Global Scale Climatic And Atmospheric Influences On The Chemical Character Of Dissolved Organic Matter In Alpine And Remote Lakes
Mladenov, Natalie 1 ; Morales-Baquero, Rafael 2 ; Sommaruga, Ruben 3 ; Camarero, Lluis 4 ; Laurion, Isabel 5 ; Dieguez, Maria 6 ; Reche, Isabel 7
1 INSTAAR, University of Å·ÃÀ¿Ú±¬ÊÓƵ
2 Universidad de Granada
3 University of Innsbruck
4 Centre d'Estudis Avançats de Blanes
5 Université du Québec
6 CRUB, UNComa
7 Universidad de Granada
Due to their position in the landscape, alpine lakes located above treeline are generally considered remote and pristine ecosystems. Alpine lakes often serve as reference sites because they lack the confounding effects of diverse terrestrial inputs and local anthropogenic pollution. Yet alpine lakes are influenced by climate change and atmospheric pollutant transport and respond rapidly to such stimuli, making them valuable as sensor sites for global change. Here we take advantage of a global network of remote lakes (ECOSENSOR) to examine spatial patterns in dissolved organic matter (DOM) variability at a global scale. We examined dissolved organic carbon (DOC) concentration, absorption, and fluorescence properties of lakes of the Atlas Mountains (Morocco), the Sierra Nevada and Pyrenees (Spain), the Alps (Austria), the Patagonian Andes (Argentina), and the Canadian Arctic and created a new Alpine Lake PARAFAC (ALP) model to evaluate the effects of climate and dust deposition, in particular, on the chemical character of DOM in these alpine and remote lakes. We found that the most remote alpine lakes exhibited high amino acid-like fluorescence and low fluorescence at excitation wavelengths greater than 350 nm. We further evaluated the influence of Saharan dust deposition on lake DOM and found that, across a gradient of low to high deposition (Austria-Morocco), there was an increase in DOC, absorption coefficients, and fluorescence intensity. In light of rising desertification linked to global change, these results suggest that atmospheric dust deposition may be an important, yet thus far unrecognized control on lake DOM dynamics and that remote lakes provide a unique opportunity to monitor this influence.