Arsenic (As) regeneration from sediments of Spy Pond, a two-basin lake near Boston, MA, continues to result in seasonally elevated As levels despite the several decades that have elapsed since the pond's historical contamination by a pulse input of As. Solid-phase speciation and partitioning of As in the sediments appear to be primary determinants of both potential As regeneration rate and, con...

landfill leachates and leachate sediments were investigated in order to survey the discharge of uranium (u) from municipal solid waste (msw) landfills and municipal solid waste incinerator (mswi) bottom ash landfills. concentrations of u in the leachates were as high as or higher than concentrations of cd, a metal more often discussed when considering the environmental effects of landfill leach...

This article reviews investigations on the formation of inhomogeneous ferrous (FeII) and ferric (FeIII) oxides in aqueous solution. These globally abundant materials are important extensive fields research including corrosion steels, mineralogy, environmental remediation, biochemistry. Iron polycations consisting FeII FeIII ions bridged by hydroxyl groups oxyanions. Solution conditions such as ...

Assessing the extent to which population subdivision during cladogenesis is necessary for long-term phenotypic evolution is of fundamental importance in a broad range of biological disciplines. Differentiating cladogenesis from anagenesis, defined as evolution within a species, has generally been hampered by dating precision, insufficient fossil data, and difficulties in establishing a direct l...

In contrast with speciation in terrestrial organisms, marine plankton frequently display gradual morphological change without lineage division (e.g., phyletic gradualism or gradual evolution), which has raised the possibility that a different mode of evolution dominates within pelagic environments. Here, we reexamine a classic case of putative gradual evolution within the Globorotalia plesiotum...

The latitudinal diversity gradient has been hypothesized to reflect past evolutionary dynamics driven by climatic niche conservation during cladogenesis, i.e. the tropical conservatism hypothesis. Here we show that the species diversity of treefrogs (Hylidae) across the western hemisphere is actually independent of evolutionary niche dynamics. We evaluated three key predictions of the tropical ...

Late Pliocene and Pleistocene climatic instability has been invoked to explain the buildup of Neotropical biodiversity, although other theories date Neotropical diversification to earlier periods. If these climatic fluctuations drove Neotropical diversification, then a large proportion of species should date to this period and faunas should exhibit accelerated rates of speciation. However, the ...

BACKGROUND Lactic fermentation of foods increases the availability of iron as shown in a number of studies throughout the years. Several explanations have been provided such as decreased content of inhibitory phytate, increased solubility of iron, and increased content of lactic acid in the fermented product. However, to our knowledge, there are no data to support that the bioavailability of ir...

Ethylzinc 2,6-bis(p-tolyl)benzoate converts between two forms in solution. Through NMR spectroscopic techniques and X-ray crystallography, the species in equilibrium were identified as [Zn2(ArTolCO2)2(Et)2(THF)2] (1), [Zn2(ArTolCO2)3(Et)(THF)] (2), and diethyl zinc (ArTol = 2,6-bis(p-tolyl)phenyl). The equilibrium provides a model for understanding the speciation between doubly and triply m-ter...

Carbon and sulfur isotopic data, together with biomarker and iron speciation analyses of the Hovea-3 core that was drilled in the Perth Basin, Western Australia, indicate that euxinic conditions prevailed in the paleowater column during the Permian-Triassic superanoxic event. Biomarkers diagnostic for anoxygenic photosynthesis by Chlorobiaceae are particularly abundant at the boundary and into ...