{"id":119362,"date":"2009-06-02T13:27:00","date_gmt":"2009-06-02T13:27:00","guid":{"rendered":"http:\/\/weblogs.madrimasd.org\/\/universo\/archive\/2009\/06\/02\/119362.aspx"},"modified":"2010-01-22T03:52:18","modified_gmt":"2010-01-22T02:52:18","slug":"contaminacion-de-suelos-y-aguas-por-arsenico-y-el-papel-de-las-bacterias-del-suelo","status":"publish","type":"post","link":"https:\/\/www.madrimasd.org\/blogs\/universo\/2009\/06\/02\/119362","title":{"rendered":"Contaminaci\u00f3n de Suelos y Aguas por Ars\u00e9nico y El Papel de las Bacterias del Suelo"},"content":{"rendered":"<link rel=\"File-List\" href=\"file:\/\/\/C:%5CDOCUME%7E1%5CJuanjo%5CCONFIG%7E1%5CTemp%5Cmsohtml1%5C01%5Cclip_filelist.xml\">\n<style> <!--  \/* Font Definitions *\/  @font-face \t{font-family:\"Comic Sans MS\"; \tpanose-1:3 15 7 2 3 3 2 2 2 4; \tmso-font-charset:0; \tmso-generic-font-family:script; \tmso-font-pitch:variable; \tmso-font-signature:647 0 0 0 159 0;}  \/* Style Definitions *\/  p.MsoNormal, li.MsoNormal, div.MsoNormal \t{mso-style-parent:\"\"; \tmargin:0pt; \tmargin-bottom:.0001pt; \tmso-pagination:widow-orphan; \tfont-size:12.0pt; \tfont-family:\"Times New Roman\"; \tmso-fareast-font-family:\"Times New Roman\";} a:link, span.MsoHyperlink \t{\ttext-decoration:underline; \ttext-underline:single;} a:visited, span.MsoHyperlinkFollowed \t{color:purple; \ttext-decoration:underline; \ttext-underline:single;} @page Section1 \t{size:612.0pt 792.0pt; \tmargin:72.0pt 90.0pt 72.0pt 90.0pt; \tmso-header-margin:36.0pt; \tmso-footer-margin:36.0pt; \tmso-paper-source:0;} div.Section1 \t{page:Section1;} --> <\/style>\n<p><!--  \/* Style Definitions *\/  table.MsoNormalTable \t{mso-style-name:\"Tabla normal\"; \tmso-tstyle-rowband-size:0; \tmso-tstyle-colband-size:0; \tmso-style-noshow:yes; \tmso-style-parent:\"\"; \tmso-padding-alt:0pt 5.4pt 0pt 5.4pt; \tmso-para-margin:0pt; \tmso-para-margin-bottom:.0001pt; \tmso-pagination:widow-orphan; \tfont-size:10.0pt; \tfont-family:\"Times New Roman\";} -->  <\/p>\n<p class=\"MsoNormal\" style=\"text-align: justify;\"><span style=\"font-size: 10pt; font-family: &quot;Comic Sans MS&quot;;\">El viernes, 22 de mayo de 2009, <a href=\"..\/..\/remtavares\/archive\/2009\/05\/22\/118694.aspx\">Blog el Agua<\/a>, compa\u00f1ero de este sistema de Bit\u00e1coras edit\u00f3 un interesant\u00edsimo post que llevaba por t\u00edtulo <a href=\"..\/..\/remtavares\/archive\/2009\/05\/22\/118694.aspx\">Ars\u00e9nico y aguas subterr\u00e1neas en Asia<\/a>. Este, recoge casi <b style=\"\"><span style=\"color: rgb(51, 102, 255);\">literalmente una muy buena traducci\u00f3n <\/span><\/b>al castellano de la noticia aparecida inicialmente en el <a href=\"http:\/\/www.soitu.es\/soitu\/2009\/05\/08\/medioambiente\/1241786441_686126.html?id=7eb00774811fc8f52ad71a5fc8088307&amp;tm=1242947887\">portal soitu.es Medioambiente<\/a> que reproducimos abajo, y que fue firmada por <b style=\"\"><span style=\"color: rgb(51, 102, 255);\">Vanesa S\u00e1nchez<\/span><\/b>. Con estas traducciones da gusto, al contrario de las que solemos padecer en la prensa espa\u00f1ola. Gracias Vanesa. Para mi sorpresa, resulta que <b style=\"\"><span style=\"color: rgb(51, 102, 255);\">las bacterias del suelo, se encontraban implicadas en un drama que afecta a m\u00e1s de 140 millones de personas en Asia<\/span><\/b>. Seguidamente, tambi\u00e9n me lleg\u00f3 la informaci\u00f3n v\u00eda <b style=\"\"><span style=\"color: rgb(51, 102, 255);\">Terradaily<\/span><\/b>. Os recomiendo que lo le\u00e1is detenidamente, as\u00ed como la <b style=\"\"><span style=\"color: rgb(51, 102, 255);\">fuente original<\/span><\/b> de la <b style=\"\"><span style=\"color: rgb(51, 102, 255);\">Universidad de Stanford<\/span><\/b>, que aporta m\u00e1s detalles (ver final del post). <b style=\"\"><span style=\"color: rgb(51, 102, 255);\">Fueron el edaf\u00f3logo Fendorf y <\/span><\/b>colegas, de la citada Universidad, los que finalmente <b style=\"\"><span style=\"color: rgb(51, 102, 255);\">descifraron el mecanismo subyacente a este tipo de contaminaci\u00f3n<\/span><\/b>, como veremos m\u00e1s adelante. <span style=\"\">&nbsp;<\/span><o:p><\/o:p><\/span><\/p>\n<p class=\"MsoNormal\" style=\"text-align: justify;\"><span style=\"font-size: 10pt; font-family: &quot;Comic Sans MS&quot;;\"><o:p>&nbsp;<\/o:p><\/span><\/p>\n<p class=\"MsoNormal\" style=\"text-align: justify;\"><span style=\"font-size: 10pt; font-family: &quot;Comic Sans MS&quot;;\"><o:p>&nbsp;<img decoding=\"async\" src=\"\/blogs\/universo\/wp-content\/blogs.dir\/42\/files\/818\/o_3d_qnam_bon_river_delta.jpg\" width=\"437\" height=\"393\"><\/o:p><\/span><\/p>\n<p class=\"MsoNormal\" style=\"text-align: justify;\"><span style=\"font-size: 10pt; font-family: &quot;Comic Sans MS&quot;;\"><o:p><\/o:p><\/span><span style=\"font-size: 8pt; font-family: &quot;Comic Sans MS&quot;;\"><a href=\"http:\/\/www.icem.com.au\/02_contents\/06\/06-maps.htm\">Cultivo de arroz sobre suelos hidromorfos <o:p><\/o:p><\/a><\/span><\/p>\n<p class=\"MsoNormal\" style=\"text-align: justify;\"><span class=\"MsoHyperlink\"><span style=\"font-size: 8pt; font-family: &quot;Comic Sans MS&quot;;\"><a href=\"http:\/\/www.icem.com.au\/02_contents\/06\/06-maps.htm\">en un delta vietnamita: Fuente: ICE<\/a><\/span><\/span><span style=\"font-size: 8pt; font-family: &quot;Comic Sans MS&quot;;\"><o:p><\/o:p><\/span><\/p>\n<p>  <!--more--><link rel=\"File-List\" href=\"file:\/\/\/C:%5CDOCUME%7E1%5CJuanjo%5CCONFIG%7E1%5CTemp%5Cmsohtml1%5C01%5Cclip_filelist.xml\"><o:smarttagtype namespaceuri=\"urn:schemas-microsoft-com:office:smarttags\" name=\"place\"><\/o:smarttagtype><o:smarttagtype namespaceuri=\"urn:schemas-microsoft-com:office:smarttags\" name=\"country-region\"><\/o:smarttagtype><o:smarttagtype namespaceuri=\"urn:schemas-microsoft-com:office:smarttags\" name=\"PlaceName\"><\/o:smarttagtype><o:smarttagtype namespaceuri=\"urn:schemas-microsoft-com:office:smarttags\" name=\"PlaceType\"><\/o:smarttagtype><!--[if !mso]><object  classid=\"clsid:38481807-CA0E-42D2-BF39-B33AF135CC4D\" id=ieooui><\/object> \n\n<style> st1\\:*{behavior:url(#ieooui) } --><\/p>\n<style> <!--  \/* Font Definitions *\/  @font-face \t{font-family:Verdana; \tpanose-1:2 11 6 4 3 5 4 4 2 4; \tmso-font-charset:0; \tmso-generic-font-family:swiss; \tmso-font-pitch:variable; \tmso-font-signature:536871559 0 0 0 415 0;} @font-face \t{font-family:\"Comic Sans MS\"; \tpanose-1:3 15 7 2 3 3 2 2 2 4; \tmso-font-charset:0; \tmso-generic-font-family:script; \tmso-font-pitch:variable; \tmso-font-signature:647 0 0 0 159 0;}  \/* Style Definitions *\/  p.MsoNormal, li.MsoNormal, div.MsoNormal \t{mso-style-parent:\"\"; \tmargin:0pt; \tmargin-bottom:.0001pt; \tmso-pagination:widow-orphan; \tfont-size:12.0pt; \tfont-family:\"Times New Roman\"; \tmso-fareast-font-family:\"Times New Roman\";} a:link, span.MsoHyperlink \t{\ttext-decoration:underline; \ttext-underline:single;} a:visited, span.MsoHyperlinkFollowed \t{color:purple; \ttext-decoration:underline; \ttext-underline:single;} @page Section1 \t{size:612.0pt 792.0pt; \tmargin:72.0pt 90.0pt 72.0pt 90.0pt; \tmso-header-margin:36.0pt; \tmso-footer-margin:36.0pt; \tmso-paper-source:0;} div.Section1 \t{page:Section1;} --> <\/style>\n<p><!