Concentration and size distribution of atmospheric particles in southern Italy during COVID-19 lockdown period

Many countries imposed lockdown (LD) to limit the spread of COVID-19, which led to a reduction in the emission of anthropogenic atmospheric pollutants. Several studies have investigated the effects of LD on air quality, mostly in urban settings and criteria pollutants. However, less information is available on background sites, and virtually no information is available on particle number size distribution (PNSD). This study investigated the effect of LD on air quality at an urban background site representing a near coast area in the central Mediterranean. The analysis focused on equivalent black carbon (eBC), particle mass concentrations in different size fractions: PM_2.5 (aerodynamic diameter D_a < 2.5 μm), PM₁₀ (D_a < 10 μm), PM_10-2.5 (2.5 < D_a < 10 μm); and PNSD in a wide range of diameters (0.01-10 μm). Measurements in 2020 during the national LD in Italy and period immediately after LD (POST-LD period) were compared with those in the corresponding periods from 2015 to 2019. The results showed that LD reduced the frequency and intensity of high-pollution events. Reductions were more relevant during POST-LD than during LD period for all variables, except quasi-ultrafine particles and PM_10-2.5. Two events of long-range transport of dust were observed, which need to be identified and removed to determine the effect of LD. The decreases in the quasi-ultrafine particles and eBC concentrations were 20%, and 15-22%, respectively. PM_2.5 concentration was reduced by 13-44% whereas PM_10-2.5 concentration was unaffected. The concentration of accumulation mode particles followed the behaviour of PM_2.5, with reductions of 19-57%. The results obtained could be relevant for future strategies aimed at improving air quality and understanding the processes that influence the number and mass particle size distributions.

Comparison of the impact of ships to size-segregated particle concentrations in two harbour cities of northern Adriatic Sea

Detailed information on in-harbour shipping contribution to size segregated particles in coastal cities are scarce, especially in the busy Mediterranean basin. This poses issues for human exposure and air quality in urban harbour agglomerates, where only criteria pollutants (i.e. PM₁₀ and/or PM_2.5) are usually monitored. In this work, particle number and mass size distributions, in a large size range (0.01-31 μm), were obtained in two coastal cities of northern Adriatic Sea: Venice (Italy) and Rijeka (Croatia). Three size ranges were investigated: nanoparticles (diameter D < 0.25 μm); fine particles (0.25<D < 1 μm), and coarse particles (D > 1 μm). Absolute concentrations were larger in Venice for all size ranges showing, using analysis of daily trends, a large influence of local meteorology and boundary-layer dynamics. Contribution of road transport was larger (in relative terms) in Rijeka compared to Venice. The highest contributions of shipping were in Venice, mainly because of the larger ship traffic. Maximum impact was on nanoparticles 7.4% (Venice) and 1.8% (Rijeka), the minimum was on fine range 1.9% (Venice) and <0.2% (Rijeka) and intermediate values were found in the coarse fraction 1.8% (Venice) and 0.5% (Rijeka). Contribution of shipping to mass concentration was not distinguishable from uncertainty in Rijeka (<0.2% for PM₁, PM_2.5, and PM₁₀) and was about 2% in Venice. Relative contributions as function of particles size show remarkable similitudes: a maximum for nanoparticles, a quick decrease and a successive secondary maximum (2-3 times lower than the first) in the fine range. For larger diameters, the relative contributions reach a minimum at 1-1.5 μm and there is a successive increase in the coarse range. Size distributions showed a not negligible contribution of harbour emissions to nanoparticle and fine particle number concentrations, compared to PM_2.5 or PM₁₀, indicating them as a better metric to monitor shipping impacts compared to mass concentrations (PM_2.5 or PM₁₀).

Characterisation of atmospheric pollution near an industrial site with a biogas production and combustion plant in southern Italy

