Airborne pollen in Alpine sites

Airborne pollen is usually monitored at urban centers, where most people live, to provide information on types and amount of allergenic pollen. Thus, very few aerobiological data are available for remote, mountainous sites. This study aims to characterize the biological quality of the air in an alpine valley in Trentino (North Italy), a region highly interested by the presence of tourists (e.g., 9.3 million overnight stays registered during June - September 2021). Materials and Methods An aerobiological study was carried out during late spring and summer in 2020 and 2021 in Val di Rabbi, an alpine valley located in the Trentino sector of Stelvio National Park. Gravitational Sigma2 samplers were selected for the survey, for their reliability and efficiency (VDI_2119 2013) and easy handling at remote sites (Gottardini et al. 2021), and installed at 2 m above ground level in 5 sites located at altitudes ranging from 700 to 2000 m a.s.l. Sampling surfaces, treated with an adhesive medium, were analyzed by optical microscopy (OM; 400×; Leitz Diaplan) for pollen identification and count (weekly samples); the average daily sedimentation rate (P cm–2 d–1 ) was calculated for the June-August period. In 2021, an active Hirst-type sampler was concurrently installed in one of the five sites (daily samples). Samples were processed and analyzed following conventional techniques and standardized protocols (UNI EN 16868:2019). Results and Discussion In the two study periods, the number of identified pollen taxa ranged from 25 at the highest elevation site (2000 m a.s.l.) to 39 at the lowest elevation (700 m a.s.l.). The proportion of arboreal pollen slightly decreased with the altitude, from 51% to 42%. The three most abundant pollen taxa were pine (Pinus), grasses (Poaceae) and neetle (Urticaceae), even if in different proportion at each site. The only grass and nettle allergenic pollen represented on average the 52% of the total pollen. The pollen season peak for grasses showed a delay of about 4 days every 100 m of elevation (Figure 1). 47 pollen taxa were identified, by active sampling, 10 more than by the passive one. The most abundant pollen taxa detected by active sampling were pine, grasses, and nettle, as for passive sampling, with the last two representing even the 71% of the total. The pollen season peak for grasses was on 22nd June, coherently with the passive sampling results at the same site. Conclusions Our mountain aerobiological study reveals the presence of allergenic pollen even at high altitude, with noteworthy shifts in the pollen season. The surveyed data can be further exploited for studying the plant biodiversity in remote areas, as well as to provide useful information for allergic tourist and hikers. Moreover, passive sampling proved to be a feasible solution for aerobiological studies in remote or orographically complex areas, typically excluded in routine air quality monitoring. References Gottardini et al. (2021). AAQR, Vol. 21, https://doi.org/10.4209/aaqr.210010 VDI_2119 (2013). Ambient air measurements. Sampling of atmospheric particles > 2.5 μm on an acceptor surface using the Sigma-2 passive sampler. Characterization by optical microscopy and calculation of number settling rate and mass concentration. ICS: 13.040.01. Beuth Verlag, Berlin. Germany. Acknowledgements The study was partially financed by Provincia Autonoma di Trento (IT). We are grateful to Mattia Precazzini and Gabriele Canella for the support in field work, and to Maria Cristina Viola for the microscope pollen analysis

