Volatilization and oxidative artifacts of PM bound PAHs at low volume sampling (2): Evaluation and comparison of mitigation strategies effects

Organic toxicants and emerging contaminants in hospital interiors before and during the SARS-CoV2 pandemic: alkanes and PAHs

Indoor pollution and deposition dust (DD), in particular, are acquiring concern, due to long exposure time and importance of intake by humans through contact and ingestion. Hospitals look a special category of sites, owing to peculiar contaminants affecting them and to presence of people prone to adverse effects induced by toxicants. Four in-field campaigns aimed at understanding the chemical composition of DD were performed in five Italian hospitals. Measurements were performed before (autumn 2019), during (spring 2021), and after (winter 2022) the peak of SARS-CoV2 and when restrictions caused by pandemic were revoked (winter 2023). Parallel measurements were made outdoors (2022), as well as in a university and a dwelling. Targeted contaminants were n-alkanes and polycyclic aromatic hydrocarbons (PAHs), while iso- and anteiso-alkanes were analyzed to assess the impact of tobacco smoking. Total n-alkanes ranged from 3.9 ± 2.3 to 20.5 ± 4.2 mg/g, with higher percentages of short chain homologs in 2019. PAHs ranged from 0.24 ± 0.22 to 0.83 ± 0.50 mg/g, with light congeners (≤ 228 a.m.u.) always exceeding the heavy ones (≥ 252 a.m.u.). According to carbon preference indexes, alkanes originated overall from anthropogenic sources. Microorganisms resulted to affect a hospital, and tobacco smoke accounted for ~ 4-20‰ of DD mass. As for PAH sources, the diagnostic concentration ratios suggested the concourse of biological matter burning and vehicle emission. Benzo[a]pyrene equivalent carcinogenic and mutagenic potencies of depositions at hospitals ranged ~ 9-39 μg/g and ~ 15-76 μg/g, respectively, which seems of concern for health. DD composition in hospitals was different from that outside the premises, as well as that found at university and at dwelling.

Land-Ocean Exchange Mechanism of Chlorinated Paraffins and Polycyclic Aromatic Hydrocarbons with Diverse Sources in a Coastal Zone Boundary Area, North China: The Role of Regional Atmospheric Transmission

The marine environment is regarded as a crucial "sink" of numerous land-origin pollutants. As typical boundary regions, the coastal and offshore areas are used to evaluate the dominating transfer process and land-ocean exchange mechanism of semivolatile organic compounds. In air samples collected from a coastal area in North China over a whole year, chlorinated paraffins (CPs), including short-chain CPs and medium-chain CPs, and prior control 16 polycyclic aromatic hydrocarbons (PAHs) were determined, with mean concentrations of 25.8 and 94.7 ng/m³, respectively. Results of different gas-particle partitioning models indicated that the steady-state hypothesis provides a better description of the possible land-ocean exchange molecular mechanism. The source-sink influences for CPs and PAHs were affected by the predominant atmospheric motion, which alternated between gaseous diffusion and particulate sedimentation in different seasons. Source apportionment results indicated that different transfer characteristics contributed to the source divergence of ambient CPs and PAHs within 12 nautical miles in the same area. Coal/biomass combustion and diesel/natural gas combustion were the main PAH sources in the coast site (43.1%) and sea site (35.3%), respectively. Similar industrial sources CP-52 and CP-42 were the main CP sources in the coast site (41.4%) and sea site (40.8%), respectively.

Molecular signatures of organic particulates as tracers of emission sources

Chemical signature of airborne particulates and deposition dusts is subject of study since decades. Usually, three complementary composition markers are investigated, namely, (i) specific organic compounds; (ii) concentration ratios between congeners, and (iii) percent distributions of homologs. Due to its intrinsic limits (e.g., variability depending on decomposition and gas/particle equilibrium), the identification of pollution sources based on molecular signatures results overall restricted to qualitative purposes. Nevertheless, chemical fingerprints allow drawing preliminary information, suitable for successfully approaching multivariate analysis and valuing the relative importance of sources. Here, the state-of-the-art is presented about the molecular fingerprints of non-polar aliphatic, polyaromatic (PAHs, nitro-PAHs), and polar (fatty acids, organic halides, polysaccharides) compounds in emissions. Special concern was addressed to alkenes and alkanes with carbon numbers ranging from 12 to 23 and ≥ 24, which displayed distinct relative abundances in petrol-derived spills and exhausts, emissions from microorganisms, high vegetation, and sediments. Long-chain alkanes associated with tobacco smoke were characterized by a peculiar iso/anteiso/normal homolog fingerprint and by n-hentriacontane percentages higher than elsewhere. Several concentration ratios of PAHs were identified as diagnostic of the type of emission, and the sources of uncertainty were elucidated. Despite extensive investigations conducted so far, the origin of uncommon molecular fingerprints, e.g., alkane/alkene relationships in deposition dusts and airborne particles, remains quite unclear. Polar organics resulted scarcely investigated for pollution apportioning purposes, though they looked as indicative of the nature of sources. Finally, the role of humans and living organisms as actual emitters of chemicals seems to need concern in the future.

