Overview of the Alaskan Layered Pollution and Chemical Analysis (ALPACA) Field Experiment.

The Alaskan Layered Pollution And Chemical Analysis (ALPACA) field experiment was a collaborative study designed to improve understanding of pollution sources and chemical processes during winter (cold climate and low-photochemical activity), to investigate indoor pollution, and to study dispersion of pollution as affected by frequent temperature inversions. A number of the research goals were motivated by questions raised by residents of Fairbanks, Alaska, where the study was held. This paper describes the measurement strategies and the conditions encountered during the January and February 2022 field experiment, and reports early examples of how the measurements addressed research goals, particularly those of interest to the residents. Outdoor air measurements showed high concentrations of particulate matter and pollutant gases including volatile organic carbon species. During pollution events, low winds and extremely stable atmospheric conditions trapped pollution below 73 m, an extremely shallow vertical scale. Tethered-balloon-based measurements intercepted plumes aloft, which were associated with power plant point sources through transport modeling. Because cold climate residents spend much of their time indoors, the study included an indoor air quality component, where measurements were made inside and outside a house to study infiltration and indoor sources. In the absence of indoor activities such as cooking and/or heating with a pellet stove, indoor particulate matter concentrations were lower than outdoors; however, cooking and pellet stove burns often caused higher indoor particulate matter concentrations than outdoors. The mass-normalized particulate matter oxidative potential, a health-relevant property measured here by the reactivity with dithiothreiol, of indoor particles varied by source, with cooking particles having less oxidative potential per mass than pellet stove particles.

Characterisation of particle size distributions and corresponding size-segregated turbulent fluxes simultaneously with CO2 exchange in an urban area.

Number and mass particle concentrations and fluxes were measured, simultaneously with CO2 concentration and flux, in the urban area of Lecce (Italy). The measurements of the turbulent exchanges of atmospheric particles and gas were performed with an eddy-covariance station located near the busiest road of the town. For the smaller particles, the diurnal evolution of the particle number concentrations and fluxes shows a clear correlation with human activities, in particular vehicular traffic, which is the obvious candidate as the source of the two clear peaks in the CPC concentration in the morning and in the evening. The fluxes were upward for all the measurement period, even though small net deposition was observed for larger particles and during weekend. For the CPC, the correlation with the traffic daily pattern is extremely strong. The city is a continuous particle source. The data analysis seems also to suggest the presence of local urban nucleation events. CO2 and particle concentrations were larger at low wind velocity, instead, fluxes were larger at high wind velocity. This opposite behaviour suggests that the influence of local urban emissions is larger on fluxes with respect to concentrations. The average daily patterns of CO2 concentration show an overlap between biogenic cycle and urban emissions. Again, traffic appears to be the dominant source for fluxes and the urban area is a net source of CO2.

Application of PMF and CMB receptor models for the evaluation of the contribution of a large coal-fired power plant to PM10 concentrations.

The evaluation of the contribution of coal-fired thermo-electrical power plants to particulate matter (PM) is important for environmental management, for evaluation of health risks, and for its potential influence on climate. The application of receptor models, based on chemical composition of PM, is not straightforward because the chemical profile of this source is loaded with Si and Al and it is collinear with the profile of crustal particles. In this work, a new methodology, based on Positive Matrix Factorization (PMF) receptor model and Si/Al diagnostic ratio, specifically developed to discriminate the coal-fired power plant contribution from the crustal contribution is discussed. The methodology was applied to daily PM10 samples collected in central Italy in proximity of a large coal-fired power plant. Samples were simultaneously collected at three sites between 2.8 and 5.8km from the power plant: an urban site, an urban background site, and a rural site. Chemical characterization included OC/EC concentrations, by thermo-optical method, ions concentrations (NH4(+), Ca(2+), Mg(2+), Na(+), K(+), Mg(2+), SO4(2-), NO3(-), Cl(-)), by high performances ion chromatography, and metals concentrations (Si, Al, Ti, V, Mn, Fe, Ni, Cu, Zn, Br), by Energy dispersive X-ray Fluorescence (ED-XRF). Results showed an average primary contribution of the power plant of 2% (±1%) in the area studied, with limited differences between the sites. Robustness of the methodology was tested inter-comparing the results with two independent evaluations: the first obtained using the Chemical Mass Balance (CMB) receptor model and the second correlating the Si-Al factor/source contribution of PMF with wind directions and Calpuff/Calmet dispersion model results. The contribution of the power plant to secondary ammonium sulphate was investigated using an approach that integrates dispersion model results and the receptor models (PMF and CMB), a sulphate contribution of 1.5% of PM10 (±0.3%) as average of the three sites was observed.

Impact of maritime traffic on polycyclic aromatic hydrocarbons, metals and particulate matter in Venice air.

