Danilo Custódio

Polycyclic aromatic hydrocarbons and their derivatives (nitro-PAHs, oxygenated PAHs, and azaarenes) in PM2.5 from Southern European cities

Atmospheric particulate matter (PM2.5) samples were collected over two one month periods during winter and summer in three Southern European cities (Oporto - traffic site, Florence - urban background, Athens - suburban). Concentrations of 27 polycyclic aromatic hydrocarbons (PAHs), 15 nitro-PAHs (NPAHs), 15 oxygenated-PAHs (OPAHs) and 4 azaarenes (AZAs) were determined. On average, the winter-summer concentrations of ΣPAHs were 16.3-5.60, 7.75-3.02 and 3.44-0.658ngm-3 in Oporto, Florence and Athens, respectively. The corresponding concentrations of ΣNPAHs were 15.8-9.15, 10.9-3.36 and 15.9-2.73ngm-3, whilst ΣOPAHs varied in the ranges 41.8-19.0, 11.3-3.10 and 12.6-0.704ngm-3. Concentrations of ΣAZAs were always below 0.5ngm-3. Irrespective of the city, the dominant PAHs were benzo[b+j+k]fluoranthene, retene, benzo[ghi]perylene and indeno[1,2,3-cd]pyrene. The most abundant OPAH in all cities was 1,8-naphthalic anhydride, whereas 5-nitroacenaphthene was the prevailing NPAH. The ΣOPAHs/ΣPAHs and ΣNPAHs/ΣPAHs were higher in summer than in winter, suggesting increasing formation of derivatives by photochemical degradation of PAHs. Molecular diagnostic ratios suggested that, after traffic, biomass burning was the dominant emission source. Apart from being influenced by seasonal sources, the marked differences between winter and summer may indicate that these diagnostic ratios are particularly sensitive to photodegradation, and thus should be applied and interpreted cautiously. The lifetime excess cancer risk from inhalation was, in part, attributable to PAH derivatives, acclaiming the need to include these compounds in regular monitoring programmes. On average, 206, 88 and 26 cancer cases per million people were estimated, by the World Health Organisation method, for the traffic-impacted, urban background and suburban atmospheres of Oporto, Florence and Athens, respectively.

A one-year record of carbonaceous components and major ions in aerosols from an urban kerbside location in Oporto, Portugal

PM2.5 aerosol samples were collected from January 2013 to January 2014 on the kerbside of a major arterial route in the city of Oporto, Portugal, and later analyzed for carbonaceous fractions and water soluble ions. The average concentrations of organic carbon (OC), elemental carbon (EC) and water soluble organic carbon (WSOC) in the aerosol were 6.2μg/m(3), 5.0μg/m(3) and 3.8μg/m(3), respectively, and fit within the range of values that have been observed close to major roads in Europe, Asia and North America. On average, carbonaceous matter accounted for 56% of the gravimetrically measured PM2.5 mass. The three carbon fractions exhibited a similar seasonal variation, with high concentrations in late autumn and in winter, and low concentrations in spring. SO4(2-) was the dominant water soluble ion, followed by NO3(-), NH4(+), Cl(-), Na(+), K(+), oxalate, Ca(2+), Mg(2+), formate, methanesulfonate and acetate. Some of these ions exhibited a clear seasonal trend during the study period. The average OC/EC ratio for the entire set of samples was 1.28±0.61, which was consistent with a significant influence of vehicle exhaust emissions on aerosol composition. On the other hand, the average WSOC/OC ratio was 0.67±0.23, reflecting the influence of other emitting sources. WSOC was highly correlated with nssK(+), a tracer of biomass combustion, and was not correlated with nssSO4(2-), a species associated with secondary processes, suggesting that the main source of WSOC was biomass burning. Most of the SO4(2-) was anthropogenic in origin and was closely associated with NH4(+), pointing to the formation of secondary aerosols. Na(+), Cl(-) and methanesulfonate were clearly associated with marine sources while NO3(-) was related with combustion of both fossil and non-fossil fuels. Mixed sources explained the occurrence of the other water soluble ions.

Seasonal variability of aerosol concentration and size distribution in Cape Verde using a continuous aerosol optical spectrometer