--  \/* Style Definitions *\/  table.MsoNormalTable \t{mso-style-name:\"Tabla normal\"; \tmso-tstyle-rowband-size:0; \tmso-tstyle-colband-size:0; \tmso-style-noshow:yes; \tmso-style-parent:\"\"; \tmso-padding-alt:0pt 5.4pt 0pt 5.4pt; \tmso-para-margin:0pt; \tmso-para-margin-bottom:.0001pt; \tmso-pagination:widow-orphan; \tfont-size:10.0pt; \tfont-family:\"Times New Roman\";} -->  <\/p>\n<p class=\"MsoNormal\" style=\"text-align: justify;\"><span style=\"font-size: 10pt; font-family: &quot;Comic Sans MS&quot;;\"><o:p>&nbsp;<\/o:p><\/span><\/p>\n<p class=\"MsoNormal\" style=\"text-align: justify;\"><span style=\"font-size: 10pt; font-family: &quot;Comic Sans MS&quot;;\">Como ya hablaremos en otros post, los <b>deltas<\/b> son ecosistemas fr\u00e1giles sobre los que sustentan su vida cientos de millones de personas, gracias tanto a la <b>gran productividad de sus suelos<\/b>, como por la <b>abundancia de agua <\/b>de estos ambientes. La subida del nivel del mar, debida al calentamiento de la atm\u00f3sfera, puede por tanto, poner en riesgo su existencia, y la&nbsp; sustentabilidad de las personas que viven all\u00ed. Por otro lado, se ha descubierto recientemente que las capas de sedimentos que se acumulan en los deltas (cuando no existen un gran n\u00famero de embalses a lo largo de los cauces fluviales que drenan) son depositarios de registros paleoambientales que suministran informaci\u00f3n paleoambiental importante. Sin embargo, poco se conoc\u00eda de la <b>existencia de procesos naturales que generaran la contaminaci\u00f3n natural de los acu\u00edferos<\/b>. Eso s\u00ed, no debemos confundir el vocablo<span style=\"\">&nbsp; <\/span>\u201cnaturalidad\u201d con la persistencia de una epidemia de c\u00e1nceres en tales ambientes. Estos e han producido por la masificaci\u00f3n humana de tales h\u00e1bitats y la puesta en cultivo de grandes extensiones que demandan enormes cantidades de agua. Esta \u00faltima, al no poder ser suministrada por las aguas pluviales y superficiales que acarrean los cauces, es extra\u00edda de los acu\u00edferos, teniendo que aumentar su profundidad conforme las demandas aumentan.<o:p><\/o:p><\/span><\/p>\n<p class=\"MsoNormal\" style=\"text-align: justify;\"><span style=\"font-size: 10pt; font-family: &quot;Comic Sans MS&quot;;\"><o:p>&nbsp;<\/o:p><\/span><\/p>\n<p class=\"MsoNormal\" style=\"text-align: justify;\"><span style=\"font-size: 10pt; font-family: &quot;Comic Sans MS&quot;;\"><o:p>&nbsp;<img decoding=\"async\" src=\"\/blogs\/universo\/wp-content\/blogs.dir\/42\/files\/818\/o_Delta%20Mekong%2039%20Escalones.JPG\" width=\"441\" height=\"324\"><\/o:p><\/span><\/p>\n<p class=\"MsoNormal\" style=\"text-align: justify;\"><span style=\"font-size: 10pt; font-family: &quot;Comic Sans MS&quot;;\"><o:p>&nbsp;<\/o:p><\/span><\/p>\n<p class=\"MsoNormal\" style=\"text-align: justify;\"><span style=\"font-size: 8pt; font-family: &quot;Comic Sans MS&quot;;\"><a href=\"http:\/\/39escalones.wordpress.com\/feed\">Delta del Mekong. Fuente: 39 Escalones<\/a><o:p><\/o:p><\/span><\/p>\n<p class=\"MsoNormal\" style=\"text-align: justify;\"><span style=\"font-size: 10pt; font-family: &quot;Comic Sans MS&quot;;\"><o:p>&nbsp;<\/o:p><\/span><\/p>\n<p class=\"MsoNormal\" style=\"text-align: justify;\"><span style=\"font-size: 10pt; font-family: &quot;Comic Sans MS&quot;;\">Cada crecida del cauce aporta sedimentos que se superponen a los ya generados por otras previas, que ve este modo van siendo enterrados. Esta es una caracter\u00edstica de los tipos de suelos denominados <b>Fluvisoles<\/b> por la WRB. Se trata de perfiles en los que tanto sus texturas, como los contenidos de materia org\u00e1nica cambian abruptamente con la profundidad, sin que exista ninguna tendencia clara en sus patrones de distribuci\u00f3n. Se trata pues de <b>suelos profundos y f\u00e9rtiles<\/b>, pero j\u00f3venes, en los que los procesos de edafog\u00e9nesis son a lo sumo incipientes. Cuando el suelo aumenta de espesor debido al aporte de nuevos materiales a su superficie, hablamos de <b>suelos cum\u00falicos<\/b>. Los sedimentos provienen de la erosi\u00f3n y disoluci\u00f3n de las suelos y rocas de toda la cuenca que drenan. Cuanto mayor sea esta, tanto m\u00e1s extenso ser\u00e1 el Delta. En el \u00e1rea afectada por la <b>contaminaci\u00f3n por ars\u00e9nico en el sudeste de Asia,<\/b> los <b>r\u00edos<\/b> m\u00e1s caudalosos nacen del <b>Himalaya.<\/b> Honestamente, desconozco su <b>composici\u00f3n litol\u00f3gica<\/b>. El estudio nos informa de que deben ser \u201c<b>relativamente ricos en ars\u00e9nico<\/b>\u201d. Este elemento es <b>arrastrado<\/b>, cuenca abajo por el agua de drenaje, u<b>nido a los sesqui\u00f3xidos de hierro en forma oxidada<\/b>, hasta que son depositados en la cuenca.<span style=\"\">&nbsp;&nbsp;&nbsp; <\/span><o:p><\/o:p><\/span><\/p>\n<p class=\"MsoNormal\" style=\"text-align: justify;\"><span style=\"font-size: 10pt; font-family: &quot;Comic Sans MS&quot;;\"><o:p>&nbsp;<\/o:p><\/span><\/p>\n<link rel=\"File-List\" href=\"file:\/\/\/C:%5CDOCUME%7E1%5CJuanjo%5CCONFIG%7E1%5CTemp%5Cmsohtml1%5C01%5Cclip_filelist.xml\">\n<style> <!--  \/* Font Definitions *\/  @font-face \t{font-family:\"Comic Sans MS\"; \tpanose-1:3 15 7 2 3 3 2 2 2 4; \tmso-font-charset:0; \tmso-generic-font-family:script; \tmso-font-pitch:variable; \tmso-font-signature:647 0 0 0 159 0;}  \/* Style Definitions *\/  p.MsoNormal, li.MsoNormal, div.MsoNormal \t{mso-style-parent:\"\"; \tmargin:0pt; \tmargin-bottom:.0001pt; \tmso-pagination:widow-orphan; \tfont-size:12.0pt; \tfont-family:\"Times New Roman\"; \tmso-fareast-font-family:\"Times New Roman\";} a:link, span.MsoHyperlink \t{\ttext-decoration:underline; \ttext-underline:single;} a:visited, span.MsoHyperlinkFollowed \t{color:purple; \ttext-decoration:underline; \ttext-underline:single;} @page Section1 \t{size:612.0pt 792.0pt; \tmargin:72.0pt 90.0pt 72.0pt 90.0pt; \tmso-header-margin:36.0pt; \tmso-footer-margin:36.0pt; \tmso-paper-source:0;} div.Section1 \t{page:Section1;} --> <\/style>\n<p><!--  \/* Style Definitions *\/  table.MsoNormalTable \t{mso-style-name:\"Tabla normal\"; \tmso-tstyle-rowband-size:0; \tmso-tstyle-colband-size:0; \tmso-style-noshow:yes; \tmso-style-parent:\"\"; \tmso-padding-alt:0pt 5.4pt 0pt 5.4pt; \tmso-para-margin:0pt; \tmso-para-margin-bottom:.0001pt; \tmso-pagination:widow-orphan; \tfont-size:10.0pt; \tfont-family:\"Times New Roman\";} --><!--  <o:shapedefaults v:ext=\"edit\" spidmax=\"1026\"\/> --><!