Analytical Determination of Allergenic Fragrances in Indoor Air

Among all the emerging contaminants, fragrances are gaining more relevance for their proven allergenic and, in some cases, endocrine-disrupting properties. To date, little information exists on their concentration in the air. This study aims to fill this gap by developing a method for the determination of semivolatile fragrances in the indoor gaseous phase with sampling protocols usually adopted for the collection of atmospheric particulate matter (sampling time 24 h, flow rate 10 L min−1) and instrumental analysis by gas chromatography coupled with mass spectrometry. The method was developed on 66 analytes and tested at three concentration levels: 20 compounds showed analytical recoveries ≥72% with percentage standard deviations always better than 20%. For most compounds, negligible sampling breakthroughs were observed. The method was then applied to real samples collected in a coffee bar and in a private house. Considering the fragrances for which the method has shown good effectiveness, the highest concentrations were observed for carvone in the coffee bar (349 ng m−3) and camphor in the house (157 ng m−3). As concerns certain or suspected endocrine disruptors, lilyal and galaxolide were detected at both sites, α-isomethylionone was the second most concentrated compound in the house (63.2 ng m−3), musk xylene and musk ketone were present at lower concentration (≈ 1 or 2 ng m−3).

Chemical characterization and phytotoxicity assessment of peri-urban soils using seed germination and root elongation tests

The peri-urban soil is exposed to pollutants because of its proximity to the city, which may influence the quality of agricultural products. In this study, the occurrence of 16 trace elements (TEs), 16 polycyclic aromatic hydrocarbons (PAHs), and 33 contaminants of emerging concern (CECs) was analyzed in two soil sites of the peri-urban area of Barcelona (Spain) (S2 and S3) and a pristine site (S1). Levels of Pb (S2 164 and S3 150 mg kg-1) are around 2.5 times higher than the guideline values. Values for Cu (178 mg kg-1) in S2 are 1.8-fold higher, whereas for Zn, levels are slightly above the threshold in S2 (208 mg kg-1) and S3 (217 mg kg-1). The total concentrations of PAHs are significantly below the limits: 24 ng g-1 dw (S1), 38 ng g-1 dw (S2), 49 ng g-1 dw (S3), whereas only some CECs are detected with low concentrations. We also developed a simple and rapid method to assess soil pollution. Here, we use two plant growth indexes (seed germination rate and root elongation at the initial stage) of three seeds (lettuce, tomato, and cauliflower) to assess soil chemical contamination on agriculture. In the peri-urban soil, the concentration of Pb was 2.5 times higher than the guideline values, whereas for Cu and Zn, values were slightly above their limits, while only few PAHs and CECs were detected. Results for principal component analysis suggest that root elongation is a more sensitive measurement endpoint than germination rate, especially for lettuce. The germination rate of tomato relied on the nitrate in the soil and decreased sharply in the site with pollution of Cu and As. Under the specific conditions of this study, cauliflower should not be recommended to assess environmental pollution due to its low sensitivity to pollutants. In conclusion, this is a low-cost, simple, and rapid method for evaluating the effects of chemical pollution of agriculture soils on seed growth.

Application of thermal desorption methods for airborne polycyclic aromatic hydrocarbon measurement: A critical review

Thermal desorption (TD) is a universal solvent-free pre-concentration technique. It is often used to pre-concentrate semi-volatile and volatile organic compounds in various sample types. Polycyclic aromatic hydrocarbons (PAHs) are widespread contaminants from incomplete combustion of organic matter and fossil fuel, which have carcinogenic effects on human health. Conventional methods for determining PAHs, represented by solvent extraction, are gradually being replaced by solvent-free methods, typically the TD technique, because of TD's many advantages, including time savings and environmentally friendly treatment. This work presents an extensive review of the universal methods used to determine PAHs in the atmosphere based on the TD technique. The methods currently used for collection and detection of both gas- and particle-phase PAHs in the air are critically reviewed. In addition, the operating parameters of the TD unit are summarized and discussed. The design shortcomings of existing studies and the problems that researchers should address are presented, and promising alternatives are suggested. This paper also discusses important parameters, such as reproducibility and limit of detection, that form a crucial part of quality assurance. Finally, the limitations and the future prospects of the TD technique for use in airborne PAH analyses are addressed. This is the first review of the latest developments of the TD technique for analysis of PAHs and their derivatives in the atmosphere.