One year of, almost continuous, measurements of aerosol optical properties and chemical composition were performed at the outskirts of Praia, Santiago Island, Cape Verde, within the framework of CV-DUST (Atmospheric aerosol in Cape Verde region: seasonal evaluation of composition, sources and transport) research project, during 2011. This article reports the aerosol number and mass concentration measurements using a GRIMM Optical Aerosol Spectrometer that provides number size discrimination into 31 size ranges from 0.25 to 32 µm. Time series of 5 min average PM10 concentrations revealed peak values higher than 1000 µg.m-3 during winter dust storm events originating over Northern Africa. The 24 hours average concentrations exceeded the World Health Organization (WHO) guidelines for PM2.5 and PM10 in 20% and 30% of the 2001 days, respectively. Annual average mass concentrations (±standard deviation) for PM1, PM2.5 and PM10 were 5±5, 19±21 and 48±64 µg.m-3, respectively. The annual PM2.5 and PM10 values were also above the limits prescribed by the WHO (10 and 20 µg.m-3, respectively). The aerosol mass size distribution revealed two main modes for particles smaller than 10 µm: a fine mode (0.7-0.8 µm), which possibly results of gas to particle conversion processes; and a coarse mode with maxima at 3-4 µm, which is associated with desert dust and sea salt sources. Within the coarse mode two sub-modes with maxima at 5-6 µm and 10-12 µm were frequently present.

Wet deposition of particulate carbon to the Central North Atlantic Ocean

Elemental carbon (EC) and water-insoluble organic carbon (WIOC) concentrations were measured in wet-only precipitation samples collected on Terceira Island (Azores, Portugal) between December 2009 and October 2010, to investigate temporal variations, source regions and wet deposition fluxes. The global volume-weighted average (vwa) concentrations were 134 ± 19 μgC L(-1) for WIOC and 15.0 ± 1.6 μgC L(-1) for EC, which fall within the range of values that have been found in the European background atmosphere. The WIOC concentration exhibited a temporal variation over the study period with a minimum in winter (vwa 88 ± 16 μgC L(-1)) and a maximum in summer (vwa 477 ± 86 μgC L(-1)). This trend was due to the higher dilution effect of winter rains and possibly to an increase of biogenic particulate carbon incorporation during the growing season. A different temporal variation was observed for the EC concentration with a minimum in summer (vwa 4.2 ± 3.3 μgC L(-1)) and a maximum in spring (vwa 17.5 ± 2.2 μgC L(-1)). The observed trend was mainly related to changes in atmospheric circulation patterns over the Azores. A backward trajectory analysis was applied to identify possible source regions of particulate carbon. The highest WIOC and EC concentrations were associated with air masses that persisted for more than four days over the Central North Atlantic Ocean and with air masses arriving from Europe, respectively. Lower concentrations were observed in samples collected under the influence of back-trajectories from North America. Despite the lower abundance of particulate carbon, the wet deposition fluxes were higher for this group of samples, which reflects the higher amount of precipitation that is normally associated with air masses arriving in the Azores from the west and northwest sectors.

Organic compounds in particulate and gaseous phase collected in the neighbourhood of an industrial complex in São Paulo (Brazil)

São Paulo, a megacity in South America, is the largest consumer of fossil fuels in Brazil. The petrochemical products play an important role in the Brazilian economy and in the energy matrix. The compounds emitted when oil is used or processed can affect air quality and endanger human health. Particulate matter and gaseous samples were collected simultaneously in 2015 at an urban site highly impacted by anthropogenic activities, in the city of Santo André, São Paulo Metropolitan Area. Samples were analysed for elemental and organic carbon, hopanes, n-alkanes, alkenes polycyclic aromatic hydrocarbons and their oxygenated and nitrated derivatives. Among the polycyclic aromatic hydrocarbon, phenanthrene presented the highest concentration in PUF and benzo(b)fluoranthene was dominant in PM. The carcinogenic equivalents for benzo(a)pyrene were 2.1 for PAH and 1.2 for nitro-PAH. The results showed that local activities as vehicular and industrial activities affected the air quality.

Case Studies of Source Apportionment and Suggested Measures at Southern European Cities

This chapter reports the results of the PM10 and PM2.5 source apportionment at 3 urban background sites (Barcelona, Florence and Milan, BCN-UB, FI-UB, MLN-UB) 1 suburban background site (Athens, ATH-SUB) and 1 traffic site (Porto, POR-TR). Road traffic (sum of vehicle exhaust, non-exhaust and traffic-related secondary nitrate) is the most important source of PM10 (23–38% at all sites) and PM2.5 (22–39%, except for ATH-SUB and BCN-UB). The second most important source of PM10 (20–26%) is secondary sulphate/OC at BCN-UB, FI-UB and ATH-SUB, while it represents 10–14% in MLN-UB and POR-TR. The relative importance of this source is higher in PM2.5 (19–37% at SUB-UB sites). Biomass burning contributions vary widely from 14–24% of PM10 in POR-TR, MLN-UB and FI-UB, 7% in ATH-SUB to <2% in BCN-UB. In PM2.5, BB is the second most important source in MLN-UB (21%) and in POR-TR (18%). This large variability is due to the degree of penetration of biomass for residential heating. Other significant sources are local dust, industries (metallurgy), remaining secondary nitrate (from industries, shipping and power generation), sea salt and Saharan dust. The same analysis is performed for exceedances days. Based on the above, a priority list of measures to improve PM levels is proposed for each city.