--  <o:shapelayout v:ext=\"edit\">   <o:idmap v:ext=\"edit\" data=\"1\"\/>  <\/o:shapelayout>-->  <\/p>\n<p class=\"MsoNormal\" style=\"text-align: justify;\"><span style=\"font-size: 10pt; font-family: &quot;Comic Sans MS&quot;;\">Pues bien como podr\u00e9is observar m\u00e1s abajo, estos materiales al ser depositados en el delta sin generar, al principio m\u00e1s da\u00f1os. No obstante conforme los sedimentos de las crecidas son sepultados por otros posteriores en un ambiente encharcado (hidromorf\u00eda), muy propenso a generar una atmosfera anaerobia (carente de ox\u00edgeno), las comunidades bacterianas t\u00edpicas de la superficie de los suelos aireados son sustituidas por otras adaptas a las condiciones comentadas. Ciertas bacterias (\u00bfY tambi\u00e9n arqueas?; lo desconozco) en ausencia de fotos\u00edntesis, extraen su energ\u00eda al inducir reacciones con sustratos minerales que les rodean. Hablamos de los microbios denominados <a href=\"http:\/\/es.geocities.com\/joakinicu\/glosario3.htm\">quimiolitotrofos<\/a>, actualmente muy estudiados, por cuanto la vida primigenia en la Tierra se sustentaba en ellos, as\u00ed como debido a que la exo-vida en otros planetas puede (por la falta de ox\u00edgeno) atesorar caracter\u00edsticas similares. En tales circunstancias, los sesqui\u00f3xidos se reducen (liberando ox\u00edgeno), y <a href=\"http:\/\/www.sos-arsenic.net\/english\/critreport.html\">desprenden el ars\u00e9nico<\/a> que se infiltra por gravedad hasta los acu\u00edferos <a href=\"http:\/\/www.sos-arsenic.net\/english\/critreport.html\">contamin\u00e1ndolos<\/a>. <span style=\"\">&nbsp;<\/span>En la <a href=\"http:\/\/www.sos-arsenic.net\/english\/critreport.html\">siguiente p\u00e1gina Web se nos informa detalladamente<\/a> sobre la contaminaci\u00f3n por ars\u00e9nico en el delta del Ganges.<o:p><\/o:p><\/span><\/p>\n<p class=\"MsoNormal\" style=\"text-align: justify;\"><span style=\"font-size: 10pt; font-family: &quot;Comic Sans MS&quot;;\"><o:p>&nbsp;<\/o:p><\/span><\/p>\n<p class=\"MsoNormal\" style=\"text-align: justify;\"><span style=\"font-size: 10pt; font-family: &quot;Comic Sans MS&quot;;\">As\u00ed, en la p\u00e1gina mencionada, en el p\u00e1rrafo anterior, tambi\u00e9n hemos visto que \u201c<b>quiz\u00e1s\u201d parte del problema se agenerara por las tecnolog\u00edas actuales<\/b>, existiendo una <b>forma tradicional de extraer el agua que no da\u00f1aba la salud p\u00fablica<\/b> de la poblaci\u00f3n. Se trata de un sistema denominado \u201c<\/span><span style=\"font-size: 10pt; font-family: &quot;Comic Sans MS&quot;;\"><a href=\"http:\/\/www.sos-arsenic.net\/english\/critreport.html\">Dug Well<\/a>\u201d abandonado hace a\u00f1os en aras de la modernidad. Entr\u00f3 la nueva tecnolog\u00eda y el desastre se desat\u00f3. Os ruego que alguien analice la noticia, ya que de ser cierta, se le habr\u00eda \u201cescapado a Fendorf, y como en otras tantas ocasiones habr\u00eda que retornar a los <b>sistemas tradicionales ind\u00edgenas<\/b>, que por aseverar su sostenibilidad durante tiempo, <b>no inducen los problemas de las actuales<\/b>. Eso si pueden ser mejoradas.<o:p><\/o:p><\/span><\/p>\n<p class=\"MsoNormal\" style=\"text-align: justify;\"><span style=\"font-size: 10pt; font-family: &quot;Comic Sans MS&quot;;\"><o:p>&nbsp;<\/o:p><\/span><\/p>\n<p class=\"MsoNormal\" style=\"text-align: justify;\"><img decoding=\"async\" src=\"\/blogs\/universo\/wp-content\/blogs.dir\/42\/files\/804\/o_DugWell.jpg\" width=\"267\" height=\"252\"><img decoding=\"async\" src=\"\/blogs\/universo\/wp-content\/blogs.dir\/42\/files\/804\/o_Dugwell%20Fuente%20FAO.gif\" width=\"172\" height=\"250\"><br \/><span style=\"font-size: 10pt; font-family: &quot;Comic Sans MS&quot;;\"><o:p><\/o:p><\/span><\/p>\n<p class=\"MsoNormal\" style=\"text-align: justify;\"><span style=\"font-size: 10pt; font-family: &quot;Comic Sans MS&quot;;\"><o:p><br \/><\/o:p><\/span><\/p>\n<p class=\"MsoNormal\" style=\"text-align: justify;\"><span style=\"font-size: 8pt; font-family: &quot;Comic Sans MS&quot;; color: blue;\">\u201cDug Well ind\u00edgena tradicional\u201d: \u201cFuente<\/span><span style=\"font-size: 8pt; font-family: &quot;Comic Sans MS&quot;;\"> <a href=\"http:\/\/www.sos-arsenic.net\/english\/critreport.html\"><span style=\"\">&nbsp;<\/span>aqu\u00ed<\/a> y <a href=\"http:\/\/www.ecoverwateraid.com\/journal-gallery-overlay.html?index=0&amp;sort=date-desc&amp;Pjournal=com.othermedia.ecoverwateraid.model.JournalHandle-L-134&amp;size=5&amp;isTitleLink=true&amp;allJournals=true\">pinchando aqu\u00ed<\/a>\u201d.<o:p><\/o:p><\/span><\/p>\n<p class=\"MsoNormal\" style=\"text-align: justify;\"><span style=\"font-size: 8pt; font-family: &quot;Comic Sans MS&quot;;\"><o:p>&nbsp;<\/o:p><\/span><\/p>\n<p class=\"MsoNormal\" style=\"text-align: justify;\"><span style=\"font-size: 10pt; font-family: &quot;Comic Sans MS&quot;;\">Generalmente, los deltas atesoran capas fre\u00e1ticas muy superficiales, por lo que muchos de ellos son rehabilitados con vistas a producir buenas cosechas. En estas circunstancias, es l\u00f3gico que las comunidades rurales del pasado no necesitaran bombear aguas de los acu\u00edferos (al menos a gran profundidad), por cuanto les sobraban con las pluviales y las procedentes de los propios r\u00edos. Pero ahora, como hemos comentado, ya no es as\u00ed. Por esta raz\u00f3n, un proceso natural que con anterioridad no indujo serias enfermedades, comenz\u00f3 a hacerlo, conforme los usos de la tierra fueron cambiando ante la demanda creciente de alimentos para abastecer a una densidad de poblaci\u00f3n en vertiginoso aumento. Y as\u00ed devino la tragedia. <o:p><\/o:p><\/span><\/p>\n<p><img decoding=\"async\" src=\"\/blogs\/universo\/wp-content\/blogs.dir\/42\/files\/804\/o_dugWellLrg.gif\" width=\"440\" height=\"385\"><\/p>\n<p class=\"MsoNormal\" style=\"text-align: justify;\"><span style=\"font-size: 8pt; font-family: &quot;Comic Sans MS&quot;;\"><a href=\"http:\/\/www.region.durham.on.ca\/health.asp?nr=\/departments\/health\/health_protection\/wellWater\/dugWell.htm&amp;setFooter=\/includes\/health\/healthFooterWell.txt&amp;pf=1\">Dug Well dise\u00f1ado con nuevas tecnolog\u00edas. <o:p><\/o:p><\/a><\/span><\/p>\n<p class=\"MsoNormal\" style=\"text-align: justify;\"><span class=\"MsoHyperlink\"><span style=\"font-size: 8pt; font-family: &quot;Comic Sans MS&quot;;\"><a href=\"http:\/\/www.region.durham.on.ca\/health.asp?nr=\/departments\/health\/health_protection\/wellWater\/dugWell.htm&amp;setFooter=\/includes\/health\/healthFooterWell.txt&amp;pf=1\">Fuente: Well Water safety<\/a><\/span><\/span><span style=\"font-size: 8pt; font-family: &quot;Comic Sans MS&quot;;\"><o:p><\/o:p><\/span><\/p>\n<p class=\"MsoNormal\" style=\"text-align: justify;\"><span style=\"font-size: 10pt; font-family: &quot;Comic Sans MS&quot;;\"><o:p>&nbsp;<\/o:p><\/span><\/p>\n<p class=\"MsoNormal\" style=\"text-align: justify;\"><span style=\"font-size: 10pt; font-family: &quot;Comic Sans MS&quot;;\"><o:p>&nbsp;<\/o:p><\/span><\/p>\n<p class=\"MsoNormal\" style=\"text-align: justify;\"><span style=\"font-size: 10pt; font-family: &quot;Comic Sans MS&quot;;\">Podemos clasificar este interesant\u00edsimo estudio, tanto desde el punto de vista b\u00e1sico, como aplicado, como <b>edafomedicina, o edafolog\u00eda m\u00e9dica<\/b>. El hallazgo de <b>este edaf\u00f3logo podr\u00eda ayudar a salvar millones de vidas<\/b>, por lo que merece toda mi admiraci\u00f3n. El problema estriba en las medidas a tomar con vistas a paliar la gravedad de la situaci\u00f3n. La nota de prensa en espa\u00f1ol, en este aspecto, aporta menor informaci\u00f3n que la original en ingl\u00e9s. Fendorf proporciona posibles soluciones, pero como finalmente argumenta, habr\u00eda que estudiar caso por caso cada una de ellas, ya que la soluci\u00f3n a escala regional no resulta ser trivial. Tambi\u00e9n coincido con el en l<b>a importancia de abordar los problemas de suelos y aguas en el contexto de las cuencas hidrogr\u00e1ficas<\/b> en los que se encuentran. Se trata de un tema de sumo inter\u00e9s que tengo intenci\u00f3n de&nbsp; desarrollar en sucesivos post. <b>\u00bfNo vale para nada la edafolog\u00eda?