Although biogas production can have some benefits, there is a research gap on potential influence of biogas plant emissions on local air quality, thus an accurate and comprehensive evaluation of impacts of this technology is needed. This study deals with this issue by means of a characterisation of air pollution near an industrial area including a biogas production (from biomass) and combustion plant located in South Italy. The methodology consists in advanced statistical analysis on concentration of gaseous pollutants, particles concentration and size distribution in number and mass, and PM_2.5 chemical composition. High-temporal resolution measurements, supported by ancillary meteorological parameters, and source apportionment of PM_2.5 using Positive Matrix Factorization (PMF) receptor model, are performed. The integrated approach provides the emissive picture consisting in different anthropogenic sources (i.e. traffic, biomass burning, and industrial facilities) with particular focus on biogas plant emissions. Results showed that CO and nitrogen oxides were influenced by vehicular traffic and biomass combustion, however, a contribution of the plant to NO was observed. SO₂ was influenced mainly by transport from the industrial zone, but a second local contribution compatible with the emissions of the biogas plant was detected. Number particle concentrations were analysed in four size ranges: nanoparticles (D < 0.05 μm), ultrafine particles (D < 0.3 μm), accumulation (0.3 < D < 1 μm) and coarse particles (D > 1 μm). Nanoparticles and ultrafine particles were mainly influenced by vehicular traffic and biomass burning, instead, a contribution of the plant was individuated in the accumulation mode. PMF5 identified the contribution of six sources: crustal (14.7% ± 2.1% of measured PM_2.5); marine aerosol (aged) (12.9% ± 2.3%); biomass burning (32.8% ± 1.4%); secondary sulphate (19.7% ± 2.4%); primary industrial emissions (5.4% ± 2.3%); traffic and secondary nitrate (17.0% ± 3.9%). The plant is likely to contribute to both sources, the industrial and the traffic plus secondary nitrate.

Seasonal variability of PM2.5 and PM10 composition and sources in an urban background site in Southern Italy

Comparison of fine and coarse fractions in terms of sources and dynamics is scarce in southeast Mediterranean countries; differences are relevant because of the importance of natural sources like sea spray and Saharan dust advection, because most of the monitoring networks are limited to PM₁₀. In this work, the main seasonal variabilities of sources and processes involving fine and coarse PM (particulate matter) were studied at the Environmental-Climate Observatory of Lecce (Southern Italy). Simultaneous PM_2.5 and PM₁₀ samples were collected between July 2013 and July 2014 and chemically analysed to determine concentrations of several species: OC (organic carbon) and EC (elemental carbon) via thermo-optical analysis, 9 major ions via IC, and 23 metals via ICP-MS. Data was processed through mass closure analysis and Positive Matrix Factorization (PMF) receptor model characterizing seasonal variabilities of nine sources contributions. Organic and inorganic secondary aerosol accounts for 43% of PM_2.5 and 12% of PM_2.5-10 with small seasonal changes. SIA (secondary inorganic aerosol) seasonal pattern is opposite to that of SOC (secondary organic carbon). SOC is larger during the cold period, sulphate (the major contributor to SIA) is larger during summer. Two forms of nitrate were identified: NaNO₃, correlated with chloride depletion and aging of sea-spray, mainly present in PM_2.5-10; NH₄NO₃ more abundant in PM_2.5. Biomass burning is a relevant source with larger contribution during autumn and winter because of the influence of domestic heating, however, is not negligible in spring and summer, because of the contributions of fires and agricultural practices. Mass closure analysis and PMF results identify two soil sources: crustal associated to long range transport and carbonates associated to local resuspended dust. Both sources contributes to the coarse fraction and have different dynamics with crustal source contributing mainly in high winds from SE conditions and carbonates during high winds from North direction.

Source apportionment of PM(2.5) in the harbour-industrial area of Brindisi (Italy): identification and estimation of the contribution of in-port ship emissions

Harbours are important for economic and social development of coastal areas but they also represent an anthropogenic source of emissions often located near urban centres and industrial areas. This increases the difficulties in distinguishing the harbour contribution with respect to other sources. The aim of this work is the characterisation of main sources of PM2.5 acting on the Brindisi harbour-industrial area, trying to pinpoint the contribution of in-port ship emissions to primary and secondary PM2.5. Brindisi is an important port-city of the Adriatic Sea considered a hot-spot for anthropogenic environmental pressures at National level. Measurements were performed collecting PM2.5 samples and characterising the concentrations of 23 chemical species (water soluble organic and inorganic carbon; major ions: SO4(2-), NO3(-), NH4(+), Cl(-), C2O4(2-), Na(+), K(+), Mg(2+), Ca(2+); and elements: Ni, Cu, V, Mn, As, Pb, Cr, Sb, Fe, Al, Zn, and Ti). These species represent, on average, 51.4% of PM2.5 and were used for source apportionment via PMF. The contributions of eight sources were estimated: crustal (16.4±0.9% of PM2.5), aged marine (2.6±0.5%), crustal carbonates (7.7±0.3%), ammonium sulphate (27.3±0.8%), biomass burning-fires (11.7±0.7%), traffic (16.4±1.7 %), industrial (0.4±0.3%) and a mixed source oil combustion-industrial including ship emissions in harbour (15.3±1.3%). The PMF did not separate the in-port ship emission contribution from industrial releases. The correlation of estimated contribution with meteorology showed directionality with an increase of oil combustion and sulphate contribution in the harbour direction with respect to the direction of the urban area and an increase of the V/Ni ratio. This allowed for the use of V as marker of primary ship contribution to PM2.5 (2.8%+/-1.1%). The secondary contribution of oil combustion to non-sea-salt-sulphate, nssSO4(2-), was estimated to be 1.3 μg/m(3) (about 40% of total nssSO4(2-) or 11% of PM2.5).

