Hydrochemistry dynamics in remote mountain lakes and its relation to catchment and atmospheric features: the case study of Sabocos Tarn, Pyrenees

Abstract

Increasing the understanding of high mountain lake dynamics is essential to use these remote aquatic ecosystems as proxies of global environmental changes. With this aim, at Sabocos, a Pyrenean cirque glacial lake or tarn, this study shows the main results of a morphological and catchment characterization, along with statistical analyses of its hydrochemical trends and their concomitant driving factors from 2010 to 2013. Dissolved oxygen, water temperature stratification, and its snow and ice cover composition and dynamics have been also investigated. According to morphological analyses, Sabocos can be classified as a medium-large and deep lake, having a circular contour and a long water retention time as compared to Pyrenean glacial lake average values. Sabocos hydrochemistry is mainly determined by very high alkalinity, pH and conductivity levels, and high Ca(2+), Mg(2+), and SO4(2-) content, coming from the easily weatherable limestone-dolomite bedrock. Thus, lake water is well buffered, and therefore, Sabocos tarn is non-sensitive to acidification processes. On the other hand, the main source of K(+), Na(+), and Cl(-) (sea salts) and nutrients (NH4(+), NO3(-), and phosphorous) to lake water appears to be atmospheric deposition. Primary production is phosphorous limited, and due to the N-saturation stage of the poorly developed soils of Sabocos catchment, NO3(-) is the chief component in the total nitrogen pool. External temperature seems to be the major driver regulating lake productivity, since warm temperatures boot primary production. Although precipitation might also play an important role in lake dynamics, especially regarding to those parameters influenced by the weathering of the bedrock, its influence cannot be easily assessed due to the seasonal isolation produced by the ice cover. Also, as occurs in the whole Pyrenean lake district, chemical composition of bulk deposition is highly variable due to the contribution of air masses with different origin.

Denitrification and Biodiversity of Denitrifiers in a High-Mountain Mediterranean Lake

“…Despite increases in global Nr deposition, previous studies have consistently observed a regional pattern of decreasing DIN in recent decades in the Pyrenean lakes ( Camarero and Catalán, 2012 ) as well as an inter-annually seasonal trend of decreasing DIN in the Sierra Nevada lakes, as La Caldera ( Carrillo et al, 1996 ; Medina-Sánchez et al, 1999 ; Delgado-Molina et al, 2009 ). The latter trend can be also elicited from data reported in other studies on high altitude mountain lakes ( Tiberti et al, 2013 ; Porcal et al, 2014 ; Santolaria et al, 2015 ). While P deposition can play a role in these trends ( Camarero and Catalán, 2012 ), the present study extends those findings by showing it is likely the loss of N could be due to denitrification activity.…”

Effect of North Atlantic Oscillation on the hydrological conditions of Lake Morskie Oko (Carphatian Mountains)

“…Detailed investigations of the specificity of high mountain lakes is undertaken by various scientific disciplines (Choiński et al 2015). The research concerns both the biological (Korbee et al 2012;Kosolapova 2012;Degefu and Shagerl 2015) as well as physical-chemical and physical and chemical aspects (Tanaka and Tominaga 1994;Rodríguez-Rodríguez et al 2004;Santolaria et al 2015).…”

Selenium distribution and speciation in waters of pristine alpine lakes from central-western Pyrenees (France–Spain)

“…3). Hypoxic conditions (DO < 4 mg L À1 ) were maintained in the deepest 5 m. Nitrate and sulphate concentrations in Sabocos were a little lower than the mean values (z1 and 4 mg L À1 , respectively) measured in 2012, 34 and higher compared to those of Gentau. This was particularly the case for the sulphate concentration that was extremely low (#0.7 mg L À1 ) in Gentau.…”

“…Conductivity values were also higher in Sabocos due to its calcareous basin. 34,36 An increase of conductivity values from the surface to the bottom was observed in Gentau. With the exception of two deviant values observed in Gentau (abnormaly high values for TDSe at 0.5 m depth in June 18, and TSe bulk at 18 m depth in June 19), total Se concentrations did not vary significantly along the water column (<14% variation) as previously observed in shallower lakes.…”