Mapping of potentially hazardous elements in the Cambrian Vendian aquifer system, northern Estonia

Abstract

Communities and towns in northern Estonia rely upon either surface waters or groundwater from Cambrian-Vendian aquifer system with limited fresh water resources. The composition of groundwater is controlled, among other factors, by the lithologic composition of water-bearing rocks and sediments. The peculiarities of the rock matrix may locally restrict the use of groundwater as a source of water supply. The distribution of fl uorine, barium and arsenic has been studied in northern Estonian water supply wells. The results of the hydrogeochemical mapping enable to delimit the barium anomaly in the Cambrian-Vendian aquifer system. Vertical distribution of studied compounds and hydraulic connection between water-bearing Vendian sediments with underlying crystalline basement refers the weathered basement rocks as the plausible source of barium and fl uorine in groundwater. The elevated concentrations of barium and fl uorine detected in groundwater from North Estonian wells may become a source of growing concern in Estonia. The results of hydrochemical research should be transformed to instructions how to avoid or eliminate the quality problems in the risk areas.

Chemical composition of bottled mineral waters in Estonia

“…Compiled by Perens (Perens and Vallner, 1997), edited by authors. Marandi, 2003). The Vendian deposits are declined to the west of Estonia and on the Estonian islands the water-bearing rocks are presented by the Cambrian sand-and siltstones interlayed by thin clay layers.…”

The origin of barium in the Cambrian–Vendian aquifer system, North Estonia; pp. 193–208

“…The barium content of world groundwaters is low, because barium-containing minerals have very low solubility in underground aqueous solutions. The concept of the earlier researchers (Karro & Marandi 2003;Marandi et al 2004) for Estonia that basement rocks are the main source of barium in the Cambrian-Vendian aquifer system is negotiable, because Ba concentrations in the basement rock water of Finland and Sweden are below 0.1 mg/L (WHO 1990;Backman et al 1999). The distinctly elevated barium concentration area in the Cambrian-Vendian aquifer system is limited by the Kunda, Rakvere, and Kohtla-Järve region near the southern coast of the Gulf of Finland (Figs 1-3).…”

“…Eh value in mV. V 2 vr, Voronka aquifer; V 2 gd, Gdov aquifer; Є-V, Cambrian-Vendian aquifer system (based on Karro & Marandi 2003 saturated state and is able to produce barium into water (Fig. 6).…”

“…1). During the last years some studies have been performed on the Ba occurrence in Estonian groundwater (Karro & Marandi 2003;Marandi et al 2004). It has been supposed in previous studies that the high barium in Cambrian-Vendian groundwater results from the upward migration of Ba from the underlying weathered crystalline basement.…”

“…Distribution of the Ba content in the CambrianVendian aquifer system of the study area (based onKarro & Marandi 2003).…”