PCDD/F Emissions From Virgin And Treated Wood Combustion

Energy from biomass is becoming increasingly important as fossil fuel reserves diminish. The utilization of biomass is already prevalent in the domestic heating sector, but produces significant amounts of pollutants that are detrimental to human health. Dioxins, formed in any combustion process where carbon, oxygen and, chlorine are present, are a subject of major interest due to their carcinogenicity. Much research has been carried out to study emissions from hazardous and municipal waste incinerators. Dioxin emission from wood combustion plants are also of interest, especially those due to combustion of treated, varnished or PVC-coated wood, which can produce high polychlorinated dibenzofurans (PCDD/F) emissions. This study compares the PCDD/F emissions produced by burning treated wood and virgin wood to verify if the differences are significant. Six different wood samples were analysed (three of treated wood and three of virgin wood) and a two-step wood gasification boiler was used. The analysis has been conducted both on off gas and on ashes. The measured PCDD/F concentrations are to be considered particularly limited and the treated wood use does not cause a general worsening in the PCDD/F emission. Thus, the wood treatment – subject of study – is not dangerous for PCDD/F. Finally, the experimental results indicated that during the thermal treatment, the formation mechanism of PCDD/F is the de novo synthesis

A dataset of tracer concentrations and meteorological observations from the Bolzano Tracer EXperiment (BTEX) to characterize pollutant dispersion processes in an Alpine valley

Abstract. The paper describes the dataset of concentrations and related meteorological measurements collected during the field campaign of the Bolzano Tracer Experiment (BTEX). The experiment was performed to characterize the dispersion of pollutants emitted from a waste incinerator in the basin of the city of Bolzano, in the Italian Alps. As part of the experiment, two controlled releases of a passive gas tracer (sulfur hexafluoride, SF6) were performed through the stack of the incinerator on 14 February 2017 for two different time lags, starting, respectively, at 07:00 and 12:45 LST. Samples of ambient air were collected at target sites with vacuum-filled glass bottles and polyvinyl fluoride bags, and they were later analyzed by means of a mass spectrometer (detectability limit 30 pptv). Meteorological conditions were monitored by a network of 15 surface weather stations, 1 microwave temperature profiler, 1 sodar and 1 Doppler wind lidar. The dataset represents one of the few examples available in the literature concerning dispersion processes in a typical mountain valley environment, and it provides a useful benchmark for testing atmospheric dispersion models in complex terrain. The dataset described in this paper is available at https://doi.org/10.1594/PANGAEA.898761 (Falocchi et al., 2019)

Contrasting physical and chemical conditions of two rock glacier springs

9openInternationalBothRock glaciers are increasingly influencing the hydrology and water chemistry of Alpine catchments. During three consecutive summers (2017–2019), we monitored by recording probes and fortnightly/monthly field campaigns the physical and chemical conditions of two rock glacier springs (ZRG, SRG) in the Zay and Solda/Sulden catchments (Eastern Italian Alps). The springs have contrasting hydrological conditions with ZRG emerging with evident ponding (pond-like), and SRG being a typical high-elevation seep (stream-like). Water temperature was constantly low (mean 1.2°C, standard deviation 0.1°C) at both springs. Concentrations of major ions (dominated by SO42−, HCO3−, Ca2+ and Mg2+) and trace elements (As, Sr, Ba, U, Rb) increased, and water became more enriched in heavy stable isotopes (δ18O, δ2H) towards autumn. This solute and isotopic enrichment had an asymptotic trend at SRG, and a unimodal pattern at ZRG, where peaks occurred 60–80 days after the snowmelt end. Wavelet analysis of electrical conductivity (EC) and water temperature records revealed daily cycles only at SRG, and significant weekly/biweekly fluctuations at both springs attributable to oscillations of meteorological conditions. Several rainfall events triggered a transient (0.5–2 h) EC drop (of 5–240 μS cm−1) and water temperature rise (of 0.2–1.4°C) at SRG (dilution and warming), whereas only intense rainfall events occasionally increased EC (by 15–85 μS cm−1) at ZRG (solute enrichment and thermal buffering), with a long-lasting effect (6–48 h). Building on previous research, we suggest that rock glacier springs with differing flow conditions, that is, stream-like and pond-like, have contrasting fluctuations of water parameters at different timescales. Thus, for pond-like springs, peaks of EC/solute concentrations might indicate a seasonal window of major permafrost thaw. Our quantitative description of the hydrochemical seasonality in rock glacier outflows and the physical and chemical response to precipitation events provides relevant information for water management in mountain areas under climate change.openBrighenti, Stefano; Engel, Michael; Tolotti, Monica; Bruno, Maria Cristina; Wharton, Geraldene; Comiti, Francesco; Tirler, Werner; Cerasino, Leonardo; Bertoldi, WalterBrighenti, S.; Engel, M.; Tolotti, M.; Bruno, M.C.; Wharton, G.; Comiti, F.; Tirler, W.; Cerasino, L.; Bertoldi, W

Controls on spatial and temporal variability in streamflow and hydrochemistry in a glacierized catchment

Understanding the hydrological and hydrochemical functioning of glacierized catchments requires the knowledge of the different controlling factors and their mutual interplay. For this purpose, the present study was carried out in two sub-catchments of the glacierized Sulden River catchment (130&thinsp;km2; eastern Italian Alps) in 2014 and 2015, characterized by a similarly sized but contrasting geological setting. Samples were taken at different space and timescales for analysis of stable isotopes in water, electrical conductivity, and major, minor and trace elements. At the monthly sampling scale, complex spatial and temporal dynamics for different spatial scales (0.05–130&thinsp;km2) were found, such as contrasting electrical conductivity gradients in both sub-catchments. For the entire Sulden catchment, the relationship between discharge and electrical conductivity showed a monthly hysteretic pattern. Hydrometric and geochemical dynamics were controlled by interplay of meteorological conditions, topography and geological heterogeneity. A principal component analysis revealed that the largest variance (36.3&thinsp;%) was explained by heavy metal concentrations (such as Al, V, Cr, Ni, Zn, Cd and Pb) during the melting period, while the remaining variance (16.3&thinsp;%) resulted from the bedrock type in the upper Sulden sub-catchment (inferred from electrical conductivity, Ca, K, As and Sr concentrations). Thus, high concentrations of As and Sr in rock glacier outflow may more likely result from bedrock weathering. Furthermore, nivo-meteorological indicators such as daily maximum air temperature and daily maximum global solar radiation represented important meteorological controls, with a significant snowmelt contribution when exceeding 5&thinsp;∘C or 1000&thinsp;W&thinsp;m−2, respectively. These insights may help in better understanding and predicting hydrochemical catchment responses linked to meteorological and geological controls and in guiding future classifications of glacierized catchments according to their hydrochemical characteristics.</p