Overview of the Chemical and Isotopic Investigations of the Mareza Springs and the Zeta River in Montenegro

Abstract

The Mareza karst aquifer is the most important drinking water resource for the water supply system of the City of Podgorica, the capital of Montenegro. This study presents the first assessment for the determination of the Mareza catchment area. Water chemistry and stable isotopic composition (δ18O and δ2H) of monthly precipitation samples (as inputs) are presented, in order to determine the Local Meteoric Water Line (LMWL) for the study area, and to analyze the behavior of the karst spring Mareza (as output) and the Zeta River water. The possible impact of the river on the Mareza springs was also investigated. Stable isotope compositions were used to analyze the origin of the four springs of the Mareza aquifer. Seasonal variations of δ18O and δ2H values and deuterium excess (d excess) changes in precipitation are explained by the mixing of air masses, such that a Mediterranean source prevails in the winter period, while in the summer period, the area is rather under the influence of air mass originating from the Atlantic Ocean. All spring water samples have lower δ values than the local precipitation and they plot above the LMWL, which may indicate recharge at a higher altitude in the distant mountainous area. The d excess values of all water samples (higher than 10‰) indicate the prevalence of the Mediterranean as a moisture source. Based on the analysis of the seasonal variations of δ18O and δ2H in precipitation and the Mareza spring, it has been estimated that the groundwater mean transit time (MTT) is 92–129 days, and that the young water fraction (Fyw) amounts to 40.9%–53.3%. These values are typical for the strong karstic springs of highly karstified terrains.

A Preliminary Assessment of Young Water Fractions in Groundwater from Alluvial Aquifers Facing the Northern Italian Apennines

“…Although it was initially proposed for river water, it has recently been proven that this approach is reliable for assessing young water fractions of groundwater from mountainous areas (spring waters: [25][26][27]) and lowlands (wells: [10]). As a matter of fact, such an approach allows estimate uncertainties to be strongly reduced compared with the wellknown Mean Travel Time formulation [9,28].…”

Impact of Snowmelt Conditions on the Isotopic Composition of the Surface Waters of the Upper Ob River during the Flood Period

“…A significant number of papers on the use of stable water isotopes (deuterium and oxygen-18) in the study of hydrological processes have recently been published [1][2][3][4][5][6][7][8][9][10]. Data on the water isotopic composition allow us to determine the genetic relationship between the surface water and atmospheric precipitation [10][11][12][13], rivers and groundwaters [11,[13][14][15]; to quantify the formation of sea-ice [16]; to evaluate the impact of water evaporation and the rate of water exchange [17,18]; and to study the mechanisms of formation of the chemical composition of water masses coming from tributaries [15,19]. In contrast to the analysis of the isotopic composition of atmospheric precipitation, the study of the isotopic composition of river water has a great advantage, since river water reflects the isotopic composition of the entire watershed rather than a single sampling site [20].…”