The kinetics of the PuO to PuO conversion.

In an oxidizing environment, the oxide formed on plutonium (Pu) metal is composed of a plutonium dioxide (PuO) top layer and a thin cubic plutonium sesquioxide (PuO) middle layer. In a reducing environment, the PuO layer auto-reduces to cubic PuO. The speed and extent of this conversion depend on the combination of temperature and time.

Ancient and methane-derived carbon subsidizes contemporary food webs.

While most global productivity is driven by modern photosynthesis, river ecosystems are supplied by locally fixed and imported carbon that spans a range of ages. Alluvial aquifers of gravel-bedded river floodplains present a conundrum: despite no possibility for photosynthesis in groundwater and extreme paucity of labile organic carbon, they support diverse and abundant large-bodied consumers (stoneflies, Insecta: Plecoptera). Here we show that up to a majority of the biomass carbon composition of these top consumers in four floodplain aquifers of Montana and Washington is methane-derived.