Characteristics of Atmospheric Small Ions and Their Application to Assessment of Air Quality in a Typical Semi-Arid City of Northwest China

Abstract

Observations of atmospheric air ions at most geographic areas have been undertaken, but there are still very few observations at middle-latitude semi-arid areas throughout the world. To quantify characteristics of small air ions in semiarid areas of China, measurements of small air ions and particulate matter (PM 10 ) were conducted at 16 different sites in Xi'an (34°26′N, 108°94'E), China, from August 2009 to July 2010 along with meteorological parameters. The influences of meteorological parameters and PM 10 concentration on small air ions as well as their influence mechanisms were discussed in detail. The results showed that both spatial and temporal distributions of small ions were uneven in Xi'an city. Spatially, the concentration of small ions increased gradually from city center to the suburbs. The mean annual concentration of small negative ions was in the range of 200-400 cm -3 with the mean value of 261 ± 39 cm -3 at urban areas, while more than 500 cm -3 at suburban areas. Significant seasonal variations of small ions were observed with highest level in summer, followed by spring and autumn, and lowest in winter at various types of sites. The positive correlations were found between small ions concentration and temperature as well as relative humidity, while negative correlation between the small ions concentration and PM 10 concentration. Air ions concentration was also applied to the assessment of air quality in Xi'an. The assessment results indicated that the air quality was better at suburban areas than at urban areas, suggesting that the unipolarity model is reasonable to indicate air cleanness.

Correlation between the Concentrations of Atmospheric Ions and Radon as Judged from Measurements at the Fonovaya Observatory

“…The results on the diurnal dynamics of radon also agree [29][30][31][32]. The number of observed ions, both positive and negative, lies within the ranges found by other authors [17,33,34]. The diurnal variations shown in Fig.…”

Measurements of Aerosols and Charged Particles On the BEXUS18 Stratospheric Balloon

“…The vertical profiles of integrated concentration of aerosols > 200 nm and of ions (Figure 2) present interesting features. Firstly, positive charges are only present relatively close to the ground, which is in agreement with previous observations (e.g., Li et al, 2015), even though we cannot exclude that the complete absence of positive charges at upper levels derives from a failure of the positive ions counter during the flight. Even though we are performing more flights with a similar instrumental setup in order to compare and provide evidence of our findings, this general behavior is also consistent with previous observations, showing that ionization from turbulent transport of radon (positively charged product ions) and gamma radiation (negative ions) prevail close to the Earth's surface, whereas ionization from cosmic rays (negative ions) dominates away from the continental surface (upper troposphere and above) (Hirsikko et al, 2011), both ion distribution playing a basic role in the terrestrial global circuit (Tinsley and Zhou, 2006).…”

Measurements of aerosols and charged particles on the BEXUS18 stratospheric balloon

“…2) present interesting features. Firstly, positive charges are only present relatively close to the ground, which is in agreement with previous observations (e.g., Li et al, 2015), even though we cannot exclude the possibility that the complete absence of positive charges at upper levels derives from a failure of the positive ions' counter during the flight. Even though we are performing more flights with a similar instrumental setup in order to compare and provide evidence of our findings, this general behavior is also consistent with previous observations, showing that ionization from turbulent transport of radon (positively charged product ions) and gamma radiation (negative ions) prevails close to the Earth's surface, whereas ionization from cosmic rays (negative ions) dominates away from the continental surface (upper troposphere and above) (Hirsikko et al, 2011), both ion distributions playing a basic role in the terrestrial global circuit (Tinsley and Zhou, 2006).…”

“…Stratospheric balloon research devoted to the collection of aerosol profiles vs. height has traditionally been carried out in the last decades with the aim of elucidating properties and processes of this fundamental air component. While as a rule, in situ observations, either onboard stratospheric balloons or onboard aircraft, are fairly demanding and costly (e.g., Sugita et al, 1999;Matsumura et al, 2001;Hervig and Deshler, 2002;Deshler et al, 2003;Kasai et al, 2003;Watanabe et al, 2004;Hunton et al, 2005;Curtius et al, 2005;Shiraishi et al, 2011;Andersson et al, 2013;Murphy et al, 2014), the present paper aims at promoting the forming of young researchers in the spirit of the BEXUS initiative (Balloon-borne Experiments for University Students; see below), but also in elaborating effective and "relatively" cheap experiments to fulfill the need for experimental vertical profiles of aerosol data useful for filling knowledge gaps in atmospheric and climatological research. The A5-Unibo (Advanced Atmospheric Aerosol Acquisition and Analysis) experiment designed by the University of Bologna has been developed with the purpose of collecting and studying vertical profiles of atmospheric ions and particles in addition to atmospheric parameters (temperature, relative humidity, and pressure) all along the flight path of the BEXUS18 stratospheric balloon, using a relatively low-cost and lightweight setup compared to the conventional instrumentation onboard stratospheric balloons.…”