Dissolved and Particulate Organic Matter in Bahia Blanca estuary, Argentina - SW Atlantic

FRANCO, MARCOS; GOMES DE ALMEIDA, MARCELO; CHERENE VAZ DE OLIVEIRA, BRÁULIO; RANGEL, THIAGO; QUITETE, DIOGO; LA COLLA, NOELIA; SERRA, ANALÍA VERÓNICA; BOTTÉ, SANDRA ELIZABETH; MARCOVECCHIO, JORGE; REZENDE, CARLOS EDUARDO

Puerto Madryn

Congreso; IV Reunión Argentina de Geoquímica de la Superficie; 2016

Facultad de Ciencias Naturales Universidad Nacional de la Patagonia San Juan Bosco

The present study aims to provide information regarding sources and spatial variability in the concentration of the dissolved and particulate organic matter (DOM and POM, respectively) in the Bahía Blanca Estuary using isotopic and elemental composition. Six sites along the estuary were defined, and surface water, porewater (PW), sediment and vegetation were sampled. Total dissolved and particulate nitrogen (TDN and TPN) in surface waters varied from 27 to 184 µmol.L-1 and, 7 to 20 µmol.L-1, respectively; and in PW, TDN varied from56 to 167 µmol.L-1. The dissolved and particulate organic carbon (DOC and POC), varied from 423 to 493 µmol.L-1 and 60 to 149 µmol.L-1; and in PW DOC varied from 1003 to 1291 µmol.L-1. The isotopic composition δ13C and δ15N and (C/N)a ratio ranged are presented respectively: DOM, from ?22.3 to -20.6, 7?, 2,6 to 4.1, 13 to 17; POM, from ? 20.9 to 18.9?, 3.3 to 6.4?, 7 to 9 and PW, from -12.8 to -20.6?, 1.5 to 1.6 and 10 to 12. Mean δ13C of sediments varied from -17.55 ± 0.45? in Villa Del Mar (an inner- medium site) to -16.27 ± 0.25? in Puerto Rosales (outer site), while δ15N values ranged between 6.56 ± 0.73? (Villa Del Mar) and 8.41 ± 0.68? (Almirante Brown). Local vegetation was composed by Sarcoconia perennis and Spartina alterniflora, and a mean carbon signature of -27.05 ± 0.71? and -14.12 ± 0.40? and mean δ15N values of 8.05 ± 0.88? and 10.23 ± 0.52? were found, respectively. A bayesian mixing model based on elemental and isotopic composition of carbon and nitrogen was developed preliminary in order to investigate possible sources contributions (S. perennis, S. alterniflora and POM) to the values observed for PW, and a 44% contribution of S. perennis, followed by POM and S. alterniflora (36 and 20%, respectively). Supported by FAPERJ and CONICET