CMB Observations: improvements of the performance of correlation radiometers by signal modulation and synchronous detection

Observation of the fine structures (anisotropies, polarization, spectral distortions) of the Cosmic Microwave Background (CMB) is hampered by instabilities, 1/f noise and asymmetries of the radiometers used to carry on the measurements. Addition of modulation and synchronous detection allows to increase the overall stability and the noise rejection of the radiometers used for CMB studies. In this paper we discuss the advantages this technique has when we try to detect CMB polarization. The behaviour of a two channel correlation receiver to which phase modulation and synchronous detection have been added is examined. Practical formulae for evaluating the improvements are presented.Comment: 18 pages, 3 figures, New Astronomy accepte

Regional geographic traceability of Treviso Red Chicory

Food traceability is the ability to track any food through food supply chain, from production to distribution, from where the food came (one step back) and to where the food will go (one step forward). Food geographical origin is essential to protect regional designation, ensure fair competition, prevent diffusing of food pathogen and, last but not least, improve consumer confidence. The technique of stable isotopes is an effective tool for food origin assessment and to recover consumers’ confidence; it’s generally adopted to various food such as wine, honey, coffee, dairy, vegetables, meat and so on. The aim of this work is to check the geographical origin of Treviso Red Chicory (tardivo and precoce varieties) applying the stable isotopes technique. Several environmental matrices (i.e. oil, water and vegetable) will be examined to ensure the uniqueness and quality of the final product. Two areas were investigated in Veneto (NE of Italy): the former, located in Treviso province, is regulated by the Consortium of variegated Red Chicory of Treviso and Castelfranco; the latter is located in Padova province and is not regulated by the Consortium. Approximately, 89 Chichory samples (63 for tardivo and 26 for precoce varieties) and 68 soil samples (taken at different depth: 0-20 cm and 20-40 cm) were collected. A monthly precipitation sampling (started from October 2015) were conducted in the study areas and 4 irrigation water samples were also collected. The next step of this work, focused on the stable isotope analysis of the above mentioned matrices, will hopefully give the isotopic signature of the examined product

Evaluation of water isotopic composition of Treviso Red Chicory and soil in northern Italy

The stable isotope approach in agricultural research is a fundamental method to understand and partition the water fluxes in the soil-plant-atmosphere continuum. Recent studies suggest that the water used by plant (soil water) could not be the same that contribute to groundwater recharge and streamflow (Evaristo et al., 2015). The aim of this work is to determine the relative contribution of the water reservoir that interest the growth of the Treviso Red Chicory (tardivo and precoce varieties). Two areas were investigated in Veneto (northern Italy): the former, located in Treviso province, is regulated by the Consortium of variegated Red Chicory of Treviso and Castelfranco; the latter is located in Padova province and is not regulated by the Consortium. Precipitation, stream water and groundwater samples have been collected from both sites to determine the isotopic composition (δ18O and δD) of the main water reservoir that could interact with plant physiology. In several studies, different procedures have been developed to extract water from soil and plant, such as lysimeter and centrifugation, respectively. Groundwater, stream water and precipitation samples were analyzed with the CO2 equilibration method using a Thermo Fisher Delta Plus Advantages Mass Spectrometer. We are now developing a cryogenic extraction apparatus to determine both the isotopic composition of plant water (leaves and roots) and soil water (topsoil and subsoil). The next step of the work will be partitioning the relative contribution of water fluxes in the soil-plant-atmosphere system. We think that this approach can be useful for future studies regarding regional traceability of food and to discriminate the plant transpiration process on land water cycle

Non-Equilibrium Fractionation Factors for D/H and 18O/16O During Oceanic Evaporation in the North-West Atlantic Region

Ocean isotopic evaporation models, such as the Craig-Gordon model, rely on the description of nonequilibrium fractionation factors that are, in general, poorly constrained. To date, only a few gradient-diffusion type measurements have been performed in ocean settings to test the validity of the commonly used parametrization of nonequilibrium isotopic fractionation during ocean evaporation. In this work, we present 6 months of water vapor isotopic observations collected from a meteorological tower located in the northwest Atlantic Ocean (Bermuda) with the objective of estimating nonequilibrium fractionation factors (k, ‰) for ocean evaporation and their wind speed dependency. The Keeling Plot method and Craig-Gordon model combination were sensitive enough to resolve nonequilibrium fractionation factors during evaporation resulting into mean values of k18 = 5.2 ± 0.6‰ and k2 = 4.3 ± 3.4‰. Furthermore, we evaluate the relationship between k and 10-m wind speed over the ocean. Such a relationship is expected from current evaporation theory and from laboratory experiments made in the 1970s, but observational evidence is lacking. We show that (a) in the observed wind speed range [0–10 m s−1], the sensitivity of k to wind speed is small, in the order of −0.2‰ m−1 s for k18, and (b) there is no empirical evidence for the presence of a discontinuity between smooth and rough wind speed regime during isotopic fractionation, as proposed in earlier studies. The water vapor d-excess variability predicted under the closure assumption using the k values estimated in this study is in agreement with observations over the Atlantic Ocean.publishedVersio

