Patterns of dissolved organic matter across the Patagonian landscape: a broad-scale survey of Chilean and Argentine lakes

Abstract

Dissolved organic matter (DOM) is a complex mixture of carbon compounds from autochthonous and allochthonous sources. Dissolved organic carbon (DOC) concentrations and optical metrics of DOM provide clues as to the sources and processes affecting the DOM pool. Herein we provide the first broad-scale characterisation of DOM from Patagonian lakes across a strong west–east precipitation gradient. Fifty-eight lakes from Northern Patagonia (Argentina and Chile) plus six lakes from the Antarctic Peninsula were sampled during summer 2000–01. Six DOM metrics were evaluated: DOC absorbance at 254nm (a254) and 350nm (a350), DOC-specific absorbance at 254nm (a254/DOC) and 350nm (a350/DOC) and spectral slope between 275 and 295nm (S275–295). The DOM of Chilean maritime lakes and shallow (<15m) Andean lakes exhibited terrestrial signatures and a pattern of variation consistent with their occurrence across the longitudinal precipitation gradient (i.e. S275–295 increased, whereas a350/DOC decreased from west to east). The contribution of allochthonous DOM was smaller in deep (>15m) Andean lakes, which is consistent with their longer water retention time. Steppe lakes, mostly from endorheic basins, made up the most heterogeneous group with regard to DOM characteristics.

Characterisation and reactivity continuum of dissolved organic matter in forested headwater catchments of Andean Patagonia

“…In the autumn, the high-water table of the Patagonian Andes increases surface run-off, thereby enhancing the transport of allochthonous materials towards streams. Moreover, high solar radiation with enhanced ultraviolet (UV) levels acts overall as a strong environmental agent that transforms aquatic DOM (Queimaliños et al, 2012;Zagarese et al, 2017). Terrestrial DOM inputs to aquatic systems of Andean Patagonia are thus shaped by highly fluctuating hydrology (Queimaliños et al, 2012) due to the seasonal precipitation and temperature pattern (autumn-winter) (Paruelo, Beltr an, Job aggy, Sala, & Golluscio, 1998).…”

“…Terrestrial DOM inputs to aquatic systems of Andean Patagonia are thus shaped by highly fluctuating hydrology (Queimaliños et al, 2012) due to the seasonal precipitation and temperature pattern (autumn-winter) (Paruelo, Beltr an, Job aggy, Sala, & Golluscio, 1998). Moreover, high solar radiation with enhanced ultraviolet (UV) levels acts overall as a strong environmental agent that transforms aquatic DOM (Queimaliños et al, 2012;Zagarese et al, 2017). In fact, the optical properties of aquatic DOM accurately reflect allochthonous inputs in autumn and spring and also the effect of photochemical and biological degradation during spring and summer (Soto C ardenas et al, 2017).…”

Characterization of dissolved organic matter from temperate wetlands: field dynamics and photoreactivity changes driven by natural inputs and diagenesis along the hydroperiod

“…2006; Zagarese et al . 1998, 2017). The region experiences high exposure to solar radiation in spring and summer and high UV levels year-round due to its lati/altitudinal location (Villafañe et al .…”

“…S2a), however, the water column is mixed by the action of strong winds, which enhances photochemical weathering (Zagarese et al . 1998, 2017). In spring, the pond displays a lower DOC concentration due to the increase in water input as a consequence of snowmelt, promoting diluted conditions and enhancing light penetration in the water column; such a pattern has been observed in shallow lakes of the area (Soto Cárdenas et al .…”

“…Challenging radiation levels enhance photochemical weathering affecting the C pool of aquatic systems, with profound effects on abiotic and biotic compartments (Zagarese et al . 2001; 2017; Pérez et al . 2003; Bastidas et al .…”