Release of oxidizing fluids in subduction zones recorded by iron isotope zonation in garnet

Subduction zones are key regions of chemical and mass transfer between the Earth’s surface and mantle. During subduction, oxidized material is carried into the mantle and large amounts of water are released due to the breakdown of hydrous minerals such as lawsonite. Dehydration accompanied by the release of oxidizing species may play a key role in controlling redox changes in the subducting slab and overlying mantle wedge. Here we present measurements of oxygen fugacity, using garnet–epidote oxybarometry, together with analyses of the stable iron isotope composition of zoned garnets from Sifnos, Greece. We find that the garnet interiors grew under relatively oxidized conditions whereas garnet rims record more reduced conditions. Garnet δ56Fe increases from core to rim as the system becomes more reduced. Thermodynamic analysis shows that this change from relatively oxidized to more reduced conditions occurred during lawsonite dehydration. We conclude that the garnets maintain a record of progressive dehydration and that the residual mineral assemblages within the slab became more reduced during progressive subduction-zone dehydration. This is consistent with the hypothesis that lawsonite dehydration accompanied by the release of oxidizing species, such as sulfate, plays an important and measurable role in the global redox budget and contributes to sub-arc mantle oxidation in subduction zones

Reducing dose omission of prescribed medications in the hospital setting: a narrative review

© 2016, Springer International Publishing Switzerland.Medication error, including dose omission of prescribed medications, can lead to adverse outcomes for hospital patients. Consequently, there is an onus on healthcare staff to understand the causes of these errors and introduce proven methods to prevent their recurrence. This paper presents a review of the literature on the reported causes of, and suggested solutions to, omitted administration of prescribed medications in hospital inpatient settings. Dose omission of prescribed medication has been shown to be one of the commonest causes of medication error in inpatient populations. Unavailable medication, poor communication and poor documentation of administered medications are commonly cited explanations. Institutions have implemented strategies, which have been shown to reduce the incidence of omissions. Such strategies include changing pharmacy processes to ensure medication is available when required; introducing electronic prescribing; encouraging improved communication between healthcare professionals involved in medication management; and educating staff about the importance of administering all prescribed medications, documenting when medications are administered and reporting all medication omissions