inland site in the South of Sardinia. Spore concentrations at the two sites differed markedly with lower concentrations at the urban site but the spore types found were similar. The general trend of the fungal airspores was also very similar at both sites as a result of the similar climatic conditions. Mould spore concentrations were greatest in late spring (May-June) and autumn (October-November) with a decrease during summer months at both sites sampled. Cladosporium was the most common spore type identified followed by Basidiomycetes, Alternaria, Fusarium. These taxa are well known as allergens. It is recommended that further aeromycological surveys should be performed in different areas to determine the clinical importance of fungi as allergens in Sardinia.

On the nature of nitrate particles in a coastal urban area

Application of micro spot and electron microscopy techniques to individual particles in a coastal urban site revealed the following: 1. (a) sulfate particles, some of them mixed, dominated the sub-μm (0.3–0.8 μm) size range; 2. (b) nitrates were found mostly in the μm size range, in the form of NaNO 3. The latter was verified by X-ray analysis of individual nitrates. Apparently the NaNO 3 particles were formed through heterogeneous reaction of gaseous HNO 3 with sea salt particles.