<\/b>. Pero en Espa\u00f1a nuestros pol\u00edticos siguen ofuscados hasta cotas delirantes.<o:p><\/o:p><\/span><\/p>\n<p class=\"MsoNormal\" style=\"text-align: justify;\"><span style=\"font-size: 10pt; font-family: &quot;Comic Sans MS&quot;;\"><o:p>&nbsp;<\/o:p><\/span><\/p>\n<p class=\"MsoNormal\" style=\"text-align: justify;\"><span style=\"font-size: 10pt; font-family: &quot;Comic Sans MS&quot;; color: red;\">Juan Jos\u00e9 Ib\u00e1\u00f1ez <span style=\"\">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<\/span><span style=\"\">&nbsp;&nbsp;<\/span><span style=\"\">&nbsp;&nbsp;&nbsp;&nbsp;<\/span><span style=\"\">&nbsp;<\/span><o:p><\/o:p><\/span><\/p>\n<p class=\"MsoNormal\"><span style=\"font-size: 10pt; font-family: &quot;Comic Sans MS&quot;;\"><o:p>&nbsp;<\/o:p><\/span><\/p>\n<p class=\"MsoNormal\"><span style=\"font-family: Verdana;\"><a href=\"http:\/\/www.soitu.es\/soitu\/2009\/05\/08\/medioambiente\/1241786441_686126.html?id=7eb00774811fc8f52ad71a5fc8088307&amp;tm=1242947887\">El proceso natural que envenena las aguas subterr\u00e1neas de Asia<\/a><o:p><\/o:p><\/span><\/p>\n<p class=\"MsoNormal\"><span style=\"font-size: 9pt; font-family: Arial;\">Cerca de 140 millones de personas beben agua subterr\u00e1nea contaminada con ars\u00e9nico <o:p><\/o:p><\/span><\/p>\n<p class=\"MsoNormal\"><b style=\"\"><span style=\"font-size: 9pt; font-family: Arial; color: green;\" lang=\"PT-BR\">Por VANESSA S\u00c1NCHEZ* (SOITU.ES) <o:p><\/o:p><\/span><\/b><\/p>\n<p class=\"MsoNormal\"><span style=\"font-size: 9pt; font-family: Arial;\">Actualizado 17-05-2009 09:32 CET <o:p><\/o:p><\/span><\/p>\n<p class=\"MsoNormal\" style=\"text-align: justify;\"><span style=\"font-size: 9pt; font-family: Arial;\">En el sur de Asia, m\u00e1s de 140 millones de personas beben agua subterr\u00e1nea contaminada con ars\u00e9nico. Seg\u00fan los expertos, se trata del mayor envenenamiento masivo de la historia. En Bangladesh, Camboya, India, Myanmar y Vietnam esta exposici\u00f3n cr\u00f3nica al ars\u00e9nico causa miles de muertes por c\u00e1ncer cada a\u00f1o, <a href=\"http:\/\/www.who.int\/water_sanitation_health\/diseases\/arsenicosis\/en\/\">seg\u00fan la Organizaci\u00f3n Mundial de la Salud<\/a>. La \u00faltima noticia es que cient\u00edficos estadounidenses de la <a href=\"http:\/\/news.stanford.edu\/pr\/2009\/pr-fendorf-040109.html\">Universidad de Stanford<\/a> (California) han resuelto el problema de c\u00f3mo este elemento qu\u00edmico envenena los pozos de agua, hasta ahora desconocido: una bacteria tiene la culpa. <o:p><\/o:p><\/span><\/p>\n<p class=\"MsoNormal\"><span style=\"font-size: 9pt; font-family: Arial;\"><o:p>&nbsp;<\/o:p><\/span><\/p>\n<p class=\"MsoNormal\"><span style=\"font-size: 9pt; font-family: Arial;\"><a href=\"http:\/\/www.flickr.com\/photos\/matthieu-aubry\/521438960\/in\/photostream\/\">Matthieu :: giik.net\/blog&#8217;s<\/a> (Flickr)<o:p><\/o:p><\/span><\/p>\n<p class=\"MsoNormal\"><b style=\"\"><span style=\"font-size: 10pt; font-family: Arial; color: rgb(51, 153, 102);\">El abastecimiento de agua en Asia es un problema.<o:p><\/o:p><\/span><\/b><\/p>\n<p class=\"MsoNormal\" style=\"text-align: justify;\"><b style=\"\"><span style=\"font-size: 9pt; font-family: Arial; color: rgb(51, 102, 255);\">En el Himalaya nacen cuatro grandes sistemas fluviales<\/span><\/b><span style=\"font-size: 9pt; font-family: Arial;\">: el Mekong, el Ganges-Brahmaputra, Irrawaddy y Red. Una <b style=\"\"><span style=\"color: rgb(51, 102, 255);\">repentina aparici\u00f3n de casos de c\u00e1ncer<\/span><\/b> en el delta del Ganges-Brahmaputra (Bangladesh) alert\u00f3 a los<b style=\"\"><span style=\"color: rgb(51, 102, 255);\"> epidemi\u00f3logos por primera vez en 1980<\/span><\/b>: esta epidemia estaba<b style=\"\"><span style=\"color: rgb(51, 102, 255);\"> relacionada con el aumento del uso de pozos para abastecimiento de agua potable. El agua de los r\u00edos se infiltraba en el suelo, llegando hasta las aguas subterr\u00e1neas y acu\u00edferos<\/span><\/b> que los habitantes extraen mediante pozos para el abastecimiento de agua potable. As\u00ed fue c\u00f3mo se descubri\u00f3 qu\u00e9 <b style=\"\"><span style=\"color: rgb(51, 102, 255);\">sedimentos de origen natural con contenido en ars\u00e9nico se diluyen en los r\u00edos que fluyen hasta \u00e1reas densamente pobladas<\/span><\/b>.<o:p><\/o:p><\/span><\/p>\n<p class=\"MsoNormal\" style=\"text-align: justify;\"><span style=\"font-size: 9pt; font-family: Arial;\"><o:p>&nbsp;<\/o:p><\/span><\/p>\n<p class=\"MsoNormal\" style=\"text-align: justify;\"><b style=\"\"><span style=\"font-size: 9pt; font-family: Arial; color: rgb(51, 102, 255);\">La cuesti\u00f3n \u2014sin resolver hasta el momento\u2014 era averiguar c\u00f3mo el ars\u00e9nico, en lugar de permanecer qu\u00edmicamente atrapado en los sedimentos del r\u00edo, lograba liberarse para alcanzar estas aguas subterr\u00e1neas a m\u00e1s de 30 metros de profundidad<\/span><\/b><span style=\"font-size: 9pt; font-family: Arial;\">. Tras cinco a\u00f1os de investigaciones, estos cient\u00edficos <b style=\"\"><span style=\"color: rgb(51, 102, 255);\">han logrado resolver el enigma<\/span><\/b>, y actualmente trabajan con organismos pol\u00edticos reguladores para tratar de revertir el envenenamiento masivo. \u00abLa verdadera cuesti\u00f3n es \u00bf<b style=\"\"><span style=\"color: rgb(51, 102, 255);\">c\u00f3mo podemos ayudar a la gente que vive all\u00ed?\u00bb, declara Fendorf, edaf\u00f3logo de la<\/span><\/b> <a href=\"http:\/\/www.stanford.edu\/\">Universidad de Stanford.<\/a> \u00abPero primero hab\u00eda que entender el acoplamiento de los procesos hidrol\u00f3gicos, el modo en que fluye el agua, con la qu\u00edmica y la biolog\u00eda\u00bb. Tras un intento fallido en Bangladesh (una zona descartada por la dificultad que supon\u00eda generar modelos hidrol\u00f3gicos en una cuenca con numerosas perforaciones), el equipo de Fendorf realiz\u00f3 el estudio de campo en Camboya en la cuenca del r\u00edo Mekong. Perforaron<b style=\"\"><span style=\"color: rgb(51, 102, 255);\"> tres pozos a diferentes profundidades y realizaron pruebas de la disoluci\u00f3n de ars\u00e9nico, instalaron dispositivos para la toma de muestras de agua a distintas profundidades y elaboraron un modelo del ciclo de ars\u00e9nico en el delta del r\u00edo<\/span><\/b>. Llegaron a determinar que este qu\u00edmico migra en el mismo acu\u00edfero.