Hydrological processes at Inle Lake (Southern Shan State, Myanmar) inferred from hydrochemical, mineralogical and isotopic data^†

† Originally presented at the IAEA International Symposium on Isotope Hydrology: Revisiting Foundations and Exploring Frontiers, 11–15 May 2015, Vienna, Austria.

ABSTRACT

A one-year hydrochemical and isotopic monitoring was conducted at the Inle Lake, the second largest lake in Myanmar, also considering sediment samples. Lake waters are characterised by low electrical conductivities (236–489 μS/cm), neutral to alkaline pH (7.36–9.26), oxidising Eh (329–457 mV) and Ca–Mg–HCO₃ facies. Stable isotopes indicate that lake waters are only slightly affected by evaporation, are fully flushed yearly and are not stratified. Carbonate equilibria dominate the lake water hydrochemistry. In summer, photosynthetic activity and temperature increase induce calcite precipitation, as testified by its high content in the sediments, up to 97 %, and by its isotopic composition. The short residence time and endogenic calcite precipitation likely prevent the accumulation of contaminants and nutrients in lake waters. This study suggests a high resilience of the system to anthropogenic disturbances and demonstrates the sediment potential for the reconstruction of the environmental evolution in time and for the anthropogenic impact assessment.

KEYWORDS:

• Anthropogenic impacts
• carbon-13
• evaporation
• hydrodynamics
• hydrogen-2
• isotope ecology
• isotope hydrology
• oxygen-18
• residence time
• tropical lake
• water quality

Acknowledgements

This study is part of the Ph.D. in physics of the main author, conducted under the supervision of Professor Htun Hlaing (supervisor), University of Lashio and Professor Kalyar Thwe (co-supervisor), University of Mandalay, Myanmar. We wish to acknowledge the kind contribution of T. Lovato (CMCC, Bologna), M. Spadoni (CNR-IGAG), E. Allais (ISO4, Pavia), and two anonymous reviewers for their constructive comments.

Disclosure statement

No potential conflict of interest was reported by the authors.

Notes on contributors

Myat Mon Thin, born in Pyinmana (Myanmar) in 1978, Myat Mon Thin graduated in Physics in 2004, at the Yadanabon University, obtained her M.Sc. Engineering (Physics) in 2006, at the University of Mandalay, and the Bachelor of Education (B. Ed) in 2011, at the Sagaing Institute of Education, Sagaing, (Myanmar). In December 2015, she obtained her Ph.D. degree in Physics at the University of Mandalay (Myanmar), with a thesis entitled “Environmental applications of physical, nuclear and geochemical techniques: origin, dynamics and impact of phosphates and heavy metals in cultivated areas and at Inle Lake, Myanmar”. Her main research interests are in the field of Applied and Environmental Physics. She is presently working as Demonstrator, at the Department of Physics, Sagaing Institute of Education, Sagaing (Myanmar).

Elisa Sacchi, born in Torino (Italy) in 1965, Elisa Sacchi graduated in Earth Sciences in 1990 and obtained her Ph.D. in Geochemistry in 1995. During her post-graduate studies she developed her research activity in the field of Environmental Geochemistry, working for Italian and International institutions in the fields of radioactive waste disposal and radiochemical contamination monitoring. In 2002, she was enrolled at the University of Pavia, where she is presently Associate Professor of Environmental Geochemistry. Occasionally, she collaborates as “Expert” in Technical Cooperation projects with the International Atomic Energy Agency. Her main research interests are in water, sediment and soil pollution, water-rock interaction and environmental applications of isotope geochemistry. She is author of more than thirty papers on international peer reviewed journals.

Massimo Setti, born in Pavia (Italy) in 1957, Massimo Setti graduated in Geological Sciences in 1983 and is presently Associate Professor at the University of Pavia in the field of Applied Mineralogy. His main area of expertise is Clay Science. His investigations concern sediments and particulate suspended matter in rivers and marine basins, in order to evaluate the clay mineral types and contents in relationship with sediment provenance, palaeoenvironmental and palaeoclimatic changes, and to assess the interactions between clay minerals and pollutants (in particular metal elements). He is author of more than one hundred papers in national and international journals.

ORCID

Myat Mon Thin http://orcid.org/0000-0001-7909-8546

Elisa Sacchi http://orcid.org/0000-0003-2144-2927

Massimo Setti http://orcid.org/0000-0001-9762-7931

Notes

† Originally presented at the IAEA International Symposium on Isotope Hydrology: Revisiting Foundations and Exploring Frontiers, 11–15 May 2015, Vienna, Austria.

Additional information

Funding

The work was developed in the frame of the EU Erasmus Mundus project PANACEA (Action 2, Strand 1, Lot-10 [grant agreement number 201-2647/001-001-EMA2]).