Daily Total Column Ozone (TCO) measurements compiled from Total Ozone Mapping Spectrometer (TOMS) and Ozone Monitoring Instruments (OMI) were used to analyze the global and hemispherical TCO interannual variations. Two periods of TCO measurements were analyzed separately covering full years. For the 1978-1994 period, the TCO showed a global decade decrease rate of 13.45 DU (about −4.3%). For the Northern Hemisphere(NH) the decade decrease rate was of 12.96 DU (−4.0%), while in the Southern Hemisphere (SH) was of 13.57 DU (−4.5%). These decreases in ozone trends, using the totality of TOMS and OMI satellite measurements, are greater than those reported in literature. The 1998-2014 period global TCO decade decrease rate was of 1.56 DU, corresponding 0.94 DU and 0.138 DU for the NH and SH, respectively. The global TCO variations must show a double annual periodicity, the first one with maxima in March due to the Northern Hemisphere (NH) and the second one during September due to the Southern Hemisphere (SH). However, the maxima due to SH TCO interannual variations have gradually vanished. A disturbance in the SH TCO interannual variations has appeared since 1980; graphically the periodicity brakes down and transforms to a double peak from 1985 and on. This effect can be attributed to the hemispheric impact of the ozone hole at the South Pole. Between October 1, 2004 and December 14, 2005 TOMS and OMI have recorded this disturbance unequivocally. We conclude that the disturbance in SH TCO has an irreversible character.
In this paper, we present an analysis of attenuation for UV-C radiation ( 290 nm λ ≤ ) as a function of the altitude z ( ) 0 100 km z ≤ ≤ by calculating the interaction ratio between the UV-C radiation and the molecular species susceptible of interact with UV-C radiation. The Rayleigh scattering spectral cross sections were calculated, the UV-C spectral cross sections of the species susceptible of interact with UV-C radiation and the UV extraterrestrial (ETR) solar spectrum were standardized with wavelength steps of 1 nm, and The International Standard Atmosphere model (ISO 1972) was adapted to calculate the molecular density. These data were utilized to calculate the photodissociation and Rayleigh scattering ratios as a function of the altitude and to determine to what measure the photodissociation and the Rayleigh diffusion were determinants of the attenuation of UV-C radiation. It became clear that the photo dissociation of O 2 is the primordial mechanism of attenuation for the UV-C radiation, but the Rayleigh diffusion appears like a mechanism that encreases the photon flux, raising the performance of the O 2 photodissociation. The attenuation capacities of N 2 O, CO 2 and water vapor (H 2 O) over the UV-C radiation are all similar, although smaller (less than 0.6%), and this is due to their low concentration. The O 3 , has the theoretical greater attenuation capacity, but it is found in mid-range altitudes ( ), where the residual UV-C photons has almost vanished by O 2 photo dissociation or Rayleigh diffusion, so the real effect over the UV-C attenuation is minimum.
The oral administration of mineral-rich spring water is known as hydropinic treatment and is used to treat certain ailments. Health benefits are attributed to thermal spring water containing radioactive elements such as radium; this has popularized use of such radioactive water in various parts of the world, causing those who ingest it to increase their internal radiation dose. The goal of this study was to assess the activity concentrations of 226Ra present in the thermal spring waters of San Diego de Alcala, in the state of Chihuahua, Mexico, and to estimate the health risk posed to patients by the effective dose received from ingesting this water during hydropinic treatments. Water samples were taken from different areas of the San Diego de Alcala thermal springs, and pH, temperature, electrical conductivity, and total dissolved solids were measured. The 226Ra activity concentrations were measured with a liquid scintillation counter. The activity concentrations of 226Ra in sampled water varied from 125 to 452 mBq L−1 with an average of 276 ± 40 mBq L−1. The committed effective dose from each of the 226Ra activity concentrations found in samples ranged from 9.80 × 10−5 to 4.0 × 10−3 mSv for hydropinic treatments being carried out in San Diego de Alcala thermal spring spas. Different treatments had different intake rates (200, 600, 1,000, and 1,500 mL d−1) and occurred over periods of 2 or 3 wk. According to the guidelines of the US Environmental Protection Agency, the maximum permissible amount of radium in drinking water is 185 mBq L−1; the 226Ra content in most of the collected samples exceeded this limit. The committed effective doses varied with 226Ra concentration and intake rate; none exceeded the World Health Organization’s reference dose for drinking water of 0.1 mSv y−1, which is the maximum amount to which the population should be exposed.
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