No abstract

Ambient concentrations of PM 10 were measured every fifteen minutes from November 2002 to October 2003 at Alsasua (Northern Spain) using a laser particle counter. A high volume sampler was also used to collect 24-h integrated PM 10 samples at a frequency of three running days per week (i.e. three consecutive PM 10 samples followed by five days without sampling) for gravimetric determination of PM 10 mass concentrations followed by chemical analysis of its chemical components. The annual mean PM 10 concentration obtained using the laser particle counter with gravimetric correction was 22.7 μg m −3 (365 days), while the mean for the gravimetric samples was 29.5 μg m −3 (134 days). A total of 94 integrated PM 10 samples were analyzed for 60 chemical species using a combination of inductively coupled plasma spectrometry (ICP) and ion chromatography (IC). The concentrations of the main PM 10 components were found to be generally in agreement with the values reported for other Spanish cities. Bilinear Positive Matrix Factorization (PMF2) was used to study the sources of PM 10 and its constituents. Six main sources of PM 10 were identified (average contribution to total PM 10 mass in parentheses): crustal material (35%), secondary sulfate (21%), secondary nitrate (14%), motor vehicles (12%), sea-salt aerosol (12%) and metallurgical industries (3%).

An ambient air quality study was undertaken in two cities (Pamplona and Alsasua) of the Province of Navarre in northern Spain from July 2001 to June 2004. The data were obtained from two urban monitoring sites. At both monitoring sites, ambient levels of ozone, NOx, and SO2 were measured. Simultaneously with levels of PM(10) measured at Alsasua (using a laser particle counter), PM(10) levels were also determined at Pamplona (using a beta attenuation monitor). Mean annual PM(10) concentrations in Pamplona and Alsasua reached 30 and 28 microg m(-3), respectively. These concentrations are typical for urban background sites in Northern Spain. By using meteorological information and back trajectories, it was found that the number of exceedances of the daily PM(10) limit as well as the PM(10) temporal variation was highly influenced by air masses from North Africa. Although North African transport was observed on only 9% of the days, it contributed the highest observed PM(10) levels. Transport from the Atlantic Ocean was observed on 68% of the days; transport from Europe on 13%; low transport and local influences on 7%; and transport from the Mediterranean region on 3% of the days. The mean O3 concentrations were 45 and 55 microg m(-3) in Pamplona and Alsasua, respectively, which were above the values reported for the main Spanish cities. The mean NO and NO2 levels were very similar in both sites (12 and 26 microg m(-3), respectively). Mean SO2 levels were 8 microg m(-3) in Pamplona and 5 microg m(-3) in Alsasua. Hourly levels of PM(10), NO and NO2 showed similar variations with the typically two coincident maximums during traffic rush hours demonstrating a major anthropogenic origin of PM(10), in spite of the sporadic dust outbreaks.