Characterization of a customized calibration unit for continuous measurements of the isotopic composition of water vapor

The objective of this work is the development, standardization and creation of a method to carry out continuous measurement of oxygen and hydrogen isotopic composition of the atmospheric water vapor using a wavelengthscanned cavity ring down spectroscopy (WS-CRDS) instrument produced by Picarro, L1102-i model. Some technical improvements of the standard instrument configuration have been made to create three different inlet gas lines: a “standard” line, a calibration line and a line connected with the external sampler. The calibration line is composed of a syringe-pump that continuously injects standard water into a steel tee heated at the temperature of 170◦C and flushed with dry nitrogen gas. In this way, instantaneous and complete vaporization of the standard water takes place. The resulting steam is characterized by a well-defined composition in δD e δ18O values. To allow comparison with other international data, we have characterized the individual instrumental response to variation of the isotopic composition of the water vapor. Several humidity-isotope response functions (6000-26000 ppmv) have been estimated with three different internal standards (0.35h -8.75h -29.11h and -40.28h for δ18O; 2.31h -58.91h -222.19h and -317.78h for δD). Moreover, we have measured the instrumental drift at regular time intervals to apply the opportune corrections to instrument data. The setup has been tested using a 3.5 day continuous measurements carried out with the Picarro sampling the water vapor outside our campus in Venice and parallel sampling using the classical cryogenic trapping procedure, obtaining excellent results. Furthermore, our analysis technique has given good results for the standards with values which are similar to those obtained with the isotope ratio mass spectrometry (IRMS) technique

Stable isotopes in water vapor and precipitation for a coastal lagoon at mid latitudes

The stable oxygen and hydrogen isotope composition in precipitation can be used in hydrology to describe the signature of local meteoric water. The isotopic composition of water vapor is usually obtained indirectly from measurements of δD and δ18O in precipitation, assuming the isotopic equilibrium between rain and water vapor. Only few studies report isotopic data in both phases for the same area, thus providing a complete Local Meteoric Water Line (LMWL). The goal of this study is to build a complete LMWL for the lagoon of Venice (northern Italy) with observations of both water vapor and precipitation. The sampling campaign has started in March 2015 and will be carried out until the end of 2016. Water vapor is collected once a week with cold traps at low temperatures (−77◦C). Precipitation is collected on event and monthly basis with a custom automatic rain sampler and a rain gauge, respectively. Liquid samples are analyzed with a Picarro L1102-i and results are reported vs VSMOW. The main meteorological parameters are continuously recorded in the same area by the campus automatic weather station. Preliminary data show an LMWL close to the Global Meteoric Water Line (GMWL) with lower slope and intercept. An evaporation line is clearly recognizable, considering samples that evaporated between the cloud base and the ground. The deviation from the GMWL parameters, especially intercept, can be attributed to evaporated rain or to the humidity conditions of the water vapor source. Water vapor collected during rainfall shows that rain and vapor are near the isotopic equilibrium, just considering air temperature measured at ground level. Temperature is one of the main factor that controls the isotopic composition of the atmospheric water vapor. Nevertheless, the circulation of air masses is a crucial parameter which has to be considered. Water vapor samples collected in different days but with the same meteorological conditions (air temperature and relative humidity) show differences in terms of δ18O up to 3h. Isotopic ratios in rain events and water vapor are in fact dominated by a seasonal component but outliers are clearly linked to air parcel origin. The monthly measurements of δD and δ18O in precipitation of August 2015, for instance, are lower than in colder months, considering monthly average temperatures. Single rain events show a small sequence of precipitation, that leads to 40% of total precipitation of August, which lowers δ−values considerably. The sampling on event basis during occasional and discontinuous rain also allows to identify the rainout effect, which leads to lightening water during a rainfall. Statistics based on back trajectories (48 hours) show that the major part of air parcels travels across central Europe and derives from sources located in the north Atlantic, whereas, a smaller fraction of the water vapor can be attributed to editerranean sources

Radiocesium Contamination in Samples of Blueberries Jams Collected in Stores of NE Italy (2013-2017)

The monitoring of radioactivity in foodstuffs is carried out for the purposes of food safety in order to follow the evolution of the contamination as result of incidents that occurred both in the past (eg Chernobyl) and in more recent times (eg, Fukushima). Then, the movement of goods from these countries to European Union may cause the propagation of foods potentially toxic for health. At the Port of Trieste, in the period of September 2013, some loads of blueberries (Vaccinum mirtyllus L.) were examined within the application of EC Regulation 733/2008, on the conditions governing imports of agricultural products originating in the countries affected by the nuclear accident of Chernobyl in 1986. The fruits came from Ukraine and were intended for the food preparations containing blueberries, in particular jams and marmalades. As in some cases significant values of Radiocesium concentrations (Cesium-137) were found in blueberries, though below the limit of 600 Bq/kg as required by the Regulations, it was decided to verify whether the presence of this contaminant in the raw material at the tested levels could interest the finished products. In this work, we have therefore collected and analyzed some samples of concentrated blueberries products in different large stores, in order to verify the magnitude of the possible contamination by radio Cesium