<o:p><\/o:p><\/span><\/p>\n<p class=\"MsoNormal\" style=\"text-align: justify;\"><span style=\"font-size: 9pt; font-family: Arial;\"><o:p>&nbsp;<\/o:p><\/span><\/p>\n<p class=\"MsoNormal\" style=\"text-align: justify;\"><span style=\"font-size: 9pt; font-family: Arial;\">Descubrieron que<span style=\"color: green;\"> <b style=\"\">los responsables de la disoluci\u00f3n de ars\u00e9nico son unas bacterias que habitan en el suelo de la cuenca hidrogr\u00e1fica. El ars\u00e9nico, que viaja en los sedimentos que arrastran los r\u00edos desde los Himalayas, se encuentra adherido a part\u00edculas de \u00f3xidos de hierro. Al llegar al delta del r\u00edo, estas part\u00edculas cargadas de ars\u00e9nico se hallan enterradas por varias capas de suelo, en un ambiente anaerobio o sin ox\u00edgeno. Normalmente, las bacterias aerobias utilizan el ox\u00edgeno para respirar. Pero en un ambiente<\/b><\/span> <a href=\"http:\/\/es.wikipedia.org\/wiki\/Anaer%C3%B3bica\">anaer\u00f3bico<\/a>, <b style=\"\"><span style=\"color: green;\">las bacterias pueden utilizar otros productos qu\u00edmicos, incluyendo los \u00f3xidos de hierro que contiene adherido el ars\u00e9nico. Por tanto, las bacterias metabolizan el hierro y el ars\u00e9nico dando lugar a formas que se disuelven f\u00e1cilmente en agua<\/span><\/b>. \u00abEl ars\u00e9nico entra en el agua y<b style=\"\"><span style=\"color: green;\"> empieza el problema<\/span><\/b>\u00ab, explica Fendorf.<o:p><\/o:p><\/span><\/p>\n<p class=\"MsoNormal\"><span style=\"font-size: 9pt; font-family: Arial;\"><o:p>&nbsp;<\/o:p><\/span><\/p>\n<p class=\"MsoNormal\" style=\"text-align: justify;\"><b style=\"\"><span style=\"font-size: 9pt; font-family: Arial; color: rgb(51, 102, 255);\">La contaminaci\u00f3n por ars\u00e9nico se produce cerca de la superficie y tarda al menos 100 a\u00f1os en alcanzar el acu\u00edfero<\/span><\/b><span style=\"font-size: 9pt; font-family: Arial;\">. Este ciclo es un proceso natural que <b style=\"\"><span style=\"color: rgb(51, 102, 255);\">ha venido ocurriendo durante miles de a\u00f1os, antes de cualquier influencia humana<\/span><\/b>. Los resultados, publicados en la revista &#8216;<a href=\"http:\/\/www.nature.com\/\">Nature<\/a>&#8216;, c<b style=\"\"><span style=\"color: rgb(51, 102, 255);\">onfirman la hip\u00f3tesis de Fendorf: la contaminaci\u00f3n por ars\u00e9nico se produce cerca de la superficie y tarda al menos 100 a\u00f1os en alcanzar el acu\u00edfero<\/span><\/b>. El equipo de Stanford demostr\u00f3 que el ciclo del ars\u00e9nico en el acu\u00edfero es u<b style=\"\"><span style=\"color: rgb(51, 102, 255);\">n proceso natural <\/span><\/b>que ha venido ocurriendo durante miles de a\u00f1os, antes de cualquier influencia humana.<o:p><\/o:p><\/span><\/p>\n<p class=\"MsoNormal\" style=\"text-align: justify;\"><span style=\"font-size: 9pt; font-family: Arial;\"><o:p>&nbsp;<\/o:p><\/span><\/p>\n<p class=\"MsoNormal\" style=\"text-align: justify;\"><b style=\"\"><span style=\"font-size: 9pt; font-family: Arial; color: rgb(51, 102, 255);\">Entender la hidrolog\u00eda de las cuencas permitir\u00e1 instalar pozos estrat\u00e9gicamente ubicados<\/span><\/b><span style=\"font-size: 9pt; font-family: Arial;\"> en \u00e1reas libres de ars\u00e9nico disuelto. Y <b style=\"\"><span style=\"color: rgb(51, 102, 255);\">\u00bfqu\u00e9 suceder\u00eda si una poblaci\u00f3n necesita agua potable pero no puede hallar un lugar libre de ars\u00e9nico para instalar sus pozos?<\/span><\/b> Fendorf propone<b style=\"\"><span style=\"color: rgb(51, 102, 255);\"> varias soluciones como la instalaci\u00f3n de filtros de ars\u00e9nico, la recogida de agua de lluvia y la depuraci\u00f3n de las aguas superficiales. \u00abCada opci\u00f3n tiene ventajas y desventajas<\/span><\/b>\u00ab, explica. Con estos retos en mente, se han propuesto encontrar la mejor opci\u00f3n aldea por aldea. Han organizado encuentros de m\u00e1s de 60 expertos, incluidos funcionarios gubernamentales, acad\u00e9micos, organizaciones no gubernamentales y organismos de financiaci\u00f3n como el Banco Mundial.<o:p><\/o:p><\/span><\/p>\n<p class=\"MsoNormal\"><span style=\"font-size: 9pt; font-family: Arial;\"><o:p>&nbsp;<\/o:p><\/span><\/p>\n<p class=\"MsoNormal\"><span style=\"font-size: 9pt; font-family: Arial;\">Para saber m\u00e1s:<o:p><\/o:p><\/span><\/p>\n<p class=\"MsoNormal\"><span style=\"font-size: 9pt; font-family: Arial;\"><a href=\"http:\/\/news.stanford.edu\/pr\/2009\/pr-fendorf-040109.html\">Informaci\u00f3n en Stanford University News Release (en ingl\u00e9s)<\/a><o:p><\/o:p><\/span><\/p>\n<p class=\"MsoNormal\" style=\"text-align: justify;\"><b style=\"\"><span style=\"font-size: 9pt; font-family: Arial; color: green;\">Vanessa S\u00e1nchez es ambient\u00f3loga<\/span><\/b><span style=\"font-size: 9pt; font-family: Arial; color: green;\"> y trabaja en la <a href=\"http:\/\/www.fundacionglobalnature.org\/\"><span style=\"color: green;\">Fundaci\u00f3n Global Nature<\/span><\/a>.<o:p><\/o:p><\/span><\/p>\n<p class=\"MsoNormal\" style=\"text-align: justify;\"><span style=\"font-size: 9pt; font-family: Arial; color: green;\">(Las conclusiones y puntos de vista<\/span><span style=\"font-size: 9pt; font-family: Arial;\"> reflejados en este art\u00edculo son responsabilidad \u00fanicamente de su autor y no representan, comprometen, ni obligan a las instituciones a las que pertenece).<o:p><\/o:p><\/span><\/p>\n<p class=\"MsoNormal\"><span style=\"font-size: 9pt; font-family: Arial;\"><o:p>&nbsp;<\/o:p><\/span><\/p>\n<p class=\"MsoNormal\" style=\"text-align: justify;\"><span style=\"font-size: 14pt;\">&nbsp;<o:p><\/o:p><\/span><\/p>\n<p class=\"MsoNormal\"><span style=\"font-family: Arial;\"><a href=\"http:\/\/news.stanford.edu\/pr\/2009\/pr-fendorf-040109.html\"><span style=\"\" lang=\"EN-GB\">Stanford scientists find new solutions for the arsenic-poisoning crisis in Asia<\/span><\/a><\/span><span style=\"font-family: Arial;\" lang=\"EN-GB\"><o:p><\/o:p><\/span><\/p>\n<p class=\"MsoNormal\" style=\"text-align: justify;\"><span style=\"font-size: 9pt; font-family: Arial;\">Every day, more than <b style=\"\"><span style=\"color: rgb(51, 102, 255);\">140 million people in southern Asia drink groundwater contaminated with arsenic<\/span><\/b>. <b style=\"\"><span style=\"color: rgb(51, 102, 255);\">Thousands of people in Bangladesh, Cambodia, India, Myanmar and Vietnam die of cancer each year from chronic exposure to arsenic<\/span><\/b>, according to the World Health Organization. Some health experts call it <b style=\"\"><span style=\"color: rgb(51, 102, 255);\">the biggest mass poisoning in history<\/span><\/b>. <o:p><\/o:p><\/span><\/p>\n<p class=\"MsoNormal\" style=\"text-align: justify;\"><span style=\"font-size: 9pt; font-family: Arial;\"><o:p>&nbsp;<\/o:p><\/span><\/p>\n<p class=\"MsoNormal\" style=\"text-align: justify;\"><b style=\"\"><span style=\"font-size: 9pt; font-family: Arial; color: rgb(51, 102, 255);\" lang=\"EN-GB\">More than 15 years ago, scientists pinpointed the source of the contamination in the <\/span><\/b><st1:place><b style=\"\"><span style=\"font-size: 9pt; font-family: Arial; color: rgb(51, 102, 255);\" lang=\"EN-GB\">Himalaya Mountains<\/span><\/b><\/st1:place><b style=\"\"><span style=\"font-size: 9pt; font-family: Arial; color: rgb(51, 102, 255);\" lang=\"EN-GB\">, where sediments containing naturally occurring arsenic were carried downstream to heavily populated river basins below<\/span><\/b><span style=\"font-size: 9pt; font-family: Arial;\" lang=\"EN-GB\">. <b style=\"\"><span style=\"color: rgb(51, 102, 255);\">But one mystery remained: Instead of remaining chemically trapped in the river sediments, arsenic was somehow working its way into the groundwater more than 100 feet below the surfac<\/span><\/b>e. <\/span><span style=\"font-size: 9pt; font-family: Arial;\">Solving that mystery could have significant implications for policymakers trying to reverse the mass poisoning, said <b style=\"\"><span style=\"color: green;\">Stanford University soil scientist Scott Fendorf<\/span><\/b>. <o:p><\/o:p><\/span><\/p>\n<p class=\"MsoNormal\" style=\"text-align: justify;\"><b style=\"\"><span style=\"font-size: 9pt; font-family: Arial; color: rgb(51, 102, 255);\" lang=\"EN-GB\">\u00abHow does the arsenic go from being in the sediment loads, in solids, into the drinking water?