Abel Carvalho

Water-soluble hydroxylated organic compounds in German and Finnish aerosols

Total suspended particulate matter was collected in a German anthropogenically influenced agricultural area and in a Finnish forest. The occurrence of water-soluble compounds leftover by a traditional dichloromethane (DCM)-extraction technique was investigated using an additional water-extraction and analyzing the corresponding trimethylsilyl derivatives by GC-MS. The organic carbon content of the samples and extracts was also measured. The additional extraction with water recovered more than 20% of total organic carbon, which is comparable to the 31% extracted with DCM. The fraction of water-extractable organic carbon that eluted was <10%, but the employed GC-MS approach proved to be useful in the identification and quantification of polar water-soluble organics containing hydroxyl groups. Concentrations and size distributions of polyhydroxymono- and dicarboxylic acids, polyols, and sugars were obtained. The German meadow presented the highest levels of sugars and acidic compounds, whilst polyols were the most abundant class in the Finnish forest. The major compounds of these classes were malic acid, mannitol, arabitol, glucose and sucrose. Levoglucosan was also detected in the water-extract. Acidic compounds occurred mainly in fine particles. Polyols and most sugars presented size distributions with variable fine or coarse maximum. Possible primary and secondary sources of polyhydroxylated compounds are discussed.

Airborne chemical elements: correlation between atmospheric levels and lichen content

Concentrations of As, Cd, Co, Na, Sb, Se and Zn have been measured in atmospheric particulate matter and Parmelia sulcata Taylor transplants at a suburban and industrial area. Levels in particulate matter were found to be much lower than European target values, Californian Acute Inhalation Reference Exposure Levels and Ontarios Ambient Air Quality Criteria. Correlations between elemental content in lichens and particulate matter (PM2.5, PM2.5-10 and PM10) were investigated. For the majority of the studied elements, the best correlations were obtained by plotting data from a lichen exposure system, allowing free influx, against the sum of monthly averages from the first month of exposure till the month of collection. All the significant correlations found were positive, suggesting that element availability contributes to enhance accumulation. The existence of significant correlation is most likely to be proven if strong gradients of chemical elements content in lichen transplants are detected.

FRACTAL GEOMETRY OF WEIERSTRASS-TYPE FUNCTIONS

The aim of this paper is twofold. First, with reference to Refs. 1 and 2 we show maximal and minimal box and Hausdorff dimensions over all continuous real functions compactly supported on ℝn, with integrability 0 0. We estimate also the box dimensions of trigonometrical Weierstrass-type functions. Secondly, we investigate some criteria in order to decide when the graph of a function is not a d-set. Moreover, for each d between n and n + 1 we construct a function on [0,1]n the graph of which is a d-set.

Chemical characterisation of marine aerosol in the azores

Abstract Ground-level concentrations of particulate matter with less than 10μm in diameter were measured in Azores Archipelago, mid-North Atlantic Ocean. Three intensive research campaigns took place between April and August 99. Observed average concentrations were 3.28±2.16 μgm−3 for non-sea-salt sulphate, 0.98±0.72μgm−3 for nitrate and 0.57±0.44μgm−3 for ammonium. The average value for non-sea-sulphate is higher than levels previously reported for other North Atlantic sites. The higher variability in non-sea-salt sulphate data collected in Azores Region most likely reflects a contribution due to active submarine volcanoes near the collection site (10–20 miles). We tried to make the connection between mass ratio sulphate/chloride maximums and maximum volcanic activity using seismic data. Average ratio between organic carbon and black carbon concentrations is 4.1±1.9.