Seasonal changes of redox potential and microbial activity in two agricultural soils of tropical Australia: some implications for soil-to-plant transfer of radionuclides

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dc.contributor.authorTwining, JRen_AU
dc.contributor.authorZaw, Men_AU
dc.contributor.authorRussell, RAen_AU
dc.contributor.authorWilde, KLen_AU
dc.date.accessioned2024-02-22T23:30:14Zen_AU
dc.date.available2024-02-22T23:30:14Zen_AU
dc.date.issued2004-05-14en_AU
dc.date.statistics2024-02-20en_AU
dc.description.abstractVery little is known of the factors controlling soil-to-plant transfer of radionuclides in tropical environments. As part of an IAEA/FAO coordinated research project (CRP) designed to elucidate some of those factors, near-surface samples of two agricultural red-earth soils (Blain and Tippera) were collected from a study site in the Northern Territory. The climate is tropical monsoonal with crops being grown over the wet season from December to March/April. It is important to understand soil variables that may be related to this dramatic seasonality. In this investigation, soil redox state and microbial populations were assessed before and after the growing season with a view to generating hypotheses for future evaluation. The X-ray absorption near edge structure (XANES) technique was used to determine overall changes in the solid-state redox speciation of Fe and Mn in soils across the growing period. Fe speciation did not change but approximately 10% of the total Mn was oxidised from Mn(II) to Mn(III) and Mn(IV) in both soils between October 1999 and April 2000. An apparent disconnect between Fe and Mn was not unexpected given the >10 times higher concentration of Fe in the soils compared with Mn. These results have implications for the bioavailability of redox sensitive radionuclides such as Tc and Pu. Similarly, microbial population estimates were derived before and after the growing period. Total bacterial populations did not vary from 106 to 107 colonies per gram. Fungal populations increased over the growing season from 3–6×105 to 1–4×106 colonies per gram of soil. Fungi have the potential to decrease soil pH and hence increase the bioavailability of radionuclides such as Cs. In addition, fungi act to facilitate plant nutrition. This could lead to enhanced accumulation of nutrient analogues (e.g. Sr and Ra for Ca; Tc for Mn), but this effect may be masked by improved biomass production. © 2004 Elsevier Ltden_AU
dc.description.sponsorshipThe authors would like to acknowledge Mr Peter Shotton and the NT Department of Primary Industries and Fisheries who operate the research farm and permitted our access to its facilities. This work was performed at the ANBF with support from the Australian Synchrotron Research Program (ASRP), which is funded by the Commonwealth of Australia under the Major National Research Facilities Program. The authors also thank ASRP and ANBF staff for their assistance and Valerie Sadler provided technical assistance at ANSTO.en_AU
dc.identifier.citationTwining, J. R., Zaw, M., Russell, R., & Wilde, K. (2004). Seasonal changes of redox potential and microbial activity in two agricultural soils of tropical Australia: some implications for soil-to-plant transfer of radionuclides. Journal of environmental radioactivity, 76(1-2), 265-272. doi:10.1016/j.jenvrad.2004.03.031en_AU
dc.identifier.issn0265-931Xen_AU
dc.identifier.issue1-2en_AU
dc.identifier.journaltitleJournal of environmental radioactivityen_AU
dc.identifier.pagination265-272en_AU
dc.identifier.urihttps://apo.ansto.gov.au/handle/10238/15397en_AU
dc.identifier.volume76en_AU
dc.language.isoenen_AU
dc.publisherElsevieren_AU
dc.relation.urihttps://doi.org/10.1016/j.jenvrad.2004.03.031en_AU
dc.subjectRedox potentialen_AU
dc.subjectSoilsen_AU
dc.subjectAgricultureen_AU
dc.subjectAustraliaen_AU
dc.subjectTropical Regionsen_AU
dc.subjectRadioisotopesen_AU
dc.subjectMicroorganismsen_AU
dc.subjectSeasonal variationsen_AU
dc.subjectRadionuclide kineticsen_AU
dc.titleSeasonal changes of redox potential and microbial activity in two agricultural soils of tropical Australia: some implications for soil-to-plant transfer of radionuclidesen_AU
dc.typeJournal Articleen_AU
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