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

GOMES DE ALMEIDA M; QUITETE, D.; BOTTÉ, S.E.; FRANCO M; RANGEL, T.; SERRA, A.; REZENDE C; CHERENE VAZ DE OLIVEIRA, B.; LA COLLA N.S; MARCOVECCHIO, J.E.

Puerto Madryn

Otro; IV REUNION ARGENTINA DE GEOQUIMICA DE LA SUPERFICIE; 2016

The present study aims to provide information regarding sources and spatial variability in theconcentration of the dissolved and particulate organic matter (DOM and POM, respectively)in the Bahía Blanca Estuary using isotopic and elemental composition. Six sites along theestuary were defined, and surface water, porewater (PW), sediment and vegetation weresampled. Total dissolved and particulate nitrogen (TDN and TPN) in surface waters variedfrom 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), variedfrom 423 to 493 µmol.L-1 and 60 to 149 µmol.L-1; and in PW DOC varied from 1003 to1291 µmol.L-1. The isotopic composition δ13C and δ15N and (C/N)a ratio ranged arepresented 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- mediumsite) 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 wascomposed 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 isotopiccomposition of carbon and nitrogen was developed preliminary in order to investigatepossible sources contributions (S. perennis, S. alterniflora and POM) to the values observedfor PW, and a 44% contribution of S. perennis, followed by POM and S. alterniflora (36 and20%, respectively). Supported by FAPERJ and CONICET