<?xml version="1.0" encoding="ISO-8859-1"?><article xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
<front>
<journal-meta>
<journal-id>0016-7169</journal-id>
<journal-title><![CDATA[Geofísica internacional]]></journal-title>
<abbrev-journal-title><![CDATA[Geofís. Intl]]></abbrev-journal-title>
<issn>0016-7169</issn>
<publisher>
<publisher-name><![CDATA[Universidad Nacional Autónoma de México, Instituto de Geofísica]]></publisher-name>
</publisher>
</journal-meta>
<article-meta>
<article-id>S0016-71692020000300208</article-id>
<article-id pub-id-type="doi">10.22201/igeof.00167169p.2020.59.3.2092</article-id>
<title-group>
<article-title xml:lang="en"><![CDATA[Radon as a natural radiotracer to investigate infiltration from surface water to nearby aquifers: a case study from the Barada riverbank, Syria]]></article-title>
</title-group>
<contrib-group>
<contrib contrib-type="author">
<name>
<surname><![CDATA[Al-Hilal]]></surname>
<given-names><![CDATA[Mohamed]]></given-names>
</name>
<xref ref-type="aff" rid="Aff"/>
</contrib>
</contrib-group>
<aff id="Af1">
<institution><![CDATA[,Atomic Energy Commission of Syria (AECS) Department of Geology ]]></institution>
<addr-line><![CDATA[Damascus ]]></addr-line>
<country>Syria</country>
</aff>
<pub-date pub-type="pub">
<day>00</day>
<month>09</month>
<year>2020</year>
</pub-date>
<pub-date pub-type="epub">
<day>00</day>
<month>09</month>
<year>2020</year>
</pub-date>
<volume>59</volume>
<numero>3</numero>
<fpage>208</fpage>
<lpage>223</lpage>
<copyright-statement/>
<copyright-year/>
<self-uri xlink:href="http://www.scielo.org.mx/scielo.php?script=sci_arttext&amp;pid=S0016-71692020000300208&amp;lng=en&amp;nrm=iso"></self-uri><self-uri xlink:href="http://www.scielo.org.mx/scielo.php?script=sci_abstract&amp;pid=S0016-71692020000300208&amp;lng=en&amp;nrm=iso"></self-uri><self-uri xlink:href="http://www.scielo.org.mx/scielo.php?script=sci_pdf&amp;pid=S0016-71692020000300208&amp;lng=en&amp;nrm=iso"></self-uri><abstract abstract-type="short" xml:lang="en"><p><![CDATA[Abstract Radon (222Rn) is an inert radioactive gas that is constantly emanated from soils, rocks and groundwater due to alpha decay of radium (226Ra). The radioactivity, inertness and gaseous nature of radon make it a significant environmental tracer for examining some hydrogeological issues that involve interactions between surface and ground waters. The main objective of the present study is to investigate possible infiltration from the surface water of the Barada River, located in the Damascus basin, to an adjacent aquifer, which includes some wells frequently exploited to support the drinking water network of Damascus city. The technique applied here is based on the principle that as low-radon river water flows through the aquifer matrix, it continuously absorbs radon emanated from clayey sediments present in the aquifer, with equilibrium between radon uptake and radioactive decay being reached. The distribution of spatial groundwater radon variation has been monitored in four pre-existing wells drilled in a fluvial aquifer system along the margin of the Barada riverbank. The results revealed clear ingrowth of radon concentration by three to four orders of magnitude, reaching a steady equilibrium state after about four half-lives. Based on the standard law of radioactivity, the residence time of infiltrated river water was estimated. Hydrochemical data in addition to geological investigations and radon activities revealed primarily evidences of infiltration from the Barada river water to the nearby aquifers system, which may become vulnerable to a risk of environmental contamination. Finally, the results also showed that ingrowth of radon activity in groundwater is positively correlated with the concentration of EC (R2 = 0.89) and to a less extent with TDS values (R2 = 0.67). This evident association is most likely due to the presence of some organic matter and clayey minerals in the sediments of the aquifer matrix.]]></p></abstract>
<abstract abstract-type="short" xml:lang="es"><p><![CDATA[Resumen El radón (222Rn) es un gas radiactivo inerte emanado constantemente de los suelos, rocas y aguas subterráneas, lo cual se debe a la desintegración alfa del radio (226 Ra). La radiactividad, la inercia y la naturaleza gaseosa del radón lo convierten en un indicador ambiental significativo para el análisis de algunos problemas hidrogeológicos que implican interacciones entre las aguas superficiales y subterráneas. El objetivo principal del presente estudio es investigar la posible infiltración de las aguas superficiales del río Barada, ubicado en la cuenca de Damasco, a un acuífero adyacente, que incluye algunos pozos que son explotados para contribuir a la red de agua potable de la ciudad de Damasco. La técnica aplicada se basa en el principio de que, a medida que el agua del río de radón bajo fluye a través de la matriz del acuífero, absorbe continuamente el radón emanado de los sedimentos arcillosos del acuífero, alcanzándose el equilibrio entre la captación de radón y la desintegración radiactiva. La distribución de la variación espacial del radón en el agua subterránea se ha monitoreado en cuatro pozos preexistentes perforados en un sistema acuífero fluvial a lo largo del margen de la orilla del río Barada. Los resultados revelaron un claro crecimiento de la concentración de radón en tres o cuatro órdenes de magnitud, con lo cual se alcanzó un estado de equilibrio estable después de aproximadamente cuatro vidas medias. Con base en la ley estándar de radiactividad, se estimó el tiempo de residencia del agua del río infiltrado. Los datos hidroquímicos además de las investigaciones geológicas y las actividades de radón revelaron principalmente evidencias de infiltración del agua del río Barada al sistema de acuíferos cercano, el cual puede volverse vulnerable ante el riesgo de contaminación ambiental. Finalmente, los resultados también mostraron que el aumento de radón en el agua subterránea se correlaciona positivamente con la concentración de EC (R2 = 0.89) y, en menor medida, con los valores de TDS (R2 = 0.67). Esta asociación evidente probablemente se deba a la presencia de algo de materia orgánica y minerales arcillosos en los sedimentos de la matriz del acuífero.]]></p></abstract>
<kwd-group>
<kwd lng="es"><![CDATA[radon]]></kwd>
<kwd lng="es"><![CDATA[marcador ambiental]]></kwd>
<kwd lng="es"><![CDATA[infiltración]]></kwd>
<kwd lng="es"><![CDATA[tiempo de estadía en el agua]]></kwd>
<kwd lng="es"><![CDATA[río Barada]]></kwd>
<kwd lng="en"><![CDATA[Radon]]></kwd>
<kwd lng="en"><![CDATA[Environmental tracer]]></kwd>
<kwd lng="en"><![CDATA[Infiltration]]></kwd>
<kwd lng="en"><![CDATA[Groundwater residence time]]></kwd>
<kwd lng="en"><![CDATA[the Barada River]]></kwd>
</kwd-group>
</article-meta>
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<name>
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<article-title xml:lang=""><![CDATA[Evidence of precursor phenomena in the Kobe earthquake obtained from atmospheric radon concentration]]></article-title>
<source><![CDATA[Applied Geochemistry]]></source>
<year>2006</year>
<volume>21</volume>
<page-range>1064-72</page-range></nlm-citation>
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</article>