First Report of Armillaria Butt Rot Caused by Armillaria mellea on Phoenix canariensis in Italy

During 2006, in a garden in the Mount Etna Piedmont, eastern Sicily (Italy), a 40-year-old specimen of Canary Island date palm (Phoenix canariensis hort. ex Chabaud) with a trunk circumference at breast height of 220 cm showed a rotted lesion with a viscous, brown ooze at the stem base and root initials. The lesion extended to approximately one-third of the trunk circumference. Trunk excavation exposed a wet rot of internal tissues, a cream-colored mycelial mat, and a mushroom-like smell. Although the rot spread inward (approximately 25 cm deep) with decay of nonlignified ground tissues and blackening of wood fibers, the palm did not show symptoms on the canopy. Conversely, ferns, apricot, and cedar trees growing at the same site had died from Armillaria rot over the last 10 years (2). In late autumn, clumps of honey mushroom-like sphorophores with a prominent annulus encircling the stalk formed at the base of the trunk. The spore print of the basidiocarp was light cream. The morphology of 100 basidiospores was determined microscopically. The basidiospores were smooth, elliptical, hyaline, and measured 7 to 9.5 × 5 to 7 μm. The fungus was isolated from diseased tissues on selective benomyl-dichloran medium (3) and was transferred to 2% malt extract agar where it formed ribbon-shaped, fast-growing, and profusely branching rhizomorphs. Armillaria mellea (Vahl.) P. Kumm. was identified on the basis of cultural and morphological characteristics. Identification was confirmed by electrophoresis of mycelial proteins and isozymes in polyacrylamide and starch slab gels (1,2). The electrophoretic patterns of the isolate from P. canariensis were identical to those of reference isolates of A. mellea from grapevine and fern isolated previously at the same site (2). The pathogenicity of the A. mellea isolate from palm (A-palm5) was tested on 20 3-year-old potted seedlings of P. canariensis grown in a greenhouse at 24 ± 4°C. Seedlings were inoculated with wood pieces of holly oak (Quercus ilex L.) colonized by the fungus (two pieces for each seedling) (4). Ten noninoculated plants served as controls. After 12 months, mycelial fans colonizing the root initials, the base of the stem, and the leaf stalks were observed on 14 inoculated seedlings. Although only four infected seedlings showed decline symptoms, the fungus was reisolated from all inoculated plants. No infections were observed in control plants. To our knowledge, this is the first report of Armillaria butt rot on a palm in Europe. References: (1) M. Bragaloni et al. Eur. J. For. Pathol. 27:147, 1997. (2) S. Grasso et al. Plant Dis. 84:592, 2000. (3) T. C. Harrington et al. Armillaria. Page 81 in: Methods for Research on Soilborne Phytopathogenic Fungi. The American Phytopathological Society, St. Paul, MN, 1992. (4) R. Metaliaj et al. Phytopathol. Mediterr. 45:3, 2006.