Isotopic composition of water vapor near the air-water interface

Evaporation is a key process in water cycle that links liquid water to the atmosphere. In the last fifty years stable isotopes of hydrogen and oxygen have been intensively used to describe climate processes related to evaporation and precipitation, ranging in different spatial and temporal scales. Evaporation introduces large isotopic effects in the phases involved. The well known Craig-Gordon model (Craig & Gordon, 1965) describes those isotopic effects involving several steps and different processes, moving from the air-water interface to the free atmosphere. However, very few works in literature have tested the vertical behavior of the Craig-Gordon model in natural conditions on both fresh and marine waters. In this work we present the results from four field experiments aimed to describe the vertical variability of δ18O and δD in the first few meters over a large water body (the coastal lagoon of Venice, northern Italy) and to test the Craig-Gordon model in such conditions. Each experiment involved cryotrapping of water vapor at different height over the water surface (0.1m, 2m and 4m) and the sampling of the liquid water at two depth (surface and 0.5m). During the experiments, water vapor was also sampled in the nearest mainland (~2.5 km from gradient measurements) to determine the isotopic composition of background water vapor. Liquid samples were then analyzed with a Picarro L1102-i and Thermo-Fisher Delta Plus Advantage for water vapor and lagoon water, respectively. The last two experiments have also involved simultaneous measurements of relative humidity using commercially-available humidity probes at each height. This approach was used to determine a reference scale in order to compare observations to modeled estimates. Despite the coarse time resolution due to cryotrapping method (measurements are averaged over 1.5 hours), preliminary results show measurable differences in the isotopic composition of water vapor along the vertical gradient and good agreement between observations and predicted values from the model. Even if this work is an exploratory phase it shows an interesting potential to grow our understanding of the processes involved as well as a useful implementation for future studies focused on fractionation of water isotopes due to evaporation in natural conditions

Characterization and preliminary risk assessment of road dust collected in Venice airport (Italy)

Road dust is a non-exhaust source that can significantly contribute to atmospheric particulate by resuspension. Beside the issue of the overcoming of guidelines limits for the air quality, the characterization of this matrix is of crucially high interest for the inherent toxicity of resuspended particles, that can act as carriers of heavy metals and toxic-carcinogenic components. In this paper, road dust collected in the Venice international airport is characterized with a multi-technique approach in order to identify the main pollutant sources and to highlight the differences between airside/landside places. The most polluted sites are identified and a preliminary risk assessment is performed taking into account ingestion, dermal intake and inhalation of fugitive particulate pathways. Specifically, the main sources are related to construction activities, anti-icing safety procedures, and brake, tire and road wear; streets are the most polluted landside places; PAHs, Na, Al, Cu, Zn, Ag, Cd are more concentrated in airside area; as regards the risk assessment As, BaP, Cr, Sb, BaA, and BbF are the most critical pollutants. Considering the high number of people passing or working in this airport and the ongoing works related to its enlargement which promotes the emission and the resuspension of fugitive dusts, this research addresses a fundamental step for the protection of potential receptors

Fast Liquid Chromatography Coupled with Tandem Mass Spectrometry for the Analysis of Vanillic and Syringic Acids in Ice Cores

The development of new analytical systems and the improvement of the existing ones to obtain high-resolution measurements of chemical markers in samples from ice cores, is one of the main challenges the paleoclimatic scientific community is facing. Different chemical species can be used as markers for tracking emission sources or specific environmental processes. Although some markers, such as methane sulfonic acid (a proxy of marine productivity), are commonly used, there is a lack of data on other organic tracers in ice cores, making their continuous analysis analytically challenging. Here, we present an innovative combination of fast liquid chromatography coupled with tandem mass spectrometry (FLC-MS/MS) to continuously determine organic markers in ice cores. After specific optimization, this approach was applied to the quantification of vanillic and syringic acids, two specific markers for biomass burning. Using the validated method, detection limits of 3.6 and 4.6 pg mL–1 for vanillic and syringic acids, respectively, were achieved. Thanks to the coupling of FLC-MS/MS with the continuous flow analytical system, we obtained one measurement every 30 s, which corresponds to a sampling resolution of a sample every 1.5 cm with a melting rate of 3.0 cm min–1. To check the robustness of the method, we analyzed two parallel sticks of an alpine ice core over more than 5 h. Vanillic acid was found with concentrations in the range of picograms per milliliter, suggesting the combustion of coniferous trees, which are found throughout the Italian Alps.publishedVersio