Biogeochemical Cycling of Tc in Alkaline Sediments.

Tc will be present in significant quantities in radioactive wastes including intermediate-level waste (ILW). The internationally favored concept for disposing of higher activity radioactive wastes including ILW is via deep geological disposal in an underground engineered facility located ∼200-1000 m deep. Typically, in the deep geological disposal environment, the subsurface will be saturated, cement will be used extensively as an engineering material, and iron will be ubiquitous.

Microbial Degradation of Citric Acid in Low Level Radioactive Waste Disposal: Impact on Biomineralization Reactions.

Organic complexants are present in some radioactive wastes and can challenge waste disposal as they may enhance subsurface mobility of radionuclides and contaminant species via chelation. The principal sources of organic complexing agents in low level radioactive wastes (LLW) originate from chemical decontamination activities. Polycarboxylic organic decontaminants such as citric and oxalic acid are of interest as currently there is a paucity of data on their biodegradation at high pH and under disposal conditions.

Enhanced microbial degradation of irradiated cellulose under hyperalkaline conditions.

Intermediate-level radioactive waste includes cellulosic materials, which under the hyperalkaline conditions expected in a cementitious geological disposal facility (GDF) will undergo abiotic hydrolysis forming a variety of soluble organic species. Isosaccharinic acid (ISA) is a notable hydrolysis product, being a strong metal complexant that may enhance the transport of radionuclides to the biosphere. This study showed that irradiation with 1 MGy of γ-radiation under hyperalkaline conditions enhanced the rate of ISA production from the alkali hydrolysis of cellulose, indicating that radionuclide mobilisation to the biosphere may occur faster than previously anticipated.

Impact of the electron donor on in situ microbial nitrate reduction in Opalinus Clay: results from the Mont Terri rock laboratory (Switzerland).

At the Mont Terri rock laboratory (Switzerland), an in situ experiment is being carried out to examine the fate of nitrate leaching from nitrate-containing bituminized radioactive waste, in a clay host rock for geological disposal. Such a release of nitrate may cause a geochemical perturbation of the clay, possibly affecting some of the favorable characteristics of the host rock. In this in situ experiment, combined transport and reactivity of nitrate is studied inside anoxic and water-saturated chambers in a borehole in the Opalinus Clay.

Therapeutic Pneumoperitoneum: Relevant or Obsolete in 2015?

 Therapeutic pneumoperitoneum (TP) is one alternative to manage pleural space problems. We describe our technique and experience.  Medical records of all patients who underwent TP from January 1, 2007, to January 1, 2015, were reviewed after Institutional Review Board approval.

The impact of γ radiation on the bioavailability of Fe(III) minerals for microbial respiration.

Conservation of energy by Fe(III)-reducing species such as Shewanella oneidensis could potentially control the redox potential of environments relevant to the geological disposal of radioactive waste and radionuclide contaminated land. Such environments will be exposed to ionizing radiation so characterization of radiation alteration to the mineralogy and the resultant impact upon microbial respiration of iron is essential. Radiation induced changes to the iron mineralogy may impact upon microbial respiration and, subsequently, influence the oxidation state of redox-sensitive radionuclides.

Alteration of sediments by hyperalkaline K-rich cement leachate: implications for strontium adsorption and incorporation.

Results are presented from 1 year batch experiments where K-rich hyperalkaline pH 13.5 young cement water (YCW) was reacted with sediments to investigate the effect of high pH, mineral alteration, and secondary mineral precipitation on (90)Sr sorption. After reaction with YCW, Sr sorption was found to be greater than 75% in all samples up to 365 days and 98% in a sample reacted for 365 days at 70 °C.