Evidence of the possible interaction between ultrasound and thiol precursors

The effect of ultrasound (20 kHz, 153 \ub5m) on the prefermentation extraction mechanisms in Sauvignon Blanc grapes was studied, focusing on 3-mercaptohexan-1-ol (3MH) and 4-mercapto-4-methyl-pentan-2-one (4MMP) precursors linked to glutathione (GSH) and cysteine (Cys). The treatment determined a positive extraction trend between the duration (untreated, 3 and 5 min) and the conductivity or the concentration of catechins and total phenols, significantly differentiated after 5 min. Nevertheless, the concentration of the thiol precursors in grape juice not only remained undifferentiated, but that of 3-S-glutathionyl mercaptohexan-1-ol showed a negative trend with the treatment time applied (168 \ub1 43, 156 \ub1 36, and 149 \ub1 32 \ub5g/L, respectively, for control, 3 and 5 min). The divergence on the effect between families of compounds suggests an interaction between the sonication treatment and thiol precursor molecules. In order to evaluate the possible degradation properly, ultrasound was applied in a model solution spiked with 3MH and 4MMP precursors, reproducing the conditions of grapes. Except for Cys-3MH, the mean concentration (n = 5) for the rest of the precursors was significantly lower in treated samples, predominantly in those linked to glutathione (~ 1222% and ~18% for GSH-3MH and GSH-4MMP) rather than to cysteine (~ 126%~ 128% for Cys-3MH and Cys-4MMP). The degradation of precursors was associated with a significant increase of 3MH and 4MMP. The formation of volatile thiols following sonication is interesting from a technological point of view, as they are key aroma compounds of wine and potentially exploitable in the wine industry through specific vinification protocols

Evaluation of an optimized enzymatic biosensor for ethanol used in apple storage management with low oxygen stress

Ethanol has been proposed to be one of the target molecules to monitor the dynamic controlled atmosphere (DCA) technique during apple storage, measured in the squeezed juice or in the air of the storage chamber. One of the proposed commercial sensors for ethanol in apple juice is based on amperometry, after a two-step enzyme-based reaction that involves a diaphorase and an alcohol-dehydrogenase. Even though this method has been reported to overestimate ethanol, this difference is fairly fixed and it is industrially used to check the correct application of the treatment and to set the gas composition protocols when the maximum acceptable ethanol is reached. During the 2018 harvest, the ethanol concentration in juices measured with the commercial sensor appeared much higher than those usually reported in precedent years, particularly for the lower concentrations. Laboratory experiments suggested that differences between years could be due to the presence of a secondary enzyme activity present in the commercial diaphorase employed. In order to increase the sensitivity and accuracy, it has been evaluated the performance of the biosensor emploting a further diaphorase. The performances of both sensors were compared with those obtained with a gaschromatophy mass spectrometry approach after head space extraction (HS-GC-MS) in which the mass spectra was acquired in selected-ion monitoring mode. Samples belonging to ‘Red Delicious’ cv. were picked up at different temporary points from industrial storage rooms following the application of low oxygen stress. The new biosensor reduced 97% the mean difference respect to the values obtained with the GC-MS method. The difference between sensors was even clearer for samples with concentrations up to 100 mg/L, that could be used as a discriminating value for the evaluation of the technique success in ‘Red Delicious’ apple juice. The increased sensitivity of the sensor allowed a more accurate monitoring of the DCA at industrial conditions, limiting the risks linked to a false positive on the monitoring during storage

Impact of landscape composition on honey bee pollen contamination by pesticides: a multi-residue analysis

The honey bee is the most common and important managed pollinator of crops. In recent years, honey bee colonies faced high mortality for multiple causes, including land-use change and the use of plant protection products (hereafter pesticides). This work aimed to explore how contamination by pesticides of pollen collected by honey bees was modulated by landscape composition and seasonality. We placed two honey bee colonies in 13 locations in Northern Italy in contrasting landscapes, from which we collected pollen samples monthly during the whole flowering season in 2019 and 2020. We searched for almost 400 compounds, including fungicides, herbicides, insecticides, and acaricides. We then calculated for each pollen sample the Pollen Hazard Quotient (PHQ), an index that provides a measure of multi-residue toxicity of contaminated pollen. Almost all pollen samples were contaminated by at least one compound. We detected 97 compounds, mainly fungicides, but insecticides and acaricides showed the highest toxicity. Fifteen % of the pollen samples had medium-high or high levels of PHQ, which could pose serious threats to honey bees. Fungicides showed a nearly constant PHQ throughout the season, while herbicides and insecticides and acaricides showed higher PHQ values in spring and early summer. Also, PHQ increased with increasing cover of agricultural and urban areas from April to July, while it was low and independent of landscape composition at the end of the season. The cover of perennial crops, i.e., fruit trees and vineyards, but not of annual crops, increased PHQ of pollen samples. Our work highlighted that the potential toxicity of pollen collected by honey bees was modulated by complex interactions among pesticide category, seasonality, and landscape composition. Due to the large number of compounds detected, our study should be complemented with additional experimental research on the potential interactive effects of multiple compounds on honey bee healt

