Arsenic is a non-essential element that poses risks in many environments, including ground and surface waters, and plants and soil. Arsenic and phosphorus are chemical analogues, which imply they have similar biogeochemical behaviors. However, this is true only for the species phosphate (PO43-) and arsenate (AsO43-); As can also exist in reduced forms in the environment, such as As(III) (arsenite, AsO33-). Phosphorus is always present in the environment as P(V) compounds; principally orthophosphate-containing inorganic and organic forms. Here we present data on P and As distribution in several natural settings, including lake sediments, wetland sediments, and in plant tissues grown in a mine-contaminated soil. In the lake and wetland sediments, redox changes cause distinct geochemical reactions of the As and P, resulting in varying distributions. Comparative analysis of the P and As in the sedimentary environments provides insight into how the redox processes impact fluxes and distribution of ions and minerals. In the mine-impacted soil, availability and uptake of arsenate and phosphate in Mountain Brome grass (Bromus marginatus) show disparate behaviors, suggesting that plant biochemistry is distinctly impacting uptake of the supposed chemical analogues. In summary, comparison of As and P distribution and biological uptake provide a unique view of how sediment neogenesis and soil development control As mobility and biological uptake.

Using phosphorus distribution in soils and sediments to understand arsenic biogeochemistry

249th National Meeting (2015)

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