Distribution and hosts of arsenic in a sediment core from the Chianan Plain in SW Taiwan: Implications on arsenic primary source and release mechanisms.

High arsenic abundance of 50-700μg/L in the groundwater from the Chianan Plain in southwestern Taiwan is a well-known environmental hazard. The groundwater-associated sediments, however, have not been geochemically characterized, thus hindering a comprehensive understanding of arsenic cycling in this region. In this study, samples collected from a 250m sediment core at the centre of the Chianan Plain were analyzed for arsenic and TOC concentrations (N=158), constituent minerals (N=25), major element abundances (N=105), and sequential arsenic extraction (N=23).

A mechanistic study of hydrogen gas sensing by PdO nanoflake thin films at temperatures below 250 °C.

We prepared PdO nanoflake thin films on the SiO2 substrate by reactive sputter deposition, and studied their sensing response to H2 at temperatures between 25 and 250 °C. In addition to the oxygen ionosorption model, which is used to describe the early H2 sensing response over the temperature range studied, the H2 sensing kinetics of the PdO thin films can be separated into three temperature regimes: temperatures below 100 °C, around 150 °C and above 200 °C. At temperatures below 100 °C, PdO reduction is the dominant reaction affecting the H2 sensing behavior.