First Occurrence of Calonectria Leaf Spot on Mexican Blue Palm in Italy

In April 2006, a new leaf disease occurred in a private garden in eastern Sicily (Italy) on young, 2-year-old seedlings of Mexican blue palm, Brahea armata S. Watson, in the Arecaceae. Symptoms were detected on 80% of seedlings. The leaves had minute, brown spots that enlarged into dark brown, circular or elliptical lesions, 3 to 6 mm in diameter, and with a necrotic, gray center. The lesions sometimes were surrounded by a chlorotic halo, and older leaves had larger chlorotic areas between spots. Conidia, conidiophores, and terminal vesicles were examined from diseased leaves. A Cylindrocladium sp. was consistently isolated from leaf lesions on Oxoid (Basingstoke, Hampshire, England) potato-dextrose agar after surface disinfestations with 0.8% NaOCl. Cylindrocladium isolates were cultured on carnation leaf agar (CLA) using single hyphal tips. Five isolates were established and identified as Calonectria pauciramosa C.L. Schoch & Crous based on obpyriform to broadly ellipsoidal terminal vesicles, conidiophore branching pattern, conidia size (52 × 4.6 μm), perithecium morphology, and ascopores size (36 × 6.8 μm). Perithecia were obtained with C. pauciramosa tester strains from Italy (G87 and G128) and South Africa (U 971 and U 1670) (2,3) that confirmed both mating types to be present. Further confirmation was obtained by internal transcribed spacer (ITS) analysis. The sequence of rDNA ITS1-5.8 S-ITS2 regions, obtained after amplification with primer ITS1 and ITS4, revealed that the Brahea isolates showed total homology with the sequence of the C. pauciramosa (STE-U 971 from soil) (= Cylindrocladium pauciramosum) available in GenBank. Isolate CBS 120619 from Mexican blue palm was deposited at Centraalbureau voor Schimmelcultures. Spray inoculations of 10 2-year-old Mexican blue palm seedlings were performed with a spore suspension of the fungus adjusted to 10⁵ conidia per ml obtained from 14-day-old single-spore colonies on CLA at 24°C under cool white fluorescent irradiation on a 12-h light/dark regimen. In addition, the following species were similarly inoculated using 10 1-year-old plants: Arecastrum romanzoffianum (Cham.) Becc., B. edulis H. Wendl. ex S. Watson, Chamaerops humilis L., Howea forsteriana Becc., Phoenix canariensis Hort. ex Chabaud., Trachycarpus fortunei (Hook.) H. Wendl., and Ravenea rivularis Jumelle & Perrier. Inoculated, and 10 control plants were placed in separate plastic bags in a growth chamber at 25 ± 1°C. After 7 to 10 days, foliar symptoms including flecks and spots developed on both species of Brahea and on Chamaerops humilis, and on these hosts, pathogenicity tests were repeated. Other palm species and control plants remained healthy. C. pauciramosa was consistently reisolated from inoculated plants on the basis of vesicle shape and conidia sizes of the anamorph. Cylindrocladium candelabrum, Cylindrocladium colhounii, Cylindrocladium floridanum, Cylindrocladium parasiticum, Cylindrocladium pteridis, Cylindrocladium scoparium, and Cylindrocladium theae have been reported as leaf spots pathogens of Arecaceae (1). To our knowledge, this is the first occurrence of C. pauciramosa on Mexican blue palm and the first report of the pathogen on Arecaceae. References: (1) P. W. Crous. Taxonomy and Pathology of Cylindrocladium (Calonectria) and Allied Genera. The American Phytopathological Society, St. Paul MN, 2002. (2) P. W. Crous et al. Stud. Mycol. 50:415, 2004. (3) G. Polizzi and P. W. Crous Eur. J. Plant Pathol. 105:407, 1999.

Identification and Detection of Phoma tracheiphila, Causal Agent of Citrus Mal Secco Disease, by Real-Time Polymerase Chain Reaction

Phoma tracheiphila is the causal agent of a tracheomycotic disease of citrus called mal secco causing the dieback of twigs and branches. This pathogen is of quarantine concern; therefore, fast and reliable protocols are required to detect it promptly. A specific primer pair and a dual-labeled fluorogenic probe were used in a real-time polymerase chain reaction (PCR) with the Cepheid Smart Cycler II System (Transportable Device TD configuration) to detect this fungus in citrus samples. Real-time PCR assay was compared to modified conventional PCR assay. The sensitivity of the former was evaluated by testing P. tracheiphila DNA dilutions, and the minimum amount detectable was about 500 fg, whereas the linear quantification range was within 100 ng to 1 pg. Conventional PCR sensitivity was 10 pg. Conventional and real-time PCR successfully detected the fungus in woody samples of naturally infected lemon and artificially inoculated sour orange seedlings. Nevertheless, real-time PCR was about 10- to 20-fold more sensitive than conventional PCR, and preliminary results indicate that the former technique achieves quantitative monitoring of the fungus in tissues. Simple and rapid procedures to obtain suitable DNA samples from fungal cultures and citrus woody samples for PCR assays enable diagnosis to be completed in a short time.