Investigating the role of sampler compartments employed by POCIS devices in pesticides sampling

Polar Organic Chemical Integrative Sampler (POCIS) is a passive sampler employed to monitor organic compounds in water (e.g. pesticides, drugs, etc.); in our case consists of a receiving phase, Oasis HLB, enclosed between two polyethersulfone (PES) membranes. In most cases, the analytes were extracted only from the receiving phase but recent works show that some compounds were also adsorbed on the PES membranes. Many aspects on the membrane behaviour are still unknown and this work aims to fill some knowledge gaps exploring the capability of PES membranes to adsorb pesticides. From experiments conducted in a controlled environment, it was seen that more than half of the investigated compounds were adsorbed more effectively by the PES membrane than the Oasis HLB phase. The affinity of these pesticides towards the two sampler compartments, can be explained only partially by the polarity of the compounds. However, a significant adsorption of the most hydrophobic compounds by the PES membrane was noticed, especially for values of LogKow higher than 4. From these experiments, it was possible to calibrate POCIS by comparing the pesticide concentration in water with the amount adsorbed by the two sampler compartments over time, with the estimation of two values of sampling rate for each pesticide (RS,HLB and RS,PES). It was seen that the combination of the two adsorbent substrates allowed to intercept almost all the studied compounds satisfactorily and this behaviour was also confirmed by a field sampling campaign

Ripening effect on the concentration of polyfunctional thiol precursors in 'Gew\ufcrztraminer

The effect of ripeness on the concentration of polyfunctional thiol precursors was investigated in 'Gew\ufcrztraminer' juices in two vintages characterised by very different climate conditions. An incremental trend of glutathionyl-3-mercaptohexan-1-ol and cysteinyl-3-mercaptohexan-1-ol during ripening was observed. The increase in the last phase of maturation was noticeable in both vintages. The concentration of 4-S-glutathionyl-4-methylpentan-2-one and 4-S-cysteinyl-4-methylpentan-2-one was confirmed to be low in 'Gew\ufcrztraminer', although the latter was found at quantifiable levels in a couple of samples. The management of the harvest date appears to be highly important in order to exploit the potential grapefruit-like note related to polyfunctional thiols of little aromatic 'Gew\ufcrztraminer' wines, particularly in case of challenging vintage years

Simultaneous extraction, derivatisation and analysis of varietal thiols and their non-volatile precursors from beer

Varietal thiols are important contributors to the aroma profile of a wide range of beverages including beer. A methodology for the simultaneous extraction and subsequent analysis of the varietal thiols 3-sulfanylhexan-1-ol (3SH), 3-sulfanylhexylacetate (3SHA) and 4-methyl-4-sulfanylpentan-2-one (4MSP), and the non-volatile precursors 3-S-cysteinylhexan-1-ol (Cys-3SH) and 3-S-glutathionylhexan-1-ol (GSH-3SH) in beer was developed and validated for the first time. The method, which utilises LC-MS/MS, was successfully tested on nine commercial beers, showing it to be widely applicable to this matrix. The syntheses of the novel internal standards d8-3SH and d8-3SHA, which allow a robust and accurate quantification of the hydronated congeners, are also reported. The simplicity of the QuEChERS-based (Quick, Easy, Cheap, Effective, Rugged and Safe) extraction allows for rapid, high throughput analyses suitable for both research and industry application