Water exchange processes estimation in a temperate shallow lake based on water stable isotope analysis

• Published in: Isotopes in environmental and health studies 2020-11, Vol.56 (5-6), p.465-479
• Main Authors: Quiroz Londoño, Orlando Mauricio, Romanelli, Asunción, Martínez, Daniel Emilio, Massone, Héctor Enrique
• Format: Article
• Language: English
• Subjects: Anthropogenic factors; Argentina; Deuterium - analysis; Environmental Monitoring - methods; Evaporation; evaporation loss; Freshwater lakes; Groundwater; Groundwater - chemistry; hydrogen-2; Hydrologic data; Hydrology; Inflow; isotope hydrology; Isotopes; Lakes; Lakes - analysis; Lakes - chemistry; Mass balance; Oxygen Isotopes - analysis; oxygen-18; Pampean shallow lake; residence time; Residence time distribution; Rivers - chemistry; Stable isotopes; Stream discharge; Stream flow; Water Cycle; Water exchange; Water inflow; Water level fluctuations; Water levels; Water management; Water Quality
• ISSN: 1025-6016; 1477-2639
• DOI: 10.1080/10256016.2020.1803857

The estimation of lake hydrological characteristics such as evaporation/inflow ratios and water residence time becomes necessary for understanding cycling and potential retention of natural and anthropogenic substances into the lake. The aim of this work was to estimate the evaporation loss and the water residence time of a temperate shallow lake based on the water isotope mass balance approach. One representative freshwater temperate shallow lake from the Argentinian Pampa Plain was selected. Groundwater, lake and stream samples (N = 56) were collected for δ 2 H-H 2 O and δ 18 O-H2O determinations. Moreover, water level fluctuations of the lake and its inflow stream were recorded with data loggers. Both the δ 2 H and δ 18 O relationship and d-excess of lake water indicated evaporation. Water isotopes and daily stream flow data recorded in the inflow stream evidenced groundwater contribution to Los Padres Stream. Monthly evaporation as a fraction of inflow estimations of the lake water indicated that about 20-25 ± 12% lake water was lost through lake surface evaporation and revealed that hydrologic balances were regulated mainly by changes in water inflow rather than evaporation. A mean residence time of 1.11 ± 0.65 year was also calculated. This lake hydrological information is relevant for the region and crucial to improve water management plans.