FN Archimer Export Format PT J TI Two-dimensional ammonium distribution in sediment pore waters using a new colorimetric diffusive equilibration in thin-film technique BT AF Metzger, Edouard Barbe, Anthony Cesbron, Florian Thibault de Chanvalon, Aubin Jauffrais, Thierry Jézéquel, Didier Mouret, Aurélia AS 1:1;2:1;3:1,2;4:1,3;5:1;6:4;7:1; FF 1:;2:;3:;4:;5:;6:;7:; C1 LPG-BIAF, UMR 6112, Université d’Angers, 2 Bd Lavoisier, 49045, Angers Cedex, France University of West Florida, Center for Environmental Diagnostics and Bioremediation, 11000 University Parkway, Pensacola, FL, 32514, USA School of Marine Science and Policy, University of Delaware, Lewes, DE, 19958, USA Institut de Physique du Globe de Paris, Université Sorbonne Paris Cité, Univ. Paris Diderot, UMR 7154 CNRS, 75005, Paris, France C2 UNIV ANGERS, FRANCE UNIV W FLORIDA, USA UNIV DELAWARE, USA IPGP, FRANCE IN DOAJ IF 9.365 TC 10 UR https://archimer.ifremer.fr/doc/00474/58557/61112.pdf LA English DT Article DE ;Biogeochemistry;High-resolution;Porewater;DET;Densitometry AB This study presents a new gel based technique to describe the pore water ammonium distribution through the sediment-water interface in two dimensions at a millimeter scale. The technique is an adaptation of the classical colorimetric method based on the Berthelot's reaction. After the thin film of the gel probe was equilibrated by diffusion either in standard solutions or in pore waters, a colorimetric reagent gel was set on the gel probe, allowing development of the characteristic green color. A flatbed scanner and subsequent densitometry image analysis allowed to determine the concentration distribution of ammonium. The gel probe was tested in the laboratory for two media, deionized water and seawater, within the range 0–3000 μM in NH4+. Detection limit is about 20 μM and accuracy about ±25 μM. The field validation was realized in a tidal mudflat of the French Atlantic coast by comparison with conventional pore water extraction and colorimetric analysis. The large range of concentrations and its applicability in continental and marine sediments suggest a wide range of applications of the technique for a reasonable cost. PY 2019 PD FEB SO Water Research X SN 2589-9147 PU Elsevier BV VL 2 UT 000461245800006 DI 10.1016/j.wroa.2018.100023 ID 58557 ER EF