19
Air-water Interface: Tropical Lake Diatoms
and Isotope Hydrology Modeling
Florence Sylvestre, Françoise Gasse, Françoise Vimeux,
and Benjamin Quesada
Regardless of the timescale, a distinctive characteristic of the
tropics is a high variability in the water cycle, in particular in
the P-E water balance [precipitation minus (evaporation + evapotranspiration)]. This variability has more impact
on life in the tropics than the variability in temperature
which only has a moderate influence compared to the high
and middle latitudes. The time frame, speed and magnitude
of hydrological events need to be established so that their
causes and mechanisms can be understood. These events are
recorded in terrestrial sediments (lacustrine deposits,
deposits in caves), in fossil waters in deep aquifers, and
imprinted in the landscape by geomorphological features
(dried-up river channels, ancient lake shorelines).
Lacustrine archives are particularly interesting because
they contain the imprint of hydrological variations recorded
in lakes. They preserve a wide range of complementary
indicators (or proxies), providing access to different environmental and climate parameters if they can be calibrated.
Lakes are today numerous in the humid tropics, and
evidence of ancient lakes (i.e. paleolakes) are plentiful in
certain regions that are now arid. They react to changes in
climate with often dramatic fluctuations, accompanied by
profound changes in chemistry, biology, water-mass
dynamics and water-atmosphere heat transfers. Indeed, one
way which is often forgotten that lakes can have a significant
interaction on the continental hydrological cycle is through
the source of water vapor they represent (Vallet-Coulomb
et al. 2008). In this chapter, we will examine specifically the
example of a hydro-isotopic reconstruction established from
sedimentary records from a paleolake located in the tropical
Andes (Fig. 19.1) and its impact on the local hydrological
cycle during the last glacial-interglacial transition (18–
12 ka) (Quesada et al. 2015). Over this period, this paleolake, called ‘Tauca’ (from the name of a village where the
eponymous outcrops were discovered, Servant and Fontes
1978) underwent a transgression phase due to an increase in
rainfall in the tropical Andes (Sylvestre et al. 1999; Blard
et al. 2011), before disappearing abruptly around 14.3 ka.
Here, we propose a reconstruction of the isotopic composition of the lake water and we explore how its disappearance
might have disturbed the local atmospheric water cycle. In
particular, we explore the possible link between a sudden
evaporation of the Tauca paleolake and an abrupt event
found in the isotopic composition (oxygen 18) of the glacier
covering Mount Sajama overlooking the former lake
(Thompson et al. 1998).
Site Selection and Collection of Samples
A fundamental criterion for the selection of study sites is the
sensitivity of the lake system (the lake and its watershed) to
variations in P-E. The change in volume of a lake during the
time interval Dt is represented by the equation:
DV L =Dt ¼ S L ðP L À E L Þ þ A À D:
ð19:1Þ
where V L is the volume of the lake (m
3 ) and S L is the surface
area (m
2 ). V L and S L are functions of the level of the lake
(H L ). P L and E L are, respectively, the rates of precipitation
F. Gasse—Deceased.
F. Sylvestre (&) Á F. Gasse Á B. Quesada
Aix-Marseille Université, CNRS, IRD, Collège de France,
INRAE, CEREGE, Europôle Méditerranéen de l’Arbois, 13545
Aix-en-Provence cedex 4, France
e-mail: sylvestre@cerege.fr
F. Vimeux
Institut de Recherche pour le Développement (IRD), Laboratoire
HydroSciences Montpellier (HSM), UMR 5569 (CNRS, IRD,
UM), 34090 Montpellier, France
F. Vimeux Á B. Quesada
Institut Pierre Simon Laplace (IPSL), Laboratoire des Sciences du
Climat et de l’Environnement, LSCE/IPSL, CEA-CNRS-UVSQ,
Université Paris-Saclay, 91190 Gif-sur-Yvette, France
© Springer Nature Switzerland AG 2021
G. Ramstein et al. (eds.), Paleoclimatology, Frontiers in Earth Sciences,
https://doi.org/10.1007/978-3-030-24982-3_19
213
Air-water Interface: Tropical Lake Diatoms
and Isotope Hydrology Modeling
Florence Sylvestre, Françoise Gasse, Françoise Vimeux,
and Benjamin Quesada
Regardless of the timescale, a distinctive characteristic of the
tropics is a high variability in the water cycle, in particular in
the P-E water balance [precipitation minus (evaporation + evapotranspiration)]. This variability has more impact
on life in the tropics than the variability in temperature
which only has a moderate influence compared to the high
and middle latitudes. The time frame, speed and magnitude
of hydrological events need to be established so that their
causes and mechanisms can be understood. These events are
recorded in terrestrial sediments (lacustrine deposits,
deposits in caves), in fossil waters in deep aquifers, and
imprinted in the landscape by geomorphological features
(dried-up river channels, ancient lake shorelines).