An overview of research and development themes in the measurement and occurrences of polyaromatic hydrocarbons in dusts and particulates

Polycyclic aromatic hydrocarbons (PAHs) are a group of organic compounds consisting of two or more fused aromatic rings and are probably one of the most studied groups of organic chemicals in environmental research. PAHs originate mainly from anthropogenic processes, particularly from incomplete combustion of organic fuels. PAHs are distributed widely in particulate matter. Due to widespread sources and persistent characteristics, PAHs disperse through atmospheric transport and exist almost everywhere. Human beings are exposed to PAH mixtures in gaseous or particulate phases in ambient air. Long-term exposure to high concentrations of PAHs is associated with adverse health problems. This review identifies the main research and development themes in the measurement and occurrences of PAHs in dusts and particulates using a new approach to carrying out a literature review where many peer-review publications have been produced. The review extracts the most important research themes from a literature search using a combination of text mining and a more detailed review of selected papers from within the identified themes.

Volatilization and oxidative artifacts of PM bound PAHs collected at low volume sampling (1): Laboratory and field evaluation

Laboratory and field studies were carried out to assess the effects of oxidative degradation and volatilization on PM₁₀ bound polycyclic aromatic hydrocarbons (PAHs), collected at low volume condition according to the EU sampling reference method EN12341:2014 (flow rate 2.3 m³ h^-1), on 47 mm quartz filters. For the laboratory experiments, pairs of twin samples were collected in field and, after treatments favoring decomposition or/and volatilization of PAHs on one sample, the PAH amount was compared with that of the corresponding untreated sample. Ozone exposure caused a general PAHs decay with more marked effects on benzo [a]pyrene, perylene and benz [a]anthracene; these compounds showed, similarly to benzo [ghi]perylene, correlations between ozone dose and losses. Treatments with zero air exhibited losses due to volatilization even for 5-ring PAHs up to benzo [a]pyrene, whereas a linear dependence was observed between filter PAH load and losses for benzo [a]anthracene, chrysene and benzofluoranthenes. Concentrations on samples collected simultaneously over 48, 24, 12 and 6 h were compared. Results confirmed a lack of temporal auto-consistency in the PAHs sampling methodology here adopted. In particular higher atmospheric PAH concentrations were ascertained on samples constituted by cumulative filters exposed over shorter sampling times. When 24-h and 2 × 12-h samples were compared, comparable losses were evaluated in the hot and cold seasons. This finding shows that, although in summer meteorology conditions favor sampling artifacts, the effectiveness of these phenomena continue in the winter, probably due to the larger amount of PAH available on the sampling filter (total PAHs ∼ 10 vs 0.5 ng m^-3).

Trends in analytical techniques applied to particulate matter characterization: A critical review of fundaments and applications

Epidemiological studies have shown the association of airborne particulate matter (PM) size and chemical composition with health problems affecting the cardiorespiratory and central nervous systems. PM also act as cloud condensation nuclei (CNN) or ice nuclei (IN), taking part in the clouds formation process, and therefore can impact the climate. There are several works using different analytical techniques in PM chemical and physical characterization to supply information to source apportionment models that help environmental agencies to assess damages accountability. Despite the numerous analytical techniques described in the literature available for PM characterization, laboratories are normally limited to the in-house available techniques, which raises the question if a given technique is suitable for the purpose of a specific experimental work. The aim of this work consists of summarizing the main available technologies for PM characterization, serving as a guide for readers to find the most appropriate technique(s) for their investigation. Elemental analysis techniques like atomic spectrometry based and X-ray based techniques, organic and carbonaceous techniques and surface analysis techniques are discussed, illustrating their main features as well as their advantages and drawbacks. We also discuss the trends in analytical techniques used over the last two decades. The choice among all techniques is a function of a number of parameters such as: the relevant particles physical properties, sampling and measuring time, access to available facilities and the costs associated to equipment acquisition, among other considerations. An analytical guide map is presented as a guideline for choosing the most appropriated technique for a given analytical information required.

Volatilization and oxidative artifacts of PM bound PAHs at low volume sampling (2): Evaluation and comparison of mitigation strategies effects

The artifacts induced by oxidative degradation and volatilization were assessed with regards to determination of particulate atmospheric PAHs collected at low volume conditions (2.3 m³ h^-1) according to the EU Reference Method EN 12341:2014. In order to evaluate the oxidative degradation, PAH measures carried out through collecting airborne particulate with and without ozone denuders were examined. Simultaneously, the influence of volatilization was investigated by comparing concentrations of PAHs in particulate samples collected over 24-h and 12-h using conventional instruments. Summer and winter/spring campaigns were carried out in order to assess the influence of environmental contour on the artifact processes. Oxidative degradation led to a general decrease of PAH concentrations in both periods; in particular, the highest losses were observed for benzo[a]pyrene and perylene reaching, in average, ca. 20%. In the summer, the effect of volatilization exceeded that of oxidative degradation for light PAHs up to benzo[e]pyrene. In the winter/spring time, the influence of both artifact typologies could be mitigated by splitting the normal 24-h collection interval starting at midnight into two 12-h intervals. A mitigation of the losses could even be obtained by fixing the start time sampling fixed at noon or in the first hours of the day. Finally, the feasibility of collecting PAHs through prolonged sampling (>1 month) at the flow rate of 1.1 L min^-1 was preliminarily investigated. Results indicated that this approach is unsuitable for minimizing the oxidative artifacts.