\u00bb<\/span><\/b><span style=\"font-size: 9pt; font-family: Arial;\" lang=\"EN-GB\"> said Fendorf, a professor of environmental Earth system science and a senior fellow at Stanford&#8217;s Woods Institute for the Environment. <span style=\"\">&nbsp;<\/span><b style=\"\"><span style=\"color: rgb(51, 102, 255);\">To find out, he launched a field study in <\/span><\/b><\/span><st1:place><b style=\"\"><span style=\"font-size: 9pt; font-family: Arial; color: rgb(51, 102, 255);\" lang=\"EN-GB\">Asia<\/span><\/b><\/st1:place><b style=\"\"><span style=\"font-size: 9pt; font-family: Arial; color: rgb(51, 102, 255);\" lang=\"EN-GB\"> in 2004 with two Stanford colleagues<\/span><\/b><span style=\"font-size: 9pt; font-family: Arial;\" lang=\"EN-GB\">: Chris Francis, an assistant professor of geological and environmental sciences, and Karen Seto, now at <\/span><st1:place><st1:placename><span style=\"font-size: 9pt; font-family: Arial;\" lang=\"EN-GB\">Yale<\/span><\/st1:placename><span style=\"font-size: 9pt; font-family: Arial;\" lang=\"EN-GB\"> <\/span><st1:placetype><span style=\"font-size: 9pt; font-family: Arial;\" lang=\"EN-GB\">University<\/span><\/st1:placetype><\/st1:place><span style=\"font-size: 9pt; font-family: Arial;\" lang=\"EN-GB\">. <\/span><span style=\"font-size: 9pt; font-family: Arial;\">The initial study was funded with a two-year Woods Institute Environmental Venture Projects grant<b style=\"\"><span style=\"color: rgb(51, 102, 255);\">. Five years later, the research team appears to have solved the arsenic mystery<\/span><\/b> and is working with policymakers and government officials to prevent the health crisis from escalating. <\/span><span style=\"font-size: 9pt; font-family: Arial;\" lang=\"EN-GB\">\u00ab<b style=\"\"><span style=\"color: rgb(51, 102, 255);\">The real thing is, how do we help the people who are there?\u00bb <\/span><\/b><\/span><b style=\"\"><span style=\"font-size: 9pt; font-family: Arial; color: rgb(51, 102, 255);\">Fendorf said. \u00abBut first, we have to understand the <\/span><\/b><span style=\"font-size: 9pt; font-family: Arial;\">coupling of hydrology\u2014the way the water is flowing\u2014with the chemistry and biology.\u00bb <o:p><\/o:p><\/span><\/p>\n<p class=\"MsoNormal\" style=\"text-align: justify;\"><span style=\"font-size: 9pt; font-family: Arial;\"><o:p>&nbsp;<\/o:p><\/span><\/p>\n<p class=\"MsoNormal\" style=\"text-align: justify;\"><b style=\"\"><span style=\"font-size: 11pt; font-family: Arial; color: rgb(51, 153, 102);\">Finding a study site <o:p><\/o:p><\/span><\/b><\/p>\n<p class=\"MsoNormal\" style=\"text-align: justify;\"><b style=\"\"><span style=\"font-size: 9pt; font-family: Arial; color: rgb(51, 102, 255);\">Arsenic-laden rocks in the Himalayas feed into four major river systems: the Mekong, Ganges-Brahmaputra, Irrawaddy and Red. Epidemiologists first identified arsenic poisoning in the 1980s<\/span><\/b><span style=\"font-size: 9pt; font-family: Arial;\"> in the Ganges-Brahmaputra Delta in Bangladesh. The sudden occurrence of the <b style=\"\"><span style=\"color: rgb(51, 102, 255);\">disease was linked to the increased use of wells for drinking water<\/span><\/b>. <\/span><b style=\"\"><span style=\"font-size: 9pt; font-family: Arial; color: green;\" lang=\"EN-GB\">Scientists had long assumed that the contamination process occurred deep underground, in buried sediments that release arsenic into aquifers 100 to 130 feet below the surface. <\/span><\/b><b style=\"\"><span style=\"font-size: 9pt; font-family: Arial; color: green;\">But Fendorf and his colleagues had data suggesting otherwise<\/span><\/b><span style=\"font-size: 9pt; font-family: Arial;\">. <b style=\"\"><span style=\"color: green;\">They suspected that the arsenic actually dissolved at a much higher depth, very close to the surface. \u00abAs the water starts to move down into the soil, it picks up arsenic. That was our hypothesis<\/span><\/b>,\u00bb he said. <\/span><span style=\"font-size: 9pt; font-family: Arial;\" lang=\"EN-GB\">\u00abWe needed to f<b style=\"\"><span style=\"color: rgb(51, 102, 255);\">ollow the chemistry of the surface water as it moved down into the groundwater<\/span><\/b>.\u00bb Fendorf and his colleagues began their fieldwork in the Brahmaputra River basin of Bangladesh. <\/span><span style=\"font-size: 9pt; font-family: Arial;\">However, <b style=\"\"><span style=\"color: rgb(51, 102, 255);\">creating a hydrology model was a challenge, because <\/span><\/b>the landscape was dotted with irrigation wells that alter the natural path of water. \u00abWhen you draw out how the water might flow, it looks like spaghetti,\u00bb Fendorf explained. <\/span><span style=\"font-size: 9pt; font-family: Arial;\" lang=\"EN-GB\">\u00abBefore we even started we said there is no way this is going to be possible.\u00bb The researchers needed a less-developed site that was chemically, biologically and geologically similar to <\/span><st1:country-region><st1:place><span style=\"font-size: 9pt; font-family: Arial;\" lang=\"EN-GB\">Bangladesh<\/span><\/st1:place><\/st1:country-region><span style=\"font-size: 9pt; font-family: Arial;\" lang=\"EN-GB\">. <\/span><span style=\"font-size: 9pt; font-family: Arial;\">The Mekong River in Cambodia offered a perfect alternative. Its headwaters are only 100 miles away from those of the Brahmaputra River. \u00abAll the chemistry up in the Himalayas is similar,\u00bb Fendorf added. <\/span><span style=\"font-size: 9pt; font-family: Arial;\" lang=\"EN-GB\">\u00abThe transport down the big river system is very similar as well.\u00bb <\/span><span style=\"font-size: 9pt; font-family: Arial;\">More importantly, the Cambodia site was mostly undeveloped. \u00abCambodia had been under a 35-year civil war that had really repressed its development, so it was in essence Bangladesh 40 or 50 years ago,\u00bb he said. \u00abIn some ways it would actually be setting the clock back and getting a snapshot back in time. By virtue of having this more simplistic system, we could really track the entire water flow.