Abstract
Abstract. Using an unprecedentedly large geochemical database, we compare temporal and spatial variations in inhalable trace metal background concentrations in a major city (Barcelona, Spain) and at a nearby mountainous site (Montseny) affected by the urban plume. Both sites are contaminated by technogenic metals, with V, Pb, Cu, Zn, Mn, Sn, Bi, Sb and Cd all showing upper continental crust (UCC) normalised values >1 in broadly increasing order. The highest metal concentrations usually occur during winter at Barcelona and summer in Montseny. This seasonal difference was especially marked at the remote mountain site in several elements such as Ti and Rare Earth Elements, which recorded campaign maxima, exceeding PM10 concentrations seen in Barcelona. The most common metals were Zn, Ti, Cu, Mn, Pb and V. Both V and Ni show highest concentrations in summer, and preferentially fractionate into the finest PM sizes (PM1/PM10 > 0.5) especially in Barcelona, this being attributed to regionally dispersed contamination from fuel oil combustion point sources. Within the city, hourly metal concentrations are controlled either by traffic (rush hour double peak for Cu, Sb, Sn, Ba) or industrial plumes (morning peak of Ni, Mn, Cr generated outside the city overnight), whereas at Montseny metal concentrations rise during the morning to a single, prolonged afternoon peak as contaminated air transported by the sea breeze moves into the mountains. Our exceptional database, which includes hourly measurements of chemical concentrations, demonstrates in more detail than previous studies the spatial and temporal variability of urban pollution by trace metals in a given city. Technogenic metalliferous aerosols are commonly fine in size and therefore potentially bioavailable, emphasising the case for basing urban background PM characterisation not only on physical parameters such as mass but also on sample chemistry and with special emphasis on trace metal content.
Highlights
It is well established that high concentrations of airborne particulate matter have negative effects on human health (US EPA, 2009 and references therein), this evidence having led to a revision of the WHO Air Quality Guidelines and increasingly worldwide imposition of mandatory limits for PM10 concentrations in the air we breathe (WHO, 2000; Council Directive 2008/50/EC; US EPA, 2004; Moreno et al, 2007)
The presence of trace metals in ambient air is due in part to emissions directly from natural processes such as volcanic eruptions, dust storms or rock weathering, most metalliferous particles are anthropogenic in origin
Normalising average metal values of our atmospheric PM samples against those for average upper continental crust (Wedepohl, 1995) reveals the extent of atmospheric enrichment in technogenic elements associated with traffic and industrial emissions
Summary
It is well established that high concentrations of airborne particulate matter have negative effects on human health (US EPA, 2009 and references therein), this evidence having led to a revision of the WHO Air Quality Guidelines and increasingly worldwide imposition of mandatory limits for PM10 concentrations in the air we breathe (WHO, 2000; Council Directive 2008/50/EC; US EPA, 2004; Moreno et al, 2007). There is still no common agreement on which size fraction (which will determine its deposition pattern in the respiratory tract) of such particles is causing most damage and likewise which chemical components are most implicated in harmful bioreactions. Key suspects among such chemical components are trace metals which, low in mass concentration, are ubiquitous in our urban environments, and are thought to play an important role in human health problems due to their commonly high bioreactivity The European Union for example has set annual limits for Pb (500 ng m−3; 2008/50/CE), and target values for As (6 ng m−3), Ni (20 ng m−3) and Cd (5 ng m−3) (2004/107/CE), whereas the WHO has published guideline values for Cd (5 ng m−3), Mn (150 ng m−3), Pb (500 ng m−3) and V (1000 ng m−3, daily values)
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
