Biogeochemical markers across a pollution gradient in a Patagonian estuary: A multidimensional approach of fatty acids and stable isotopes

GERMÁN A. KOPPRIO; SOFÍA DUTTO; JOHN E. GARZÓN CARDONA; A. GÄRDES; RUBÉN J. LARA; M. GRAEVE

MARINE POLLUTION BULLETIN

PERGAMON-ELSEVIER SCIENCE LTD

Lugar: Amsterdam; Año: 2018 vol. 137 p. 617 - 626

0025-326X

A combined approach merging stable isotopes and fatty acids was applied to study anthropogenic pollution inthe Río Negro estuary. Fatty acid markers of vegetal detritus indicated considerable allochthonous inputs atfreshwater sites. Correlative evidence of diatom fatty acids,δ⁠13C, chlorophyll and particulate organic matter suggestedthe importance of diatoms for the autochthonous organic matter production at the river mouth. Lowδ⁠15Nvalues (~0?) and high fatty acid 18:1(n-7) concentrations in the suspended particulate matter, in combinationwith the peaks of coliforms and ammonium, indicated a strong impact of untreated sewage discharge. The ⁠15Ndepletion was related to oxygen-limited ammonification processes and incorporation of ⁠15N depleted ammoniumto microorganisms. This work demonstrates that the combined use of lipid and isotopic markers can greatly increaseour understanding of biogeochemical factors and pollutants influencing estuaries, and our findings highlightthe urgent need for water management actions to reduce eutrophication.