{"created":"2023-05-15T14:44:37.927916+00:00","id":61015,"links":{},"metadata":{"_buckets":{"deposit":"b4dc8eb2-3968-476b-9930-35a8e8aa31ef"},"_deposit":{"created_by":1,"id":"61015","owners":[1],"pid":{"revision_id":0,"type":"depid","value":"61015"},"status":"published"},"_oai":{"id":"oai:repo.qst.go.jp:00061015","sets":["10:29"]},"author_link":["604710","604708","604711","604709","604706","604707"],"item_10005_date_7":{"attribute_name":"発表年月日","attribute_value_mlt":[{"subitem_date_issued_datetime":"2004-11-16","subitem_date_issued_type":"Issued"}]},"item_10005_description_5":{"attribute_name":"抄録","attribute_value_mlt":[{"subitem_description":"Technetium-99 (99Tc) is produced by thermal fission of 235U and 239Pu with a yield of 6%, making 99Tc relatively high in abundance among fission products.  In addition, the half-life of 99Tc is very long (2.1 * 10^5 y).  Under aerobic conditions, Tc is present in the heptavalent form as pertechnetate (TcO4-).  This chemical species is soluble and mobile in the environment and is readily taken up by plants [1].  Especially the uptake of Tc by rice is a serious issue in the transfer of 99Tc to humans.  Therefore, we would like to be able to predict the behavior of 99Tc in agricultural environments.  Recently, we found that soluble TcO4- was changed to insoluble forms in ponding water in paddy soil [2] and that the formation of insoluble Te was mainly caused by bacteria [3].  In the above experiments 0.3% glucose water was used for flooding the paddy soil to demonstrate the possibility of the formation of insoluble Tc.  Paddy fields in nature, however, are not flooded by glucose water even though there are other sources of organic carbon.  Our aim in this study was to determine relative amounts of insoluble Tc in ponding water without the addition of glucose.\nPaddy soil containing Tc insolubilizing bacteria [3] was collected from Koriyama City, Japan.  The soil was air-dried and passed through a 2-mm-mesh sieve.  For flooding, five grams of the air-dried soil was put in a polypropylene tube and then filled with 7.5 mL of autoclaved deionized water.The flooded soil was incubated for 120 days at 25?C.  During the incubation period, 1 mL of the ponding water was collected every week.  After collection, samples were supplemented with autoclaved deionized water to maintain the initial volume of flooding.  In order to determine relative amounts of insoluble Tc, each collected sample was incubated for 14 days following the addition of 99TcO4-.  After incubating for 0, 4, 7, and 14 days, a part of the sample was passed through a 0.2-um-pore size filter to separate insoluble Tc.The relative amount of insoluble Tc was calculated by dividing \"the radioactivity of 99Tc at each sampling time\" by \"the 99Tc radioactivity at day 0\".  The radioactivity of 99Tc was measured with a liquid scintillation counter.\nVariations in the relative amounts of insoluble Tc were small for 120 days of flooding.  For 4-day incubation samples with different flooding periods, the average value of the relative amounts of the insoluble Tc was 0.2% of the total 99Tc.  Similar results were observed for the samples after incubating for 7 and 14 days.  These data indicate a slight formation of insoluble Tc in the ponding water, although Tc insolubilizing bacteria were present in the used paddy soil [3].  It was hypothesized that the reason for the slight formation of insoluble Tc was aerobic conditions or low metabolic activity of bacteria in the ponding water.  To clarify the reason, three subsamples were prepared using the ponding water of 120 days' flooding: 1) an untreated sample (control), 2) a sample incubated under anaerobic conditions (anaerobic culture), and 3) a sample with organic substrates added to promote bacterial activity (promote culture).  These subsamples were also incubated for 14 days following the addition of 99Tc.  A slight formation of insoluble Tc was observed in the control and even in the anaerobic culture, although it is known that soluble Tc changes to insoluble forms under anaerobic conditions [4].  A significant increase in the relative amount of insoluble Tc, however, was observed in the promote culture.  These results suggested that Tc-insolubilizing bacteria were present in the water column sample but their low metabolic activity resulted in the slight formation of insoluble Tc.  Insoluble Tc formation in the water column above paddy fields would depend on bacterial metabolic activity.\n\\nReferences\n[1] R.E. Wildung, T.R. Garland, and D.A. Cataldo, Health Phys. 32, 314 (1977).\n[2] N. Ishii, K. Tagami, and S. Uchida, Chemosphere. (in press).\n[3] N. Ishii, and K. Tagami, Radioisotopes. 52. 475 (2003).\n[4] Henrot, Health Phys. 57, 239 (1989).","subitem_description_type":"Abstract"}]},"item_10005_description_6":{"attribute_name":"会議概要（会議名, 開催地, 会期, 主催者等）","attribute_value_mlt":[{"subitem_description":"the Fourth International Symposium on Advanced Science Research","subitem_description_type":"Other"}]},"item_access_right":{"attribute_name":"アクセス権","attribute_value_mlt":[{"subitem_access_right":"metadata only access","subitem_access_right_uri":"http://purl.org/coar/access_right/c_14cb"}]},"item_creator":{"attribute_name":"著者","attribute_type":"creator","attribute_value_mlt":[{"creatorNames":[{"creatorName":"Ishii, Nobuyoshi"}],"nameIdentifiers":[{"nameIdentifier":"604706","nameIdentifierScheme":"WEKO"}]},{"creatorNames":[{"creatorName":"Koiso, Hiroyuki"}],"nameIdentifiers":[{"nameIdentifier":"604707","nameIdentifierScheme":"WEKO"}]},{"creatorNames":[{"creatorName":"Uchida, Shigeo"}],"nameIdentifiers":[{"nameIdentifier":"604708","nameIdentifierScheme":"WEKO"}]},{"creatorNames":[{"creatorName":"石井 伸昌","creatorNameLang":"en"}],"nameIdentifiers":[{"nameIdentifier":"604709","nameIdentifierScheme":"WEKO"}]},{"creatorNames":[{"creatorName":"小礒 寛之","creatorNameLang":"en"}],"nameIdentifiers":[{"nameIdentifier":"604710","nameIdentifierScheme":"WEKO"}]},{"creatorNames":[{"creatorName":"内田 滋夫","creatorNameLang":"en"}],"nameIdentifiers":[{"nameIdentifier":"604711","nameIdentifierScheme":"WEKO"}]}]},"item_language":{"attribute_name":"言語","attribute_value_mlt":[{"subitem_language":"eng"}]},"item_resource_type":{"attribute_name":"資源タイプ","attribute_value_mlt":[{"resourcetype":"conference object","resourceuri":"http://purl.org/coar/resource_type/c_c94f"}]},"item_title":"Formation of insoluble Tc depending on bacterial activity","item_titles":{"attribute_name":"タイトル","attribute_value_mlt":[{"subitem_title":"Formation of insoluble Tc depending on bacterial activity"}]},"item_type_id":"10005","owner":"1","path":["29"],"pubdate":{"attribute_name":"公開日","attribute_value":"2005-07-05"},"publish_date":"2005-07-05","publish_status":"0","recid":"61015","relation_version_is_last":true,"title":["Formation of insoluble Tc depending on bacterial activity"],"weko_creator_id":"1","weko_shared_id":-1},"updated":"2023-05-15T21:47:11.156582+00:00"}