\u00bb <o:p><\/o:p><\/span><\/p>\n<p class=\"MsoNormal\" style=\"text-align: justify;\"><span style=\"font-size: 9pt; font-family: Arial;\"><o:p>&nbsp;<\/o:p><\/span><\/p>\n<p class=\"MsoNormal\" style=\"text-align: justify;\"><b style=\"\"><span style=\"font-size: 11pt; font-family: Arial; color: teal;\">Field results <o:p><\/o:p><\/span><\/b><\/p>\n<p class=\"MsoNormal\" style=\"text-align: justify;\"><span style=\"font-size: 9pt; font-family: Arial;\">The new field site was located just south of Cambodia&#8217;s capital, Phnom Penh. Fendorf hired local workers to <b style=\"\"><span style=\"color: rgb(51, 102, 255);\">drill wells at three different depths<\/span><\/b> throughout the 20-square-mile site. <b style=\"\"><span style=\"color: rgb(51, 102, 255);\">Testing the water for dissolved arsenic at various depths allowed the researchers to pinpoint where the toxin was migrating into the aquifer<\/span><\/b>. To observe <b style=\"\"><span style=\"color: rgb(51, 102, 255);\">solids, they also installed water-sampling devices a foot or two below the surface<\/span><\/b>. The data they collected allowed them to put together a model of arsenic cycling in the river delta. <o:p><\/o:p><\/span><\/p>\n<p class=\"MsoNormal\" style=\"text-align: justify;\"><span style=\"font-size: 9pt; font-family: Arial;\"><o:p>&nbsp;<\/o:p><\/span><\/p>\n<p class=\"MsoNormal\" style=\"text-align: justify;\"><span style=\"font-size: 9pt; font-family: Arial;\">\u00ab<b style=\"\"><span style=\"color: rgb(51, 102, 255);\">We found out that, sure enough, within the first 2 to 3 feet from the surface, arsenic was coming out of the solids\u2014that is, the sediments transported down from the Himalayas<\/span><\/b>\u2014and into the water, <b style=\"\"><span style=\"color: rgb(51, 102, 255);\">and then it migrated down into the aquifer,\u00bb Fendorf said. Aquifers are the source of drinking water <\/span><\/b>for people who use wells throughout Cambodia, Bangladesh, Myanmar, India and Vietnam. <\/span><span style=\"font-size: 9pt; font-family: Arial;\" lang=\"EN-GB\">The culprits <b style=\"\"><span style=\"color: green;\">responsible for dissolving the arsenic turned out to be bacteria that live in the soil and sediment of the river basin<\/span><\/b>. <\/span><span style=\"font-size: 9pt; font-family: Arial;\">The researchers discovered that a<b style=\"\"><span style=\"color: green;\">rsenic flowing down the river from the Himalayas sticks to rust particles called iron oxides. Upon reaching the river delta, these arsenic-laden particles are buried by several layers of soil, creating an oxygen-free, or anaerobic, environment<\/span><\/b>. <b style=\"\"><span style=\"color: green;\">Normally, bacteria use oxygen to breathe. But in an anaerobic environment, they can use other chemicals, including rust and arsenic<\/span><\/b>. <b style=\"\"><span style=\"color: green;\">As the bacteria metabolize the iron and arsenic, they convert it to a form that readily dissolves in water<\/span><\/b>. <o:p><\/o:p><\/span><\/p>\n<p class=\"MsoNormal\" style=\"text-align: justify;\"><span style=\"font-size: 9pt; font-family: Arial;\"><o:p>&nbsp;<\/o:p><\/span><\/p>\n<p class=\"MsoNormal\" style=\"text-align: justify;\"><span style=\"font-size: 9pt; font-family: Arial;\" lang=\"EN-GB\">\u00abAs <b style=\"\"><span style=\"color: green;\">these sediments get buried very rapidly, th<\/span>e<span style=\"color: green;\"> bacteria go through an anaerobic metabolism that dissolves the iron minerals and the arsenic<\/span><\/b> with it,\u00bb Fendorf said. \u00abThe arsenic goes <b style=\"\"><span style=\"color: green;\">into the water and the problem starts<\/span><\/b>.\u00bb The results, published in the <b style=\"\"><span style=\"color: rgb(51, 102, 255);\">journal Nature, confirmed Fendorf&#8217;s hypothesis<\/span><\/b>: <b style=\"\"><span style=\"color: green;\">Arsenic contamination was occurring near the surface and, in fact, would take at least 100 years to reach the aquifer below<\/span><\/b>. <\/span><span style=\"font-size: 9pt; font-family: Arial;\">The Stanford team also showed that the <b style=\"\"><span style=\"color: green;\">100-year-scale cycling <\/span><\/b>of arsenic into the aquifer was a natural process t<b style=\"\"><span style=\"color: green;\">hat had been occurring for thousands of years, preceding any human influence<\/span><\/b>. \u00abWe showed that there is a perpetual source of arsenic that replenishes from the surface,\u00bb Fendorf said. <o:p><\/o:p><\/span><\/p>\n<p class=\"MsoNormal\" style=\"text-align: justify;\"><span style=\"font-size: 9pt; font-family: Arial;\"><o:p>&nbsp;<\/o:p><\/span><\/p>\n<p class=\"MsoNormal\" style=\"text-align: justify;\"><b style=\"\"><span style=\"font-size: 11pt; font-family: Arial; color: teal;\">Solutions to the crisis <o:p><\/o:p><\/span><\/b><\/p>\n<p class=\"MsoNormal\" style=\"text-align: justify;\"><b style=\"\"><span style=\"font-size: 9pt; font-family: Arial; color: rgb(51, 102, 255);\">Understanding the area&#8217;s hydrology will allow developers to strategically install wells that draw from areas free of dissolved arsenic, providing clean, drinkable water<\/span><\/b><span style=\"font-size: 9pt; font-family: Arial;\">. Such targeted excavation can be extremely accurate, Fendorf said. <\/span><span style=\"font-size: 9pt; font-family: Arial;\" lang=\"EN-GB\">But what if a village needs a well but is unable to find an arsenic-free location to install it?<b style=\"\"><span style=\"color: rgb(51, 102, 255);\"> <\/span><\/b><\/span><b style=\"\"><span style=\"font-size: 9pt; font-family: Arial; color: rgb(51, 102, 255);\">Fendorf has proposed several solutions<\/span><\/b><span style=\"font-size: 9pt; font-family: Arial;\">, including <b style=\"\"><span style=\"color: rgb(51, 102, 255);\">installing arsenic filters, collecting rainwater and purifying surface water<\/span><\/b>. <b style=\"\"><span style=\"color: rgb(51, 102, 255);\">Each option has pros and cons, he said. <\/span><\/b><\/span><b style=\"\"><span style=\"font-size: 9pt; font-family: Arial; color: rgb(51, 102, 255);\" lang=\"EN-GB\">Filtering arsenic from<\/span><\/b><span style=\"font-size: 9pt; font-family: Arial;\" lang=\"EN-GB\"> well water raises the problem of how to dispose of leftover waste. <\/span><span style=\"font-size: 9pt; font-family: Arial;\">\u00abThere aren&#8217;t hazardous waste landfill sites,\u00bb he noted. Additionally, the filter approach requires a dependable monitoring system. \u00abIf you do have a failure of the filter, how do you know when it occurs, and how are you going to be testing for that?\u00bb he asked<b style=\"\"><span style=\"color: rgb(51, 102, 255);\">. <\/span><\/b><\/span><b style=\"\"><span style=\"font-size: 9pt; font-family: Arial; color: rgb(51, 102, 255);\" lang=\"EN-GB\">Harvesting rainwater with collection tanks or <\/span><\/b><span style=\"font-size: 9pt; font-family: Arial;\" lang=\"EN-GB\">rooftop gutters can be effective in certain locations and for certain people, he said. <\/span><span style=\"font-size: 9pt; font-family: Arial;\">B<b style=\"\"><span style=\"color: rgb(51, 102, 255);\">ut areas with longer dry seasons require big tanks that <\/span><\/b>are often too expensive. \u00abThese are areas where people are making less than $2 a day,\u00bb Fendorf noted. <\/span><b style=\"\"><span style=\"font-size: 9pt; font-family: Arial; color: rgb(51, 102, 255);\" lang=\"EN-GB\">Another option is to use a disinfectant to purify surface water collected from ponds or rivers<\/span><\/b><span style=\"font-size: 9pt; font-family: Arial;\" lang=\"EN-GB\">. <\/span><b style=\"\"><span style=\"font-size: 9pt; font-family: Arial; color: rgb(51, 102, 255);\">The