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N:P as driver of As retention

Parameters: Ammonium

Congratulations to Keely MacNeil who was awarded a travel stipend for her presentation "N:P as driver of As retention" at the ASLO Summer Meeting 2018 featuring our AquaFluor Handheld Fluorometer.


Arsenic (As), a toxic trace element, can be taken into cells in place of phosphorus (P) and decouple phosphorylation, hindering energy production. Organisms take up more As when P is low, and our research shows that microbial As uptake depends on relative nitrogen (N:P), not just P concentration alone. However, the effects on higher trophic levels of increased As uptake resulting from variation in background N:P are unknown. Here, we evaluate if the N:P stoichiometry of a stream and its effects on processes associated with trophic exchanges control the retention and transport of As in geothermal streams, which are naturally rich in As. We measured food web A! s and invertebrate As excretion in three geothermal streams and three c! orresponding non-geothermal streams, all with varying N:Ps. Invertebrate P excretion was greater in As-rich geothermal streams than non-geothermal streams, and As and P excretion were both higher in low N:P (N-limited) streams; both results indicate that invertebrate excretory mechanisms may fail to distinguish between As and P and support our hypothesis that N:P drives As retention and transport in stream food webs.

Author: Keeley MacNeil

Institution: Cornell University, Ithaca, NY, USA

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