Dynamics of the dissolved organic matter in a stream-lake system within an extremely acid to neutral pH range: Agrio-Caviahue watershed

CABRERA, JM; GARCÍA, PE; PEDROZO, FL; QUEIMALIÑOS, CP

SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY.

PERGAMON-ELSEVIER SCIENCE LTD

Lugar: Amsterdam; Año: 2020 vol. 235

1386-1425

TheAgrio-Caviahue is a natural stream-lake system composed of the UpperAgrio River (UAR) -Lake Caviahue-Lower Agrio River (LAR). The systemhas a broad pH gradient from extremely acid in the hot spring toalmost neutral pH only 60 km downstream the source, and varies as afunction of the distance. The aim of this study was to analyze thedynamics of the dissolved organic matter (DOM) of this extremesystem. For that matter, an absorbance and fluorescence-basedcharacterization was performed on natural water samples andhydrophobic resin DOM extracts during different seasons in ninesampling stations. BetweenAugust and December, the hydrological connectivity is maximum due toprecipitation and snowmelt, respectively. During these months, thestream that exits the lake governs the chemical characteristicsdownstream mainly in the period of high connectivity. In contrast, inthe dry season when the flow of LAR is minimum, the two majoraffluents of this river influence its pH and DOM features, anddeliver inputs of humified DOM from the wetlands where thetributaries are born. DOM was characterized by having low absorbance.The PARAFAC analysis of the fluorescent DOM (FDOM) validated threefluorescent components in the natural samples (with humic andnon-humic features), two of which were also recorded in the extracts,meaning that no additional hydrophobic components were missed underthe limit of detection of the fluorometer. The unique features ofAgrio-Caviahue DOM resembles those found in DOM from yellowstone hotsprings, both acid and alkaline.p { margin-bottom: 0.25cm; direction: ltr; color: #000000; line-height: 120%; orphans: 2; widows: 2 }p.western { font-family: "Liberation Serif", "Times New Roman", serif; font-size: 12pt; so-language: es-AR }p.cjk { font-family: "WenQuanYi Micro Hei", "Times New Roman", serif; font-size: 12pt; so-language: zh-CN }p.ctl { font-family: "Lohit Devanagari", "Times New Roman"; font-size: 12pt; so-language: hi-IN }