Harbours are important hubs for economic growth in both tourism and commercial activities. They are also an environmental burden being a source of atmospheric pollution often localized near cities and industrial complexes. The aim of this study is to quantify the relative contribution of maritime traffic and harbour activities to atmospheric pollutant concentration in the Venice lagoon. The impact of ship traffic was quantified on various pollutants that are not directly included in the current European legislation for shipping emission reduction: (i) gaseous and particulate PAHs; (ii) metals in PM10; and (iii) PM10 and PM2.5. All contributions were correlated with the tonnage of ships during the sampling periods and results were used to evaluate the impact of the European Directive 2005/33/EC on air quality in Venice comparing measurements taken before and after the application of the Directive (year 2010). The outcomes suggest that legislation on ship traffic, which focused on the issue of the emissions of sulphur oxides, could be an efficient method also to reduce the impact of shipping on primary particulate matter concentration; on the other hand, we did not observe a significant reduction in the contribution of ship traffic and harbour activities to particulate PAHs and metals. Graphical abstract Impact of maritime traffic on polycyclic aromatic hydrocarbons, metals and particulate matter and evaluation of the effect of an European Directive on air quality in Venice.

Contribution of harbour activities and ship traffic to PM2.5, particle number concentrations and PAHs in a port city of the Mediterranean Sea (Italy).

In this work, an assessment of the impact of ship traffic and related harbour activities (loading/unloading of ships and hotelling in harbour) on PM 2.5 and particle number concentrations (PNC) separating the contribution associated to ship traffic from that of harbour-related activities is reported. Further, an assessment of the impact and environmental risks associated to polycyclic aromatic hydrocarbon (PAH) concentrations was performed. Results refer to the city of Brindisi (88,500 inhabitants) in the south-eastern part of Italy and its harbour (with yearly 9.5 Mt of goods, over 520,000 passengers and over 175,000 vehicles). PM2.5 and PNC concentrations show a clear daily pattern correlated with daily ship traffic pattern in the harbour. High temporal resolution measurements and correlations with wind direction were used to estimate the average direct contribution to measured concentrations of this source. The average relative contribution of ship traffic was 7.4% (±0.5%) for PM2.5 and 26% (±1%) for PNC. When the contribution associated to harbour-related activities is added, the percentages become 9.3% (±0.5%) for PM2.5 and 39% (±1%) for PNC. In the site analysed, air coming from the harbour/industrial sector was richer in PAHs (5.34 ng/m3) than air sampled from all directions (3.89 ng/m3). The major compounds were phenanthrene, fluoranthene and pyrene, but the congener profiles were different in the two direction sectors: air from the harbour/industrial sector was richer in phenanthrene and fluorene, which are the most abundant PAHs in ship emissions. Results showed that lighter PAHs are associated to the gas phase, while high molecular weight congeners are mostly present in the particulate phase. The impact on the site studied of the harbour/industrial source to PAHs was 56%(range, 29-87%).

Gas-particle distributions, sources and health effects of polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs) and polychlorinated naphthalenes (PCNs) in Venice aerosols.

Air samples were collected in Venice during summer 2009 and 2012 to measure gas and particulate concentrations of polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs) and polychlorinated naphthalenes (PCNs). PCB-11, considered a marker for non-Aroclor contamination of the environment, was found for the first time in the Venetian lagoon and in Europe. An investigation on sources has been conducted, evidencing traffic as the major source of PAHs, whereas PCBs have a similar composition to Aroclor 1248 and 1254; in 2009 a release of PCN-42 has been hypothesized. Toxicological evaluation by TCA and TEQ methods, conducted for the first time in Venice air samples, identified BaP, PCB-126 and PCB-169 as the most important contributors to the total carcinogenic activity of PAHs and the total dioxin-like activity of PCBs and PCNs.

Pahs and trace elements in PM(2.5) at the Venice Lagoon.

The results of an experimental analysis carried out to investigate PM(2.5) concentration levels and the content of polycyclic aromatic hydrocarbons, as well as inorganic trace elements in the atmospheric particles are presented. Measurements were taken with a micrometeorological station equipped with an optical PM(2.5) detector, and simultaneously, particles were collected on filters for subsequent chemical analyses. The average value of daily PM(2.5) concentration is 21.5 ug/m3 and real-time measurements indicate that the average concentration during the day (8 am to 8 pm) is about 25% lower than the nocturnal average. Short-time averages of PM2.5 decrease when the wind speed increases as consequence of the more efficient mixing. Meteorological measurements indicate the presence of a local daily (breeze) circulation with wind blowing from the Alps or the Adriatic Sea and, during this circulation, larger concentrations were observed, with wind coming from the Alps. Days of high PM(2.5) concentration with dominant anthropic or with prevalent crustal contributions were identified. Regarding trace metals, their average concentrations are comparable to those found in others urban areas, except for Cd (3 ng m(-3)), probably due to the presence of glass-works in Murano. The highest concentrations are observed for K (99 ng m(-3)) and Na (73 ng m(-3)), which are the main constituents of marine spray, while the lowest concentrations are observed for elements such as Cs and Co (respectively 0.01 and 0.02 ng m(-3)). Also the concentrations of PAH are comparable with those of other industrial areas, as their sum ranges from 0.16 ng m(-3) to 3.73 ng m(-3), but if considered as B(a)P toxicity equivalent, they are largely lower (0.036 +/- 0.026 ng m(-3)). From the analyses of discriminating ratios, it has been found that the main origin of PAH in PM(2.5) samples may be petrogenic, probably related to the presence of refinery and petrochemical plants on the mainland, although the contribution of combustion processes cannot be excluded.