problem,<\/span><\/b><span style=\"font-size: 9pt; font-family: Arial;\"> he said,<b style=\"\"><span style=\"color: rgb(51, 102, 255);\"> is<\/span><\/b> that the filters have to be very cheap and easy to use. <b style=\"\"><span style=\"color: rgb(51, 102, 255);\">To solve the problem, Fendorf has been collaborating with<\/span><\/b> Resource Development International (RDI), a non-governmental organization in Cambodia that <b style=\"\"><span style=\"color: rgb(51, 102, 255);\">makes affordable filters from locally discarded clay and rice hulls<\/span><\/b>. <\/span><span style=\"font-size: 9pt; font-family: Arial;\" lang=\"EN-GB\">With these challenges in mind, Fendorf and Stanford post-doctoral scholar Matt Polizzotto have <b style=\"\"><span style=\"color: rgb(51, 102, 255);\">proposed finding the best option on a village-by-village basis<\/span><\/b>. <o:p><\/o:p><\/span><\/p>\n<p class=\"MsoNormal\" style=\"text-align: justify;\"><span style=\"font-size: 9pt; font-family: Arial;\" lang=\"EN-GB\"><o:p>&nbsp;<\/o:p><\/span><\/p>\n<p class=\"MsoNormal\" style=\"text-align: justify;\"><span style=\"font-size: 9pt; font-family: Arial;\" lang=\"EN-GB\">Beginning <b style=\"\"><span style=\"color: rgb(51, 102, 255);\">March 24, Fendorf will co-host a four-day meeting on arsenic poisoning in Siam Reap, Cambodia, with about 60 experts, including<\/span><\/b> government officials, scholars, NGOs and funding agencies, such as the World Bank. <\/span><span style=\"font-size: 9pt; font-family: Arial;\">The meeting was convened by the American Geophysical Union and the Woods Institute. <\/span><span style=\"font-size: 9pt; font-family: Arial;\" lang=\"EN-GB\">\u00abThe first three days will be devoted to the arsenic groundwater problem,\u00bb Fendorf said. <\/span><span style=\"font-size: 9pt; font-family: Arial;\">\u00ab<b style=\"\"><span style=\"color: rgb(51, 102, 255);\">We hope to converge on a resolution, as a scientific body, on what we agree about the problem, what remains unresolved and what needs to be done to fill the gap<\/span><\/b>.<b style=\"\"><span style=\"color: rgb(51, 102, 255);\"> The final day <\/span><\/b>of the meeting will look more<b style=\"\"><span style=\"color: rgb(51, 102, 255);\"> holistically at the water problem<\/span><\/b>, examining best options for bringing safe drinking water to the populace.\u00bb <o:p><\/o:p><\/span><\/p>\n<p class=\"MsoNormal\" style=\"text-align: justify;\"><span style=\"font-size: 9pt; font-family: Arial;\"><o:p>&nbsp;<\/o:p><\/span><\/p>\n<p class=\"MsoNormal\" style=\"text-align: justify;\"><b style=\"\"><span style=\"font-size: 11pt; font-family: Arial; color: teal;\">Land-use changes <o:p><\/o:p><\/span><\/b><\/p>\n<p class=\"MsoNormal\" style=\"text-align: justify;\"><span style=\"font-size: 9pt; font-family: Arial;\">According to Fendorf, the new understanding of arsenic cycling comes at a critical time for Cambodia, which is finally recovering from years of political unrest and is looking to bolster its economy by installing wells for drinking water and irrigation, and excavating soil to make roads and bricks. Such <b style=\"\"><span style=\"color: rgb(51, 102, 255);\">land-use changes could affect arsenic flow patterns throughout the delta<\/span><\/b>, he warned, although in some cases, this may not be a bad thing. \u00ab<b style=\"\"><span style=\"color: rgb(51, 102, 255);\">The land-use changes will definitely modify the arsenic levels<\/span><\/b>,\u00bb he said. <\/span><span style=\"font-size: 9pt; font-family: Arial;\" lang=\"EN-GB\">\u00abSometimes they might increase the level, and sometimes they might decrease it, depending on where they are situated and what the surrounding environment is like.\u00bb Although Fendorf and his colleagues came to <\/span><st1:country-region><st1:place><span style=\"font-size: 9pt; font-family: Arial;\" lang=\"EN-GB\">Cambodia<\/span><\/st1:place><\/st1:country-region><span style=\"font-size: 9pt; font-family: Arial;\" lang=\"EN-GB\"> focused on understanding the science of arsenic contamination, they soon realized that what mattered most was the potential to make a difference in the lives of individuals. <\/span><span style=\"font-size: 9pt; font-family: Arial;\">For example, the researchers tested each well they drilled for arsenic contamination. If it tested clean, they installed an additional well for domestic use and offered it to the landowner. If a well proved contaminated, the researchers would buy the landowner a rainwater-harvesting unit locally made by RDI. <\/span><span style=\"font-size: 9pt; font-family: Arial;\" lang=\"EN-GB\">\u00ab<b style=\"\"><span style=\"color: rgb(51, 102, 255);\">If we can give people a clean well or a rainwater harvesting unit<\/span><\/b>, that&#8217;s going to go a lot further, in the short term at least, than any of our study results,\u00bb Fendorf said. Chelsea Anne Young is a former science-writing intern at the Stanford News Service. <o:p><\/o:p><\/span><\/p>\n","protected":false},"excerpt":{"rendered":"<p>El viernes, 22 de mayo de 2009, Blog el Agua, compa\u00f1ero de este sistema de Bit\u00e1coras edit\u00f3 un interesant\u00edsimo post que llevaba por t\u00edtulo Ars\u00e9nico y aguas subterr\u00e1neas en Asia. Este, recoge casi literalmente una muy buena traducci\u00f3n al castellano de la noticia aparecida inicialmente en el portal soitu.es Medioambiente que reproducimos abajo, y que fue firmada por Vanesa S\u00e1nchez. Con estas traducciones da gusto, al contrario de las que solemos padecer en la prensa espa\u00f1ola. Gracias Vanesa. Para mi sorpresa, resulta que las bacterias del suelo, se encontraban implicadas en un drama que afecta a m\u00e1s de 140 millones\u2026<\/p>\n","protected":false},"author":26,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"ngg_post_thumbnail":0},"categories":[596,594,612,591,599,587,592,611],"tags":[],"blocksy_meta":{"styles_descriptor":{"styles":{"desktop":"","tablet":"","mobile":""},"google_fonts":[],"version":4}},"aioseo_notices":[],"_links":{"self":[{"href":"https:\/\/www.madrimasd.org\/blogs\/universo\/wp-json\/wp\/v2\/posts\/119362"}],"collection":[{"href":"https:\/\/www.madrimasd.org\/blogs\/universo\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.madrimasd.org\/blogs\/universo\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.madrimasd.org\/blogs\/universo\/wp-json\/wp\/v2\/users\/26"}],"replies":[{"embeddable":true,"href":"https:\/\/www.madrimasd.org\/blogs\/universo\/wp-json\/wp\/v2\/comments?post=119362"}],"version-history":[{"count":2,"href":"https:\/\/www.madrimasd.org\/blogs\/universo\/wp-json\/wp\/v2\/posts\/119362\/revisions"}],"predecessor-version":[{"id":134921,"href":"https:\/\/www.madrimasd.org\/blogs\/universo\/wp-json\/wp\/v2\/posts\/119362\/revisions\/134921"}],"wp:attachment":[{"href":"https:\/\/www.madrimasd.org\/blogs\/universo\/wp-json\/wp\/v2\/media?parent=119362"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.madrimasd.org\/blogs\/universo\/wp-json\/wp\/v2\/categories?post=119362"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.madrimasd.org\/blogs\/universo\/wp-json\/wp\/v2\/tags?post=119362"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}