1. A new optical-based technique for real-time measurements of mineral dust concentration in PM10 using a virtual impactorLuka Drinovec, Jean Sciare, IASONAS STAVROULAS, Spiros Bezantakos, Michael Pikridas, FLORIN UNGA, Chrysanthos Savvides, Bojana Višnjić, Maja Remškar, Griša Močnik, 2020, original scientific article Abstract: Atmospheric mineral dust influences Earth’s radiative
budget, cloud formation, and lifetime; has adverse
health effects; and affects air quality through the increase of
regulatory PM10 concentrations, making its real-time quantification
in the atmosphere of strategic importance. Only
few near-real-time techniques can discriminate dust aerosol
in PM10 samples and they are based on the dust chemical
composition. The online determination of mineral dust using
aerosol absorption photometers offers an interesting and
competitive alternative but remains a difficult task to achieve.
This is particularly challenging when dust is mixed with
black carbon, which features a much higher mass absorption
cross section. We build on previous work using filter photometers
and present here for the first time a highly timeresolved
online technique for quantification of mineral dust
concentration by coupling a high-flow virtual impactor (VI)
sampler that concentrates coarse particles with an aerosol absorption
photometer (Aethalometer, model AE33). The absorption
of concentrated dust particles is obtained by subtracting
the absorption of the submicron (PM1) aerosol fraction
from the absorption of the virtual impactor sample (VIPM1
method). This real-time method for detecting desert
dust was tested in the field for a period of 2 months (April and
May 2016) at a regional background site of Cyprus, in the
Eastern Mediterranean. Several intense desert mineral dust
events were observed during the field campaign with dust
concentration in PM10 up to 45 μgm
Keywords: aerosol absorption, mineral dust, on-line detection, air quality
Published in RUNG: 20.07.2020; Views: 2733; Downloads: 0
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2. Trace detection of C2H2 in ambient air using continuous wave cavity ring-down spectroscopy combined with sample pre-concentrationManik Pradhan, Ruth Lindley, Roberto Grilli, Iain R. White, Damien Martin, Orr-Ewing Andrew, 2008, original scientific article Abstract: Continuous wave cavity ring-down spectroscopy (cw-CRDS) coupled with sample pre-concentration has been used to measure acetylene (C2H2) mixing ratios in ambient air. Measurements were made in the near-infrared region (λ∼1535.393 nm), using the P(17) rotational line of the (ν1+ν3) vibrational combination band, a region free from interference by overlapping spectral absorption features of other air constituents. The spectrometer is shown to be capable of fast, quantitative and precise C2H2 mixing ratio determinations without the need for gas chromatographic (GC) separation. The current detection limit of the spectrometer following sample pre-concentration is estimated to be 35 parts per trillion by volume (pptv), which is sufficient for direct atmospheric detection of C2H2 at concentrations typical of both urban and rural environments. The CRDS apparatus performance was compared with an instrument using GC separation and flame ionization detection (GC-FID); both techniques were used to analyze air samples collected within and outside the laboratory. These measurements were shown to be in quantitative agreement. The indoor air sample was found to contain C2H2 at a mixing ratio of 3.87±0.22 ppbv (3.90±0.23 ppbv by GC-FID), and the C2H2 fractions in the outside air samples collected on two separate days from urban locations were 1.83±0.20 and 0.69±0.14 ppbv (1.18±0.09 and 0.60±0.04 ppbv by GC-FID). The discrepancy in the first outdoor air sample is attributed to degradation over a 2-month interval between the cw-CRDS and GC-FID analyses.
Keywords: Rotational Line, Cavity Enhance Absorption Spectroscopy, Adsorbent Trap, Trace Atmospheric Constituent, CRDS Instrument
Published in RUNG: 15.07.2019; Views: 3235; Downloads: 0
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3. Arsenic in natural waters: hydrogeochemistry characterization and toxicity effectsDoroteja Gošar, 2018, master's thesis Abstract: Arsenic contamination in natural water is a worldwide problem and a major health concern. In master thesis hydrogeochemistry and toxicity effects of natural waters rich in arsenic were studied. The main objective of the master thesis was to evaluate As pollution of the Freixeda stream and groundwater in abandoned Freixeda gold mine area in NE Portugal near Mirandela city (41.413767 N 7.103562 W) and compare it with the data from previous studies. Further on, toxicological evaluation of selected water samples was performed in the in vitro system of human cell line Caco-2.
Chemical analyses of sampled water samples with use of different modelling sofware show that groundwater have higher sulphate and bicarbonate values than surface water, which could be the reason for As desorption and higher As values in groundwater. Water-rock interaction promotes reduction and dissolution of sulphide minerals and in reductive environments dissolution of secondary Fe minerals releases adsorbed As into solution.
Toxicological testing on human cells included cytotoxicity assay, genotoxicity assay and production of reactive oxigene species (ROS). Genotoxicity was only modestly affected by a short-term exposure to As-contaminated water samples, however, higher concentrations of As in real samples lead to higher level of oxidative stress and decreased cell viability. Exposure of cells to pure As(III) solution show clear concentration dependent decrease in cell metabolism and viability, strong genotoxicity and increased ROS generation.
Considering the worldwide extent of As contamination in natural waters and ability of intestinal epithelium to reduce the potential harmful effects of As, more studies evaluating the human intestinal permeability for As should be done in the future.
Keywords: Water quality, arsenic, hydrogeochemistry, toxicity, Caco-2 cell line
Published in RUNG: 26.09.2018; Views: 5377; Downloads: 197
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