Lacustrine archives are particularly interesting because
they contain the imprint of hydrological variations recorded
in lakes. They preserve a wide range of complementary
indicators (or proxies), providing access to different environmental and climate parameters if they can be calibrated.
Lakes are today numerous in the humid tropics, and
evidence of ancient lakes (i.e. paleolakes) are plentiful in
certain regions that are now arid. They react to changes in
climate with often dramatic fluctuations, accompanied by
profound changes in chemistry, biology, water-mass
dynamics and water-atmosphere heat transfers. Indeed, one
way which is often forgotten that lakes can have a significant
interaction on the continental hydrological cycle is through
the source of water vapor they represent (Vallet-Coulomb
et al. 2008). In this chapter, we will examine specifically the
example of a hydro-isotopic reconstruction established from
sedimentary records from a paleolake located in the tropical
Andes (Fig. 19.1) and its impact on the local hydrological
cycle during the last glacial-interglacial transition (18–
12 ka) (Quesada et al. 2015). Over this period, this paleolake, called ‘Tauca’ (from the name of a village where the
eponymous outcrops were discovered, Servant and Fontes
1978) underwent a transgression phase due to an increase in
rainfall in the tropical Andes (Sylvestre et al. 1999; Blard
et al. 2011), before disappearing abruptly around 14.3 ka.
Here, we propose a reconstruction of the isotopic composition of the lake water and we explore how its disappearance
might have disturbed the local atmospheric water cycle. In
particular, we explore the possible link between a sudden
evaporation of the Tauca paleolake and an abrupt event
found in the isotopic composition (oxygen 18) of the glacier
covering Mount Sajama overlooking the former lake
(Thompson et al. 1998).
Site Selection and Collection of Samples
A fundamental criterion for the selection of study sites is the
sensitivity of the lake system (the lake and its watershed) to
variations in P-E. The change in volume of a lake during the
time interval Dt is represented by the equation:
DV L =Dt ¼ S L ðP L À E L Þ þ A À D:
ð19:1Þ
where V L is the volume of the lake (m
3 ) and S L is the surface
area (m
2 ). V L and S L are functions of the level of the lake
(H L ). P L and E L are, respectively, the rates of precipitation
F. Gasse—Deceased.
F. Sylvestre (&) Á F. Gasse Á B. Quesada
Aix-Marseille Université, CNRS, IRD, Collège de France,
INRAE, CEREGE, Europôle Méditerranéen de l’Arbois, 13545
Aix-en-Provence cedex 4, France
e-mail: sylvestre@cerege.fr
F. Vimeux
Institut de Recherche pour le Développement (IRD), Laboratoire
HydroSciences Montpellier (HSM), UMR 5569 (CNRS, IRD,
UM), 34090 Montpellier, France
F. Vimeux Á B. Quesada
Institut Pierre Simon Laplace (IPSL), Laboratoire des Sciences du
Climat et de l’Environnement, LSCE/IPSL, CEA-CNRS-UVSQ,
Université Paris-Saclay, 91190 Gif-sur-Yvette, France
© Springer Nature Switzerland AG 2021
G. Ramstein et al. (eds.), Paleoclimatology, Frontiers in Earth Sciences,
https://doi.org/10.1007/978-3-030-24982-3_19
213