Tracing and quantifying lake water and groundwater fluxes in the area under mining dewatering pressure using coupled O and H stable isotope approach

Abstract

Oxygen and hydrogen stable isotopic compositions of precipitation, lake water and groundwater were used to quantitatively asses the water budget related to water inflow and water loss in natural lakes, and mixing between lake water and aquifer groundwater in a mining area of the Lignite Mine Konin, central Poland. While the isotopic composition of precipitation showed large seasonal variations (δ²H from−140 to+13 ‰ and δ¹⁸O from−19.3 to+7.6 ‰), the lake waters were variously affected by evaporation (δ²H from−44 to−21 ‰ and δ¹⁸O from−5.2 to−1.7 ‰) and the groundwater showed varying contribution from mixing with surface water (δ²H from−75 to−39 ‰ and δ¹⁸O from−10.4 to−4.8 ‰).

The lake water budget was estimated using a Craig–Gordon model and isotopic mass balance constraint, which enabled us to identify various water sources and to quantify inflow and outflow for each lake. Moreover, we documented that a variable recharge of lake water into the Tertiary aquifer was dependent on mining drainage intensity. A comparison of coupled δ²H–δ¹⁸O data with hydrogeological results indicated better precision of the δ²H-based calculations.

Keywords:

• Craig–Gordon model
• groundwater
• hydrogen-2
• isotopic mass balance
• lake
• oxygen-18
• water budget
• water cycle

Acknowledgements

The authors acknowledge Piotr Jezierski, Adriana Trojanowska, Maciej Górka and Krzysztof Moskwa for their substantial help in field sampling and preliminary laboratory work, Marta Kurasiewicz for her help in mass spectrometry analysis, the Institute of Meteorology and Water Management in Poznań for access to meteorological data and the Lignite Mine Konin for cooperation during field sampling. Great thanks are due to Thomas Edwards for his professional advice on the use of Craig–Gordon model, to Kazimierz Różański and Joel Gat for their valuable suggestions about lake water balances and to Anna Szynkiewicz for comments and language edition which have largely improved this manuscript. The manuscript has also benefited a lot from the comments of two anonymous reviewers.

This publication was prepared by financial support from the Foundation for Polish Science. The field studies were supported from ‘S’ and ‘W’ grants of the University of Wrocław. During the course of this project, the first author was a scholarship holder of Wroclaw Municipality and a grant holder of the European Social Fund and the Marshal of Lower Silesia Voivodship.